Gene-environment interactions in asthma and allergic diseases: challenges and perspectives

Influence of household pet ownership and filaggrin loss-of-function mutations on eczema prevalence in children: A birth cohort study

BACKGROUND

The association between pet exposure in infancy, early childhood eczema, and FLG mutations remains unclear.

METHODS

This was a birth cohort study performed in Tokyo, Japan. The primary outcome was current eczema based on questionnaire responses collected repeatedly from birth to 5 years of age. Generalized estimating equations and generalized linear modeling were used to evaluate the association.

RESULTS

Data from 1448 participants were used for analyses. Household dog ownership during gestation, early infancy, and 18 months of age significantly reduced the risk of current eczema. Household cat ownership also reduced the risk of current eczema, albeit without statistical significance. The combined evaluation of children from households with pets, be it cats, dogs or both, the risk of current eczema at 1-5 years of age was lower in those with household pet exposure ownership during gestation (RR = 0.59, 95 % CI 0.45-0.77) and at 6 months (RR = 0.49, 95 % CI 0.36-0.68). , Reduced risks of eczema were also observed at 2-5 (RR = 0.52, 95 % CI 0.37-0.73) and 3-5 years of age (RR = 0.50 95 % CI 0.35-0.74) when the respective household pet ownership were evaluated at 18 months and 3 years of age. These protective associations of reduced risk of eczema were only observed in children without FLG mutations.

CONCLUSIONS

Household dog and pet (dog, cat, or both) ownership was protective against early childhood eczema in a birth cohort dataset. This protective association was observed only in children without FLG mutations, which should be confirmed in studies with larger cohorts.

Research on the Mechanism and Application of Acupuncture Therapy for Asthma: A Review

Asthma is a high-risk disease based on airway hyperresponsiveness (AHR). In this review, we found that there are many studies on clinical therapy for asthma that focus on the efficacy of acupuncture therapy and its mechanisms, including the functional connectivity of different brain regions, with the aid of functional magnetic resonance imaging (fMRI), immune responses/cell recognition (innate lymphoid cells and balance of Th1/Th2 and Treg/Th17), intracellular mechanism (autophagy, endoplasmic reticulum stress, and epigenetic alteration), and ligand-receptor/chemical signaling pathway (neurotransmitter, hormone, and small molecules). In this review, we summarized the clinical and experimental evidence for the mechanisms of acupuncture therapy in asthma to offer insights into drug discovery and clinical therapy. Given the paucity of clinical studies on the mechanisms of acupuncture in the treatment of asthma, this review notably included studies based on animal models to investigate the mechanisms of acupuncture in the treatment of asthma.

The Impact of Air Pollution on Asthma Severity among Residents Living near the Main Industrial Complex in Oman: A Cross-Sectional Study

BACKGROUND

Asthma is a widespread chronic respiratory disease that poses a significant public health challenge. The current study investigated the associations between air pollution and asthma severity among individuals residing near the Sohar industrial port (SIP) in Oman. Despite the presence of multiple major industrial complexes in Oman, limited knowledge regarding their impact on respiratory health is accredited. Hence, the primary objective of this study is to offer valuable insights into the respiratory health consequences of industrial air pollution in Al Batinah North.

METHODS

The state health clinics' records for patient visits related to asthma were collected for the timeframe spanning 2014 to 2022. Exposure was defined as the distance from the SIP, Majan Industerial Area (MIA), and Sohar Industerial Zone (SIZ) to determine high-, intermediate-, and low-exposure zones (<6 km, 6-12 km and >12 km, respectively). Exposure effect modifications by age, gender, and smoking status were also examined.

RESULTS

The conducted cross-sectional study of 410 patients (46.1% males and 53.9% females) living in over 17 areas around SIP revealed that 73.2% of asthmatics were under 50 years old, with severity significantly associated with closeness to the port. Risk ratios were estimated to be (RR:2.42; CI95%: 1.01-5.78), (RR:1.91; CI95%: 1.01-3.6), and (RR:1.68; CI95%: 0.92-3.09) for SIP, MIP, and SIZ areas, respectively, compared to the control area. Falaj Al Qabail (6.4 km) and Majees (6 km) had the highest number of asthma patients (N 69 and N 72) and highest percentages of severe asthma cases among these patients (28% and 24%) with significant risk ratios (RR:2.97; CI95%: 1.19-7.45 and RR:2.55; CI95%: 1.00-6.48), correspondingly. Moreover, severe asthma prevalence peaked in the 25-50 age group (RR:2.05; CI95%: 1.26-3.33), and this linkage between asthma and age was much more pronounced in males than females. Smoking and exposure to certain contaminants (dust and smoke) also increased the risk of severe asthma symptoms, but their effects were less important in the high-risk zone, suggesting much more important risk factors. A neural network model accurately predicted asthma risk (94.8% accuracy), with proximity to SIP as the most influential predictor.

CONCLUSIONS

This study highlights the high asthma burden near SIP, linked to port proximity, smoking, and wind direction as major risk factors. These findings inform vital public health policies to reduce air pollution and improve respiratory health in the region, prompting national policy review.

Gene-environment interactions that influence CVD, lipid traits, obesity, diabetes, and hypertension appear to be able to influence gene therapy

Most mind boggling diseases are accepted to be impacted by both genetic and environmental elements. As of late, there has been a flood in the improvement of different methodologies, concentrate on plans, and measurable and logical techniques to examine gene-environment cooperations (G × Es) in enormous scope studies including human populaces. The many-sided exchange between genetic elements and environmental openings has long charmed the consideration of clinicians and researchers looking to grasp the complicated starting points of diseases. While single variables can add to disease, the blend of genetic variations and environmental openings frequently decides disease risk. The fundamental point of this paper is to talk about the Gene-Environment Associations That Impact CVD, Lipid Characteristics, Obesity, Diabetes, and Hypertension Have all the earmarks of being Ready to Impact Gene Therapy. This survey paper investigates the meaning of gene-environment collaborations (G × E) in disease advancement. The intricacy of genetic and environmental communications in disease causation is explained, underlining the multifactorial idea of many circumstances. The job of gene-environment cooperations in cardiovascular disease, lipid digestion, diabetes, obesity, and hypertension is investigated. This audit fixates on Gene by Environment (G × E) collaborations, investigating their importance in disease etiology.

SNPs inFAM13AandIL2RBgenes are associated with FeNO in adult subjects with asthma

Nitric oxide has different roles in asthma as both an endogenous modulator of airway function and a pro-inflammatory mediator. Fractional exhaled nitric oxide (FeNO) is a reliable, quantitative, non-invasive, simple, and safe biomarker for assessing airways inflammation in asthma. Previous genome-wide and genetic association studies have shown that different genes and single nucleotide polymorphisms (SNPs) are linked to FeNO. We aimed at identifying SNPs in candidate genes or gene regions that are associated with FeNO in asthma. We evaluated 264 asthma cases (median age 42.8 years, female 47.7%) who had been identified in the general adult population within the Gene Environment Interactions in Respiratory Diseases survey in Verona (Italy; 2008-2010). Two hundred and twenty-one tag-SNPs, which are representative of 50 candidate genes, were genotyped by a custom GoldenGate Genotyping Assay. A two-step association analysis was performed without assuming ana priorigenetic model: step (1) a machine learning technique [gradient boosting machine (GBM)] was used to select the 15 SNPs with the highest variable importance measure; step (2) the GBM-selected SNPs were jointly tested in a linear regression model with natural log-transformed FeNO as the normally distributed outcome and with age, sex, and the SNPs as covariates. We replicated our results within an independent sample of 296 patients from the European Community Respiratory Health Survey III. We found that SNP rs987314 in family with sequence similarity 13 member A (FAM13A) and SNP rs3218258 in interleukin 2 receptor subunit beta (IL2RB) gene regions are significantly associated with FeNO in adult subjects with asthma. These genes are involved in different mechanisms that affect smooth muscle constriction and endothelial barrier function responses (FAM13A), or in immune response processes (IL2RB). Our findings contribute to the current knowledge on FeNO in asthma by identifying two novel SNPs associated with this biomarker of airways inflammation.

IL18 Gene Polymorphism Is Associated with Total IgE in Adult Subjects with Asthma

The allergic asthma phenotype is characterized by a T helper type 2 (Th2) immune response, based on Immunoglobulin E (IgE)-mediated type 1 hypersensitivity reactions. Total IgE is the sum of all IgE types produced by the human body and is used as a biomarker of inflammation in asthma. We analysed data collected in 143 asthma cases (median age 42.1 years) from the general Italian population (GEIRD survey; 2008-2010) to identify single nucleotide polymorphisms (SNPs) in candidate genes that are associated with total IgE in adult subjects with asthma. These patients reported respiratory symptoms in response to perennial allergens and provided data on 166 SNPs tagging 50 candidate genes or gene regions. Replication of the statistically significant results was performed in 842 asthma cases from other European countries (ECRHS II survey; 1998-2002). SNP rs549908 in interleukin 18 (IL18) gene was significantly associated with total IgE in GEIRD, and this result was replicated in ECRHS II. SNP rs1063320 in the human leukocyte antigen G (HLA-G) gene was identified in GEIRD, but this association was not replicated in ECRHS II. Further investigating IL18 and its biological pathways could be important for developing new therapeutic targets, due to its involvement in inflammatory response processes.

Evaluating Rural Ethiopian Youths' Willingness and Competency to Promote Literacy Regarding G × E Influences on Podoconiosis

INTRODUCTION

Engaging youth as peer educators has yet to be considered to promote literacy concerning conjoint genetic and environmental (G × E) influences on health conditions. Whether youth living in low- and middle-income countries (LMICs) could and would be willing to serve as lay educators of G × E education is unclear.

METHODS

A cross-sectional survey of youth living in Southern Ethiopia was conducted from August to September 2017. Trained data collectors administered the survey on 377 randomly selected youth who ranged in age from 15 to 24; 52% were female and 95% reported having some formal education. Self-reported willingness and a constructed competency score were assessed. Bivariate analyses tested for factors associated with willingness and competency to serve as lay G × E literacy builders.

RESULTS

Competency and willingness were significantly greater (p < 0.05) for youth who were male, had some formal education, and had civic or leadership experience. Differences in median willingness were significant for youth who scored as more competent versus those who scored as less competent (p < 0.001). There were no characteristics that moderated the association of competency with willingness.

CONCLUSION

Youth peer educator programs hold promise for disseminating improved G Χ E literacy and reducing stigma associated with deterministic misunderstandings. Thoughtful recruitment and training strategies will be needed to ensure that the broadest representation of youth in LMIC contexts has the opportunity to serve in this role, particularly girls and those without formal education.

Prevalence of Asthma, Allergic Rhinitis, and Atopic Dermatitis and Their Association With Oral Health in Saudi Arabia

Background  The word "atopy" is frequently used to describe immunoglobulin E (IgE)-mediated diseases. The prevalence of atopic dermatitis, allergic rhinitis, and asthma is increasing and disconcerting in Saudi Arabia. This study aims to investigate the association between allergic rhinitis, atopic dermatitis, asthma, and oral health among adults in the Makkah region of Saudi Arabia. Methods A cross-sectional study of 726 adults using an electronic questionnaire was adopted. The study was carried out from January to December 2022. The questionnaire included demographic data, patients' diseases in response to inclusion and exclusion criteria, oral health status and symptoms, and dental health-related behaviors. Results Most participants were aged from 18 to <40 years (79.1%). More than half of the participants were females (53.6%); 39.7% of participants had poor oral health. Poor health was significantly higher among obese subjects as well as those with lower levels of physical activity, higher perceived levels of stress, those who received a sealant, and those who brushed their teeth for ≤ one time per day. The results showed that the individual symptoms of oral health did not associate significantly with being diagnosed with allergic rhinitis or asthma in the past 12 months. However, atopic dermatitis was independently associated with a chipped or broken tooth (OR = 1.52) and pain in the tongue or inside the cheeks (OR = 3.57). Conclusion Poor oral health was significantly associated with atopic dermatitis in Saudi adults. Some systemic diseases are considered chronic diseases, and they are multifactorial; thus, we cannot claim that periodontal pathogens are the definite cause of systemic infections. More studies are necessary to find a definitive association.

Serum antibodies to periodontal pathogens are related to allergic symptoms

BACKGROUND

The association between periodontitis and allergic symptoms has been investigated. However, the difference in immune signatures between them remains poorly understood. This cross-sectional study assessed the relationship between serum immunoglobulin G (IgG) antibodies to periodontal pathogens and allergic symptoms in a nationwide population cohort.

METHODS

Two phases of the Third National Health and Nutrition Examination Survey (NHANES III) were used as discovery dataset (n = 3700) and validation dataset (n = 4453), respectively. Based on the antibodies against 19 periodontal pathogens, we performed an unsupervised hierarchical clustering to categorize the population into three clusters. In the discovery dataset, cluster 1 (n = 2847) had the highest level of IgG antibodies, followed by clusters 2 (n = 588) and 3 (n = 265). Data on allergic symptoms (asthma, hay fever, and wheezing) were obtained using a self-reported questionnaire. Survey-weighted multivariable logistic regression evaluated the association between these clusters and allergic symptoms.

RESULTS

In the discovery dataset, the participants with lower levels of antibodies to periodontal pathogens exhibited a higher risk of asthma (odds ratio [OR]_{cluster 3 vs. cluster 1} = 1.820, 95% confidence interval [CI]: 1.153-2.873) and wheezing (OR_{cluster 3 vs. cluster 1} = 1.550, 95% CI: 1.095-2.194) compared to those with higher periodontal antibodies, but the non-significant association with hay fever. Consistent results were found in the validation dataset.

CONCLUSIONS

Serum IgG titers to periodontal pathogens were inversely associated with the risk of asthma and wheezing, suggesting the potentially protective role against allergic conditions.

Gene-environment interactions and their impact on human health

The molecular processes underlying human health and disease are highly complex. Often, genetic and environmental factors contribute to a given disease or phenotype in a non-additive manner, yielding a gene-environment (G × E) interaction. In this work, we broadly review current knowledge on the impact of gene-environment interactions on human health. We first explain the independent impact of genetic variation and the environment. We next detail well-established G × E interactions that impact human health involving environmental toxicants, pollution, viruses, and sex chromosome composition. We conclude with possibilities and challenges for studying G × E interactions.

Mice Expressing Cosegregating Single Nucleotide Polymorphisms (D298G and N397I) in TLR4 Have Enhanced Responses to House Dust Mite Allergen

Asthma is a common and ubiquitous chronic respiratory disease that is associated with airway inflammation and hyperreactivity resulting in airway obstruction. It is now accepted that asthma is controlled by a combination of host genetics and environment in a rather complex fashion; however, the link between sensing of the environment and development and exacerbation of allergic lung inflammation is unclear. Human populations expressing cosegregating D299G and T399I polymorphisms in the TLR4 gene are associated with a decreased risk for asthma in adults along with hyporesponsiveness to inhaled LPS, the TLR4 ligand. However, these data do not account for other human genetic or environmental factors. Using a novel mouse strain that expresses homologous human TLR4 polymorphisms (TLR4-single nucleotide polymorphism [SNP]), we directly tested the effect of these TLR4 polymorphisms on in vivo responses to allergens using two models of induction. We report that intact TLR4 is required for allergic inflammation when using the OVA and LPS model of induction, as cellular and pathological benchmarks were diminished in both TLR4-SNP and TLR4-deficent mice. However, in the more clinically relevant model using house dust mite extract for induction, responses were enhanced in the TLR4-SNP mice, as evidenced by greater levels of eosinophilic inflammation, Th2 cytokine production, and house dust mite-specific IgG1 production compared with wild-type mice; however, mucus production and airway hyperreactivity were not affected. These results suggest that the TLR4 polymorphic variants (genes) interact differently with the allergic stimulation (environment).

Gene-environment interactions in childhood asthma revisited; expanding the interaction concept

Investigation of gene-environment interactions (GxE) may provide important insights into the gene regulatory framework in response to environmental factors of relevance for childhood asthma. Over the years, different methodological strategies have been applied, more recently using genome-wide approaches. The best example to date is the major asthma locus on the 17q12-21 chromosome region, viral infections, and airway epithelium processes where recent studies have shed much light on mechanisms in childhood asthma. However, there are challenges with the traditional single variant-single exposure interaction models, as they do not encompass the complexity and cumulative effects of multiple exposures or multiple genetic variants. As such, we need to redefine our traditional GxE thinking, and we propose in this review to expand the GxE concept by also evaluating other omics layers, such as epigenetics, transcriptomics, metabolomics, and proteomics. In addition, host factors such as age, gender, and other exposures are very likely to influence GxE effects and need firmly to be considered in future studies.

Sex Plays a Multifaceted Role in Asthma Pathogenesis

Sex is considered an important risk factor for asthma onset and exacerbation. The prevalence of asthma is higher in boys than in girls during childhood, which shows a reverse trend after puberty—it becomes higher in adult females than in adult males. In addition, asthma severity, characterized by the rate of hospitalization and relapse after discharge from the emergency department, is higher in female patients. Basic research indicates that female sex hormones enhance type 2 adaptive immune responses, and male sex hormones negatively regulate type 2 innate immune responses. However, whether hormone replacement therapy in postmenopausal women increases the risk of current asthma and asthma onset remains controversial in clinical settings. Recently, sex has also been shown to influence the pathophysiology of asthma in its relationship with genetic or other environmental factors, which modulate asthmatic immune responses in the airway mucosa. In this narrative review, we highlight the role of sex in the continuity of the asthmatic immune response from sensing allergens to Th2 cell activation based on our own data. In addition, we elucidate the interactive role of sex with genetic or environmental factors in asthma exacerbation in women.

Prevalence of asthma and allergies among children in the United Arab Emirates: A cross-sectional study

Background

Asthma, allergic rhinitis, and atopic dermatitis are the most common chronic inflammatory disorders in children worldwide. These conditions place a significant burden on the healthcare system due to their multiple related complications and the necessity of hospital visits. This study aimed to evaluate the prevalence and severity of asthma and allergic diseases among school children aged 6-7 years and 13-14 years in Dubai and the Northern Emirates, United Arab Emirates (UAE).

Patients and methods

This was a multicenter, cross-sectional study that recruited children from March to June 2019 via school class registers in Dubai and the Northern Emirates, UAE. The Arabic and English versions of the International Study of Asthma and Allergies in Childhood (ISAAC) core questionnaires on asthma, allergic rhinitis, and atopic dermatitis were completed by parents or legal guardians of children aged 6-7 years, and by the children themselves in those aged 13-14 years.

Results

In this study, we included 3436 children (1944 children aged 6-7 years and 1793 children aged 13-14 years). We estimated the prevalence of asthma (11.9%), wheezing (44.2%), allergic rhinitis (46.5%), hay fever (22.1%), and atopic dermatitis (12.9%) in the 6- to 7-year-old group. In the 13- to 14-year-old group, the prevalence was 9.8%, 33.1%, 51.3%, 19.9%, and 14.6%, respectively. The prevalence of any history of asthma was higher in boys than girls in the 6- to 7-year-old group (13.9% vs. 10%) and in the 13- to 14-year-old group (11.2% vs. 8.7%). In the 6- to 7-year-old group, the highest prevalence of asthma, sneezing, and atopic dermatitis was observed in Dubai, Ajman, and Umm Al Quwain, respectively. In the 13- to 14-year-old group, the highest prevalence of asthma was observed in Ras Al Khaimah, and the highest prevalence of sneezing and atopic dermatitis was observed in Sharjah.

Conclusion

We found that the prevalence of asthma, allergic rhinitis, and atopic dermatitis in the UAE is comparable to that in neighboring countries; the prevalence of asthma, wheezing, and hay fever was higher in the 6- to 7-year-old group, while in the 13- to 14-year-old group, the prevalence of allergic rhinitis and atopic dermatitis was higher. Overall, the prevalence of any history of asthma was highest in Ras Al Khaimah, followed by Dubai, and lowest in Ajman. Our findings suggest that allergic disorders represent a healthcare burden in the UAE and more efforts are needed to organize nationwide campaigns to detect undiagnosed children to overcome the burden caused by these conditions.

Studies to Improve Perinatal Health through Diet and Lifestyle among South Asian Women Living in Canada: A Brief History and Future Research Directions

South Asians (i.e., people who originate from India, Pakistan, Sri Lanka, Nepal, and Bangladesh) have higher cardiovascular disease rates than other populations, and these differences persist in their offspring. Nutrition is a critical lifestyle-related factor that influences fetal development, and infant and child health in early life. In high-income countries such as Canada, nutrition-related health risks arise primarily from overnutrition, most strikingly for obesity and associated non-communicable diseases. Evidence for developmental programming during fetal life underscores the critical influence of maternal diet on fetal growth and development, backed by several birth cohort studies including the Pune Maternal Nutrition Study, the South Asian Birth Cohort Study, and the Born in Bradford Study. Gestational diabetes mellitus is a strong risk factor for type 2 diabetes, future atherosclerosis and cardiovascular disease in the mother and increases the risk of type 2 diabetes in her offspring. Non-pharmacological trials to prevent gestational diabetes are few, often not randomized, and are heterogeneous with respect to design, and outcomes have not converged upon a single optimal prevention strategy. The aim of this review is to provide an understanding of the current knowledge around perinatal nutrition and gestational diabetes among the high-risk South Asian population as well as summarize our research activities investigating the role of culturally-tailored nutrition advice to South Asian women living in high-income settings such as Canada. In this paper, we describe these qualitative and quantitative studies, both completed and underway. We conclude with a description of the design of a randomized trial of a culturally tailored personalized nutrition intervention to reduce gestational glycaemia in South Asian women living in Canada and its implications.

A probiotic has differential effects on allergic airway inflammation in A/J and C57BL/6 mice and is correlated with the gut microbiome

The phenotypes of allergic airway diseases are influenced by the interplay between host genetics and the gut microbiota, which may be modulated by probiotics. We investigated the probiotic effects on allergic inflammation in A/J and C57BL/6 mice. C57BL/6 mice had increased gut microbiota diversity compared to A/J mice at baseline. Acetate producer probiotics differentially modulated and altered the genus abundance of specific bacteria, such as Akkermansia and Allistipes, in mouse strains. We induced airway inflammation followed by probiotic treatment and found that only A/J mice exhibited decreased inflammation, and the beneficial effects of probiotics in A/J mice were partially due to acetate production. To understand the relevance of microbial composition colonization in the development of allergic diseases, we implanted female C57BL/6 mice with A/J embryos to naturally modulate the microbial composition of A/J mice, which increased gut microbiota diversity and reduced eosinophilic inflammation in A/J. These data demonstrate the central importance of microbiota to allergic phenotype severity. Video Abstract.

The intersect of genetics, environment, and microbiota in asthma-perspectives and challenges

In asthma, a significant portion of the interaction between genetics and environment occurs through microbiota. The proposed mechanisms behind this interaction are complex and at times contradictory. This review covers recent developments in our understanding of this interaction: the "microbial hypothesis" and the "farm effect"; the role of endotoxin and genetic variation in pattern recognition systems; the interaction with allergen exposure; the additional involvement of host gut and airway microbiota; the role of viral respiratory infections in interaction with the 17q21 and CDHR3 genetic loci; and the importance of in utero and early-life timing of exposures. We propose a unified framework for understanding how all these phenomena interact to drive asthma pathogenesis. Finally, we point out some future challenges for continued research in this field, in particular the need for multiomic integration, as well as the potential utility of asthma endotyping.

Energy-drink consumption is associated with asthma, allergic rhinitis, and atopic dermatitis in Korean adolescents

BACKGROUND/OBJECTIVES

Few studies have evaluated the effects of energy drinks on allergic diseases. The purpose of this investigation was to evaluate the association between energy drinks and various allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, in a large representative Korean adolescent population.

SUBJECTS/METHODS

This cross-sectional study used data from the Korea Youth Risk Behavior Web-based Survey collected from 2015 to 2016. A total of 129,809 participants (n = 67,056 for males; n = 62,753 for females) aged 12-18 years were included and were asked about their frequency of consumption of energy drinks such as Hot6^®, Redbull^®, and Bacchus^®. Their history of asthma, allergic rhinitis, and atopic dermatitis throughout life and in the last 12 months were obtained. The association between the frequency of energy-drink consumption and allergic diseases was analyzed using multiple logistic regression with adjustment for various covariates.

RESULTS

Age, sex, physical activity, obesity, region of residence, economic level, paternal and maternal educational level, smoking, and alcohol consumption differed significantly according to the frequency of energy-drink consumption (each P < 0.001). Frequent energy-drink consumption (≥7 times a week) was significantly associated with asthma throughout life (odds ratio [OR] = 1.30, 95% confidence interval (CI) = 1.03-1.64, P = 0.025), asthma within the last 12 months (OR = 1.65, 95% CI = 1.16-2.35, P = 0.006), allergic rhinitis within the last 12 months (OR = 1.21, 95% CI = 1.02-1.44, P = 0.030), and atopic dermatitis within the last 12 months (OR = 1.49, 95% CI = 1.17-1.90, P = 0.001) compared to no energy-drink consumption in the full-adjusted model.

CONCLUSIONS

Frequent energy-drink consumption is associated with allergic diseases, including asthma, allergic rhinitis, and atopic dermatitis, in Korean adolescents.

The association between high hygiene scores and allergic rhinitis in Korean adolescents

BACKGROUND

Recent studies have proposed that handwashing can lead to the development of allergic disease by reducing skin epithelial barrier integrity. The purpose of this study was to evaluate the association between personal hygiene practices and allergic rhinitis (AR) in a nationally representative sample of Korean adolescents.

METHODS

A total of 62,276 adolescent participants (aged 12 to 18 years) were analyzed using the Korea Youth Risk Behavior Web-based Survey, which was conducted in 2017. Participants were asked about the frequency of handwashing considering 5 situations. AR histories throughout life and in the last 12 months were obtained. The associations between AR and hygiene scores were analyzed using multiple logistic regression, with adjustment for possible confounders. Subgroup analyses were conducted for school level, age, economic level, and education level of each parent.

RESULTS

The analysis of the general characteristics showed that younger age, increased number of days of physical activity, male sex, living in a large city, high economic level, high education levels of father and mother, nonsmoking status, and no alcohol consumption were associated with a relatively high hygiene score (p < 0.001). The adjusted odds ratio (aOR) of AR was 1.12 (95% confidence interval [CI], 1.06 to 1.18; p < 0.001) throughout life and 1.21 (95% CI, 1.14 to 1.29; p < 0.001) for the previous 12 months in the highest compared with the lowest hygiene score groups. Consistent results were obtained in the female sex, any school level, middle economic level, and both parents with any education level.

CONCLUSION

The association between high hygiene scores and AR was significant in Korean adolescents after adjustment for several variables.

Poor oral health is associated with asthma, allergic rhinitis, and atopic dermatitis in Korean adolescents: A cross-sectional study

The purpose of this study was to evaluate the association between oral health and asthma/allergic rhinitis/atopic dermatitis in a large representative Korean adolescent population.A total of 136,027 participants (aged 12-18 years old) were selected from the Korea Youth Risk Behavior Web-based Survey 2014 to 2015. The subjects' history of asthma, allergic rhinitis, and atopic dermatitis was determined by inquiring whether they had been diagnosed by a medical doctor within the previous 12 months or throughout life. Participants were asked if they had experienced the following 6 symptoms regarding oral health in the past 12 months: "chipped or broken tooth," "toothache when eating or drinking," "throbbing and sore tooth," "sore and bleeding gums," "pain in the tongue or inside the cheeks," and "unpleasant breath." The participants were divided into 3 groups according to the number of oral health-related symptoms as follows: good oral health (symptoms = 0), moderate oral health (symptoms = 1), and poor oral health (symptoms = 2-6). Multiple logistic regression analyses calculated the adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for asthma/allergic rhinitis/atopic dermatitis within the past 12 months and throughout life among groups with oral health-related symptom groups.Older age, female sex, fewer days of physical activity, lower parental economic level, lower parental education level, smoking, and frequent alcohol consumption were associated with poor oral health (each P < .001). The aORs for asthma/allergic rhinitis/atopic dermatitis were 1.48 (95% CI = 1.34-1.63, P < .001), 1.42 (95% CI = 1.36-1.47, P < .001), and 1.35 (95% CI = 1.28-1.43, P < .001), respectively, in the poor oral health group compared to the good oral health group.Poor oral health was significantly correlated with the prevalence of asthma/allergic rhinitis/atopic dermatitis within the past 12 months and throughout life in Korean adolescents. Based on our comparative data, oral health-related education may be considered to adolescents with allergic disease for good oral health.

Genome-wide analysis highlights contribution of immune system pathways to the genetic architecture of asthma

Asthma is a chronic and genetically complex respiratory disease that affects over 300 million people worldwide. Here, we report a genome-wide analysis for asthma using data from the UK Biobank and the Trans-National Asthma Genetic Consortium. We identify 66 previously unknown asthma loci and demonstrate that the susceptibility alleles in these regions are, either individually or as a function of cumulative genetic burden, associated with risk to a greater extent in men than women. Bioinformatics analyses prioritize candidate causal genes at 52 loci, including CD52, and demonstrate that asthma-associated variants are enriched in regions of open chromatin in immune cells. Lastly, we show that a murine anti-CD52 antibody mimics the immune cell-depleting effects of a clinically used human anti-CD52 antibody and reduces allergen-induced airway hyperreactivity in mice. These results further elucidate the genetic architecture of asthma and provide important insight into the immunological and sex-specific relevance of asthma-associated risk variants.

Asthma is a common disease of the airways for which numerous genetic loci have been identified. Here, Han et al. carry out a genome-wide analysis for asthma to identify additional loci, report sex-stratified and genetic risk score analyses, and functionally follow-up one locus using a murine model of airway hyperreactivity.

Metabolomic Analysis Reveals Distinct Profiles in the Plasma and Urine Associated with IgE Reactions in Childhood Asthma

Several metabolomics studies have identified altered metabolic pathways that are related to asthma. However, an integrative analysis of the metabolic responses across blood and urine for a comprehensive framework of asthma in early childhood remains lacking. Fifty-four age-matched children with asthma (n = 28) and healthy controls (n = 26) were enrolled. Metabolome analysis of the plasma and urine samples was performed using ¹H-nuclear magnetic resonance (NMR) spectroscopy coupled with partial least-squares discriminant analysis (PLS-DA). Integrated analysis of blood and urine metabolic profiling related to IgE reactions for childhood asthma was investigated. A significantly higher plasma histidine level was found, in parallel with lower urinary 1-methylnicotinamide and trimethylamine N-oxide (TMAO) levels, in children with asthma compared to healthy controls. Compared to children without allergic sensitization, 11 (92%) plasma metabolites and 8 (80%) urinary metabolites were found to be significantly different in children with IgE and food sensitization respectively. There were significant correlations between the plasma 3-hydroxybutyric acid and excreted volumes of the hydroxy acids, which were strongly correlated to plasma leucine and valine levels. Urine N-phenylacetylglycine, a microbial-host co-metabolite, was strongly correlated with total serum and food allergen-specific IgE levels. Plasma pyruvate and urine valine, leucine, and isoleucine degradation metabolisms were significantly associated with allergic sensitization for childhood asthma. In conclusion, blood and urine metabolome reflect different metabolic pathways in allergic reactions. Plasma pyruvate metabolism to acetic acid appears to be associated with serum IgE production, whereas urine branched-chain amino acid metabolism primarily reflects food allergic reactions against allergies.

Occupational exposure to disinfectants and asthma incidence in U.S. nurses: A prospective cohort study

BACKGROUND

Exposure to disinfectants among healthcare workers has been associated with respiratory health effects, in particular, asthma. However, most studies are cross-sectional and the role of disinfectant exposures in asthma development requires longitudinal studies. We investigated the association between occupational exposure to disinfectants and incident asthma in a large cohort of U.S. female nurses.

METHODS

The Nurses' Health Study II is a prospective cohort of 116 429 female nurses enrolled in 1989. Analyses included 61 539 participants who were still in a nursing job and with no history of asthma in 2009 (baseline; mean age: 55 years). During 277 744 person-years of follow-up (2009-2015), 370 nurses reported incident physician-diagnosed asthma. Occupational exposure was evaluated by questionnaire and a Job-Task-Exposure Matrix (JTEM). We examined the association between disinfectant exposure and subsequent asthma development, adjusted for age, race, ethnicity, smoking status, and body mass index.

RESULTS

Weekly use of disinfectants to clean surfaces only (23% exposed) or to clean medical instruments (19% exposed) was not associated with incident asthma (adjusted hazard ratio [95% confidence interval] for surfaces, 1.12 [0.87-1.43]; for instruments, 1.13 [0.87-1.48]). No association was observed between high-level exposure to specific disinfectants/cleaning products evaluated by the JTEM (formaldehyde, glutaraldehyde, bleach, hydrogen peroxide, alcohol quats, or enzymatic cleaners) and asthma incidence.

CONCLUSIONS

In a population of late career nurses, we observed no significant association between exposure to disinfectants and asthma incidence. A potential role of disinfectant exposures in asthma development warrants further study among healthcare workers at earlier career stage to limit the healthy worker effect.

Gene-environment interactions in primary atopic disorders

Environmental factors modify disease presentation and severity in allergic disorders. Primary atopic disorders (PADs) are a heterogenous group of single gene disorders that lead to significant atopic and allergic disease manifestations. However, a number of these monogenic diseases have variable penetrance suggesting that gene-gene and/or gene-environment interactions could modulate the clinical phenotype. Environmental factors such as diet, the microbiome at the epithelial-environment interface, the presence and/or extent of infection, and psychologic stress can alter disease phenotypic expression of allergic diseases, and PADs provide discrete contexts in which to understand these influences. We outline how gene-environment interactions likely contribute to a variable penetrance and expressivity in PADs. Dietary modifications of both macronutrients and/or micronutrients alter T-cell metabolism and may influence effector T-cell function. The mucosal microbiome may affect local inflammation and may remotely influence regulatory elements, while psychologic stress can affect mast cell and other allergic effector cell function. Understanding gene-environment interactions in PADs can hopefully provide a foundation for interrogating gene-environment interactions to common allergic disorders, and also present opportunities for personalized interventions based on the altered pathways and environmental influences in affected individuals.

The influence of maternal and infant nutrition on cardiometabolic traits: novel findings and future research directions from four Canadian birth cohort studies

A mother's nutritional choices while pregnant may have a great influence on her baby's development in the womb and during infancy. There is evidence that what a mother eats during pregnancy interacts with her genes to affect her child's susceptibility to poor health outcomes including childhood obesity, pre-diabetes, allergy and asthma. Furthermore, after what an infant eats can change his or her intestinal bacteria, which can further influence the development of these poor outcomes. In the present paper, we review the importance of birth cohorts, the formation and early findings from a multi-ethnic birth cohort alliance in Canada and summarise our future research directions for this birth cohort alliance. We summarise a method for harmonising collection and analysis of self-reported dietary data across multiple cohorts and provide examples of how this birth cohort alliance has contributed to our understanding of gestational diabetes risk; ethnic and diet-influences differences in the healthy infant microbiome; and the interplay between diet, ethnicity and birth weight. Ongoing work in this birth cohort alliance will focus on the use of metabolomic profiling to measure dietary intake, discovery of unique diet-gene and diet-epigenome interactions, and qualitative interviews with families of children at risk of metabolic syndrome. Our findings to-date and future areas of research will advance the evidence base that informs dietary guidelines in pregnancy, infancy and childhood, and will be relevant to diverse and high-risk populations of Canada and other high-income countries.

Potential Beneficial Effects of Wine Flavonoids on Allergic Diseases

Wine, a widely consumed beverage, comprises several biophenols that promote health. Flavonoids, majorly present in red wine, have been shown to have antioxidant, anti-inflammatory, anticancer, and immunomodulatory activities. Regular consumption of red wine (100 mL/day) is estimated to provide an average of 88 mg of flavonoids, whereas recent epidemiological studies indicate that wine is one of the major sources of flavonoid intake amongst wine lovers in European countries (providing an average intake of 291⁻374 mg/day of flavonoids). In addition to being antioxidants, in vitro studies suggest that flavonoids also have anti-allergic activities that inhibit IgE synthesis, activation of mast cells and basophils or other inflammatory cells, and production of inflammatory mediators, including cytokines. Furthermore, they affect the differentiation of naïve CD4+ T cells into effector T cell subsets. Moreover, several studies have reported the benefits of flavonoids in allergic models such as atopic dermatitis, asthma, anaphylaxis, and food allergy; however, evidence in humans is limited to allergic rhinitis and respiratory allergy. Although further evaluation is required, it is expected that an appropriate intake of flavonoids may be beneficial in preventing, and eventually managing, allergic diseases.

Genomic Predictors of Asthma Phenotypes and Treatment Response

Asthma is a complex respiratory disease considered as the most common chronic condition in children. A large genetic contribution to asthma susceptibility is predicted by the clustering of asthma and allergy symptoms among relatives and the large disease heritability estimated from twin studies, ranging from 55 to 90%. Genetic basis of asthma has been extensively investigated in the past 40 years using linkage analysis and candidate-gene association studies. However, the development of dense arrays for polymorphism genotyping has enabled the transition toward genome-wide association studies (GWAS), which have led the discovery of several unanticipated asthma genes in the last 11 years. Despite this, currently known risk variants identified using many thousand samples from distinct ethnicities only explain a small proportion of asthma heritability. This review examines the main findings of the last 2 years in genomic studies of asthma using GWAS and admixture mapping studies, as well as the direction of studies fostering integrative perspectives involving omics data. Additionally, we discuss the need for assessing the whole spectrum of genetic variation in association studies of asthma susceptibility, severity, and treatment response in order to further improve our knowledge of asthma genes and predictive biomarkers. Leveraging the individual's genetic information will allow a better understanding of asthma pathogenesis and will facilitate the transition toward a more precise diagnosis and treatment.

Association of FcεRIβ polymorphisms with risk of asthma and allergic rhinitis: evidence based on 29 case-control studies

Purpose: Accumulating evidence has shown that allergic diseases are caused by a complex interaction of genetic and environmental factors, some single nucleotide polymorphisms (SNPs) existing in high-affinity IgE receptor β chain (FcεRIβ) are potential risk factors for allergic diseases. However, the results have been inconsistent and inconclusive due to the limited statistical power in individual study. Thus, we conducted a meta-analysis to systematically evaluate the association between FcεRIβ SNPs and allergic diseases risk.

Methods: Eligible studies were collected from PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure, and WanFang databases. Pooled odd ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated to assess the strength of the relationships between five polymorphisms (E237G, -109 C/T, RsaI_in2, RsaI_ex7, and I181L) and the risk of allergic diseases by using five genetic models. In addition, the stability of our analysis was evaluated by publication bias, sensitivity, and heterogeneity analysis.

Results: Overall, a total of 29 case–control studies were included in this meta-analysis. We found that E237G (B vs. A: OR = 1.28, 95% CI = 1.06–1.53, P<0.001, I² = 63.1%) and -109 C/T (BB vs. AA + AB: OR = 1.58, 95%CI = 1.26–1.98, P<0.001, I² = 66.4%) were risk factors for allergic diseases.

Conclusion: Our meta-analysis suggests that polymorphisms in FcεRIβ may be associated with the development of allergic diseases.

Patterns of cleaning product exposures using a novel clustering approach for data with correlated variables

PURPOSE

Clustering methods may be useful in epidemiology to better characterize exposures and account for their multidimensional aspects. In this context, application of clustering models allowing for highly dependent variables is of particular interest. We aimed to characterize patterns of domestic exposure to cleaning products using a novel clustering model allowing for highly dependent variables.

METHODS

To identify domestic cleaning patterns in a large population of French women, we used a mixture model of dependency blocks. This novel approach specifically models within-class dependencies, and is an alternative to the latent class model, which assumes conditional independence. Analyses were conducted in 19,398 participants of the E3N study (women aged 61-88 years) who completed a questionnaire regarding household cleaning habits.

RESULTS

Seven classes were identified, which differed with the frequency of cleaning tasks (e.g., dusting/sweeping/hoovering) and use of specific products (e.g., bleach, sprays). The model also grouped the variables into conditionally independent blocks, providing a summary of the main dependencies among the variables.

CONCLUSIONS

The mixture model of dependency blocks, a useful alternative to the latent class model, may have broader application in epidemiology, in particular, in the context of exposome research and growing need for data-reduction methods.

Blood and nasal epigenetics correlate with allergic rhinitis symptom development in the environmental exposure unit

BACKGROUND

Epigenetic alterations may represent new therapeutic targets and/or biomarkers of allergic rhinitis (AR). Our aim was to examine genome-wide epigenetic changes induced by controlled pollen exposure in the environmental exposure unit (EEU).

METHODS

38 AR sufferers and eight nonallergic controls were exposed to grass pollen for 3 hours on two consecutive days. We interrogated DNA methylation at baseline and 3 hours in peripheral blood mononuclear cells (PBMCs) using the Infinium Methylation 450K array. We corrected for demographics, cell composition, and multiple testing (Benjamini-Hochberg) and verified hits using bisulfite PCR pyrosequencing and qPCR. To extend these findings to a clinically relevant tissue, we investigated DNA methylation and gene expression of mucin 4 (MUC4), in nasal brushings from a separate validation cohort exposed to birch pollen.

RESULTS

In PBMCs of allergic rhinitis participants, 42 sites showed significant DNA methylation changes of 2% or greater. DNA methylation changes in tryptase gamma 1 (TPSG1), schlafen 12 (SLFN12), and MUC4 in response to exposure were validated by pyrosequencing. SLFN12 DNA methylation significantly correlated with symptoms (P < 0.05), and baseline DNA methylation pattern was found to be predictive of symptom severity upon grass allergen exposure (P = 0.029). Changes in MUC4 DNA methylation in nasal brushings in the validation cohort correlated with drop in peak nasal inspiratory flow (Spearman's r = 0.314, P = 0.034), and MUC4 gene expression was significantly increased (P < 0.0001).

CONCLUSION

This study revealed novel and rapid epigenetic changes upon exposure in a controlled allergen challenge facility, and identified baseline epigenetic status as a predictor of symptom severity.

Lessons from ten years of genome-wide association studies of asthma

Twenty-five genome-wide association studies (GWAS) of asthma were published between 2007 and 2016, the largest with a sample size of 157242 individuals. Across these studies, 39 genetic variants in low linkage disequilibrium (LD) with each other were reported to associate with disease risk at a significance threshold of P<5 × 10⁻⁸, including 31 in populations of European ancestry. Results from analyses of the UK Biobank data (n=380 503) indicate that at least 28 of the 31 associations reported in Europeans represent true-positive findings, collectively explaining 2.5% of the variation in disease liability (median of 0.06% per variant). We identified 49 transcripts as likely target genes of the published asthma risk variants, mostly based on LD with expression quantitative trait loci (eQTL). Of these genes, 16 were previously implicated in disease pathophysiology by functional studies, including TSLP, TNFSF4, ADORA1, CHIT1 and USF1. In contrast, at present, there is limited or no functional evidence directly implicating the remaining 33 likely target genes in asthma pathophysiology. Some of these genes have a known function that is relevant to allergic disease, including F11R, CD247, PGAP3, AAGAB, CAMK4 and PEX14, and so could be prioritized for functional follow-up. We conclude by highlighting three areas of research that are essential to help translate GWAS findings into clinical research or practice, namely validation of target gene predictions, understanding target gene function and their role in disease pathophysiology and genomics-guided prioritization of targets for drug development.

Altered vulnerability to asthma at various levels of ambient Benzo[a]Pyrene by CTLA4, STAT4 and CYP2E1 polymorphisms

BACKGROUND

Within fossil- and solid-fuel dependent geographic locations, mechanisms of air pollution-induced asthma remains unknown. In particular, sources of greater genetic susceptibility to airborne carcinogen, namely, benzo[a]pyrene (B[a]P) has never been investigated beyond that of a few well known genes.

OBJECTIVES

To deepen our understanding on how the genotypic variations within the candidate genes contribute to the variability in the children's susceptibility to ambient B[a]P on doctor-diagnosed asthma.

METHODS

Clinically confirmed asthmatic versus healthy control children (aged, 7-15) were enrolled from historically polluted and rural background regions in Czech Republic. Contemporaneous ambient B[a]P concentration was obtained from the routine monitoring network. The sputum DNA was genotyped for 95 genes. B[a]P interaction with SNPs was studied by two-stage, semi-agnostic screening of 621 SNPs.

RESULTS

The median B[a]P within the highly polluted urban center was 8-times higher than that in the background region (7.8 vs. 1.1 ng/m³) during the period of investigation. Within the baseline model, which considered B[a]P exposure-only, the second tertile range was associated with a significantly reduced odds (aOR = 0.28) of asthma (95% CI, 0.16 to 0.50) compared to those at the lowest range. However, the highest range of B[a]P was associated with 3.18-times greater odds of the outcome (95% CI, 1.77 to 5.71). Within the gene-environment interaction models, joint occurrence of a high B[a]P exposure range and having a high-risk genotype at CTLA4 gene (rs11571316) was associated with 9-times greater odds (95% CI, 4.56-18.36) of the asthma diagnosis. Similarly, rs11571319 at CTLA4 and a high B[a]P exposure range was associated with a 8-times greater odds (95% CI, 3.95-14.27) of asthma diagnosis. Furthermore, having TG + GG genotypes on rs1031509 near STAT4 was associated with 5-times (95% CI, 3.03-8.55) greater odds of asthma diagnosis at the highest B[a]P range, compared to the odds at the reference range. Also CYP2E1 AT + TT genotypes (rs2070673) was associated with 5-times (95% CI, 3.1-8.8) greater odds of asthma diagnosis at the highest B[a]P exposure.

CONCLUSIONS

The children, who jointly experience a high B[a]P exposure (6.3-8.5 ng/m3) as well as susceptible genotypes in CTLA4 (rs11571316 and rs11571319), STAT4 (rs1031509), and CYP2E1 (rs2070673), respectively, are associated with a significantly greater odds of having doctor-diagnosed asthma, compared to those with neither risk factors.

Sensitization to dust mite defines different phenotypes of asthma: A multicenter study

BACKGROUND

Indoor allergens are risk factors for asthma: Thus, the characterization of indoor air quality is important for studying environment-health relationships in children. In particular, Dermatophagoides pteronyssinus is the dominant allergen for asthma. We cross-sectionally investigated the relationships among respiratory symptoms and function, airway inflammation, allergen sensitization, and indoor allergen concentration.

METHODS

One hundred and thirty-two children aging 10-14 years and living in a Southern Mediterranean area were evaluated by parental questionnaires. Spirometry, exhaled nitric oxide (FeNO), skin prick tests, total, and specific serum IgE analyses were performed along with the evaluation of home dust samples for the content in Der p 1 allergen. Three clusters were created on the basis of the presence/absence of wheeze in the last 12 months (Wh12m) and Der p 1-specific IgE level.

RESULTS

Cluster 1 (Wh12m+/high Der p 1 IgE) presented higher FeNO and poorer pulmonary function (lower FEV₁ and FEF_25%-75% ), while its symptom score was not different from Cluster 2 (Wh12m+/low Der p 1 IgE). Cluster 3 (Wh12m-/low IgE) showed the lowest FeNO values and pulmonary function similar to Cluster 2. Within Cluster 1, both Der p 1-specific IgE and FeNO were positively correlated with dust Der p 1.

CONCLUSIONS

Similar asthma phenotypes may occur in children despite differences in their atopic state. In atopic children, sensitizing allergens in the indoor environment may increase airway inflammation worsening pulmonary function. Moreover, environmental exposures may contribute to the development of asthma-like symptoms also in the absence of atopic sensitization, thus contributing to asthma overdiagnosis.

A Role of the ABCC4 Gene Polymorphism in Airway Inflammation of Asthmatics

The ATP-binding cassette subfamily C member 4 gene encodes a transmembrane protein involved in the export of proinflammatory molecules, including leukotriene, prostaglandin, and sphingosine-1-phosphate across the plasma membrane. Those metabolites play important roles in asthma. We investigated the potential associations between ABCC4 gene polymorphisms and asthma phenotype. In total, 270 asthma patients and 120 normal healthy controls were enrolled for a genetic association study. Two polymorphisms (-1508A>G and -642C>G) in the ABCC4 promoter were genotyped. The functional variability of the promoter polymorphisms was analyzed by luciferase reporter assay. Inflammatory cytokine levels were measured by enzyme-linked immunosorbent assay. Serum and urinary eicosanoid metabolites, sphingosine-1-phosphate, were evaluated by quadrupole time-of-flight mass spectrometry. Asthma patients carrying the G allele at -1508A>G had significantly higher serum levels of periostin, myeloperoxidase, and urinary levels of 15-hydroxyeicosatetraenoic acid and sphingosine-1-phosphate (P = 0.016, P = 0.027, P = 0.032, and P = 0.010, resp.) compared with noncarrier asthma patients. Luciferase activity was significantly enhanced in human epithelial A549 cells harboring a construct containing the -1508G allele (P < 0.01 for each) compared with a construct containing the -1508A allele. A functional polymorphism in the ABCC4 promoter, -1508A>G, may increase extracellular 15-hydroxyeicosatetraenoic acid, sphingosine-1-phosphate, and periostin levels, contributing to airway inflammation in asthmatics.

Genes Interacting with Occupational Exposures to Low Molecular Weight Agents and Irritants on Adult-Onset Asthma in Three European Studies

BACKGROUND

The biological mechanisms by which cleaning products and disinfectants-an emerging risk factor-affect respiratory health remain incompletely evaluated. Studying genes by environment interactions (G × E) may help identify new genes related to adult-onset asthma.

OBJECTIVES

We identified interactions between genetic polymorphisms of a large set of genes involved in the response to oxidative stress and occupational exposures to low molecular weight (LMW) agents or irritants on adult-onset asthma.

METHODS

Our data came from three large European cohorts: Epidemiological Family-based Study of the Genetics and Environment of Asthma (EGEA), Swiss Cohort Study on Air Pollution and Lung and Heart Disease in Adults (SAPALDIA), and European Community Respiratory Health Survey in Adults (ECRHS). A candidate pathway-based strategy identified 163 genes involved in the response to oxidative stress and potentially related to exposures to LMW agents/irritants. Occupational exposures were evaluated using an asthma job-exposure matrix and job-specific questionnaires for cleaners and healthcare workers. Logistic regression models were used to detect G × E interactions, adjusted for age, sex, and population ancestry, in 2,599 adults (mean age, 47 years; 60% women, 36% exposed, 18% asthmatics). p-Values were corrected for multiple comparisons.

RESULTS

Ever exposure to LMW agents/irritants was associated with current adult-onset asthma [OR = 1.28 (95% CI: 1.04, 1.58)]. Eight single nucleotide polymorphism (SNP) by exposure interactions at five loci were found at p < 0.005: PLA2G4A (rs932476, chromosome 1), near PLA2R1 (rs2667026, chromosome 2), near RELA (rs931127, rs7949980, chromosome 11), PRKD1 (rs1958980, rs11847351, rs1958987, chromosome 14), and PRKCA (rs6504453, chromosome 17). Results were consistent across the three studies and after accounting for smoking.

CONCLUSIONS

Using a pathway-based selection process, we identified novel genes potentially involved in adult asthma by interaction with occupational exposure. These genes play a role in the NF-κB pathway, which is involved in inflammation. Citation: Rava M, Ahmed I, Kogevinas M, Le Moual N, Bouzigon E, Curjuric I, Dizier MH, Dumas O, Gonzalez JR, Imboden M, Mehta AJ, Tubert-Bitter P, Zock JP, Jarvis D, Probst-Hensch NM, Demenais F, Nadif R. 2017. Genes interacting with occupational exposures to low molecular weight agents and irritants on adult-onset asthma in three European studies. Environ Health Perspect 125:207-214; http://dx.doi.org/10.1289/EHP376.

Gene-Environment Interactions-What Can These Tell Us about the Relationship between Asthma and Allergy?

Asthma is a common condition, which is associated with atopy and allergic conditions including hay fever, eczema, and food allergies. Asthma and atopy are both complex conditions where genetic and environmental factors are implicated in causation. Interactions between genetic and environmental factors, likely via epigenetic mechanisms, are widely thought to be important in determining the risk for developing asthma and atopy. The nature of the relationship between asthma and atopy is unclear and the answer to the question "does atopy cause asthma?" remains unknown. This review explores the relationship between asthma and atopy from a gene-environment interaction perspective and tackles the question "are similar gene-environment interactions present for asthma and atopy?" The main finding is that gene-environment interactions are described for asthma and atopy in children but these interactions are seldom sought for both asthma and atopy in the same population. In the few instances where a gene-environment interaction is related to both asthma and atopy, there is no consistent evidence that similar interactions are common to asthma and atopy. Many plausible gene-environment interactions for asthma and atopy are yet to be explored. Overall, from the gene-environment interaction perspective, there is absence of evidence to better understand the complex relationship between asthma and atopy.

Resolving the etiology of atopic disorders by using genetic analysis of racial ancestry

Atopic dermatitis (AD), food allergy, allergic rhinitis, and asthma are common atopic disorders of complex etiology. The frequently observed atopic march from early AD to asthma, allergic rhinitis, or both later in life and the extensive comorbidity of atopic disorders suggest common causal mechanisms in addition to distinct ones. Indeed, both disease-specific and shared genomic regions exist for atopic disorders. Their prevalence also varies among races; for example, AD and asthma have a higher prevalence in African Americans when compared with European Americans. Whether this disparity stems from true genetic or race-specific environmental risk factors or both is unknown. Thus far, the majority of the genetic studies on atopic diseases have used populations of European ancestry, limiting their generalizability. Large-cohort initiatives and new analytic methods, such as admixture mapping, are currently being used to address this knowledge gap. Here we discuss the unique and shared genetic risk factors for atopic disorders in the context of ancestry variations and the promise of high-throughput "-omics"-based systems biology approach in providing greater insight to deconstruct their genetic and nongenetic etiologies. Future research will also focus on deep phenotyping and genotyping of diverse racial ancestry, gene-environment, and gene-gene interactions.

Preconceptional exposure to oral contraceptive pills and the risk of wheeze, asthma and rhinitis in children

BACKGROUND

The prevalence of maternal oral contraceptive pills (OCP) use and that of childhood asthma are high in western countries. The aim of this study is to examine the association of OCP use with childhood wheeze and allergic diseases in Japan.

METHODS

Relevant data were extracted from a hospital based birth cohort study named as Tokyo-Children's Health, Illness and Development Study (T-CHILD) of which questionnaire conducted during pregnancy included maternal history and duration of OCP use. To identify wheeze and allergic diseases in the children, the questionnaire of the International Study of Asthma and Allergies in Childhood (ISAAC) was used. Logistic regression models were applied to estimate those association and adjustments were made for maternal history of allergy, maternal education level, maternal age at pregnancy, maternal BMI, maternal smoking during pregnancy, mode of delivery, gestational age at delivery, daycare attendance, number of previous live births, and gender of child.

RESULTS

OCP use was associated with ever wheeze (adjusted odds ratio [aOR], 1.62; 95% confidence interval [CI], 1.10-2.40), current wheeze (aOR, 1.59; 95% CI, 1.01-2.50), ever asthma (aOR, 1.65; 95% CI, 1.02-2.65), and ever rhinitis (aOR, 1.90; 95% CI, 1.30-2.80). Compared with no prior OCP use, using OCP for more than three months statistically increased the odds of ever wheeze (P = 0.012), current wheeze (P = 0.035), and ever rhinitis (P = 0.002).

CONCLUSIONS

Our findings suggest that maternal OCP use has a role in the development of wheeze, asthma and rhinitis in children. Extended use of OCP is likely to increase the risk of wheeze and rhinitis.

Association between thromboxane A2 receptor polymorphisms and asthma risk: A meta-analysis

OBJECTIVE

To determine whether there is an association between thromboxane A2 receptor (TBXA2R) gene polymorphisms (+924C/T and +795C/T) and asthma risk by conducting a meta-analysis.

DATA SOURCES

Pubmed, Embase, Chinese National Knowledge Infrastructure (CNKI) and Wanfang database were searched (updated May 1, 2015).

STUDY SELECTIONS

Articles evaluating the association between TBXA2R gene polymorphisms and asthma risk were selected.

RESULTS

A total of 7 studies on +924C/T polymorphism and 6 studies on +795C/T polymorphism were included in this meta-analysis. There was a significant association between TBXA2R +924C/T polymorphism and asthma risk in the recessive model (OR = 1.33, 95% CI = 1.01-1.75, P = 0.045). No significant association between +795C/T polymorphism and asthma risk in the overall population was demonstrated. In subgroup analyzes, significant association was observed in atopic asthma risk in the recessive model (OR = 1.43, 95% CI = 1.01-2.01, P = 0.043), but no significant association was found between TBXA2R +924C/T polymorphism and asthma risk in Asians (OR = 1.14, 95% CI = 0.80-1.63, P = 0.457). TBXA2R +795C/T polymorphism was associated with aspirin-intolerant asthma (AIA) risk when stratified by asthma subphenotype in the allelic model (OR = 1.30, 95% CI = 1.05-1.60, P = 0.014) and dominant model (OR = 1.50, 95% CI = 1.11-2.03, P = 0.008).

CONCLUSION

Our results suggested that TBXA2R +924C/T polymorphism is associated with asthma risk, and +795C/T polymorphism may be a risk factor for AIA. Larger-scale and well-designed studies are required to validate the association identified in the current meta-analysis.

Four-locus gene interaction between IL13, IL4, FCER1B, and ADRB2 for asthma in Chinese Han children

RATIONALE

IL13, IL4, IL4RA, FCER1B, and ADRB2 are important inflammatory genes associated with immunoglobulin E levels. This study attempts to determine whether there are gene-gene interactions in the five genes among asthmatic children of Chinese Han nationality.

METHODS

Nine single-nucleotide polymorphisms (SNPs) in the five genes were genotyped in 1,000 asthmatic children and 1,000 healthy controls using TaqMan real-time quantitative polymerase chain reaction. Multifactor-dimensionality reduction method was applied for the analysis.

RESULTS

A four-way gene-gene interaction model consisting of IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108 was chosen as the optimal one for determining asthma susceptibility (testing balanced accuracy = 0.6089, cross-validation consistency = 10/10, P = 6.98E-05). Each of the four SNPs was identified to have an independent association with childhood asthma (G allele of rs20541, odds ratio (OR) = 1.24, P = 1.23E-03; T allele of rs2243250, OR = 1.25, P = 3.81E-03; A allele of rs1042713, OR = 1.29, P = 6.75E-05; G allele of rs569108, OR = 1.27, P = 3.86E-03). Individuals homozygous for the risk alleles at all the four loci (rs20541 GG, rs2243250 TT, rs1042713 AA, and rs569108 GG) had a significantly higher risk of asthma compared with those without any risk homozygotes (OR = 13.55, P = 4.28E-03), and also greater than those with less than four risk homozygotes (OR = 10.09, P = 6.51E-03).

CONCLUSIONS

Our results suggest that IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108, four SNPs with significant sole effect on asthma, interact to confer a higher risk for the disease in Chinese Han children.

Food Allergy and Helicobacter pylori Infection: A Systematic Review

Introduction: Based on the hygiene hypothesis, a low prevalence of Helicobacter pylori (H. pylori) infection may explain the recent high prevalence of allergic diseases including food allergy. However, there are very few studies that investigate the relationship between H. pylori and food allergy.

Summary: We searched for PubMed, Ovid Medline and the Cochrane library for relevant articles published in English from inception to November 2015. The inverse relationship between H. pylori and food allergy remains unproven because of contradictory and limited evidence at the moment. Likewise, only limited studies have examined the relationship between CagA; one of H. pylori virulence factor and food allergy. On the other hand, in vitro evidence seems to point out a role of H. pylori in the causation of food allergy. The inconsistent results from epidemiological data may be due to small sample size, heterogeneous populations and unstandardised methods or food allergens.

Conclusion: Available studies do not support the role of H. pylori in food allergy.

Vitamin D supplementation protects against bone loss following inhalant organic dust and lipopolysaccharide exposures in mice

Systemic bone loss is associated with airway inflammatory diseases; yet, strategies to halt disease progression from inhalant exposures are not clear. Vitamin D might be a potentially protective approach against noxious respirable environmental exposures. We sought to determine whether vitamin D supplementation represents a viable lung- and bone-protective strategy following repetitive inhalant treatments with organic dust extract (ODE) or lipopolysaccharide (LPS) in mice. C57BL/5 mice were maintained on diets with low (1 IU/D/g) or high (10 IU/D/g) vitamin D for 5 weeks and treated with ODE from swine confinement facilities, LPS, or saline daily for 3 weeks per established intranasal inhalation protocol. Lungs, hind limbs, and sera were harvested for experimental outcomes. Serum 25-hydroxyvitamin D levels were tenfold different between low and high vitamin D treatment groups with no differences between inhalant agents and saline treatments. Serum calcium levels were not affected. There was no difference in the magnitude of ODE- or LPS-induced inflammatory cell influx or lung histopathology between high and low vitamin D treatment groups. However, high vitamin D treatment reversed the loss of bone mineral density, bone volume, and bone micro-architecture deterioration induced by ODE or LPS as determined by micro-CT analysis. Bone-resorbing osteoclasts were also reduced by high vitamin D treatment. In the low vitamin D treatment groups, ODE induced the greatest degree of airway inflammatory consequences, and LPS induced the greatest degree of bone loss. Collectively, high-concentration vitamin D was protective against systemic bone loss, but not airway inflammation, resulting from ODE- or LPS-induced airway injury.

Epigenetics of Peripheral B-Cell Differentiation and the Antibody Response

Epigenetic modifications, such as histone post-translational modifications, DNA methylation, and alteration of gene expression by non-coding RNAs, including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), are heritable changes that are independent from the genomic DNA sequence. These regulate gene activities and, therefore, cellular functions. Epigenetic modifications act in concert with transcription factors and play critical roles in B cell development and differentiation, thereby modulating antibody responses to foreign- and self-antigens. Upon antigen encounter by mature B cells in the periphery, alterations of these lymphocytes epigenetic landscape are induced by the same stimuli that drive the antibody response. Such alterations instruct B cells to undergo immunoglobulin (Ig) class switch DNA recombination (CSR) and somatic hypermutation (SHM), as well as differentiation to memory B cells or long-lived plasma cells for the immune memory. Inducible histone modifications, together with DNA methylation and miRNAs modulate the transcriptome, particularly the expression of activation-induced cytidine deaminase, which is essential for CSR and SHM, and factors central to plasma cell differentiation, such as B lymphocyte-induced maturation protein-1. These inducible B cell-intrinsic epigenetic marks guide the maturation of antibody responses. Combinatorial histone modifications also function as histone codes to target CSR and, possibly, SHM machinery to the Ig loci by recruiting specific adaptors that can stabilize CSR/SHM factors. In addition, lncRNAs, such as recently reported lncRNA-CSR and an lncRNA generated through transcription of the S region that form G-quadruplex structures, are also important for CSR targeting. Epigenetic dysregulation in B cells, including the aberrant expression of non-coding RNAs and alterations of histone modifications and DNA methylation, can result in aberrant antibody responses to foreign antigens, such as those on microbial pathogens, and generation of pathogenic autoantibodies, IgE in allergic reactions, as well as B cell neoplasia. Epigenetic marks would be attractive targets for new therapeutics for autoimmune and allergic diseases, and B cell malignancies.

The Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort study: assessment of environmental exposures

The Canadian Healthy Infant Longitudinal Development birth cohort was designed to elucidate interactions between environment and genetics underlying development of asthma and allergy. Over 3600 pregnant mothers were recruited from the general population in four provinces with diverse environments. The child is followed to age 5 years, with prospective characterization of diverse exposures during this critical period. Key exposure domains include indoor and outdoor air pollutants, inhalation, ingestion and dermal uptake of chemicals, mold, dampness, biological allergens, pets and pests, housing structure, and living behavior, together with infections, nutrition, psychosocial environment, and medications. Assessments of early life exposures are focused on those linked to inflammatory responses driven by the acquired and innate immune systems. Mothers complete extensive environmental questionnaires including time-activity behavior at recruitment and when the child is 3, 6, 12, 24, 30, 36, 48, and 60 months old. House dust collected during a thorough home assessment at 3-4 months, and biological specimens obtained for multiple exposure-related measurements, are archived for analyses. Geo-locations of homes and daycares and land-use regression for estimating traffic-related air pollution complement time-activity-behavior data to provide comprehensive individual exposure profiles. Several analytical frameworks are proposed to address the many interacting exposure variables and potential issues of co-linearity in this complex data set.

Developing Primary Intervention Strategies to Prevent Allergic Disease

Allergic diseases are a major cause of morbidity in the developed world, now affecting up to 40 % of the population with no evidence that this is abating. If anything, the prevalence of early onset allergic diseases such as eczema and food allergy appears to be still increasing. This is almost certainly due to the changing modern environment and lifestyle factors, acting to promote immune dysfunction through early perturbations in immune maturation, immune tolerance and regulation. This early propensity to inflammation may also have implications for the rising risk of other inflammatory non-communicable diseases (NCDs) later in life. Identifying risk factors and pathways for preventing early onset immune disease like allergy is likely to have benefits for many aspects of human health, particularly as many NCDs share similar risk factors. This review focuses on recent advances in primary intervention strategies for promoting early immune health and preventing allergic disease, highlighting the current evidence-based guidelines where applicable and areas requiring further investigation.

Gene-environment interactions in the study of asthma in the postgenomewide association studies era

PURPOSE OF REVIEW

Asthma is a complex disease characterized by an intricate interplay of both heritable and environmental factors. Understanding the mechanisms through which genes and environment interact represents one of the major challenges for pulmonary researchers. This review provides an overview of the recently published literature on gene-environment (G × E) interactions in asthma, with a special focus on the new methodological developments in the postgenomewide association studies (GWAS) era.

RECENT FINDINGS

Most recent studies on G × E interaction in asthma used a candidate-gene approach. Candidate-gene studies considering exposure to outdoor air pollutants showed significant interactions mainly with variants in the GSTP1 gene on asthma in children. G × E studies on passive and active smoking, including one genomewide interaction study, identified novel genes of susceptibility to asthma and a time-dependent effect of maternal smoking. Other recent studies on asthma found interactions between candidate genes and occupational allergen exposure and several domestic exposures such as endotoxin and gas cooking. New methods were developed to efficiently estimate G × E interaction in GWAS, and a pathway-based strategy to select an enriched gene-set for G × E studies has recently been proposed.

SUMMARY

The G × E studies presented in this review offer a good example on how candidate-gene approaches can complement and help in validating GWAS findings.

Influences of large sets of environmental exposures on immune responses in healthy adult men

Environmental factors have long been known to influence immune responses. In particular, clinical studies about the association between migration and increased risk of atopy/asthma have provided important information on the role of migration associated large sets of environmental exposures in the development of allergic diseases. However, investigations about environmental effects on immune responses are mostly limited in candidate environmental exposures, such as air pollution. The influences of large sets of environmental exposures on immune responses are still largely unknown. A simulated 520-d Mars mission provided an opportunity to investigate this topic. Six healthy males lived in a closed habitat simulating a spacecraft for 520 days. When they exited their “spacecraft” after the mission, the scenario was similar to that of migration, involving exposure to a new set of environmental pollutants and allergens. We measured multiple immune parameters with blood samples at chosen time points after the mission. At the early adaptation stage, highly enhanced cytokine responses were observed upon ex vivo antigen stimulations. For cell population frequencies, we found the subjects displayed increased neutrophils. These results may presumably represent the immune changes occurred in healthy humans when migrating, indicating that large sets of environmental exposures may trigger aberrant immune activity.

Associations of Pet Ownership with Wheezing and Lung Function in Childhood: Findings from a UK Birth Cohort

Background

Asthma is a heterogeneous condition and differential effects of pet ownership on non-atopic versus atopic asthma have been reported. The aim of this study was to investigate whether pet ownership during pregnancy and early childhood was associated with wheezing from birth to age 7 years and with lung function at age 8 years in a UK population-based birth cohort.

Methods

Data from the Avon Longitudinal Study of Parents and Children (ALSPAC) were used to investigate associations of pet ownership at six time-points from pregnancy to age 7 years with concurrent episodes of wheezing, wheezing trajectories (phenotypes) and lung function at age 8 years using logistic regression models adjusted for child’s sex, maternal history of asthma/atopy, maternal smoking during pregnancy, and family adversity.

Results

4,706 children had complete data on pet ownership and wheezing. From birth to age 7 years, cat ownership was associated with an overall 6% lower odds of wheezing (OR=0.94 (0.89-0.99)). Rabbit and rodent ownership was associated with 21% (OR=1.21 (1.12-1.31)) and 11% (OR=1.11 (1.02–1.21)) higher odds of wheezing, respectively, with strongest effects evident during infancy. Rabbit and rodent ownership was positively associated with a ‘persistent wheeze’ phenotype. Pet ownership was not associated with lung function at age 8 years, with the exception of positive associations of rodent and bird ownership with better lung function.

Conclusions

Cat ownership was associated with reduced risk, and rabbit and rodent ownership with increased risk, of wheezing during childhood. The mechanisms behind these differential effects warrant further investigation.