Urinary leukotriene E₄ levels identify children with tobacco smoke exposure at risk for asthma exacerbation

Prediction of Asthma Exacerbations in Children

Asthma exacerbations are common in asthmatic children, even among those with good disease control. Asthma attacks result in the children and their parents missing school and work days; limit the patient's social and physical activities; and lead to emergency department visits, hospital admissions, or even fatal events. Thus, the prompt identification of asthmatic children at risk for exacerbation is crucial, as it may allow for proactive measures that could prevent these episodes. Children prone to asthma exacerbation are a heterogeneous group; various demographic factors such as younger age, ethnic group, low family income, clinical parameters (history of an exacerbation in the past 12 months, poor asthma control, poor adherence to treatment, comorbidities), Th2 inflammation, and environmental exposures (pollutants, stress, viral and bacterial pathogens) determine the risk of a future exacerbation and should be carefully considered. This paper aims to review the existing evidence regarding the predictors of asthma exacerbations in children and offer practical monitoring guidance for promptly recognizing patients at risk.

Multi-Omics Analysis of Lung Tissue Demonstrates Changes to Lipid Metabolism during Allergic Sensitization in Mice

Allergy and asthma pathogenesis are associated with the dysregulation of metabolic pathways. To understand the effects of allergen sensitization on metabolic pathways, we conducted a multi-omics study using BALB/cJ mice sensitized to house dust mite (HDM) extract or saline. Lung tissue was used to perform untargeted metabolomics and transcriptomics while both lung tissue and plasma were used for targeted lipidomics. Following statistical comparisons, an integrated pathway analysis was conducted. Histopathological changes demonstrated an allergic response in HDM-sensitized mice. Untargeted metabolomics showed 391 lung tissue compounds were significantly different between HDM and control mice (adjusted p < 0.05); with most compounds mapping to glycerophospholipid and sphingolipid pathways. Several lung oxylipins, including 14-HDHA, 8-HETE, 15-HETE, 6-keto-PGF1α, and PGE2 were significantly elevated in HDM-sensitized mice (p < 0.05). Global gene expression analysis showed upregulated calcium channel, G protein–signaling, and mTORC1 signaling pathways. Genes related to oxylipin metabolism such as Cox, Cyp450s, and cPla2 trended upwards. Joint analysis of metabolomics and transcriptomics supported a role for glycerophospholipid and sphingolipid metabolism following HDM sensitization. Collectively, our multi-omics results linked decreased glycerophospholipid and sphingolipid compounds and increased oxylipins with allergic sensitization; concurrent upregulation of associated gene pathways supports a role for bioactive lipids in the pathogenesis of allergy and asthma.

Lipid mediators are detectable in the nasal epithelium and differ by asthma status in female subjects

BACKGROUND

Lipid mediators, bioactive products of polyunsaturated fatty acid metabolism, contribute to inflammation initiation and resolution in allergic diseases; however, their presence in lung-related biosamples has not been fully described.

OBJECTIVE

We aimed to quantify lipid mediators in the nasal airway epithelium and characterize preliminary associations with asthma.

METHODS

Using liquid chromatography-mass spectrometry, we conducted a pilot study to quantify 56 lipid mediators from nasal epithelial samples collected from 11 female participants of an outpatient asthma clinic and community controls (aged 30-55 years). We examined the presence of each compound using descriptive statistics to test whether lipid mediators could distinguish subjects with asthma (n = 8) from control subjects (n = 3) using linear regression and partial least squares discriminant analysis.

RESULTS

Fifteen lipid mediators were detectable in all samples, including resolvin (Rv) D5 (RvD5), with the highest median concentrations (in pg/μg protein) of 13-HODE (126.481), 15-HETE (32.869), and 13-OxoODE (13.251). From linear regression adjusted for age, prostaglandin E2 (PGE2) had a trend (P < .1) for higher concentrations in patients with severe asthma compared to controls (mean difference, 0.95; 95% confidence interval, -0.04 to 1.95). Asthma patients had higher scores on principal component 3 compared to controls (mean difference, 2.42; 95% confidence interval, 0.89 to 3.96), which represented lower levels of proresolving 15-HEPE, 19,20-DiHDPA, RvD5, 14-HDHA, 17-HDHA, and 13-HOTrE. Most of these compounds were best at discriminating asthma cases from controls in partial least squares discriminant analysis.

CONCLUSION

Lipid mediators are detectable in the nasal epithelium, and their levels distinguish asthma cases from controls.

Discovering metabolite quantitative trait loci in asthma using an isolated population

BACKGROUND

Integration of metabolomics with genetics may advance understanding of disease pathogenesis but has been underused in asthma genetic studies.

OBJECTIVE

We sought to discover new genetic effects in asthma and to characterize the molecular consequences of asthma genetic risk through integration with the metabolome in a homogeneous population.

METHODS

From fasting serum samples collected on 348 Tangier Island residents, we quantified 2612 compounds using untargeted metabolomics. Genotyping was performed using Illumina's MEGA array imputed to the TOPMed reference panel. To prioritize metabolites for genome-wide association analysis, we performed a metabolome-wide association study with asthma, selecting asthma-associated metabolites with heritability q value less than 0.01 for genome-wide association analysis. We also tested the association between all metabolites and 8451 candidate asthma single nucleotide polymorphisms previously associated with asthma in the UK Biobank. We followed up significant associations by characterizing shared genetic signal for metabolites and asthma using colocalization analysis. For detailed Methods, please see this article's Online Repository at www.jacionline.org.

RESULTS

A total of 60 metabolites were associated with asthma (P < .01), including 40 heritable metabolites tested in genome-wide association analysis. We observed a strong association peak for the endocannabinoid linoleoyl ethanolamide on chromosome 6 in VNN1 (P < 2.7 × 10-9). We found strong evidence (colocalization posterior probability >75%) for a shared causal variant between 3 metabolites and asthma, including the polyamine acisoga and variants in LPP, and derivative leukotriene B4 and intergenic variants in chr10p14.

CONCLUSIONS

We identified novel metabolite quantitative trait loci with asthma associations. Identification and characterization of these genetically driven metabolites may provide insight into the functional consequences of genetic risk factors for asthma.

Profiles of Nicotine and Cannabis Exposure among Young Adults with Asthma

There is a paucity of data on nicotine and cannabis use among young adults (YAs) with asthma. This study aimed to do the following among YAs with asthma: (1) describe YAs' active and passive exposure to nicotine and cannabis; (2) identify latent classes of active use of nicotine and cannabis; and (3) explore predictors of class membership (i.e., demographics, parental and friend use of nicotine and cannabis, and hours of environmental exposure to tobacco smoke, e-cigarette vapor, and marijuana smoke). YAs with asthma (N = 178) self-reported on nicotine and cannabis exposure and the included covariates. Latent class analysis was used to identify latent classes of lifetime nicotine and cannabis use. High rates of nicotine and cannabis use among YAs with asthma were found: 37% reporting a lifetime history of using both nicotine and cannabis. Regarding past year use, 25% had smoked cigarettes, 40% had used e-cigarettes, and 35% had used cannabis. Five classes of lifetime use were identified. The largest class was a non-user class (53%); the other four classes indicate concerning patterns of nicotine and cannabis use. The most consistent predictor of being in a class characterized by more nicotine and cannabis exposure (versus being in the non-user class) was past week exposure to cannabis smoke. This is the first study to identify classes of lifetime nicotine and cannabis use, and examine predictors of class membership, among YAs with asthma. There is a critical need to address environmental and active tobacco and marijuana exposure among YAs with asthma.

Exacerbation-Prone Asthma: A Biological Phenotype or a Social Construct

Asthma is a complex syndrome with multiple phenotypes and endotypes. Asthma exacerbations are not only the clearest indictor of the morbidity of asthma and of the risk for mortality due to asthma, but also comprise a significant amount of the cost to care for poorly controlled asthma. There continues to be significant disparity in the prevalence, mortality, and morbidity due to asthma. Patients with asthma who suffer recurrent exacerbations are considered to have exacerbation-prone asthma (EPA). Efforts to characterize patients with frequent exacerbations show that the etiology is likely multifactorial. Research to determine the intrinsic risk factors for EPA include studies of both genetic and inflammatory biomarkers. External factors contributing to exacerbations have been extensively reviewed and include viral infection, environmental exposures, air pollution, and psychosocial and economic barriers to optimizing health. It is likely that EPA occurs when patients who have an increased underlying intrinsic/biological risk are placed in a given exposome (environments with a variety of exposures and triggers including allergens, pollution, stress, barriers, and occupational exposures). It is the social construct combined with underlying biology that frequently drives an EPA phenotype.

The Predictive Role of Biomarkers and Genetics in Childhood Asthma Exacerbations

Asthma exacerbations are associated with significant childhood morbidity and mortality. Recurrent asthma attacks contribute to progressive loss of lung function and can sometimes be fatal or near-fatal, even in mild asthma. Exacerbation prevention becomes a primary target in the management of all asthmatic patients. Our work reviews current advances on exacerbation predictive factors, focusing on the role of non-invasive biomarkers and genetics in order to identify subjects at higher risk of asthma attacks. Easy-to-perform tests are necessary in children; therefore, interest has increased on samples like exhaled breath condensate, urine and saliva. The variability of biomarker levels suggests the use of seriate measurements and composite markers. Genetic predisposition to childhood asthma onset has been largely investigated. Recent studies highlighted the influence of single nucleotide polymorphisms even on exacerbation susceptibility, through involvement of both intrinsic mechanisms and gene-environment interaction. The role of molecular and genetic aspects in exacerbation prediction supports an individual-shaped approach, in which follow-up planning and therapy optimization take into account not only the severity degree, but also the risk of recurrent exacerbations. Further efforts should be made to improve and validate the application of biomarkers and genomics in clinical settings.

Urinary Cotinine as a Biomarker of Cigarette Smoke Exposure: A Method to Differentiate Among Active, Second-Hand, and Non-Smoker Circumstances

Objective:

To review the literature on the use of urinary cotinine as a biological marker of cigarette smoke exposure.

Methods:

Narrative review of original and review articles on the topic of interest, published in Portuguese or English by June 2018, and selected in the following online databases: PubMed and Virtual Health Library (VHL).

Results:

Urinary cotinine is usually the recommended biomarker to estimate exposure to cigarette smoke, and can be used alone or, preferably, in association with questionnaires. Different analytical techniques can be used to quantify urinary cotinine and are differently performed because of urine sample interfering factors.

Conclusion:

The precise classification of smoking status is essential. It is advisable to use objective measurements regarding smoking habits since self-reported smoking may not always represent the true smoking status of the individual, particularly in groups that are more vulnerable to omitting the information of questionnaries, in addition, it has possible biases of memory. The accurate assessment of smoking is crucial to improve clinical management and counseling for different diseases as well as the establishment of preventive strategies. So, the use of urinary cotinine as a biomarker of cigarette smoke exposure seems to be a suitable assay to distinguish non-smokers from passive and active smokers.

Influence of Second-Hand Smoke and Prenatal Tobacco Smoke Exposure on Biomarkers, Genetics and Physiological Processes in Children-An Overview in Research Insights of the Last Few Years

Children are commonly exposed to second-hand smoke (SHS) in the domestic environment or inside vehicles of smokers. Unfortunately, prenatal tobacco smoke (PTS) exposure is still common, too. SHS is hazardous to the health of smokers and non-smokers, but especially to that of children. SHS and PTS increase the risk for children to develop cancers and can trigger or worsen asthma and allergies, modulate the immune status, and is harmful to lung, heart and blood vessels. Smoking during pregnancy can cause pregnancy complications and poor birth outcomes as well as changes in the development of the foetus. Lately, some of the molecular and genetic mechanisms that cause adverse health effects in children have been identified. In this review, some of the current insights are discussed. In this regard, it has been found in children that SHS and PTS exposure is associated with changes in levels of enzymes, hormones, and expression of genes, micro RNAs, and proteins. PTS and SHS exposure are major elicitors of mechanisms of oxidative stress. Genetic predisposition can compound the health effects of PTS and SHS exposure. Epigenetic effects might influence in utero gene expression and disease susceptibility. Hence, the limitation of domestic and public exposure to SHS as well as PTS exposure has to be in the focus of policymakers and the public in order to save the health of children at an early age. Global substantial smoke-free policies, health communication campaigns, and behavioural interventions are useful and should be mandatory.

Smokers with children with asthma: Parental perceptions about prototype intervention messages focused on reducing child tobacco exposure and use

Formative research is needed to develop effective interventions that eliminate secondhand smoke exposure (SHSe) and prevent tobacco use (TU) among children with asthma. This online study included 300 parents who smoke and had a child with asthma (ages 10-14) and evaluated their perceptions about prototypes of parent-directed and child-directed feedback intervention messages focused on reducing child SHSe and future TU; correlates of perceptions were explored. Parents rated examples of parent-directed messages on motivation and helpfulness for eliminating SHSe and promoting conversations about TU and also rated child-directed messages on acceptability and helpfulness for promoting conversations about TU. Messages differed by level of personalization, theoretical background, or message content. Parents found all parent-directed messages similarly motivating and helpful and all child-directed messages similarly acceptable and helpful for reducing child tobacco exposure. Differences in perceptions about feedback emerged based on parent gender, parent readiness to quit, smoking ban status, and the presence of additional smokers in the home. Overall, parents rated parent-directed and child-directed feedback message prototypes positively, including established and novel types of feedback. Parent-child feedback interventions may hold promise for breaking the intergenerational transmission of smoking among families with a parent who smokes and a child with asthma.

Emergency department visit count: a practical tool to predict asthma hospitalization in children

Objectives: Resource limitations and low rates of follow-up with primary care providers currently limit the impact of emergency department (ED)-based preventative strategies for children with asthma. A mechanism to recognize the children at highest risk of future hospitalization is needed to target comprehensive preventative interventions at discharge. The primary objective of this study was to determine whether frequency of ED visits predicts future asthma hospitalization in children.Methods: Children aged 2-16.99 years with asthma ED visits between 2012 and 2015 were identified through health administrative data. Survival analysis using Kaplan-Meier estimator and multivariable Cox regression models with time-varying covariates were used to quantify the number of ED visits in the previous year that would best predict hospitalization risk in the following year, after adjustment for age, sex, and presentation severity.Results: We identified 2669 patients with 3300 asthma ED visits. ED visit count was an independent predictor of future hospitalization risk (p < 0.001), demonstrating a dose-dependent response. Compared with zero previous visits, the adjusted hazard of future hospitalization in children with one visit or two or more visits was 2.9 (95% CI 1.6-5.0) and 4.4 (95% CI 1.9-10.4), respectively.Conclusions: ED visit count is a reliable predictor of future asthma hospitalization risk. Future studies could aim to validate these findings to support using ED visit count as a practical and objective tool to predict the children at the highest risk of future hospitalization and therefore, those who may benefit most from ED-based preventative interventions.

Association of Organophosphate Pesticide Exposure and a Marker of Asthma Morbidity in an Agricultural Community

Objectives: We explored the short-term impact of pesticide exposure on asthma exacerbation among children with asthma in an agricultural community.Methods: We obtained repeated urine samples from a subset of 16 school-age children with asthma (n = 139 samples) as part of the Aggravating Factors of Asthma in a Rural Environment (AFARE) study cohort. Biomarkers of organophosphate (OP) pesticide exposure (dialkylphosphates (DAPs)), and asthma exacerbation (leukotriene E4 (uLTE4)) were assessed in urine samples. We used generalized estimating equations to examine the association of summed measures of creatinine-adjusted DAPs (total dimethyl alkylphosphate (EDM), total diethyl alkylphosphate (EDE), and total dialkylphosphate pesticides (EDAP)) and uLTE4 concentration, adjusting for multiple confounders, yielding beta-coefficients with 95% CIs.Results: A total of 139 observations were obtained from the 16 children over the study period, the total number of samples per subject ranged from 1 to 12 (median: 10.5). The geometric mean (GM) of creatinine-adjusted EDE, EDM, and EDAP in this population were 81.0, 71.8 and 168.0 nmol/g, respectively. Increase in uLTE4 levels was consistently associated with increased exposures to DAPs (interquartile range in μg/g): β_EDE: 8.7 (95%CI: 2.8, 14.6); β_EDM: 1.1 (0.5, 1.7); β_EDAP: 4.1 (0.7, 7.5).Conclusion: This study suggests that short-term OP exposure is associated with a higher risk of asthma morbidity, as indicated by increased uLTE4 levels in this cohort of children with asthma in an agricultural community. Additional studies are required to confirm these adverse effects, and explore the mechanisms underlying this relationship.

Asthma exacerbation prediction: recent insights

PURPOSE OF REVIEW

Asthma attacks are frequent in children with asthma and can lead to significant adverse outcomes including time off school, hospital admission and death. Identifying children at risk of an asthma attack affords the opportunity to prevent attacks and improve outcomes.

RECENT FINDINGS

Clinical features, patient behaviours and characteristics, physiological factors, environmental data and biomarkers are all associated with asthma attacks and can be used in asthma exacerbation prediction models. Recent studies have better characterized children at risk of an attack: history of a severe exacerbation in the previous 12 months, poor adherence and current poor control are important features which should alert healthcare professionals to the need for remedial action. There is increasing interest in the use of biomarkers. A number of novel biomarkers, including patterns of volatile organic compounds in exhaled breath, show promise. Biomarkers are likely to be of greatest utility if measured frequently and combined with other measures. To date, most prediction models are based on epidemiological data and population-based risk. The use of digital technology affords the opportunity to collect large amounts of real-time data, including clinical and physiological measurements and combine these with environmental data to develop personal risk scores. These developments need to be matched by changes in clinical guidelines away from a focus on current asthma control and stepwise escalation in drug therapy towards inclusion of personal risk scores and tailored management strategies including nonpharmacological approaches.

SUMMARY

There have been significant steps towards personalized prediction models of asthma attacks. The utility of such models needs to be tested in the ability not only to predict attacks but also to reduce them.

Biomarkers in asthma: state of the art

Asthma is a heterogenous disease characterized by multiple phenotypes driven by different mechanisms. The implementation of precision medicine in the management of asthma requires the identification of phenotype-specific markers measurable in biological fluids. To become useful, these biomarkers need to be quantifiable by reliable systems, reproducible in the clinical setting, easy to obtain and cost-effective. Using biomarkers to predict asthma outcomes and therapeutic response to targeted therapies has a great clinical significance, particularly in severe asthma. In the last years, significant research has been realized in the identification of valid biomarkers for asthma. This review focuses on the existent and emerging biomarkers with clinical higher applicability in the management of asthma.

Urinary Leukotriene E4 as a Biomarker of Exposure, Susceptibility, and Risk in Asthma: An Update

Measurement of urinary leukotriene E₄ (uLTE₄) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene (CysLT) production and changes in CysLT production. Recent studies have reported on novel LTE4 receptor interactions and genetic polymorphisms causing CysLT variability. The applications of uLTE₄ as a biomarker continue to expand, including evaluation of environmental exposures, asthma severity risk, aspirin sensitivity, predicting atopy in preschool age children, obstructive sleep apnea, and predicting susceptibility to leukotriene receptor antagonists.

At-risk children with asthma (ARC): a systematic review

Introduction

Asthma attacks are responsible for considerable morbidity and may be fatal. We aimed to identify and weight risk factors for asthma attacks in children (5–12 years) in order to inform and prioritise care.

Methods

We systematically searched six databases (May 2016; updated with forward citations January 2017) with no language/date restrictions. Two reviewers independently selected studies for inclusion, assessed study quality and extracted data. Heterogeneity precluded meta-analysis. Weighting was undertaken by an Expert Panel who independently assessed each variable for degree of risk and confidence in the assessment (based on study quality and size, effect sizes, biological plausibility and consistency of results) and then achieved consensus by discussion. Assessments were finally presented, discussed and agreed at a multidisciplinary workshop.

Results

From 16 109 records, we included 68 papers (28 cohort; 4 case-control; 36 cross-sectional studies). Previous asthma attacks were associated with greatly increased risk of attack (ORs between 2.0 and 4.1). Persistent symptoms (ORs between 1.4 and 7.8) and poor access to care (ORs between 1.2 and 2.3) were associated with moderately/greatly increased risk. A moderately increased risk was associated with suboptimal drug regimen, comorbid atopic/allergic disease, African-American ethnicity (USA), poverty and vitamin D deficiency. Environmental tobacco smoke exposure, younger age, obesity and low parental education were associated with slightly increased risk.

Discussion

Assessment of the clinical and demographic features identified in this review may help clinicians to focus risk reduction management on the high-risk child. Population level factors may be used by health service planners and policymakers to target healthcare initiatives.

Trial registration number

CRD42016037464.

The role of the indoor environment: Residential determinants of allergy, asthma and pulmonary function in children from a US-Mexico border community

The El Paso Children's Health Study examined environmental risk factors for allergy and asthma among fourth and fifth grade schoolchildren living in a major United States-Mexico border city. Complete questionnaire information was available for 5210 children, while adequate pulmonary function data were available for a subset of 1874. Herein we studied indoor environmental health risk factors for allergy and asthma. Several indoor environmental risk factors were associated with allergy and asthma. In particular, we found that ant and spider pest problems, pet dogs, fireplace heat, central air conditioning, humidifier use, and cooking with gas stoves were positively associated with both allergy and asthma prevalence. With regards to asthma severity, our analysis indicated that exposure to pet dogs increased monotonically with increasing asthma severity while the lack of any heat source and gas stove use for cooking decreased monotonically with increasing asthma severity. Lung function also decreased among children who lived in homes with reported cockroach pest problem in the past year without concurrent use of pesticides. These effects on pulmonary function were present even after excluding children with a current physician's diagnosis of asthma. Clinicians and public health professionals may need to look closely at the contribution of these indoor risk factors on pulmonary health and quality of life among susceptible populations.

Application of Metabolomics in Lung Research

Advancements in omics technologies have increased our potential to evaluate molecular changes in a rapid and comprehensive manner. This is especially true in mass spectrometry-based metabolomics where improvements, including ease of use, in high-performance liquid chromatography (HPLC), column chemistries, instruments, software, and molecular databases, have advanced the field considerably. Applications of this relatively new omics technology in clinical research include discovering disease biomarkers, finding new drug targets, and elucidating disease mechanisms. Here we describe a typical clinical metabolomics workflow, which includes the following steps: (1) extraction of metabolites from the lung, plasma, bronchoalveolar lavage, or cells; (2) sample analysis via liquid chromatography-mass spectrometry; and (3) data analysis using commercial and freely available software packages. Overall, the methods delineated here can help investigators use metabolomics to discovery novel biomarkers and to understand lung diseases.

Smokers who have children with asthma: Perceptions about child secondhand smoke exposure and tobacco use initiation and parental willingness to participate in child-focused tobacco interventions

OBJECTIVE

This study examined, among parents who smoke and have children with asthma, perceptions about child secondhand smoke exposure (SHSe), child tobacco use (TU) initiation, and parent willingness to participate in child-focused tobacco interventions.

METHODS

Participants were 300 caregivers who smoked and had a child with asthma (aged 10-14). Parents completed an online survey and self-reported perceptions about child SHSe elimination, child TU prevention, and willingness to participate in three types of interventions with and without their child (SHSe reduction intervention, tobacco prevention intervention, and the combination of the two). Correlates of perceptions and willingness were examined.

RESULTS

Parents who were ready to quit smoking and who reported home smoking bans (HSBs) were more motivated to eliminate SHSe (p < 0.05). Being white, younger, ready to quit, and having HSBs were associated with greater confidence to eliminate SHSe (p < 0.05). Parents with HSBs reported higher perceived importance about preventing child TU (p < 0.05). Parents were less confident about preventing male children from using tobacco (p = 0.001). Parents were highly willing to participate in all the described intervention approaches, with or without their child.

CONCLUSIONS

Parents were willing to participate in child-focused tobacco interventions, with or without their child with asthma, including interventions that address both child SHSe and TU prevention. This research demonstrates the acceptability of child-focused tobacco interventions among a high-risk population and may be a foundational step for intervention development.

Biomarkers in inflammometry pediatric asthma: utility in daily clinical practice

Asthma is a common disease in both high and lower income countries that starts early and persists often for life. A correct and accurate diagnosis, treatment and follow-up during childhood are essential for a better understanding of adult asthma and avoiding over- or under-treatment. Th2 inflammation in children with asthma symptoms is usually assessed by measuring with serum total IgE, blood eosinophilia and FeNO levels that may help to predict asthma, particularly in those infants and young children in whom lung function tests are difficult to perform. FeNO measurement, compared to intra-individual levels, may be useful also for ascertaining treatment adherence. Nevertheless, an isolated measurement may be insufficient and only the combination of these markers improves the diagnosis, phenotyping and follow-up of an asthmatic child.

Current and future biomarkers in allergic asthma

Diagnosis early in life, sensitization, asthma endotypes, monitoring of disease and treatment progression are key motivations for the exploration of biomarkers for allergic rhinitis and allergic asthma. The number of genes related to allergic rhinitis and allergic asthma increases steadily; however, prognostic genes have not yet entered clinical application. We hypothesize that the combination of multiple genes may generate biomarkers with prognostic potential. The current review attempts to group more than 161 different potential biomarkers involved in respiratory inflammation to pave the way for future classifiers. The potential biomarkers are categorized into either epithelial or infiltrate-derived or mixed origin, epithelial biomarkers. Furthermore, surface markers were grouped into cell-type-specific categories. The current literature provides multiple biomarkers for potential asthma endotypes that are related to T-cell phenotypes such as Th1, Th2, Th9, Th17, Th22 and Tregs and their lead cytokines. Eosinophilic and neutrophilic asthma endotypes are also classified by epithelium-derived CCL-26 and osteopontin, respectively. There are currently about 20 epithelium-derived biomarkers exclusively derived from epithelium, which are likely to innovate biomarker panels as they are easy to sample. This article systematically reviews and categorizes genes and collects current evidence that may promote these biomarkers to become part of allergic rhinitis or allergic asthma classifiers with high prognostic value.

Urinary leukotriene and Bcl I polymorphism of glucocorticoid receptor gene in preschoolers with recurrent wheezing and high risk of asthma

BACKGROUND

Urinary leukotriene (LTE4) is an important marker of airway inflammation presence. A relationship between single nucleotide polymorphism in the glucocorticoid receptor (GCR) gene promoter (Bcl I polymorphism), development of asthma and sensitivity to glucocorticoids has been hypothesised.

OBJECTIVE

To explore the possible association between the Bcl I polymorphism and baseline levels of urinary LTE4 in preschoolers with recurrent wheezing episodes. We prospectively enrolled and classified 86 preschoolers based on the risk of developing asthma (by the Asthma Predictive Index [API]).

METHODS

At admission standardised questionnaires for demographics and respiratory illness characteristics were completed. The Bcl I polymorphism of the GCR was determined by a PCR-RFLP assay from blood samples, and urinary leukotriene was assessed from urine samples by an enzyme immunoassay.

RESULTS

We enrolled 86 preschoolers (46 with positive API and 40 with negative API). There were no statistical differences in demographic, respiratory illnesses and wheezing episodes characteristics between both groups. Also, the prevalence of Bcl I polymorphism was similar between positive vs. negative API groups (34.8% vs. 38.9% for homozygote GG, 56.5% vs. 52.8% for heterozygote GC, 8.7% vs. 8.3% for homozygote CC, respectively, p=0.94). However, urinary LTE4 (median [IQR]) was higher in preschoolers with positive than negative API (7.18 [5.57-8.96pg/ml] vs. 6.42 [3.96-8.07pg/ml], p=0.02, respectively).

CONCLUSIONS

In our population, wheezing preschoolers with positive API exhibit higher levels of urinary LTE4 than those with negative API; but there were no differences in Bcl I polymorphism of the GCR.

Urinary leukotriene E4 levels in atopic and non-atopic preschool children with recurrent episodic (viral) wheezing: a potential marker?

Backround: Reliable biological markers for the differentiation of asthma phenotypes in preschool children with wheezing are lacking. The purpose of the study is to assess the relationship of urinary Leukotriene E4 (U-LTE4) to particular asthma phenotypes in preschool children with recurrent episodic (viral) wheezing following upper respiratory tract infections with or without atopic predisposition.

METHODS

Ninety-six preschool patients with recurrent episodic wheezing participated, 52 atopic and 44 non-atopic, during exacerbation and in remission. Exacerbation was defined on clinical basis (wheeze in the presence of coryzal symptoms). Atopy was determined by specific serum IgE measurement and skin-prick testing. U-LTE4 was determined by enzyme immunoassay. Thirty-six age-matched, non-asthmatic, non-atopic children served as controls.

RESULTS

During exacerbation, U-LTE4 was significantly higher in all children with recurrent episodic wheezing in comparison to A: Remission: 642.20 ± 268 versus 399.45 ± 204, p value <0.001 and B:

CONTROLS

642.20 ± 268 versus 271.39 ± 83, p value <0.001. Atopic patients demonstrated significantly higher levels of U-LTE4 compared to non-atopic, both during exacerbation 872.13 ± 246 versus 613.15 ± 150, p value = 0.0013 and during remission 507.59 ± 182 versus 283.59 ± 160, p value <0.001. During remission, a highly significant difference of U-LTE4 was found when controls were compared to atopic patients: 271.39 ± 83 versus 507.59 ± 182, p value = 0.002 but not when compared to non-atopic ones: 271.39 ± 83 versus 283.59 ± 160, p value = 0.432.

CONCLUSION

U-LTE4 is strongly associated with the acute wheeze episode in preschool children, more so in atopics. Increased basal levels of U-LTE4 occur only in atopics. This suggests a potential role of U-LTE4 as a marker of atopic, virus-induced asthma in preschool children.

[Use of inflammatory markers for monitoring paediatric asthma]

The assessment of asthma control takes into account the symptoms, quality of life, lung function, and inflammatory markers. In the last few years, there has been a large increase in the number of publications related to the study of biomarkers in the management of paediatric asthma. Despite the large variety of inflammatory markers described in research studies, only a small group has shown to be useful in monitoring the disease. Induced sputum eosinophils offer the most solid evidence in assessing asthma control. Exhaled breath condensate and urinary leucotrienes could be useful in the future if there is standardisation in their procedures and interpretation of the results. Nitric oxide, basic eosinophil cationic protein, and bronchial biopsy with bronchoalveolar lavage, only appeared to be useful in a reduced group of patients.

Arachidonic acid metabolites and enzyme transcripts in asthma are altered by cigarette smoking

BACKGROUND

Arachidonic acid metabolites are implicated in the pathogenesis of asthma although only limited information is available on the impact of current smoking history on these metabolites. The aim of the study was to examine the effect of smoking status on urinary, sputum, and plasma eicosanoid concentrations and relevant enzyme transcripts in asthma.

METHODS

In 108 smokers and never smokers with asthma and 45 healthy controls [smokers and never smokers], we measured urinary tetranor prostaglandin (PG)D2 (PGDM) and leukotriene (LT)E4 , induced sputum fluid LTB4 , LTE4 , PGD2 , and PGE2 , plasma secretory phospholipase A2 (sPLA2 ), and 11β prostaglandin F2α (11βPGF2α ), and, in a subgroup with severe asthma, airway leukocyte and epithelial cell mRNA expression levels of arachidonic acid metabolic enzymes.

RESULTS

Smokers with asthma had higher urinary LTE4 ; 83 (59, 130) vs 59 (40, 90) pg/mg creatinine, P = 0.008, and PGDM; 60 (35, 100) vs 41 (28, 59) ng/mg creatinine, P = 0.012 concentrations, respectively, and lower sputum PGE2 concentrations 80 (46, 157) vs 192 (91, 301) pg/ml, P = 0.001 than never smokers with asthma. Sputum LTB4 (P = 0.013), and plasma 11βPGF2α (P = 0.032), concentrations, respectively, were increased in smokers with asthma compared with healthy smokers. Asthma-specific and smoking-related increases (>1.5-fold expression) in arachidonate 15-lipoxygenase and gamma-glutamyltransferase transcripts were demonstrated.

CONCLUSIONS

Several arachidonic acid metabolites and enzyme transcripts involving both lipoxygenase and cyclooxygenase pathways are increased in smokers with asthma and differ from never smokers with asthma. Possibly targeting specific lipoxygenase and cyclooxygenase pathways that are activated by asthma and cigarette smoking may optimize therapeutic responses.

Low-level environmental tobacco smoke exposure and inflammatory biomarkers in children with asthma

OBJECTIVE

The effects of low-level environmental tobacco smoke (ETS) exposure, on asthma control, lung function and inflammatory biomarkers in children with asthma have not been well studied. The objective of the study was to assess ETS exposure in school-age children with asthma whose parents either deny smoking or only smoke outside the home, and to assess the impact of low-level ETS exposure on asthma control, spirometry and inflammatory biomarkers.

METHODS

Forty patients age 8-18 years with well-controlled, mild-to-moderate persistent asthma treated with either inhaled corticosteroids (ICS) or montelukast were enrolled. Subjects completed an age-appropriate Asthma Control Test and a smoke exposure questionnaire, and exhaled nitric oxide (FeNO), spirometry, urinary cotinine and leukotriene E(4) (LTE(4)) were measured. ETS-exposed and unexposed groups were compared.

RESULTS

Only one parent reported smoking in the home, yet 28 (70%) subjects had urinary cotinine levels ≥1 ng/ml, suggesting ETS exposure. Seven subjects (18%) had FeNO levels >25parts per billion, six of whom were in the ETS-exposed group. In the ICS-treated subjects, but not in the montelukast-treated subjects, ETS exposure was associated with higher urinary LTE(4), p = 0.04, but had no effect on asthma control, forced expiratory volume in 1 s or FeNO.

CONCLUSIONS

A majority of school-age children with persistent asthma may be exposed to ETS, as measured by urinary cotinine, even if their parents insist they don't smoke in the home. Urinary LTE(4) was higher in the ETS-exposed children treated with ICS, but not in children treated with montelukast.

Asthma exacerbations: predisposing factors and prediction rules

PURPOSE OF REVIEW

Asthma is a multifaceted disease that is associated with decreased lung function, multiple symptoms, varying levels of asthma control, and risk of acute exacerbations. The ability to predict the risk of developing acute exacerbations may improve the management of asthmatics and facilitate identification of these patients for interventional studies.

RECENT FINDINGS

Factors that are associated with different manifestations of asthma differ. Biomarkers that are correlated with airways hyper-responsiveness do not necessarily correlate with risk of future exacerbations. Genetic factors that segregate with exacerbation risk are beginning to emerge. Outcome measures that demonstrate predictive validity have been developed and may facilitate patient management and provide novel clinically meaningful endpoints in clinical trials.

SUMMARY

This review will emphasize underlying factors associated with asthma exacerbations and clinical prediction rules that correlate with the risk of developing severe exacerbations of asthma.

Hands-on workshops as an effective means of learning advanced technologies including genomics, proteomics and bioinformatics

Genomics and proteomics have emerged as key technologies in biomedical research, resulting in a surge of interest in training by investigators keen to incorporate these technologies into their research. At least two types of training can be envisioned in order to produce meaningful results, quality publications and successful grant applications: (1) immediate short-term training workshops and (2) long-term graduate education or visiting scientist programs. We aimed to fill the former need by providing a comprehensive hands-on training course in genomics, proteomics and informatics in a coherent, experimentally-based framework. This was accomplished through a National Heart, Lung, and Blood Institute (NHLBI)-sponsored 10-day Genomics and Proteomics Hands-on Workshop held at National Jewish Health (NJH) and the University of Colorado School of Medicine (UCD). The course content included comprehensive lectures and laboratories in mass spectrometry and genomics technologies, extensive hands-on experience with instrumentation and software, video demonstrations, optional workshops, online sessions, invited keynote speakers, and local and national guest faculty. Here we describe the detailed curriculum and present the results of short- and long-term evaluations from course attendees. Our educational program consistently received positive reviews from participants and had a substantial impact on grant writing and review, manuscript submissions and publications.

Passive smoking induces leukotriene production in children: influence of asthma

BACKGROUND

Passive smoking is associated with poor asthma control in children, but the mechanism is unknown. Leukotrienes are involved in the asthma pathogenesis and their synthesis is increased in adult subjects who actively smoke.

OBJECTIVE

To evaluate whether passive smoking, as assessed by urinary cotinine levels, increases leukotriene production in children with or without asthma.

METHODS

This was a prospective, cross-sectional study in which children with stable intermittent asthma (without exacerbation) and healthy control children were studied through spirometry and urinary concentrations of cotinine and leukotriene E(4) (LTE(4)). Both groups were balanced to include children with and without passive smoking.

RESULTS

Ninety children (49 with asthma and 41 controls, 54.4% females) aged 9 years (range, 5-13 years) were studied. Urinary LTE(4) concentrations were progressively higher as cotinine levels increased (r(S) = 0.23, p = .03). LTE(4) also correlated with body mass index (BMI) (r(S) = 0.30, p = .004), and multiple regression analysis revealed that BMI was even more influential than cotinine for determining LTE(4) levels. LTE(4) concentrations were unrelated with gender, age, or spirometry. In turn, cotinine inversely correlated with forced expiratory volume in one second (FEV(1)) (r(S) = -0.22, p = .04) and forced vital capacity (FVC) (r(S) = -0.25, p = .02), but when analyzed by groups, these relationships were statistically significant only in children with asthma.

CONCLUSIONS

Exposure to environmental tobacco smoke, as assessed by urinary cotinine levels, was associated with an increased urinary concentration of LTE(4), although BMI exerted more influence in determining its concentration. Urinary cotinine was associated with decreased lung function, mainly in children with asthma.

Effect of montelukast for treatment of asthma in cigarette smokers

OBJECTIVE

Many asthmatic patients are unable to quit cigarettes; therefore information is needed on treatment options for smokers. This study evaluates 10 mg/d montelukast and 250 μg of fluticasone propionate twice daily, each compared with placebo, in patients with self-reported active smoking (unable to quit) and asthma.

METHODS

Patients (ages 18-55 years, with asthma [≥1 year], FEV1 of 60% to 90% of predicted value, airway reversibility [≥12%], and self-reported active smoking [≥0.5 to ≤2 packs per day]) were randomized (after a 3-week, single-blind, placebo, run-in period) to 1 of 3 parallel, 6-month, double-blind treatment arms. The primary efficacy end point was the percentage of days with asthma control during treatment. Adverse experiences (AEs) were also evaluated.

RESULTS

There were 347, 336, and 336 patients randomized to montelukast, fluticasone, and placebo, respectively. The mean percentage of days with asthma control over 6 months of treatment was 45% (montelukast, P < .05 vs placebo), 49% (fluticasone, P < .001 vs placebo), and 39% (placebo); the difference between montelukast and fluticasone was not significant (P = .14). Patients with a smoking history of ≤11 pack years (the median value) tended to show more benefit with fluticasone, whereas those with a smoking history of >11 pack years tended to show more benefit with montelukast. AEs occurred in similar proportions among treatment groups.

CONCLUSIONS

In a population of asthmatic patients actively smoking cigarettes, both 10 mg/d montelukast and 250 μg of fluticasone propionate twice daily significantly increased the mean percentage of days with asthma control compared with placebo.

Biologic mechanisms of environmental tobacco smoke in children with poorly controlled asthma: results from a multicenter clinical trial

BACKGROUND

Environmental tobacco smoke (ETS) negatively affects children with asthma. The prevalence of ETS exposure among children with poor asthma control may be changing. Importantly, the mechanisms by which ETS worsens asthma control are poorly understood.

OBJECTIVE

We describe how ETS affects gastroesophageal reflux (GER), respiratory infections, and leukotriene production among children with poor asthma control.

METHODS

We analyzed data from 306 children between 6 and 17 years of age with poorly controlled asthma enrolled in a 6-month clinical trial. We evaluated prevalence and determinants of ETS exposure by interview, questionnaire, and urinary cotinine and the association of ETS exposure on leukotriene production, respiratory infections, GER, lung function, and asthma control. We used multivariable linear, logistic, and Poisson regressions to assess outcomes.

RESULTS

ETS prevalence estimates ranged from 6% to 30%. Children with domestic indoor exposure had worse asthma control (c-Asthma Control Test, 17.8 vs 21.5; P = .04), worse FEV1 % predicted (84.1 vs 90.7; P = .02), and a trend for increased mean urinary leukotriene E4. ETS from any setting was associated with increased symptomatic respiratory infections (adjusted incidence rate ratio: 1.30; P = .02). However, children exposed to ETS did not have symptoms or pH probe results, suggestive of heightened GER.

CONCLUSIONS

Domestic smoking exposure was associated with both higher rates of symptomatic respiratory infection and poorer asthma control despite generally intensive controller therapy. ETS exposure is common among asthmatic children with poor control and may worsen asthma control by promoting respiratory infections. Further investigation is required to elucidate ETS mechanisms in poor asthma control.

Urinary leukotriene E4 as a biomarker of exposure, susceptibility and risk in asthma

Measurement of urinary leukotriene E(4) (uLTE(4)) is a sensitive and noninvasive method of assaying total body cysteinyl leukotriene production and changes in cysteinyl leukotriene production. Recent studies have reported on novel uLTE(4) receptor interactions, and new applications for uLTE(4), as a biomarker of environmental exposure to tobacco smoke and ambient air pollution, a predictor of risk for asthma exacerbations related to tobacco smoke, and a marker of susceptibility to leukotriene receptor antagonists.

Respiratory viral infections in children with asthma: do they matter and can we prevent them?

BACKGROUND

Asthma is a major public health problem with a huge social and economic burden affecting 300 million people worldwide. Viral respiratory infections are the major cause of acute asthma exacerbations and may contribute to asthma inception in high risk young children with susceptible genetic background. Acute exacerbations are associated with decreased lung growth or accelerated loss of lung function and, as such, add substantially to both the cost and morbidity associated with asthma.

DISCUSSION

While the importance of preventing viral infection is well established, preventive strategies have not been well explored. Good personal hygiene, hand-washing and avoidance of cigarette smoke are likely to reduce respiratory viral infections. Eating a healthy balanced diet, active probiotic supplements and bacterial-derived products, such as OM-85, may reduce recurrent infections in susceptible children. There are no practical anti-viral therapies currently available that are suitable for widespread use.

SUMMARY

Hand hygiene is the best measure to prevent the common cold. A healthy balanced diet, active probiotic supplements and immunostimulant OM-85 may reduce recurrent infections in asthmatic children.

Severe asthma in childhood: recent advances in phenotyping and pathogenesis

PURPOSE OF REVIEW

Children with severe asthma have a high degree of respiratory morbidity despite treatment with high doses of inhaled corticosteroids and are therefore very difficult to treat. This review will discuss phenotypic and pathogenic aspects of severe asthma in childhood, as well as remaining knowledge gaps.

RECENT FINDINGS

As a group, children with severe asthma have a number of distinct phenotypic features compared with children with mild-to-moderate asthma. Clinically, children with severe asthma are differentiated by greater allergic sensitization, increased exhaled nitric oxide, and significant airflow limitation and air trapping that worsens as a function of age. These findings are accompanied by structural airway changes and increased and dysregulated airway inflammation and oxidant stress which may explain the differential nature of corticosteroid responsiveness in this population. Because children with severe asthma themselves are a heterogeneous group, current efforts are focused on improved definition and sub-phenotyping of the disorder. Whereas the clinical relevance of phenotyping approaches in severe asthma is not yet clear, they may provide important insight into the mechanisms underlying the disorder.

SUMMARY

Improved classification of severe asthma through unified definitions, careful phenotypic analyses, and mechanism-focused endotyping approaches may ultimately advance knowledge and personalized treatment.

Advances in pediatric asthma in 2011: moving forward

Last year's "Advances in pediatric asthma" concluded with the following statement: "Perhaps new directions in personalized medicine and improved health care access and communication will help maintain steady progress in alleviating the burden of this disease in children, especially young children." This year's summary will focus on recent advances in pediatric asthma that show significant accomplishments in reducing asthma morbidity and mortality over the last 10 years and discuss some pathways to further reduce asthma burden, as indicated in Journal of Allergy and Clinical Immunology publications in 2011. Some of the recent reports continue to shed light on methods to improve asthma management through steps to reduce asthma exacerbations, identify features of the disease in early childhood, alter asthma progression, intervene with nutrition, and more effectively implement the asthma guidelines. As new information evolves, it is also time to consider a revision of the asthma guidelines based on key studies that affect our management of the disease since the last revision in 2007. Now is also the time to use information recorded in electronic medical records to develop innovative disease management plans that will track asthma over time and enable timely decisions on interventions to maintain control that can lead to disease remission and prevention.

Advances in adult asthma diagnosis and treatment and health outcomes, education, delivery, and quality in 2011: what goes around comes around

Last year's review of research advances in adults with asthma emphasized the linear trajectory of translation: the initial studies translating bench findings to the first patients (T1) are connected to larger efficacy studies, including clinical trials studying subjects under tightly controlled conditions (T2), and these in turn are connected to research, including comparative effectiveness research, that tests how the efficacy findings of T2 research fare in the real world, diverse populations, and varied practice settings (T3). This year what was observed was a more interwoven relationship (rather than a linear one), in which each translational level informs the others and new approaches to answering old questions have led to new discoveries. Within this framework, the present review summarizes clinical research on asthma in adults that was reported in the Journal of Allergy and Clinical Immunology in 2011, with emphasis on health outcomes, education, delivery, and quality in terms of discoveries related to mechanisms of disease, environmental exposures, and management.