Gender Differences in Asthma Development and Progression

Arginase 1 deletion in myeloid cells affects the inflammatory response in allergic asthma, but not lung mechanics, in female mice

BACKGROUND

(Over-)expression of arginase may limit local availability of arginine for nitric oxide synthesis. We investigated the significance of arginase1 (ARG1) for the development of airway hyperresponsiveness (AHR) and lung inflammation in female mice with ovalbumin (OVA)-induced allergic asthma.

METHODS

Arg1 was ablated in the lung by crossing Arg1 fl/fl and Tie2Cre tg/- mice. OVA sensitization and challenge were conducted, and AHR to methacholine was determined using the Flexivent system. Changes in gene expression, chemokine and cytokine secretion, plasma IgE, and lung histology were quantified using RT-qPCR, ELISA, and immunohistochemistry, respectively.

RESULTS

Arg1 ablation had no influence on the development of OVA-induced AHR, but attenuated OVA-induced increases in expression of Arg2 and Nos2, Slc7a1, Slc7a2, and Slc7a7 (arginine transporters), Il4, Il5 and Il13 (TH2-type cytokines), Ccl2 and Ccl11 (chemokines), Ifng (TH1-type cytokine), Clca3 and Muc5ac (goblet cell markers), and OVA-specific IgE. Pulmonary IL-10 protein content increased, but IL-4, IL-5, IL-13, TNFα and IFNγ content, and lung histopathology, were not affected. Arg1 elimination also decreased number and tightness of correlations between adaptive changes in lung function and inflammatory parameters in OVA/OVA-treated female mice. OVA/OVA-treated female mice mounted a higher OVA-IgE response than males, but the correlation between lung function and inflammation was lower. Arg1-deficient OVA/OVA-treated females differed from males in a more pronounced decline of arginine-metabolizing and -transporting genes, higher plasma arginine levels, a smaller OVA-specific IgE response, and no improvement of peripheral lung function.

CONCLUSION

Complete ablation of Arg1 in the lung affects mRNA abundance of arginine-transporting and -metabolizing genes, and pro-inflammatory genes, but not methacholine responsiveness or accumulation of inflammatory cells.

Leukotrienes and sex: strange bedfellows?

Leukotrienes are proinflammatory lipid mediators that have been shown to be upregulated in several diseases, including asthma, aspirin-exacerbated respiratory disease (AERD), inflammatory bowel disease, and acute respiratory distress syndrome. Leukotrienes have been explored as therapeutic targets for these diseases and others; however, leukotriene inhibitors have had limited success in the clinic. There are noted differences in the incidence of leukotriene-mediated diseases in males and females, but sex as a factor in the response to leukotriene inhibitors has not been fully explored. In this issue of the JCI, Pace and colleagues present evidence that there are sex-specific differences in the effectiveness of certain leukotriene inhibitors and link the differences in response to the presence of androgens. The results of this study indicate that sex needs to be taken into consideration in the future evaluation of leukotriene inhibitors to treat disease.

Prevalence trends in the characteristics of patients with allergic asthma in Beijing, 1994 to 2014

This study aimed to determine the clinical profiles and prevalence trends during 1994 to 2014 among patients with allergic asthma (AA), which is a clinical phenotype of asthma.We retrospectively analyzed the characteristics of 319 patients who were diagnosed with AA between March 1, 1994 and February 28, 2014 at 3 Beijing centers.The patients included 155 males and 164 females, and the mean age was 50.86 ± 15.27 years (range 13-86 years). The proportions of asthma attacks in summer and autumn were 60.7% (1994-1999), 61.8% (1999-2004), 56.4% (2004-2009), and 33.1% (2009-2014). The most frequently used medication at home was theophylline (27.9%), which was followed by inhaled corticosteroids (20.38%), inhaled corticosteroids/long-acting beta-2-agonists (10.66%), and leukotriene receptor antagonists (9.4%). The elderly group had the highest rates of summer and autumn attacks, multiple hospitalizations, reduced pulmonary function, smoking history, and positive allergen tests. The middle-aged group had the lowest rates of summer and autumn attacks, and multiple hospitalizations. The youngest group had the lowest rates of reduced pulmonary function, smoking history, and positive allergen tests. The top 5 allergens were dust (9.1%), mites (8.8%), seafood (8.2%), pollen (6.3%), and animal fur (6%). Women were significantly more likely to have a positive allergen test (93 women vs 68 men).The present study revealed the characteristics of Chinese patients with AA, and allergen-specific differences in sex and age during 1994 to 2014. The use of therapeutic drugs at home remains insufficient.

Sex-Related Allergic Rhinitis Prevalence Switch from Childhood to Adulthood: A Systematic Review and Meta-Analysis

BACKGROUND

A sex-related switch in the prevalence of asthma from childhood (male predominance) to adulthood (female predominance) has been described, but for allergic rhinitis this remains unclear. We aimed to examine sex- and age-group-specific differences in allergic rhinitis prevalence by systematically evaluating studies from across the globe.

METHODS

A systematic search of MEDLINE and Embase for population-based cross-sectional studies was performed regardless of the language of publication. The search was restricted to the present millennium (2000 to June 2014). Study quality was defined by the sampling method, response rate, sample size, and data collection method. To assess sex differences in the prevalence of self- or parent-reported symptoms of rhinitis, calculated pooled estimates of the male-female ratio (MFR) were obtained using random-effects model meta-analyses due to heterogeneity. A meta-regression analysis was also performed.

RESULTS

Out of 6,539 publications identified, 67 cross-sectional population-based studies (291,726 males and 301,781 females) were included in our meta-analysis. In children (<11 years of age) significantly more boys than girls had rhinitis symptoms (MFR 1.21, 95% CI 1.17-1.25), whereas in adolescents (11 to <18 years of age) males were significantly less often affected than females (MFR 0.90, 95% CI 0.85-0.95). No sex-specific prevalence difference was observed in adults (MFR 0.96, 95% CI 0.83-1.17). These findings were consistent in all continents except in Asia, where the male predominance remained beyond childhood.

CONCLUSIONS

The male predominance of rhinitis prevalence in childhood changed towards a female predominance in adolescence across the globe, except in Asia. Longitudinal studies are needed to confirm these cross-sectional data and examine possible determinants and underlying mechanisms.

Sex discordance in asthma and wheeze prevalence in two longitudinal cohorts

Sex discordance in asthma prevalence has been previously reported, with higher prevalence in males before puberty, and in females after puberty; the adolescent "switch". However, cross-sectional studies have suggested a narrowing of this discordance in recent decades. We used a combination of cross-sectional and longitudinal modelling to examine sex differences in asthma, wheeze and longitudinal wheezing phenotypes in two UK birth cohorts, the Avon Longitudinal Study of Parents and Children (ALSPAC; born 1991-92 with data from age 0-18 years) and the Millennium Cohort Study (MCS; born 2000-02 with data from age 3-10 years). We derived measures of asthma and wheeze from questionnaires completed by mothers and cohort children. Previously-derived ALSPAC wheezing phenotype models were applied to MCS. Males had a higher prevalence of asthma at 10.7 years in ALSPAC (OR 1.45 95%CI: 1.26, 1.66 n = 7778 for current asthma) and MCS (OR 1.42 95%CI: 1.29, 1.56 n = 6726 for asthma ever) compared to females, decreasing in ALSPAC after puberty (OR 0.94 95%CI: 0.79, 1.11 n = 5023 for current asthma at 16.5 years). In longitudinal models using restricted cubic splines, males had a clear excess for asthma in the last 12 months and wheeze in the last 12 months up until 16.5 years of age in ALSPAC. Males had an increased risk of all derived longitudinal wheezing phenotypes in MCS when compared to never wheeze and no evidence of being at lower risk of late wheeze when compared to early wheeze. By comparing data in two large, contemporary cohorts we have shown the persistence of sex discordance in childhood asthma, with no evidence that the sex discordance is narrowing in recent cohorts.

Exploring Workforce Participation Patterns and Chronic Diseases Among Middle-Aged Australian Men and Women Over the Life Course

OBJECTIVE

This study identified associations between chronic diseases (diabetes, asthma, depression, and arthritis) and workforce participation patterns with a gendered perspective.

METHOD

We used data from 1,261 middle-aged participants of the Australian Life Histories and Health (LHH) Survey, aged 60 to 64 years in 2011. Latent class analysis identified dominant workforce patterns and associations between chronic diseases and these patterns were explored by multinomial regression models.

RESULTS

Diabetes, asthma, depression, and arthritis were less prevalent in men and women in class "mostly full-time work," compared with other workforce patterns. The odds of "mostly full-time work" were lower for men reporting depression or arthritis, whereas among women, depression was associated with "increasing part-time work" after adjusting early and adult life factors.

DISCUSSION

The results strengthen the importance of gender focused policies aimed to promote and preserve health of young and middle-aged workers, and creating supportive environment for those with chronic health issues over the life course.

Differential Expression of Estrogen Receptor Variants in Response to Inflammation Signals in Human Airway Smooth Muscle

The prevalence of asthma is higher in pre-pubescent and aging males, and in post-pubertal females, strongly indicating that sex steroids (especially estrogen) may be an important modulator in lung disease. We recently demonstrated that airway smooth muscle (ASM) expresses both alpha and beta forms of the estrogen receptor (ERα and ERβ) in males and females, and that these receptors regulate intracellular [Ca²⁺ ] and ASM contractility. Although both ERα and ERβ have multiple splice variants, it is unclear if and how the expression of these variants is modulated under conditions such as chronic inflammation/asthma. In order to test the hypothesis that the differential expression of ERα and ERβ variants contributes to the pathogenesis of asthma, we profiled the expression of various ERα and ERβ genes in asthmatic and inflamed (TNFα- or IL-13-treated) ASM. Gene expression was assessed at both the mRNA and protein levels in asthmatic ASM cells or non-asthmatic cells treated with TNFα (20 ng/ml) or IL-13 (50 ng/ml). We observed marked variation in the expression of ER isoforms in response to inflammatory stimuli, and in non-asthmatic versus asthmatic ASM. Changes in protein levels of ERα and ERβ corresponded with the observed differential mRNA patterns. Pharmacological studies implicate cytosolic (p42/44 MAPK and PI3 K) and nuclear (NFκB, STAT6, and AP-1) signaling pathways as putative mechanisms that mediate and/or regulate effects of inflammation on ER expression. We conclude that variations in ASM ER expression profiles occur with inflammation and that ER variants could contribute to estrogen signaling in airway diseases such as asthma. J. Cell. Physiol. 232: 1754-1760, 2017. © 2016 Wiley Periodicals, Inc.

Lifetime secondhand smoke exposure and childhood and adolescent asthma: findings from the PIAMA cohort

BACKGROUND

Secondhand smoke (SHS) exposure is a modifiable risk factor associated with childhood asthma. Associations with adolescent asthma and the relevance of the timing and patterns of exposure are unclear. Knowledge of critical windows of exposure is important for targeted interventions.

METHODS

We used data until age 17 from 1454 children of the Dutch population-based PIAMA birth cohort. Residential SHS exposure was assessed through parental questionnaires completed at ages 3 months, 1-8 (yearly), 11, 14, and 17 years. Lifetime exposure was determined as; a) time window-specific exposure (prenatal, infancy, preschool, primary school, and secondary school); b) lifetime cumulative exposure; c) longitudinal exposure patterns using latent class growth modeling (LCGM). Generalized estimation equations and logistic regression were used to analyze associations between exposure and asthma at ages 4 to 17 years, adjusting for potential confounders.

RESULTS

With all three methods, we consistently found no association between SHS exposure and asthma at ages 4 to 17 years e.g. adjusted overall odds ratio (95% confidence interval) 0.67 (0.41-1.12), 1.00 (0.66-1.51) and 0.67 (0.41-1.11) for prenatal maternal active smoking, infancy, and preschool school time window exposures, respectively.

CONCLUSION

We assessed lifetime SHS exposure using different methods. Different timing and patterns of SHS exposure were not associated with an increased risk of asthma in childhood and adolescence in our study. More longitudinal studies could investigate effects of lifetime SHS exposure on asthma in adolescence and later life.

Factors associated with relapse in adult patients discharged from the emergency department following acute asthma: a systematic review

A significant proportion of patients discharged from the emergency department (ED) with asthma exacerbations will relapse within 4 weeks. This systematic review summarises the evidence regarding relapses and factors associated with relapse in adult patients discharged from EDs after being treated for acute asthma. Following a registered protocol, comprehensive literature searches were conducted. Studies tracking outcomes for adults after ED management and discharge were included if they involved adjusted analyses. Methodological quality was assessed using the Newcastle–Ottawa Scale (NOS) and the Risk of Bias (RoB) Tool. Results were summarised using medians and IQRs or mean and SD, as appropriate. 178 articles underwent full-text review and 10 studies, of various methodologies, involving 32 923 patients were included. The majority of the studies were of high quality according to NOS and RoB Tool. Relapse proportions were 8±3%, 12±4% and 14±6% at 1, 2 and 4 weeks, respectively. Female sex was the most commonly reported and statistically significant factor associated with an increased risk of relapse within 4 weeks of ED discharge for acute asthma. Other factors significantly associated with relapse were past healthcare usage and previous inhaled corticosteroids (ICS) usage. A median of 17% of patients who are discharged from the ED will relapse within the first 4 weeks. Factors such as female sex, past healthcare usage and ICS use at presentation were commonly and significantly associated with relapse occurrence. Identifying patients with these features could provide clinicians with guidance during their ED discharge decision-making.

Suggestive association between variants in IL1RAPL and asthma symptoms in Latin American children

Several genome-wide association studies have been conducted to investigate the influence of genetic polymorphisms in the development of allergic diseases, but few of them have included the X chromosome. The aim of present study was to perform an X chromosome-wide association study (X-WAS) for asthma symptoms. The study included 1307 children of which 294 were asthma cases. DNA was genotyped using 2.5 HumanOmni Beadchip from Illumina. Statistical analyses were performed in PLINK 1.9, MACH 1.0 and Minimac2. The variant rs12007907 (g.29483892C>A) in IL1RAPL gene was suggestively associated with asthma symptoms in discovery set (odds ratio (OR)=0.49, 95% confidence interval (CI): 0.37-0.67; P=3.33 × 10^-6). This result was replicated in the ProAr cohort in men only (OR=0.45, 95% CI: 0.21-0.95; P=0.038). Furthermore, investigating the functional role of the rs12007907 on the production a Th2-type cytokine, IL-13, we found a negative association between the minor allele A with IL-13 production in the discovery set (P=0.044). Gene-based analysis revealed that NUDT10 was the most consistently associated with asthma symptoms in discovery sample. In conclusion, the rs12007907 variant in IL1RAPL gene was negatively associated with asthma and IL-13 production in our study and a sex-specific association was observed in one of the validation samples. It suggests an effect on asthma susceptibility and may explain differences in severe asthma frequency between women and men.

Sex differences in asthma in swimmers and tennis players

BACKGROUND

Elite athletes, independent of sport, have increased risk of developing asthma, but little is known about sex difference among adolescent athletes.

OBJECTIVE

To investigate and compare sex-related differences according to symptoms and treatment of asthma, allergy, and health among elite athletes and a reference group.

METHODS

Adolescent elite swimmers (n = 101), tennis players (n = 86), and a reference group (n = 1,628) responded to a questionnaire about respiratory symptoms, allergy, health behavior, psychosomatic symptoms, self- esteem, and well-being. The athletes performed a mannitol provocation and a sport-specific exercise provocation. Atopy was assessed by skin prick tests, and fractional exhaled nitric oxide was measured.

RESULTS

The females reported more asthma symptoms than the males in both the reference group (29.1% vs 22.3%) and the athlete group (56.4% vs 40.2%). However, no significant differences were found in physician-diagnosed asthma or treatment with inhaled corticosteroids. More female athletes had a positive mannitol provocation result (48.7% vs 35.8% in male athletes), and more female swimmers had a positive exercise provocation result (15.1% vs 7.7% in male swimmers). The females in all groups had more psychosomatic symptoms compared with the respective males, and the males in the reference group reported higher self-esteem and felt more well-being compared with the reference group females.

CONCLUSION

Overall, we found a higher prevalence of asthma symptoms in the females. However, the frequency of physician-diagnosed asthma and the prescription of inhaled corticosteroids were the same in both sexes. This finding demonstrates an insufficient diagnosis of asthma in females.

Vocal Symptoms and Voice Quality in Children With Allergy and Asthma

OBJECTIVES

The background for dysphonia is multifactorial, and health-related factors have been listed among the factors affecting voice. In previous studies with adult participants, allergy and asthma have been indicated to have a connection to vocal symptoms. With the majority of previous research being studies involving adult participants, it is unclear what the effect of allergy and asthma on children's voices is. The aim of this study was to investigate if allergies and asthma are risk factors for having vocal symptoms.

METHODS

The material was collected through paper questionnaires distributed to the parents of new pediatric patients at an allergy clinic. The participants were 108 children aged 9 months to 17 years and 1 month.

RESULTS

Of the children whose parents had filled in the questions on vocal symptoms, 18.2% (n = 18) had frequently occurring vocal symptoms, which was defined as having two or more vocal symptoms every week or more often. The most common vocal symptoms were throat clearing and coughing. There was a significant connection between inhalant allergy and having frequently occurring vocal symptoms. The connection between cough that lasted for more than 4 weeks and having frequently occurring vocal symptoms was also significant. In this study, we found no significant connection between having an asthma diagnosis and having frequently occurring vocal symptoms.

CONCLUSIONS

Based on the results of this study, voice screening for children with inhalant allergy would be advisable. Prolonged cough should be taken seriously and be treated, as the mechanical trauma caused by cough seems to have a connection to vocal symptoms.

Epidemiology, triggers, and severity of childhood asthma in Ilesa, Nigeria: Implications for management and control

Background:

Knowledge about childhood asthma in a locality will assist clinicians to adequately manage the condition. This study set out to report the epidemiology, triggers of exacerbation, comorbid conditions, and severity of childhood asthma at a tertiary health facility in Nigeria and the implication of these, in management and symptoms control.

Methods:

Over a 15-month study period, children (aged <15 years) with physician-diagnosed asthma were consecutively recruited at the pediatric chest clinic of the hospital. Sociodemographic history, triggers, and comorbidities in the children were recorded. The severity and level of symptoms control were determined using Global Initiative for Asthma criteria. The children were examined and had lung function test. Appropriate descriptive and inferential statistics were used to analyze the data obtained.

Results:

A total of 110 children were recruited for the study with an overall male preponderance 1.6:1, however, more adolescent females than males were observed. The ages of the children ranged from 10 months to 14 years with mean (standard deviation) of 6.4 (3.9) years. The median (interquartile range) age at diagnosis was 2.5 (1.5–6.0) years. The comorbidities were allergic rhinoconjunctivitis (45.5%), atopic dermatitis (10.9%), and overweight/obesity (7.3%). The recognizable triggers of exacerbations were respiratory tract infections (RTIs) seen more in preschool than school age children (χ² = 6.225; P = 0.031), exercise, dust, and fumes. Mild intermittent asthma (82.7%) was the most common forms, 13 (25.0%) of the children who had Spirometry had obstructive ventilatory pattern and 17.3% had suboptimal asthma control.

Conclusion:

The majority of children with asthma at the Wesley Guild Hospital, Ilesa were school age children, however, 10% were <2 years and most asthmatics (72.7%) were diagnosed before age five. RTI is a major trigger of exacerbation and more than one-half had other allergic conditions which should be looked for and managed to ensure successful asthma management.

Sex differences in child and adolescent physical morbidity: cohort study

BACKGROUND

Evidence on sex differences in physical morbidity in childhood and adolescence is based largely on studies employing single/few physical morbidity measures and different informants. We describe sex differences in a wide range of parent/carer-reported physical morbidity measures between ages 4 and 13 years to determine evidence for a generalised pattern of an emerging/increasing female 'excess'.

METHODS

Parents/carers (approximately 90% mothers) of the population-based UK ALSPAC cohort provided data on general health, physical conditions/symptoms and infections in their child approximately annually between ages 4 and 13. Logistic regression analyses determined the odds of each morbidity measure being reported in respect of females (vs males) at each age and the sex-by-age interaction, to investigate any changing sex difference with age.

RESULTS

Six measures (general health past year/month, high temperature, rash, eye and ear infections) demonstrated an emerging female 'excess', and six (earache, stomach-ache, headache, lice/scabies, cold sores, urinary infections) an increasing female 'excess'; one (breathlessness) showed a disappearing male 'excess'. Just two showed either an emerging or increasing male 'excess'. Most changes were evident during childhood (prepuberty). Six measures showed consistent female 'excesses' and four consistent male 'excesses'. Few measures showed no sex differences throughout this period of childhood/early adolescence.

CONCLUSION

Sex differences are evident for a wide range of parent-reported physical morbidity measures in childhood and early adolescence. Far more measures showed an emerging/increasing female 'excess' than an emerging/increasing male 'excess'. Further studies are required to examine whether patterns differ across sociodemographic/cultural groups, and to explain this generalised pattern.

Asthma in adolescence: Is there any news?

Asthma is a chronic disease that has a significant impact quality of life, which is particularly important in adolescence. We will discuss aspects of epidemiology, the clinical spectrum, diagnostics, and management of asthma in adolescence. In particular, we will highlight the psychological implications of having asthma during this developmental period. Data published in the past 10 years, since we last reviewed the subject, will be the main focus of this paper. The care of the teenager with asthma should take into account the rapid physical, emotional, cognitive, and social changes that occur during normal adolescence. The diagnostic process may be more difficult since teenagers tend to deny their illness. Thus, both under-diagnosis and under-assessment of asthma severity may lead to under-treatment and potentially avoidable morbidity and even mortality. Conversely, teenagers may be often misdiagnosed as having asthma or their asthma severity may be overestimated leading to inappropriate and sometimes excessive treatment. Educational programs, environmental avoidance measures, proper use of medications along with a skilled approach, and a caring attitude of health providers are all very important for successful management. Pediatr Pulmonol. 2017;52:129-138. © 2016 Wiley Periodicals, Inc.

The impact of parity and age at first and last childbirth on the prevalence of delayed-onset asthma in women: The Korean National Health and Nutrition Examination Survey

OBJECT

Asthma is a chronic inflammatory airway disease. The aim of this study was to investigate the relationships between asthma and reproductive factors, including age at first childbirth and parity, in a representative sample of Korean women.

MAIN OUTCOME MEASURES

We analyzed data from the Korean National Health and Nutrition Examination Survey (2010-2012). A total of 7837 adults who completed a questionnaire and examination were evaluated. The presence of asthma was based on the Health Interview Survey. Reproductive factors were estimated by trained interviewers using participant recall.

RESULTS

The women with asthma were significantly older than those without asthma. BMI, hypertension, education level, income level, occupation, alcohol consumption, and age at menarche and first birth were significantly associated with the diagnosis of asthma. Higher parity was positively associated with later-onset asthma. In addition, women who were younger at first birth had a greater prevalence of later-onset asthma. After controlling for confounders, being aged under 20 at first birth was significantly associated with an asthma diagnosis compared with women aged 25-29 at first birth (OR [95% CI]: 1.81 [1.14-2.89]).

CONCLUSIONS

Although higher parity was associated with asthma in women, its significance disappeared after adjustment. These results warrant future studies to explore the mechanisms responsible for the association between reproductive factors and asthma.

Eosinophil Count Is a Common Factor for Complex Metabolic and Pulmonary Traits and Diseases: The LifeLines Cohort Study

There is ongoing debate on the association between eosinophil count and diseases, as previous studies were inconsistent. We studied the relationship of eosinophil count with 22 complex metabolic, cardiac, and pulmonary traits and diseases. From the population-based LifeLines Cohort Study (N = 167,729), 13,301 individuals were included. We focused on relationship of eosinophil count with three classes of metabolic (7 traits, 2 diseases), cardiac (6 traits, 2 diseases), and pulmonary (2 traits, 2 diseases) outcomes. Regression analyses were applied in overall, women and men, while adjusted for age, sex, BMI and smoking. A p-value of <0.00076 was considered statistically significant. 58.2% of population were women (mean±SD 51.3±11.1 years old). In overall, one-SD higher of ln-eosinophil count was associated with a 0.04 (±SE ±0.002;p = 6.0×10⁻⁶) SD higher levels in ln-BMI, 0.06 (±0.007;p = 3.1×10⁻¹²) SD in ln-TG, 0.04 (±0.003;p = 7.0×10⁻⁶) SD in TC, 0.04 (±0.004;p = 6.3×10⁻⁷) SD in LDL, 0.04 (±0.006;p = 6.0×10⁻⁶) SD in HbA1c; and with a 0.05 (±0.004;p = 1.7×10⁻⁸) SD lower levels in HDL, 0.05 (±0.007;p = 3.4×10⁻²³) SD in FEV1, and 0.09 (±0.001;p = 6.6×10⁻²⁸) SD in FEV1/FVC. A higher ln-eosinophil count was associated with 1.18 (95%CI 1.09–1.28;p = 2.0×10⁻⁵) odds ratio of obesity, 1.29 (1.19–1.39;p = 1.1×10⁻¹⁰) of metabolic syndrome, 1.40 (1.25–1.56;p = 2.7×10⁻⁹) of COPD and 1.81 (1.61–2.03;p = 1.0×10⁻²³) of asthma. Similar results were found in women. We found no association between ln-eosinophil count either with blood pressure indices in overall, women and men; or with BMI, LDL, HbA1c and obesity in men. In a large population based cohort, we confirmed eosinophil count as a potential factor implicated in metabolic and pulmonary outcomes.

Asthma as a disruption in iron homeostasis

Over several decades, asthma has evolved from being recognized as a single disease to include a diverse group of phenotypes with dissimilar natural histories, pathophysiologies, responses to treatment, and distinctive molecular pathways. With the application of Occam's razor to asthma, it is proposed that there is one cause underlying the numerous phenotypes of this disease and that the responsible molecular pathway is a deficiency of iron in the lung tissues. This deficiency can be either absolute (e.g. asthma in the neonate and during both pregnancy and menstruation) or functional (e.g. asthma associated with infections, smoking, and obesity). Comparable associations between asthma co-morbidity (e.g. eczema, urticaria, restless leg syndrome, and pulmonary hypertension) with iron deficiency support such a shared mechanistic pathway. Therapies directed at asthma demonstrate a capacity to impact iron homeostasis, further strengthening the relationship. Finally, pathophysiologic events producing asthma, including inflammation, increases in Th2 cells, and muscle contraction, can correlate with iron availability. Recognition of a potential association between asthma and an absolute and/or functional iron deficiency suggests specific therapeutic interventions including inhaled iron.

Sex differences in asthma and gastroesophageal reflux disease incidence among the World Trade Center Health Program General Responder Cohort

BACKGROUND

Asthma and gastroesophageal reflux disease (GERD) are two common conditions among the responders to the WTC attacks. This study examined whether the cumulative incidence rates of asthma and GERD differed by sex among 24,022 and 23,557 WTC responders, respectively.

METHODS

Cox proportional hazards regression was used to examine the sex difference in the rate of onset of physician-diagnosed asthma or GERD, from 9/12/2001 through 12/31/2015.

RESULTS

The cumulative incidence of asthma reached 23% for women and 17% for men by the end of 2015, and the cumulative incidence of GERD reached 45% for women and 38% for men. Comparing women to men, the hazard ratio was 1.48 (95% confidence interval (CI): 1.27, 1.74) for asthma, and 1.25 (95% CI: 1.13, 1.38) for GERD.

CONCLUSIONS

WTC general responders have a substantial burden of asthma and GERD, with higher incidence in women. Am. J. Ind. Med. 59:815-822, 2016. © 2016 Wiley Periodicals, Inc.

Associations of wheezing phenotypes with late asthma outcomes in the Avon Longitudinal Study of Parents and Children: A population-based birth cohort

Background

Variable patterns of childhood wheezing might indicate differences in the cause and prognosis of respiratory illnesses. Better understanding of these patterns could facilitate identification of modifiable factors related to development of asthma.

Objectives

We characterized childhood wheezing phenotypes from infancy to adolescence and their associations with asthma outcomes.

Methods

Latent class analysis was used to derive phenotypes based on patterns of wheezing recorded at up to 14 time points from birth to 16½ years among 12,303 participants from the Avon Longitudinal Study of Parents and Children. Measures of lung function (FEV₁, forced vital capacity [FVC], and forced expiratory flow between 25% and 75% [FEF_25-75]) and fraction of exhaled nitric oxide (Feno) were made at 14 to 15 years of age.

Results

Six wheezing phenotypes were identified: never/infrequent, preschool-onset remitting, midchildhood-onset remitting, school age–onset persisting, late childhood–onset persisting, and continuous wheeze. The 3 persistent phenotypes were associated with bronchodilator reversibility of 12% or greater (BDR) from baseline (odds ratio [OR] range, 2.14-3.34), a Feno value of 35 ppb or greater (OR range, 3.82-6.24), and lung function decrements (mean range of differences: −0.22 to −0.27 SD units (SDU) for FEV₁/FVC ratio and −0.21 to −0.33 SDU for FEF_25-75) compared with never/infrequent wheeze. Midchildhood-onset (4½ years) remitting wheeze was associated with BDR (OR, 1.77; 95% CI, 1.11-2.82), a Feno value of 35 ppb or greater (OR, 1.72; 95% CI, 1.14-2.59), FEV₁/FVC ratio decrements (OR, −0.22 SDU; 95% CI, −0.36 to −0.08 SDU), and FEF_25-75 decrements (OR, −0.16 SDU; 95% CI, −0.30 to −0.01 SDU). Preschool-onset (18 months) remitting wheeze was only associated with FEV₁/FVC ratio decrements (OR, −0.15 SDU; 95% CI, −0.25 to −0.05 SDU) and FEF_25-75 decrements (OR, −0.14 SDU; 95% CI, −0.24 to −0.04 SDU). The persisting phenotypes showed evidence of sex stratification during adolescence.

Conclusions

Early childhood–onset wheezing that persists into adolescence represents the clearest target group for interventions to maximize lung function outcomes.

Prevalence and risk factors of asthma in First Nations children living on reserves in Canada

OBJECTIVES

To explore the prevalence and determine the risk factors of asthma in First Nations children aged 0 to 11 years living on reserves in Canada.

METHODS

In this cross-sectional study, we considered the data collected as part of the First Nations Regional Health Survey involving 6,657 children living in 238 First Nations communities in the 10 Canadian provinces, the Northwest Territories and the Yukon.

RESULTS

The overall prevalence of asthma that has lasted or is expected to last at least six months (ever-asthma) among children living on reserves was 14.6%: a prevalence of 12.9% among 0 to 4 year olds and 15.6% among 5 to 11 year olds. The prevalence of ever-asthma was greater among boys (16.1%) than girls (13.2%). Children from homes with two or more children aged less than 11 years and those who were engaged in daily physical activities were less likely to have a report of ever-asthma. Children from high-income families and smoke-free homes were more likely to have a report of ever-asthma. The association between allergy and ever-asthma was stronger in children with low birth weight. The association between chronic ear infections and ever-asthma was stronger in girls than boys.

CONCLUSIONS

The overall prevalence of ever-asthma and factors associated with ever-asthma in First Nations children living on reserves were similar to those reported for off-reserve Aboriginal children and non-Aboriginal Canadian children.

Roles of the Y chromosome genes in human cancers

Male and female differ genetically by their respective sex chromosome composition, that is, XY as male and XX as female. Although both X and Y chromosomes evolved from the same ancestor pair of autosomes, the Y chromosome harbors male-specific genes, which play pivotal roles in male sex determination, germ cell differentiation, and masculinization of various tissues. Deletions or translocation of the sex-determining gene, SRY, from the Y chromosome causes disorders of sex development (previously termed as an intersex condition) with dysgenic gonads. Failure of gonadal development results not only in infertility, but also in increased risks of germ cell tumor (GCT), such as gonadoblastoma and various types of testicular GCT. Recent studies demonstrate that either loss of Y chromosome or ectopic expression of Y chromosome genes is closely associated with various male-biased diseases, including selected somatic cancers. These observations suggest that the Y-linked genes are involved in male health and diseases in more frequently than expected. Although only a small number of protein-coding genes are present in the male-specific region of Y chromosome, the impacts of Y chromosome genes on human diseases are still largely unknown, due to lack of in vivo models and differences between the Y chromosomes of human and rodents. In this review, we highlight the involvement of selected Y chromosome genes in cancer development in men.

Stress and Androgen Activity During Fetal Development

Prenatal stress is known to alter hypothalamic-pituitary-adrenal axis activity, and more recent evidence suggests that it may also affect androgen activity. In animal models, prenatal stress disrupts the normal surge of testosterone in the developing male, whereas in females, associations differ by species. In humans, studies show that (1) associations between prenatal stress and child outcomes are often sex-dependent, (2) prenatal stress predicts several disorders with notable sex differences in prevalence, and (3) prenatal exposure to stressful life events may be associated with masculinized reproductive tract development and play behavior in girls. In this minireview, we examine the existing literature on prenatal stress and androgenic activity and present new, preliminary data indicating that prenatal stress may also modify associations between prenatal exposure to diethylhexyl phthalate, (a synthetic, antiandrogenic chemical) and reproductive development in infant boys. Taken together, these data support the hypothesis that prenatal exposure to both chemical and nonchemical stressors may alter sex steroid pathways in the maternal-placental-fetal unit and ultimately alter hormone-dependent developmental endpoints.

Age-of-asthma onset as a determinant of different asthma phenotypes in adults: a systematic review and meta-analysis of the literature

Age-of-asthma onset is often used to distinguish different adult asthma phenotypes; however, similarities and differences between early- and late-onset adult asthma have not been summarized to date. Of the 2921 records found, we identified 12 studies comparing early- and late-onset current asthma in adults. Age 12 was most commonly used to delineate the two age-of-onset phenotypes. Adults with early-onset current asthma were more likely to be atopic and had a higher frequency of asthma attacks, whereas adults with late-onset disease were more likely to be female, smokers and had greater levels of spirometrically defined fixed airflow obstruction. The prevalence of severe asthma was similar in both groups, and, in general, there were few phenotypic differences between severe asthmatics regardless of age of onset. Findings for several key characteristics, including lung function, were inconsistent between studies. Overall, there appears to be distinctive phenotypic differences with age of asthma onset. Although early-onset adult asthma is likely more attributable to atopy and potentially genetic factors, late-onset adult asthma appears to be more related to environmental risk factors, and so may be better targeted by preventive strategies. More detailed research is required to better characterize these phenotypes and to clarify potential clinical implications.

Relationships among obesity, physical activity and sedentary behavior in young adolescents with and without lifetime asthma

OBJECTIVE

To examine the inter-relationships among body mass index (BMI), physical activity, sedentary behavior and gender in urban, low-income, primarily African American young adolescents with or without lifetime asthma.

METHODS

Data were collected in 2002-2004 from 626 12-year old adolescents who were children of women who participated in the New Mother's Study in Memphis, TN (1990-1991). Adolescents with and without asthma were compared on BMI, physical activity and sedentary behavior. Multiple linear regression models were used to examine the association of asthma, gender and BMI with physical activity and sedentary behavior.

RESULTS

Complete data were available for 545 adolescents. Eleven percent of adolescents had lifetime asthma. Asthma and gender were associated with high-intensity physical activity (p < 0.001). Adolescents with asthma participated in less physical activity and girls participated less than boys. Gender was associated with sedentary behavior (p < 0.001): boys used personal computer (pc)/video after school more than girls. Girls with asthma had a higher BMI than girls without asthma (p = 0.027). Boys with asthma were less physically active than boys without asthma (p < 0.05).

CONCLUSIONS

Adolescents with asthma are less physically active than those without asthma and girls are less active than boys. Clinicians who provide care for adolescents with asthma are encouraged to assess physical activity/sedentary behavior and provide guidance that promotes active lifestyles. A longitudinal study is needed to shed light on the unique contribution of asthma separated from the effects of overweight/obesity on physical activity and sedentary behaviors.

The influence of childhood asthma on puberty and height in Swedish adolescents

BACKGROUND

Evidence relating to the effect of asthma on puberty or height is inconclusive. We aimed to examine whether the exposure of childhood asthma, including timing and phenotypes, and inhaled corticosteroid (ICS) use is either cross-sectionally or longitudinally associated with the outcomes of pubertal staging or height.

METHODS

This study employed data from a longitudinal, population-based cohort of Swedish children (born 1994-1996). At ages 1, 2, 4, 8, and 12 years, parent-reported data on asthma and ICS use in the previous 12 months were collected. At 8 and 12 years, height was ascertained at a clinical visit, and child-reported, respectively. At 12 years, children answered puberty-related questions.

RESULTS

Retention through 12 years was 82% (3366/4089). Participants without puberty data (n = 620) were excluded, yielding a study population of 2746 (67%). Asthma at 8 years, including timing of onset and phenotypes, was not statistically significantly associated with pubertal staging in adjusted models. Children with asthma averaged 0.93 cm (95% CI 0.35-1.50) shorter than children without asthma. Children with asthma using ICS were 1.28 (95% CI 0.62-1.95) shorter than those with asthma without using ICS.

CONCLUSIONS

We found no consistent association between asthma and pubertal staging. Children with asthma were shorter than those without asthma. Moreover, children with asthma using ICS were shorter than those not using ICS.

Gender differences in the perception of asthma and respiratory symptoms in a population sample of asthma patients in four Brazilian cities

OBJECTIVE

To evaluate the impact of asthma, by gender, in a population sample of asthma patients in Brazil.

METHODS

We conducted face-to-face interviews with 400 subjects (> 12 years of age) included in a national probability telephone sample of asthma patients in the Brazilian state capitals of São Paulo, Rio de Janeiro, Curitiba, and Salvador. Each of those 400 subjects completed a 53-item questionnaire that addressed five asthma domains: symptoms; impact of asthma on quality of life; perception of asthma control; exacerbations; and treatment/medication.

RESULTS

Of the 400 patients interviewed, 272 (68%) were female. In relation to respiratory symptoms, the proportion of women reporting extremely bothersome symptoms (cough with sputum, tightness in the chest, cough/shortness of breath/tightness in the chest during exercise, nocturnal shortness of breath, and nocturnal cough) was greater than was that of men. Daytime symptoms, such as cough, shortness of breath, wheezing, and tightness in the chest, were more common among women than among men. Women also more often reported that their asthma interfered with normal physical exertion, social activities, sleep, and life in general. Regarding the impact of asthma on quality of life, the proportion of subjects who reported that asthma caused them to feel that they had no control over their lives and affected the way that they felt about themselves was also greater among women than among men.

CONCLUSIONS

Among women, asthma tends to be more symptomatic, as well as having a more pronounced effect on activities of daily living and on quality of life.

Gender differences in adult-onset asthma: results from the Swiss SAPALDIA cohort study

A higher incidence of asthma is reported in women compared with men, but evidence in later adulthood is limited. We aimed to determine the 20-year cumulative incidence of adult asthma in Switzerland and its relation to sex, taking into account age and allergic sensitisation.We assessed incidence of self-report of doctor-diagnosed asthma between 1991/1992 and 2010/2011 in 5128 subjects without asthma, aged 18-60 years at baseline. The age-related probability of asthma onset was analysed by logistic regression adjusting for potential confounders and stratified by sex and allergic sensitisation at baseline.Over 20 years, 128 (5.1%) men and 198 (7.5%) women newly reported doctor-diagnosed asthma. The adjusted odds ratio for female sex was 1.99 (95% CI 1.54-2.57) overall, 3.21 (95% CI 2.12-4.85) among nonsensitised subjects, and 1.43 (95% CI 1.02-2.02) in sensitised subjects. The probability of asthma onset decreased with increasing baseline age in women but not in men. The higher probability of new asthma in sensitised compared with nonsensitised men was unrelated to age, whereas in women it decreased with age.Asthma incidence was higher in women than in men but decreased with increasing age. The female predominance was considerably stronger in nonsensitised adults compared with those with allergic sensitisation.

Women and Lung Disease. Sex Differences and Global Health Disparities

There is growing evidence that a number of pulmonary diseases affect women differently and with a greater degree of severity than men. The causes for such sex disparity is the focus of this Blue Conference Perspective review, which explores basic cellular and molecular mechanisms, life stages, and clinical outcomes based on environmental, sociocultural, occupational, and infectious scenarios, as well as medical health beliefs. Owing to the breadth of issues related to women and lung disease, we present examples of both basic and clinical concepts that may be the cause for pulmonary disease disparity in women. These examples include those diseases that predominantly affect women, as well as the rising incidence among women for diseases traditionally occurring in men, such as chronic obstructive pulmonary disease. Sociocultural implications of pulmonary disease attributable to biomass burning and infectious diseases among women in low- to middle-income countries are reviewed, as are disparities in respiratory health among sexual minority women in high-income countries. The implications of the use of complementary and alternative medicine by women to influence respiratory disease are examined, and future directions for research on women and respiratory health are provided.

Human trachealis and main bronchi smooth muscle are normoresponsive in asthma

RATIONALE

Airway smooth muscle (ASM) plays a key role in airway hyperresponsiveness (AHR) but it is unclear whether its contractility is intrinsically changed in asthma.

OBJECTIVES

To investigate whether key parameters of ASM contractility are altered in subjects with asthma.

METHODS

Human trachea and main bronchi were dissected free of epithelium and connective tissues and suspended in a force-length measurement set-up. After equilibration each tissue underwent a series of protocols to assess its methacholine dose-response relationship, shortening velocity, and response to length oscillations equivalent to tidal breathing and deep inspirations.

MEASUREMENTS AND MAIN RESULTS

Main bronchi and tracheal ASM were significantly hyposensitive in subjects with asthma compared with control subjects. Trachea and main bronchi did not show significant differences in reactivity to methacholine and unloaded tissue shortening velocity (Vmax) compared with control subjects. There were no significant differences in responses to deep inspiration, with or without superimposed tidal breathing oscillations. No significant correlations were found between age, body mass index, or sex and sensitivity, reactivity, or Vmax.

CONCLUSIONS

Our data show that, in contrast to some animal models of AHR, human tracheal and main bronchial smooth muscle contractility is not increased in asthma. Specifically, our results indicate that it is highly unlikely that ASM half-maximum effective concentration (EC50) or Vmax contribute to AHR in asthma, but, because of high variability, we cannot conclude whether or not asthmatic ASM is hyperreactive.

Hormonal factors and incident asthma and allergic rhinitis during puberty in girls

BACKGROUND

Accumulating evidence is indicating that hormonal factors play a role in new-onset allergic rhinitis and asthma after puberty.

OBJECTIVE

To determine whether age at menarche and use of hormonal contraceptives predict new-onset allergic rhinitis and asthma after puberty in young German women.

METHODS

A prospective community-based cohort study followed 1,191 girls 9 to 11 years old to early adulthood (19-24 years old). Self-administrated questionnaires concerning age at menarche, use of hormonal contraceptives, and status and age at onset of physician-diagnosed allergic rhinitis and asthma were collected at 16 to 18 and 19 to 24 years of age. Logistic regression models were used to analyze the incidence of asthma and allergic rhinitis after puberty and pooled estimates were obtained from the final model.

RESULTS

Eleven percent of girls developed allergic rhinitis after menarche and 3% reported new-onset asthma. Late menarche (>13 years of age) was statistically significantly inversely related to allergic rhinitis (adjusted odds ratio [OR] 0.32, 95% confidence interval [CI] 0.14-0.74) but did not reach the level of statistical significance for asthma (OR 0.32, 95% CI 0.07-1.42). Use of hormonal contraceptives was inversely associated with new-onset allergic rhinitis (OR 0.14, 95% CI 0.08-0.23) and asthma (OR 0.27, 95% CI 0.12-0.58) after puberty.

CONCLUSION

This study shows that girls with late onset of menarche are less likely to develop allergic rhinitis after puberty compared with those who have menarche at an average age. These findings also suggest that, in addition to endogenous hormones, hormonal contraceptives play a role and might protect young women from allergies and asthma.

Epidemiology and economic burden of asthma

BACKGROUND

The "asthma epidemic" is on the rise, with the Center for Disease Control (CDC) epidemiological studies reporting a 3.0% asthma prevalence in the United States in 1970, 5.5% in 1996, and 7.8% in 2006 to 2008. This results in an immense economic burden, with asthma costing an estimated $56 billion in the United States in 2007, which is a 6% increase from the $53 billion that was spent in 2002.

METHODS

A review of the current literature and CDC reports were used to thoroughly examine and summarize the epidemiology and economic burden of asthma domestically and globally.

RESULTS

Asthma shows a male predominance before puberty, and a female predominance in adulthood. Studies show Puerto Ricans to be the most commonly affected ethnicity, and a higher prevalence of asthma is found in lower income populations. Asthma is related to some of the more common otolaryngologic diseases such as allergy and obstructive sleep apnea. The condition results in significant morbidity, such as an increase in emergency department visits and a decrease in productivity due to missed school and works days.

CONCLUSION

Epidemiological statistics report an undisputable increase of asthma both domestically and worldwide, which means the economic burden of this disease is also on the rise. Better access to healthcare, improved asthma education, and bridging the gap between ethnic and racial disparities in the treatment and management of asthma may help to control this epidemic, promote better outcomes, and prevent continued rising costs related to the management of this widespread disease.

Updated prevalences of asthma, allergy, and airway symptoms, and a systematic review of trends over time for childhood asthma in Shanghai, China

BACKGROUND

The prevalence of asthma among Shanghai children has increased over time. This increase might be associated with changes in environmental exposures. Investigation of the time-trend of asthma and current prevalences is essential to understanding the causes.

OBJECTIVE

To estimate the current prevalences of asthma, allergies and other respiratory symptoms among Shanghai preschool children, and to investigate the time-trend of childhood asthma prevalence of from 1990 to 2011.

METHODS

From April 2011 to April 2012, the CCHH (China, Children, Homes, Health) cross-sectional study was conducted in Shanghai. Questionnaires were distributed to 17,898 parents or guardians of preschool children from 72 kindergartens in 5 districts. Previous similar studies were also summarized by a systematic literature review.

RESULTS

From a total of 14,884 questionnaires for 3-7 year old children, prevalences of the following diseases and symptoms were calculated: asthma 10.2%, wheeze (ever) 28.1%, pneumonia (ever) 33.5%, otitis media 11.0%, rhinitis (ever) 54.1%, hay fever 12.2%, eczema (ever) 22.7%, and food allergy 15.7%. Urban children had higher prevalences of most symptoms than suburban children. The prevalence of asthma has increased significantly, almost five-fold, from 2.1% in 1990 to 10.2% in the present study. The prevalence of asthma in boys was higher than in girls in the present study and in all reviewed studies.

CONCLUSIONS

Asthma, allergy and airway symptoms are common among preschool children in Shanghai. The prevalence of childhood asthma in Shanghai has increased rapidly from 1990 to 2011.

Evaluation of sexual dimorphism in the efficacy and safety of simvastatin/atorvastatin therapy in a southern Brazilian cohort

BACKGROUND

Dyslipidemia is the primary risk factor for cardiovascular disease, and statins have been effective in controlling lipid levels. Sex differences in the pharmacokinetics and pharmacodynamics of statins contribute to interindividual variations in drug efficacy and toxicity.

OBJECTIVE

To evaluate the presence of sexual dimorphism in the efficacy and safety of simvastatin/atorvastatin treatment.

METHODS

Lipid levels of 495 patients (331 women and 164 men) were measured at baseline and after 6 ± 3 months of simvastatin/atorvastatin treatment to assess the efficacy and safety profiles of both drugs.

RESULTS

Women had higher baseline levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) compared with men (p < 0.0001). After treatment, women exhibited a greater decrease in plasma TC and LDL-C levels compared with men. After adjustment for covariates, baseline levels of TC and LDL-C influenced more than 30% of the efficacy of lipid-lowering therapy (p < 0.001), regardless of sex. Myalgia [with or without changes in creatine phosphokinase (CPK) levels] occurred more frequently in women (25.9%; p = 0.002), whereas an increase in CPK and/or abnormal liver function was more frequent in in men (17.9%; p = 0.017).

CONCLUSIONS

Our results show that baseline TC and LDL-C levels are the main predictors of simvastatin/atorvastatin therapy efficacy, regardless of sex. In addition, they suggest the presence of sexual dimorphism in the safety of simvastatin/atorvastatin. The effect of sex differences on receptors, transporter proteins, and gene expression pathways needs to be better evaluated and characterized to confirm these observations.

X-inactivation informs variance-based testing for X-linked association of a quantitative trait

Background

The X chromosome plays an important role in human diseases and traits. However, few X-linked associations have been reported in genome-wide association studies, partly due to analytical complications and low statistical power.

Results

In this study, we propose tests of X-linked association that capitalize on variance heterogeneity caused by various factors, predominantly the process of X-inactivation. In the presence of X-inactivation, the expression of one copy of the chromosome is randomly silenced. Due to the consequent elevated randomness of expressed variants, females that are heterozygotes for a quantitative trait locus might exhibit higher phenotypic variance for that trait. We propose three tests that build on this phenomenon: 1) A test for inflated variance in heterozygous females; 2) A weighted association test; and 3) A combined test. Test 1 captures the novel signal proposed herein by directly testing for higher phenotypic variance of heterozygous than homozygous females. As a test of variance it is generally less powerful than standard tests of association that consider means, which is supported by extensive simulations. Test 2 is similar to a standard association test in considering the phenotypic mean, but differs by accounting for (rather than testing) the variance heterogeneity. As expected in light of X-inactivation, this test is slightly more powerful than a standard association test. Finally, test 3 further improves power by combining the results of the first two tests. We applied the these tests to the ARIC cohort data and identified a novel X-linked association near gene AFF2 with blood pressure, which was not significant based on standard association testing of mean blood pressure.

Conclusions

Variance-based tests examine overdispersion, thereby providing a complementary type of signal to a standard association test. Our results point to the potential to improve power of detecting X-linked associations in the presence of variance heterogeneity.

Urban-rural differences in asthma prevalence among young adolescents: The role of behavioural and environmental factors

BACKGROUND

Asthma prevalence has been reported to be lower in rural areas compared to urban areas, although this has been inconsistent. This study aims to identify the influence of urban-rural residence on asthma prevalence in adolescents in the Republic of Macedonia and to investigate characteristics that may explain observed associations.

METHODS

Following International Study of Asthma and Allergies in Childhood protocol, a national sample of Macedonian urban and rural dwelling adolescents (12-16 years) was recruited in 2006. Self-completed questionnaires were used to collect data on wheeze and asthma as well as personal, environmental and dietary characteristics. Following descriptive and multiple logistic regression analyses, a mediation analysis approach was performed to help explain observed associations.

RESULTS

A lower prevalence of current wheeze and ever-diagnosed asthma was observed in rural compared to urban dwelling adolescents (4.9% vs. 7.2% and 1.2% vs. 1.9%, respectively). After adjustment for potential confounders, the associations, although still protective, were not statistically significant (wheeze: OR=0.74, 95%CI=0.46-1.21; asthma: OR=0.97, 95%CI=0.38-2.46). The associations between urban-rural status with current wheeze and asthma were mediated by region of the country (wheeze 9%; asthma 19%) and by diet (>5% change for both wheeze and asthma). Having a dog resulted in a strengthening of the association between urban-rural status and current wheeze by 11.9%.

CONCLUSIONS

The prevalence of asthma and wheeze was lower in rural dwelling Macedonian adolescents and the association was mediated by the region of the country with diet likely to be part of the reason for this mediating effect.

Children hospitalised with bronchiolitis in the first year of life have a lower quality of life nine months later

AIM

Acute bronchiolitis increases the risk of asthma, and reduced quality of life (QoL) is reported in children with asthma and allergy. However, the impact of asthma risk factors on QoL is unclear. This study investigated whether bronchiolitis and common asthma risk factors in infancy had an influence on later QoL.

METHODS

The parents of 209 infants recruited during hospitalisation for bronchiolitis at a mean age of 4 months, and 206 controls responded to the generic Infant Toddler Quality of Life Questionnaire 9 months later. We used robust regression analyses to assess the association between four asthma risk factors, atopic eczema, parental asthma, parental allergic rhinoconjunctivitis and second-hand smoke and QoL in the two groups.

RESULTS

QoL was lower among children with previous bronchiolitis in the overall health and general health domains and lower in six of 13 domains in children with atopic eczema. Compared with no risk factors, children with previous bronchiolitis and three risk factors had lower scores in four domains, and control children with three risk factors had lower scores in three domains.

CONCLUSION

Having acute bronchiolitis, atopic eczema and three asthma risk factors were negatively associated with later QoL in early childhood.

Bisphenol A exposure and asthma development in school-age children: a longitudinal study

BACKGROUND

Although the effect of bisphenol A on various health outcomes has been extensively examined, few studies have investigated its effect on asthma.

OBJECTIVE

We hypothesized that exposure to bisphenol A in school-age children was associated with wheezing and asthma.

METHODS

Participants included 127 children aged 7-8 years without a previous asthma diagnosis in an elementary school in Seoul, Korea. Three surveys were conducted, each 2 years apart. Bisphenol A concentration was measured at the baseline survey, and PC20, which is defined as the methacholine concentration that induces a decrease in FEV1 of 20% from baseline, was measured at every survey. Associations between bisphenol A concentration at 7-8 years of age and wheezing, asthma, and PC20 at ages up to 11-12 years were examined using generalized estimating equations, a marginal Cox regression model, and a linear mixed model.

RESULTS

The log-transformed creatinine-adjusted urinary bisphenol A concentration at 7-8 years was positively associated with wheezing (odds ratio, 2.48; 95% confidence interval, 1.15-5.31; P = .02) and asthma (hazard ratio, 2.13; 95% confidence interval, 1.51-3.00; P<.001) at ages up to 11-12 years. Bisphenol A was also negatively associated with PC20 (ß = -2.33; P = .02). When stratified by sex, the association between bisphenol A and asthma remained significant only in girls (hazard ratio, 2.45; 95% confidence interval, 2.18-2.76; P<.001).

CONCLUSION

Increased urinary bisphenol A concentrations at 7-8 years old were positively associated with wheezing and asthma and negatively associated with PC20 at ages up to 11-12 years.

Oral contraceptives modify the effect of GATA3 polymorphisms on the risk of asthma at the age of 18 years via DNA methylation

BACKGROUND

The prevalence of asthma in girls increases after puberty. Previous studies have detected associations between sex hormones and asthma, as well as between sex hormones and T helper 2 (Th2) asthma-typical immune responses. Therefore, we hypothesized that exogenous or endogenous sex hormone exposure (represented by oral contraceptive pill (OCP) use and early menarche, respectively) are associated with DNA methylation (DNA-M) of the Th2 transcription factor gene, GATA3, in turn affecting the risk of asthma in girls, possibly in interaction with genetic variants. Blood samples were collected from 245 female participants aged 18 years randomly selected for methylation analysis from the Isle of Wight birth cohort, UK. Information on use of OCPs, age at menarche, and concurrent asthma were assessed by questionnaire. Genome-wide DNA-M was determined using the Illumina Infinium HumanMethylation450 beadchip. In a first stage, we tested the interaction between sex hormone exposure and genetic variants on DNA-M of specific cytosine-phosphate-guanine (CpG) sites. In a second stage, we determined whether these CpG sites interact with genetic variants in GATA3 to explain the risk of asthma.

RESULTS

Interactions between OCP use and seven single nucleotide polymorphisms (SNPs) of GATA3 were analyzed for 14 CpG sites (stage 1). The interaction between OCP use and SNP rs1269486 was found to be associated with the methylation level of cg17124583 (P = 0.002, false discovery rate (FDR) adjusted P = 0.04). DNA-M of this same CpG site was also influenced by the interaction between age at menarche and rs1269486 (P = 0.0017). In stage 2, we found that cg17124583 modified the association of SNP rs422628 with asthma risk at the age of 18 years (P = 0.006, FDR adjusted P = 0.04). Subjects with genotype AG showed an increase in average risk ratio (RR) from 0.31 (95% CI: 0.10 to 0.8) to 11.65 (95% CI: 1.71 to 79.5) when methylation level increased from 0.02 to 0.12, relative to genotype AA.

CONCLUSION

A two-stage model consisting of genetic variants in the GATA3 gene, OCP use, age at menarche, and DNA-M may explain how sex hormones in women can increase the asthma prevalence after puberty.

Modelling survival and mortality risk to 15 years of age for a national cohort of children with serious congenital heart defects diagnosed in infancy

BACKGROUND

Congenital heart defects (CHDs) are a significant cause of death in infancy. Although contemporary management ensures that 80% of affected children reach adulthood, post-infant mortality and factors associated with death during childhood are not well-characterised. Using data from a UK-wide multicentre birth cohort of children with serious CHDs, we observed survival and investigated independent predictors of mortality up to age 15 years.

METHODS

Data were extracted retrospectively from hospital records and death certificates of 3,897 children (57% boys) in a prospectively identified cohort, born 1992-1995 with CHDs requiring intervention or resulting in death before age one year. A discrete-time survival model accounted for time-varying predictors; hazards ratios were estimated for mortality. Incomplete data were addressed through multilevel multiple imputation.

FINDINGS

By age 15 years, 932 children had died; 144 died without any procedure. Survival to one year was 79.8% (95% confidence intervals [CI] 78.5, 81.1%) and to 15 years was 71.7% (63.9, 73.4%), with variation by cardiac diagnosis. Importantly, 20% of cohort deaths occurred after age one year. Models using imputed data (including all children from birth) demonstrated higher mortality risk as independently associated with cardiac diagnosis, female sex, preterm birth, having additional cardiac defects or non-cardiac malformations. In models excluding children who had no procedure, additional predictors of higher mortality were younger age at first procedure, lower weight or height, longer cardiopulmonary bypass or circulatory arrest duration, and peri-procedural complications; non-cardiac malformations were no longer significant.

INTERPRETATION

We confirm the high mortality risk associated with CHDs in the first year of life and demonstrate an important persisting risk of death throughout childhood. Late mortality may be underestimated by procedure-based audit focusing on shorter-term surgical outcomes. National monitoring systems should emphasise the importance of routinely capturing longer-term survival and exploring the mechanisms of mortality risk in children with serious CHDs.

Androgens are bronchoactive drugs that act by relaxing airway smooth muscle and preventing bronchospasm

Changes in the androgen levels in asthmatic men may be associated with the severity of asthma. Androgens induce a nongenomic relaxation in airway smooth muscle, but the underlying mechanisms remain unclear. The aim of this study was to investigate the potential bronchorelaxing action of testosterone (TES) and its metabolites (5α- and 5β-dihydrotestosterone (DHT). A preventive effect on ovalbumin (OVA)-induced bronchospasm was observed in sensitized guinea pigs for each androgen. Androgens were studied in response to bronchoconstrictors: carbachol (CCh) and KCl in isolated trachea rings with and without epithelium from non-sensitized and sensitized animals as well as on OVA-induced contraction. Androgens concentration-dependently abolished the contraction in response to CCh, KCl, and OVA. There were significant differences in the sensitivity to the relaxation induced by each androgen. 5β-DHT was more potent for relaxing KCl-induced contraction, while TES and 5α-DHT were more potent for CCh- and OVA-induced contraction. No differences were found in preparations with and without epithelium or in the presence of a nitric oxide (NO) synthase inhibitor or an inhibitor of K(+) channels. These data indicate the absence of involvement of the epithelium-, NO- and K(+) channels-dependent pathway in androgen-induced relaxation. However, in dissociated tracheal myocytes loaded with the calcium-binding fluorescent dye Fura -2, physiological concentrations of androgens decreased the KCl-induced [Ca(2+)]i increment. 5β-DHT was the most potent at decreasing KCl-induced [Ca(2+)]i increment and preventing bronchospasm. We suggest that androgen-induced brochorelaxation was mediated via decreased Ca(2+) influx through L-type Ca(2+)channels but additional Ca(2+) entry blockade may be involved. Molecular changes in androgen structure may determine its preferential site of action.

Parity, age at first birth, and risk of death from asthma: evidence from a cohort in taiwan

This study was undertaken to examine whether there is an association between age at first birth and parity and risk of asthma death. The study cohort consisted of 1,292,462 women in Taiwan who had a first live birth between 1 January 1978 and 31 December 1987. We tracked each woman from the date of their first childbirth to 31 December 2009, and their vital status was ascertained by linking records with the computerized mortality database. Cox proportional hazard regression models were used to estimate hazard ratios of death from asthma associated with parity and age at first birth. A trend of increasing risk of asthma death was seen with increasing age at first birth. The adjusted hazard ratio was 0.75 (95% confidence interval (CI) = 0.53–1.08) among women with two live births and 0.53 (95% CI = 0.36–0.78) among those with three or more births, compared with women who had one live birth. There was a significant decreasing trend in adjusted hazard ratios of asthma death with increasing parity. This study is the first to provide evidences to support an association between reproductive factors (parity and early age at first birth) and the risk of asthma death.

DNA methylation of the allergy regulatory gene interferon gamma varies by age, sex, and tissue type in asthmatics

Background

Asthma is associated with allergic sensitization in about half of all cases, and asthma phenotypes can vary by age and sex. DNA methylation in the promoter of the allergy regulatory gene interferon gamma (IFNγ) has been linked to the maintenance of allergic immune function in human cell and mouse models. We hypothesized that IFNγ promoter methylation at two well-studied, key cytosine phosphate guanine (CpG) sites (-186 and -54), may differ by age, sex, and airway versus systemic tissue in a cohort of 74 allergic asthmatics.

Results

After sampling buccal cells, a surrogate for airway epithelial cells, and CD4+ lymphocytes, we found that CD4+ lymphocyte methylation was significantly higher in children compared to adults at both CpG sites (P <0.01). Buccal cell methylation was significantly higher in children at CpG -186 (P = 0.03) but not CpG -54 (P = 0.66). Methylation was higher in males compared to females at both CpG sites in CD4+ lymphocytes (-186: P <0.01, -54: P = 0.02) but not buccal cells (-186: P = 0.14, -54: P = 0.60). In addition, methylation was lower in CD4+ lymphocytes compared to buccal cells (P <0.01) and neighboring CpG sites were strongly correlated in CD4+ lymphocytes (r = 0.84, P <0.01) and weakly correlated in buccal cells (r = 0.24, P = 0.04). At CpG -186, there was significant correlation between CD4+ lymphocytes and buccal cells (r = 0.24, P = 0.04) but not at CpG -54 (r = -0.03, P = 0.78).

Conclusions

These findings highlight significant age, sex, and tissue-related differences in IFNγ promoter methylation that further our understanding of methylation in the allergic asthma pathway and in the application of biomarkers in clinical research.