Interrelationships of quantitative asthma-related phenotypes in the Epidemiological Study on the Genetics and Environment of Asthma, Bronchial Hyperresponsiveness, and Atopy

Mechanism and clinical evidence of immunotherapy in allergic rhinitis

Allergic rhinitis is a common upper airway disease caused by hypersensitivity to various aeroallergens. It causes increased inflammation throughout the body and may be complicated by other otolaryngological pathologies such as chronic hyperplastic eosinophilic sinusitis, nasal polyposis, and serous otitis media. Allergic rhinitis is an IgE-mediated disease and immunotherapy can be a possible approach for patients to limit the use of antihistamines and corticosteroids. There is evidence that allergen immunotherapy can prevent the development of new sensitizations and reduce the risk of later development of asthma in patients with allergic rhinitis. However, some patients do not benefit from this approach and the efficacy of immunotherapy in reducing the severity and relapse of symptoms is still a matter of debate. This review highlights new aspects of allergic rhinitis with a particular focus on the impact of sexual dimorphism on the disease manifestation and efficacy to the allergen specific immunotherapy.

Daytime and Nighttime Visual Analog Scales May Be Useful in Assessing Asthma Control Levels Before and After Treatment

PURPOSE

Few questionnaires evaluate daytime and nighttime symptoms separately, although these assessments could contribute to the improvement of disease control levels and prevention of future risks in asthma. The purpose of this retrospective study was to investigate whether daytime and nighttime visual analog scales (VAS) are useful in measuring the perception of symptoms, assessing disease control levels, and evaluating the treatment effects in asthma.

PATIENTS AND METHODS

Self-reporting asthma control tests (ACT) before and after treatment are standardized tests used to determine disease control levels. A multiple regression analysis was performed to determine the correlation between daytime and nighttime VAS and the characteristics of patients before treatment, as well as the changes in VAS and lung functions and fractional exhaled nitrogen oxide after treatment in 55 treatment-naïve symptomatic adult patients with asthma.

RESULTS

Both daytime (r = -0.57, P < 0.0001) and nighttime (r = -0.46, P < 0.0001) VAS correlated well with ACT scores, and there was a correlation between daytime and nighttime VAS (r = 0.33, P = 0.0148) before treatment. In addition, the changes in daytime (r = -0.65, P < 0.0001) and nighttime (r = -0.44, P < 0.0001) VAS were significantly associated with changes in the ACT scores. The multiple regression analysis (β [95% confidence interval]) revealed that improvements in the daytime (-2.33 [-4.55 to -0.11], P = 0.0405) and nighttime (-3.09 [-6.25 to 0.07], P = 0.0505) VAS were associated with an increased forced vital capacity after treatment, although there was no correlation between the VAS and characteristics before treatment.

CONCLUSION

Our study demonstrated that daytime and nighttime VAS were useful in assessing disease control levels and evaluating the treatment effects in asthma.

Association of use of cleaning products with respiratory health in a Canadian birth cohort

BACKGROUND

Comprehensive longitudinal studies are important for understanding the complex risk factors, pathways, exposures and interactions that lead to the development and persistence of asthma. We aimed to examine associations between use of household cleaning products in early life and childhood respiratory and allergic disease using data from the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study.

METHODS

We summed responses from parental questionnaires that indicated the frequency of use of 26 household cleaning products in the homes of 2022 children from this birth cohort when they were 3-4 months of age to create a cumulative Frequency of Use Score (FUS). We used multivariable logistic regression models to assess whether frequent compared with less frequent use was associated with recurrent wheeze, atopy or asthma diagnosis, as defined by the questionnaire and clinical assessments at age 3 years. Data were collected between 2008 and 2015.

RESULTS

Children in homes with a higher frequency of use of cleaning products in infancy, as determined by an interquartile range increase, had higher odds of recurrent wheeze (adjusted odds ratio [OR] 1.35, 95% confidence interval [CI] 1.11-1.64), recurrent wheeze with atopy (adjusted OR 1.49, 95% CI 1.02-2.16) and asthma diagnosis (adjusted OR 1.37, 95% CI 1.09-1.70), but no increase in the odds of atopy at age 3 years (adjusted OR 1.14, 95% CI 0.96-1.35). Compared with the lowest tertile of FUS exposure, infants in the highest tertile had higher odds of acquiring asthma. Stratification of the results showed that females had higher ORs than males for all outcomes, although the p values for this sex difference did not reach statistical significance.

INTERPRETATION

Frequent use of household cleaning products in early life was associated with an increased risk for childhood wheeze and asthma but not atopy at age 3 years. Our findings add to the understanding of how early life exposures to cleaning products may be associated with the development of allergic airway disease and help to identify household behaviours as a potential area for intervention.

The sensitization pattern differs according to rhinitis and asthma multimorbidity in adults: the EGEA study

BACKGROUND

Mono- and polysensitization are different IgE-mediated allergic phenotypes in children. Allergic sensitization is associated with both allergic asthma and allergic rhinitis, however, associations between the sensitization pattern and particularly polysensitization with asthma and rhinitis remains poorly studied in adults.

AIM

The aim of this study was to assess how the allergic sensitization pattern associates with asthma, rhinitis and their multimorbidity.

METHODS

1199 adults from the EGEA study, with extensive phenotypic characterization and all data available on skin prick tests to 10 allergens, total IgE and blood eosinophils were included. Using questionnaires only, participants were classified into 6 groups: asymptomatic (no asthma, no rhinitis), non-allergic rhinitis alone, allergic rhinitis alone, asthma alone, asthma+non-allergic rhinitis and asthma+allergic rhinitis. Mono- and polysensitization were defined by a positive skin prick test to one or more than one allergen respectively.

RESULTS

Asymptomatic participants and those with non-allergic rhinitis alone were mostly non-sensitized (around 72%) while around 12% were polysensitized. Between 32% and 43% of participants with allergic rhinitis alone, asthma alone and asthma+non-allergic rhinitis were non-sensitized and between 37% and 46% of them were polysensitized. 65% of the participants with asthma+allergic rhinitis were polysensitized. The level of total IgE followed a similar trend to that of allergic sensitization. Eosinophils were increased in asthma, especially when associated with rhinitis. Nasal symptoms were more severe and eczema more common in participants with both asthma and allergic rhinitis than in the other groups.

CONCLUSIONS

Allergic sensitization and particularly polysensitization rates widely differ according to asthma and rhinitis status. This study emphasized the importance of taking into account multimorbidity between asthma and rhinitis and showed that allergic sensitization is not a dichotomic variable.

Age, sex and the association between skin test responses and IgE titres with asthma

BACKGROUND

Skin prick tests (SPTs) and allergen-specific serum IgE (sIgE) measurements are the main diagnostic tools for confirming atopic sensitization. Results are usually reported as 'positive' or 'negative', using the same arbitrary cut-offs (SPT>3 mm, sIgE>0.35 kUA /l) across different ages and sexes. We investigated the influence of age and sex on the interpretation of allergy test in the context of childhood asthma.

METHODS

In a population-based birth cohort (n = 1051), we ascertained the information on asthma/wheeze (validated questionnaires) and performed SPTs and sIgE measurement to inhalant allergens (dust mite, cat, dog) at follow-ups between ages three and 11 years. We investigated the association between quantitative sensitization (sum of SPT mean wheal diameters [MWD] and sIgE titres to the three allergens) and current wheeze and asthma across ages and sexes.

RESULTS

We observed a significant association between the SPT MWD and sIgE titres and wheeze/asthma at most ages and for both sexes. However, the strength of this association was age- and sex-dependent. For SPTs, the strength of the association between MWD and asthma increased with increasing age; we observed the opposite pattern for sIgE titre. For any given SPT MWD/sIgE titre, boys were significantly more likely to express clinical symptoms, particularly in early life; this difference between males and females diminished with age and was no longer significant by age 11 years.

CONCLUSIONS

Age and sex should be taken into account when interpreting the results of skin tests and sIgE measurement, and age- and sex-specific normative data are needed for these allergy tests.

Risk factors associated with asthma phenotypes in dental healthcare workers

BACKGROUND

Exposure in the dental environment can increase the risk of respiratory disease in dental healthcare workers (HCWs). This study investigated the prevalence of asthma phenotypes in dental HCWs and associated risk factors.

METHODS

A cross-sectional study of 454 dental HCWs in five dental institutions in South Africa was conducted. A self-administered questionnaire elicited the health and employment history of subjects. Sera was analyzed for atopic status and latex sensitization. Pre- and post-bronchodilator spirometry was performed.

RESULTS

The prevalence of atopic asthma was 6.9%, non-atopic asthma 5.9% and work-exacerbated asthma (WEA) 4.0%. Atopy and work-related ocular-nasal symptoms were strong predictors of WEA (OR: 3.4; 95% CI: 1.07-10.8; OR: 6.7, 95% CI: 2.4-19.1), respectively. Regular use of personal protective equipment (PPE) was associated with a protective affect (OR: 0.23, 95% CI: 0.1-0.7) among non-atopic asthmatics, while glove use and respiratory protection was protective among atopic asthmatics (OR: 0.39, 95% CI: 0.17-0.89).

CONCLUSION

Identification of risk factors associated with specific asthma phenotypes in dental HCWs can be used to focus preventive strategies for asthmatics.

Asthma and COPD - The C/EBP Connection

Asthma and chronic obstructive pulmonary disease (COPD) are the two most prominent chronic inflammatory lung diseases with increasing prevalence. Both diseases are associated with mild or severe remodeling of the airways. In this review, we postulate that the pathologies of asthma and COPD may result from inadequate responses and/or a deregulated balance of a group of cell differentiation regulating factors, the CCAAT/Enhancer Binding Proteins (C/EBPs). In addition, we will argue that the exposure to environmental factors, such as house dust mite and cigarette smoke, changes the response of C/EBPs and are different in diseased cells. These novel insights may lead to a better understanding of the etiology of the diseases and may provide new aspects for therapies.

Risk factors for bronchial hyperresponsiveness in teenagers differ with sex and atopic status

BACKGROUND

Sex-related differences in bronchial hyperresponsiveness (BHR) have been reported in adolescents, but the mechanisms remain obscure.

OBJECTIVE

To investigate the risk factors for BHR in the Raine Study, a community-based longitudinal birth cohort.

METHODS

At 14 years of age, children underwent a respiratory assessment including a questionnaire, lung function testing, methacholine challenge, and determination of atopic status.

RESULTS

A total of 1779 children provided data for assessment, with 1510 completing lung function and methacholine challenge testing. Current asthma was present in 152 (10.4%), 762 (50.5%) were atopic, and 277 (18.6%) had BHR. BHR was more common in girls, whereas atopy was more common in boys, with no sex differences in asthma or current wheeze. Independent risk factors for BHR were being female (odds ratio [OR], 3.45; P < .001), atopy at 14 years (OR, 1.27; P = .004), and current asthma (OR, 2.15; P = .005). Better lung function was protective against BHR (forced expiratory flow between 25% and 75% of forced vital capacity/forced vital capacity, OR, 0.09; P < .001). Risk factors differed with sex and atopic status. Early-life factors were generally not independent risk factors for BHR at 14 years of age, with the exception of being smaller at birth in boys (birth length, OR, 6 × 10(-9); P = .017) and maternal asthma in girls (OR, 1.84; P = .041). Current asthma was not a risk for BHR in nonatopic children.

CONCLUSION

Bronchial hyperresponsiveness was more common and more severe in girls. These differences could not be explained by differences in lung function or atopic status.

Epidemiology of asthma: risk factors for development

This comprehensive review of the recent literature was undertaken to determine the current state of knowledge of the risk factors involved in the development of asthma in order to focus investigations in a proposed new longitudinal birth cohort study. The origins of asthma appear to lie in the prenatal and early postnatal period, and renewed investigations in this period with long-term close follow-up and objective phenotypic characterization will help to unravel the role of the multiple putative environmental factors in the development of asthma. It is only after understanding these effects that one can hope to design rational prevention studies for asthma.

Sex-specific effect of IL9 polymorphisms on lung function and polysensitization

Sex differences in asthma-associated phenotypes are well known but the genetic factors that may account for these differences have received little attention. This study aimed to characterize sex-specific and pleiotropic genetic factors underlying four quantitative phenotypes involved in the main asthma physiopathological pathways: immunoglobulin E levels, a measure of polysensitization (SPTQ), eosinophil counts and a measure of lung function FEV(1)/H(2) (forced expiratory volume in one second divided by height square). Sex-stratified univariate and bivariate linkage analyses were conducted in 295 families from the Epidemiological study on the Genetics and Environment of Asthma study. We found genome-wide significant evidence for a male-specific pleiotropic QTL (quantitative trait loci) on 5q31 (P=7 x 10(-9)) influencing both FEV(1)/H(2) and SPTQ and for a female-specific pleiotropic QTL on 11q23 underlying SPTQ and immunoglobulin E (P=2 x 10(-5)). Three other sex-specific regions of linkage were detected for eosinophil: 4q24 and 22q13 in females, and 3p25 in males. Further, bivariate association analysis of FEV(1)/H(2) and SPTQ with 5q31 candidate genes in males showed a significant association with two single-nucleotide polymorphisms within IL9 gene, rs2069885 and rs2069882 (P=0.02 and P=0.002, respectively, after Bonferroni's correction). This study underlies the importance of taking into account complex mechanisms, such as heterogeneity according to sex and pleiotropy to unravel the genes involved in asthma phenotypes.

Cat sensitization according to cat window of exposure in adult asthmatics

BACKGROUND

In adults, there is limited information on tolerance to cat, which may be reflected by high IgG4 without IgE sensitization. Early exposure to cat may play a critical role.

OBJECTIVE

The aim was to assess among adults the association of Fel d 1 IgG4, Fel d 1 IgE, skin prick test (SPT) response to cat and pet-related symptoms in relation to exposure to cat considering the period of exposure.

METHODS

SPT response to cat, specific IgE and IgG4 to Fel d 1 were assessed in 167 asthmatics recruited in chest clinics (40 years of age in average) from the French Epidemiological study on the Genetics and Environment of Asthma (EGEA). Childhood and/or current exposure to cat were studied retrospectively.

RESULTS

IgG4 was higher in relation to current cat exposure (0.53 vs. 0.09 ng/mL; P<0.001) and higher in women than in men. The period of cat exposure was significantly related to Fel d 1 IgE, the IgE/IgG4 pattern and cat weal size. The lowest values of Fel d 1 IgE, cat weal size, pet-related nasal or respiratory symptoms were observed in those with both childhood and current exposure as well as the highest proportion of the IgE-/IgG4+ pattern observed in 1.4%, 4.0%, 38.1% and 12.5% of those with -/-, +/-, +/+, -/+ childhood/current exposure, respectively.

CONCLUSIONS

Adult asthmatics exposed to cats since childhood present an immunologic pattern with high IgG4 and low IgE. Continuous exposure may maintain a state of immunological tolerance to cat.

An imbalance in C/EBPs and increased mitochondrial activity in asthmatic airway smooth muscle cells: novel targets in asthma therapy?

The asthma prevalence was increasing over the past two decades worldwide. Allergic asthma, caused by inhaled allergens of different origin or by food, is mediated by inflammatory mechanisms. The action of non-allergic asthma, induced by cold air, humidity, temperature or exercise, is not well understood. Asthma affects up to 15% of the population and is treated with anti-inflammatory and muscle relaxing drugs which allow symptom control. Asthma was first defined as a malfunction of the airway smooth muscle, later as an imbalanced immune response of the lung. Recent studies placed the airway smooth muscle again into the focus. Here we summarize the molecular biological basis of the deregulated function of the human airway smooth muscle cell as a cause or important contributor to the pathology of asthma. In the asthmatic human airway smooth muscle cells, there is: (i) a deregulation of cell differentiation due to low levels of maturation-regulating transcription factors such as CCAAT/enhancer binding proteins and peroxisome proliferator-activated receptors, thereby reducing the cells threshold to proliferate and to secrete pro-inflammatory cytokines under certain conditions; (ii) a higher basal energy turnover that is due to increased number and activity of mitochondria; and (iii) a modified feedback mechanism between cells and the extracellular matrix they are embedded in. All these cellular pathologies are linked to each other and to the innate immune response of the lung, but the sequence of events is unclear and needs further investigation. However, these findings may present the basis for the development of novel curative asthma drugs.

An interdisciplinary analysis of sex and gender in relation to the pathogenesis of bronchial asthma

BACKGROUND

An increasing number of studies confirm that pathogenesis and prevalence of bronchial asthma are age and sex dependent. Detailed physiological mechanisms of the changing sex ratios with age are not fully known, however, the gender (socio-cultural) factors are also imperative. Although multiple factors definitely influence the pathogenesis of asthma, only individual or few combinations of these have been investigated.

METHODS

The terms 'sex', 'gender' and plausible combinations of both were systematically researched in selected databases (Medline, Scopus) or other sources, including publications from January 2000 to June 2007. Generated articles were categorized, either as endogenous or exogenous factors influencing the pathogenesis of asthma, and divided into the following subgroups: genetic, immunological, hormonal, gynaecological, nutritional, and environmental parameters.

RESULTS

An increasing number of studies investigate the influence of sex and gender in the aetiology, therapy and prevention of asthma. While their results are still debatable, others regarding its initiation, perpetuation and cessation have been clarified. Recent insights into interactions at biomolecular and immunological levels greatly contribute to clarifying sex-specific influences. Despite occasional oversimplifications, a trend for explanations considering the complex interplay of different factors can be observed. This work is in line with this trend and offers explanation models from our point of view.

CONCLUSIONS

Some disagreements regarding the patho-physiology, diagnosis, treatment and prevention of asthma still prevail. Nevertheless, in order to better appreciate its complexity, openness to and persistent consideration for interdisciplinary as well as sex- and gender-related factors is required of the medical-research community in future investigations.

Air pollution and asthma severity in adults

BACKGROUND/OBJECTIVES

There is evidence that exposure to air pollution affects asthma, but the effect of air pollution on asthma severity has not been addressed. The aim was to assess the relation between asthma severity during the past 12 months and home outdoor concentrations of air pollution.

METHODS

Asthma severity over the past 12 months was assessed in two complementary ways among 328 adult asthmatics from the French Epidemiological study on the Genetics and Environment of Asthma (EGEA) examined between 1991 and 1995. The four-class severity score integrated clinical events and type of treatment. The five-level asthma score is based only on the occurrence of symptoms. Nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)) and ozone (O(3)) concentrations were assigned to each residence using two different methods. The first was based on the closest monitor data from 1991 to 1995. The second consisted of spatial models that used geostatistical interpolations and then assigned air pollutants to the geo-coded residences (1998).

RESULTS

Higher asthma severity score was significantly related to the 8-hour average of ozone during April-September (O(3)-8 h) and the number of days (O(3)-days) with 8-hour ozone averages above 110 microg.m(-3) (for a 36-day increase, equivalent to the interquartile range, in O(3)-days, odds ratio 2.22 (95% confidence interval 1.61 to 3.07) for one class difference in score). Adjustment for age, sex, smoking habits, occupational exposure, and educational level did not alter results. Asthma severity was unrelated to NO(2). Both exposure assessment methods and severity scores resulted in very similar findings. SO(2) correlated with severity but reached statistical significance only for the model-based assignment of exposure.

CONCLUSIONS

The observed associations between asthma severity and air pollution, in particular O(3), support the hypothesis that air pollution at levels far below current standards increases asthma severity.

Interpatient variability in rates of asthma progression: can genetics provide an answer?

Asthma is a heterogeneous disorder with a variable natural history. In children 3 patterns of the natural history of asthma have been described: early onset but transient, persistent, and later onset, with only the former leading to persistent asthma later in childhood. In adults a range of different asthma phenotypes differing in their environmental, inflammatory, and prognostic characteristics have also been described. These extend beyond allergic (extrinsic) and nonallergic (intrinsic) asthma to include persistent airflow obstruction and accelerated decrease in lung function over time. Asthma progression can be defined as the change in an individual's phenotype along a continuum ranging from nonasthmatic to asthmatic and subsequent development of severe chronic disease. It is clear that for prevention of asthma progression in patients, there is a need for both better understanding of the pathophysiology of asthma and identification of predictors of progression. Interpatient genetic variability has been shown to affect multiple facets of asthma progression, including increased susceptibility to atopy and subsequent asthma, progression to severe disease, and modification of the response to treatment. Thus genetic testing might provide a means for predicting the likely progression of an individual along the continuum, allowing targeting of preventative treatment. However, the prospect of the use of genetic information in clinical practice raises important social and ethical issues that will need to be addressed before genetic testing can be used to inform the preventative treatment of patients to prevent the development of progression of asthma in individuals.

Advances in pediatric asthma in 2007

This year's summary focuses on recent advances in pediatric asthma as reported in 2007 publications in the Journal. This past year, new National Asthma Education and Prevention Program asthma guidelines were released with a special emphasis on new information in pediatric asthma. Journal theme issues in 2007 included the revised National Asthma Education and Prevention Program asthma guidelines, the accomplishments of the National Institutes of Health asthma networks, and focused discussions on environmental allergens, neutrophils, eosinophils, T cells, and epithelial cells, all of which affect pediatric asthma. The new asthma guidelines emphasize several key terms including severity, control, impairment, risk, and responsiveness that are relevant for advancing the care of children with asthma. This review highlights journal articles that relate to these guideline topics.

[Environmental factors for asthma severity and allergy: results from the EGEA study]

INTRODUCTION

EGEA (Epidemiological study on the genetics and environment of asthma, bronchial hyperresponsiveness and atopy), a case control and family study including 2048 individuals, was initiated to look for environmental and genetic risk factors for asthma. A synthesis of the results obtained since 2002 on phenotypic and environmental aspects of asthma severity and allergy are presented in this article.

METHODS AND RESULTS

The results support a role for hormonal factors in asthma severity and in various allergic markers of asthma. A greater body mass index was related to a more severe asthma in women with early menarche. Associations between markers of allergy (eosinophils, IgE and atopy) and hormonal dependent events in women (premenstrual asthma, menopause and oral contraceptive use) have been found. In asthmatics, exposure to agents known to be associated with occupational asthma, active and passive smoking were associated with an increased clinical asthma severity score. The study underlines the protective role of country living and exposure to pets in early life on allergy markers in adulthood, supporting the hygiene hypothesis.

CONCLUSIONS

New hypothesis will be tested in the near future from the second stage of this survey.

Evidence for a pleiotropic QTL on chromosome 5q13 influencing both time to asthma onset and asthma score in French EGEA families

Although many genome screens have been conducted for asthma as a binary trait, there is limited information regarding the genetic factors underlying variation of asthma expression. Phenotypes related to variable disease expression include time to asthma onset and variation in clinical expression as measured by an asthma score built from EGEA data. A recent genome scan conducted for this score led to detection of a new region (18p11) not revealed by analysis of dichotomous asthma. Our goal was to characterize chromosomal regions harboring genes underlying time to asthma onset and to search for pleiotropic QTL influencing both time to asthma onset and the asthma score. We conducted a genome-wide linkage screen for time to asthma onset, modeled by martingale residuals from Cox survival model, in EGEA families with at least two asthmatic sibs. This was followed by a bivariate linkage scan of these residuals and asthma score. Univariate linkage analysis was performed using the Maximum Likelihood Binomial method that we extended to bivariate analysis. This screen revealed two regions potentially linked to time to asthma onset, 1p31 (LOD = 1.70, P = 0.003) and 5q13 (LOD = 1.87, P = 0.002). Bivariate linkage analysis led to a substantial improvement of the linkage signal on 5q13 (P = 0.00007), providing evidence for a pleiotropic QTL influencing both variation of time to asthma onset and of clinical expression. Use of quantitative phenotypes of variable disease expression and suitable statistical methodology can improve the power to detect new regions harboring genes which may play an important role in onset and course of disease.