Prevalence and severity of asthma, rhinitis, and atopic eczema in 13- to 14-year-old schoolchildren from southern Brazil

Matters of life and death: How estrogen and estrogen receptor binding to the immunoglobulin heavy chain locus may influence outcomes of infection, allergy, and autoimmune disease

Sex hormones are best known for their influences on reproduction, but they also have profound influences on the immune response. Examples of sex-specific differences include: (i) the relatively poor control of influenza virus infections in males compared to females, (ii) allergic asthma, an IgE-associated hypersensitivity reaction that is exacerbated in adolescent females compared to males, and (iii) systemic lupus erythematosus, a life-threatening autoimmune disease with a 9:1 female:male bias. Here we consider how estrogen and estrogen receptor α (ERα) may influence the immune response by modifying class switch recombination (CSR) and immunoglobulin expression patterns. We focus on ERα binding to enhancers (Eμ and the 3' regulatory region) and switch sites (Sµ and Sε) in the immunoglobulin heavy chain locus. Our preliminary data from ChIP-seq analyses of purified, activated B cells show estrogen-mediated changes in the positioning of ERα binding within and near Sµ and Sε. In the presence of estrogen, ERα is bound not only to estrogen response elements (ERE), but also to adenosine-cytidine (AC)-repeats and poly adenosine (poly A) sequences, in some cases within constant region gene introns. We propose that by binding these sites, estrogen and ERα directly participate in the DNA loop formation required for CSR. We further suggest that estrogen regulates immunoglobulin expression patterns and can thereby influence life-and-death outcomes of infection, hypersensitivity, and autoimmune disease.

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.

Environmental tobacco smoke and the risk of eczema symptoms among school children in South Africa: a cross-sectional study

OBJECTIVE

The aim of this study was to investigate the association between eczema ever (EE) and current eczema symptoms (ES) in relation to exposure to environmental tobacco smoke (ETS).

DESIGN

A cross-sectional study using the International Study of Asthma and Allergies in Childhood questionnaire.

SETTING

16 schools were randomly selected from two neighbourhoods situated in Ekurhuleni Metropolitan Municipality, Gauteng Province, South Africa.

PARTICIPANTS

From a total population of 3764 school children aged 12-14 years, 3468 completed the questionnaire (92% response rate). A total of 3424 questionnaires were included in the final data analysis.

PRIMARY OUTCOME

The prevalence of EE and current ES was the primary outcome in this study.

RESULTS

Data were analysed using Multilevel Logistic Regression Analysis (MLRA). The likelihood of EE was increased by exposure to ETS at home (OR 1.30 95% CI 1.01 to 1.67) and at school (OR 1.26 95% CI 1.00 to 1.60). The likelihood of EE was lower for males (OR 0.66 95% CI 0.51 to 0.84). The likelihood of ES was increased by ETS at home (OR 1.93 95% CI 1.43 to 2.59) and school (1.44 95% CI 1.09 to 1.90). The likelihood of ES was again lower for males (OR 0.56 95% CI 0.42 to 0.76). Smoking by mother/female guardian increased the likelihood of EE and ES, however, this was not significant in the multivariate analysis.

CONCLUSIONS

Symptoms of eczema were positively associated with exposure to ETS at home and school. The results support the hypothesis that ETS is an important factor in understanding the occurrence of eczema.

Asthma and Rhinitis in South America: How Different They are From Other Parts of the World

Asthma and rhinitis epidemiology has wide variations around the world. The aim of this review was verify the prevalence of asthma and rhinitis in South America and report differences from other regions of the world. We reviewed studies with International Study of Asthma and Allergies in Childhood (ISAAC) methodology in South America, Phases I and III. In South America the ISAAC Phase I ranked four countries among top ten in prevalence of asthma and three countries among top ten in prevalence of rhinoconjunctivitis. ISAAC Phase III showed little changes in asthma and rhinitis prevalence in South American countries. The prevalence increases of asthma and rhinitis in South American centers indicate that the burden of both is continuing to rise, but the differences in prevalence are lessening.