Investigating the causal effect of smoking on hay fever and asthma: a Mendelian randomization meta-analysis in the CARTA consortium

Importance of GWAS Risk Loci and Clinical Data in Predicting Asthma Using Machine-learning Approaches

INTRODUCTION

To understand the risk factors of asthma, we combined genome-wide association study (GWAS) risk loci and clinical data in predicting asthma using machine-learning approaches.

METHODS

A case-control study with 123 asthmatics and 100 controls was conducted in the Zhuang population in Guangxi. GWAS risk loci were detected using polymerase chain reaction, and clinical data were collected. Machine-learning approaches were used to identify the major factors that contribute to asthma.

RESULTS

A total of 14 GWAS risk loci with clinical data were analyzed on the basis of 10 times the 10-fold cross-validation for all machine-learning models. Using GWAS risk loci or clinical data, the best performances exhibited area under the curve (AUC) values of 64.3% and 71.4%, respectively. Combining GWAS risk loci and clinical data, the XGBoost established the best model with an AUC of 79.7%, indicating that the combination of genetics and clinical data can enable improved performance. We then sorted the importance of features and found the top six risk factors for predicting asthma to be rs3117098, rs7775228, family history, rs2305480, rs4833095, and body mass index.

CONCLUSION

Asthma-prediction models based on GWAS risk loci and clinical data can accurately predict asthma, and thus provide insights into the disease pathogenesis.

Systematic replication of smoking disease associations using survey responses and EHR data in the All of Us Research Program

OBJECTIVE

The All of Us Research Program (All of Us) aims to recruit over a million participants to further precision medicine. Essential to the verification of biobanks is a replication of known associations to establish validity. Here, we evaluated how well All of Us data replicated known cigarette smoking associations.

MATERIALS AND METHODS

We defined smoking exposure as follows: (1) an EHR Smoking exposure that used International Classification of Disease codes; (2) participant provided information (PPI) Ever Smoking; and, (3) PPI Current Smoking, both from the lifestyle survey. We performed a phenome-wide association study (PheWAS) for each smoking exposure measurement type. For each, we compared the effect sizes derived from the PheWAS to published meta-analyses that studied cigarette smoking from PubMed. We defined two levels of replication of meta-analyses: (1) nominally replicated: which required agreement of direction of effect size, and (2) fully replicated: which required overlap of confidence intervals.

RESULTS

PheWASes with EHR Smoking, PPI Ever Smoking, and PPI Current Smoking revealed 736, 492, and 639 phenome-wide significant associations, respectively. We identified 165 meta-analyses representing 99 distinct phenotypes that could be matched to EHR phenotypes. At P < .05, 74 were nominally replicated and 55 were fully replicated. At P < 2.68 × 10-5 (Bonferroni threshold), 58 were nominally replicated and 40 were fully replicated.

DISCUSSION

Most phenotypes found in published meta-analyses associated with smoking were nominally replicated in All of Us. Both survey and EHR definitions for smoking produced similar results.

CONCLUSION

This study demonstrated the feasibility of studying common exposures using All of Us data.

The Link between Periodontal Disease and Asthma: How Do These Two Diseases Affect Each Other?

A growing body of evidence suggests that the effects of poor oral hygiene extend beyond the oral cavity and are associated with a variety of systemic diseases, including asthma. Asthma, which results in symptoms of cough, wheezing, and dyspnoea, and is characterized by airflow limitation with variability and (partial or complete) reversibility, is amongst the most prevalent respiratory diseases with approximately 262 million patients worldwide, and its prevalence and disease burden is on the increase. While asthma can occur at a young age, it can also develop later in life and affects a variety of age groups. Both of these diseases have a chronic course, and various researchers have suggested a link between the two. In this article, we aim to provide a literature review focusing on the association between the two diseases. The results demonstrate that medications (primarily, inhaler medicine), hypoxia induced by asthma, and the breathing behaviour of patients potentially trigger periodontal disease. In contrast, oral periodontopathogenic microorganisms and the inflammatory mediators produced by them may be involved in the onset and/or exacerbation of asthma. Common contributing factors, such as smoking, gastro-oesophageal reflux, and type-2 inflammation, should also be considered when evaluating the relationship between the two diseases.

Socioeconomic and environmental determinants of asthma prevalence: a cross-sectional study at the U.S. County level using geographically weighted random forests

BACKGROUND

Some studies have established associations between the prevalence of new-onset asthma and asthma exacerbation and socioeconomic and environmental determinants. However, research remains limited concerning the shape of these associations, the importance of the risk factors, and how these factors vary geographically.

OBJECTIVE

We aimed (1) to examine ecological associations between asthma prevalence and multiple socio-physical determinants in the United States; and (2) to assess geographic variations in their relative importance.

METHODS

Our study design is cross sectional based on county-level data for 2020 across the United States. We obtained self-reported asthma prevalence data of adults aged 18 years or older for each county. We applied conventional and geographically weighted random forest (GWRF) to investigate the associations between asthma prevalence and socioeconomic (e.g., poverty) and environmental determinants (e.g., air pollution and green space). To enhance the interpretability of the GWRF, we (1) assessed the shape of the associations through partial dependence plots, (2) ranked the determinants according to their global importance scores, and (3) mapped the local variable importance spatially.

RESULTS

Of the 3059 counties, the average asthma prevalence was 9.9 (standard deviation ± 0.99). The GWRF outperformed the conventional random forest. We found an indication, for example, that temperature was inversely associated with asthma prevalence, while poverty showed positive associations. The partial dependence plots showed that these associations had a non-linear shape. Ranking the socio-physical environmental factors concerning their global importance showed that smoking prevalence and depression prevalence were most relevant, while green space and limited language were of minor relevance. The local variable importance measures showed striking geographical differences.

CONCLUSION

Our findings strengthen the evidence that socio-physical environments play a role in explaining asthma prevalence, but their relevance seems to vary geographically. The results are vital for implementing future asthma prevention programs that should be tailor-made for specific areas.

Beta2-adrenoreceptor agonists and long-term risk of Parkinson's disease

INTRODUCTION

There is limited information on how the association between Parkinson's disease and the use of beta2-adrenoreceptor (β2AR) agonists varies among groups of short-, long-, and ultra-long-acting β2AR agonists (SABA, LABA and ultraLABA).

METHODS

In this prospective study of the Norwegian population, we estimated the incidence of Parkinson's disease according to exposure to β2AR agonists as a time-dependent variable by means of Cox regression. We adjusted for educational level, comorbidity and performed a sensitivity analysis excluding individuals with chronic obstructive pulmonary disease (COPD), all factors associated with smoking. Anticholinergics and corticosteroids as drugs with the same indication were analyzed for comparison.

RESULTS

In the follow-up period from 2005 to 2019, 15,807 incident Parkinson's cases were identified. After adjustments for sex, education and age as the timescale, SABA (Hazard ratio (HR) = 0.84; 95%CI: 0.79, 0.89; p < 0.001), LABA (HR = 0.85; 95%CI: 0.81, 0.90; p < 0.001) and ultraLABA (HR = 0.6; 95%CI: 0.49, 0.73; p < 0.001) were all associated with a lower risk of Parkinson's disease. After exclusion of COPD patients, corticosteroids and anticholinergics were no longer inversely associated, whereas β2AR agonists remained associated.

CONCLUSION

Of drugs with the same indication of use, only β2AR agonists remained inversely associated with PD risk after all adjustments, with ultraLABA displaying the overall strongest association. Although the precision of the estimate is limited by the modest number of exposed PD cases without COPD, the association is intriguing and suggest that longer-acting, more lipophilic, and thus likely more brain-penetrant β2AR agonists could be prioritized for further studies.

Causal risk factors for asthma in Mendelian randomization studies: A systematic review and meta-analysis

BACKGROUND

Several risk factors for asthma have been proposed; however, the causality of these associations is sometimes unclear. Mendelian randomization is a powerful epidemiological approach that can help elucidate the causality of risk factors. The aim of the present study was to identify causal risk factors for asthma through Mendelian Randomization studies.

METHODS

A systematic search of PubMed and EMBASE was conducted, to identify studies investigating risk factors for asthma or respiratory allergies through Mendelian Randomization. When two or more studies investigated the same risk factor a meta-analysis was conducted. Of 239 studies initially identified, 41 were included.

RESULTS

A causal association between adiposity and adult asthma risk was found in 10 out of 12 studies with a summary risk ratio of 1.05 per kg/m² increase in BMI (95% CI: 1.03-1.07). Puberty timing (n = 3), alcohol (n = 2), and linoleic acid (n = 1) had causal effects on asthma risk, while vitamins/minerals (n = 6) showed no consistent effect on asthma. The effect of smoking on adult asthma conflicted between studies. Several of the significant associations of asthma with immune related proteins (n = 5) and depression (n = 2) investigated through multiple traits analyses could generally benefit from replications in independent datasets.

CONCLUSION

This systematic review and meta-analysis found evidence for causal effects of adiposity, puberty timing, linoleic acid, alcohol, immune related proteins, and depression on risk of asthma.

Outcome Expectancies and Resistance Self-Efficacy Mediate the Relationship Between Asthma Diagnosis and E-cigarette Use among Youth and Young Adults

Introduction: The use of electronic cigarettes (e-cigarettes) may exacerbate pulmonary complications in youth and young adults with asthma. We sought to identify the cognitive mechanisms that might explain e-cigarette use in this population. We hypothesized that e-cigarette outcome expectancies and e-cigarette resistance self-efficacy would mediate the relationship between asthma diagnosis and e-cigarette use in youth and young adults. Methods: We enrolled youth and young adults (15-25 years old) in Alabama with a clinical diagnosis of asthma (n = 130) or without a diagnosis of any chronic pulmonary disease (n = 115; reference group). Author-constructed and validated questionnaires (young adult e-cigarette use outcome expectancies and modified Self-efficacy Scale for Adolescent Smoking) were administered to collect demographic data and assess susceptibility to e-cigarette use as well as current use of e-cigarettes, e-cigarette outcome expectancies, and e-cigarette resistance self-efficacy. We then conducted structural equation modeling to test whether e-cigarette expectancies and e-cigarette resistance self-efficacy mediate the relationship between asthma and susceptibility to e-cigarette use as well as current e-cigarette use. Results: The frequency of the susceptibility to e-cigarette use and current e-cigarette use was lower among those with clinically diagnosed asthma than among those without asthma (35.8% vs 59.8% for susceptibility and 6.0% vs 18.2% for current use). Individuals with asthma reported weaker expectancies that e-cigarettes would make them feel relaxed which, in turn, was a significant predictor of lower susceptibility to e-cigarette use and current e-cigarette use, suggesting mediation. Finally, individuals with asthma demonstrated greater e-cigarette resistance self-efficacy in the context of social opportunities and friends' influence to use e-cigarettes. This self-efficacy was associated with lower susceptibility to e-cigarette use as well as current e-cigarette use. Conclusion: Although longitudinal studies are needed to determine relationships prospectively, targeted interventions that reduce outcome expectancies and increase resistance self-efficacy to e-cigarette use may further reduce e-cigarette use among youth and young adults with asthma.

Multiple Tobacco Product Use among Adolescents with Asthma in Korea

Few studies have examined the use of multiple tobacco products among adolescents with asthma. The purpose of this study was to examine multiple tobacco product use and smoking behaviors. In this study, data from the Korea Youth Risk Behavior Web-based Survey (KYRBWS) were used, and 57,303 samples from 400 middle schools and 400 high schools in Korea were classified as study participants. Statistical analysis was performed with a complex sample design, using frequency analysis, chi-square test, and multiple logistic regression analysis. Adolescents with asthma had a higher current smoking rate for combustible cigarettes (CC), e-cigarettes (EC), and heated tobacco products (HTPs) than those without asthma (p < 0.001). The rates of dual use (using two types of tobacco; CC + EC or CC + HTPs or EC + HTPs; OR = 2.62, 95% CI: 1.626−4.240, R2 = 26.8%) and triple use (using three types of tobacco; CC + EC + HTPs; OR = 2.61, 95% CI: 1.678−4.065, R2 = 34.9%) were higher in adolescents with asthma than those without asthma, after adjusting for confounders. The smoking rate of new types of tobacco among adolescents with asthma is on the rise. Therefore, the calculation of basic data related to new tobacco smoking among adolescents is essential for establishing a continuous monitoring system to alleviate the burden of disease on national health.

Asthma and Tobacco Smoking

Asthma is a prevalent chronic pulmonary condition with significant morbidity and mortality. Tobacco smoking is implicated in asthma pathophysiology, diagnosis, prognosis and treatment. Smokers display increased prevalence and incidence of asthma, but a causal association cannot be claimed using existing evidence. Second-hand smoking and passive exposure to tobacco in utero and early life have also been linked with asthma development. Currently, approximately one-fourth of asthma patients are smokers. Regular smokers with asthma might display accelerated lung function decline and non-reversible airflow limitation, making their distinction from chronic obstructive pulmonary disease patients challenging. Asthma patients who smoke typically have uncontrolled disease, as shown by increased symptoms, more exacerbations and impaired quality of life. On the other hand, smoking cessation improves lung function and asthma severity. Thus, asthma patients and their caregivers should be actively questioned about their smoking status at each medical encounter, and smoking cessation ought to be strongly encouraged both for patients with asthma and their close contacts. Smokers with asthma should be provided with comprehensive smoking cessation interventions on top of other anti-asthma medications.

Association of milk intake with hay fever, asthma, and lung function: a Mendelian randomization analysis

BACKGROUND

Previous observational studies have indicated a protective effect of drinking milk on asthma and allergy. In Mendelian Randomization, one or more genetic variants are used as unbiased markers of exposure to examine causal effects. We examined the causal effect of milk intake on hay fever, asthma, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) by using the lactase rs4988235 genotype associated with milk intake.

METHODS

We performed a Mendelian Randomization study including 363,961 participants from the UK Biobank.

RESULTS

Observational analyses showed that self-reported milk-drinkers vs. non-milk drinkers had an increased risk of hay fever: odds ratio (OR) = 1.36 (95% CI 1.32, 1.40, p < 0.001), asthma: OR = 1.33 (95% CI 1.38, 1.29, p < 0.001), yet a higher FEV1: β = 0.022 (SE = 0.004, p < 0.001) and FVC: β = 0.026 (SE = 0.005, p < 0.001). In contrast, genetically determined milk-drinking vs. not drinking milk was associated with a lower risk of hay fever: OR = 0.791 (95% CI 0.636, 0.982, p = 0.033), and asthma: OR = 0.587 (95% CI 0.442, 0.779, p = 0.001), and lower FEV1: β = - 0.154 (standard error, SE = 0.034, p < 0.001) liter, and FVC: β = - 0.223 (SE = 0.034, p < 0.001) liter in univariable MR analyses. These results were supported by multivariable Mendelian randomization analyses although not statistically significant.

CONCLUSIONS

As opposed to observational results, genetic association findings indicate that drinking milk has a protective effect on hay fever and asthma but may also have a negative effect on lung function. The results should be confirmed in other studies before any recommendations can be made.

Cigarette Smoking and Asthma

Globally, around half the adult asthma population are current or former cigarette smokers. Cigarette smoking and asthma interact to induce an "asthma-smoking phenotype(s)," which has important implications for diagnosis, pathogenic mechanisms, and management. The lack of progress in understanding the effects of smoking on adults with asthma is due in part to their exclusion from most investigative studies and large clinical trials. In this review, we summarize the adverse clinical outcomes associated with cigarette smoking in asthma, highlight challenges in diagnosing asthma among cigarette smokers with chronic respiratory symptoms, particularly in older individuals with a long-standing smoking history, and review pathogenic mechanisms involving smoking- and asthma-related airway inflammation, tissue remodeling, corticosteroid insensitivity, and low-grade systemic inflammation. We discuss the key components of management including the importance of smoking cessation strategies, evidence for the effectiveness of the Global Initiative for Asthma recommendations on treatment in cigarette smokers, and the role of treatable traits such as type 2 eosinophilic airway inflammation. Lastly, we provide an algorithm to aid clinicians to manage current and former smokers with asthma. In the future, controlled and pragmatic trials in real-world populations should include cigarette smokers with asthma to provide an evidence base for treatment recommendations.

Smoking behavior might affect allergic rhinitis and vasomotor rhinitis differently: A mendelian randomization appraisal

Background

Allergic rhinitis and vasomotor rhinitis are harassing numerous patients and their risk factors have not been well investigated. Here, we try to identify their risk factors and distinguish these 2 diseases.

Methods

A two-sample Mendelian randomization (MR) study was implemented to discover the risk factors of allergic and vasomotor rhinitis. Based on previous studies, we selected 15 potential risk factors and the genome-wide summary statistics were extracted from the non-FinnGen consortium. The genome-wide summary statistics of rhinitis were obtained from the FinnGen consortium. Both univariable MR and multivariable MR analyses were performed to identify the causal risk factors. The Cochrane's Q value was calculated to appraise the heterogeneity. MR-Egger intercept and MR-RPESSO were utilized to appraise the pleiotropy.

Results

In the univariable model, the number of cigarettes per day can decrease the risk of allergic rhinitis (IVW OR = 0.29[0.18, 0.47], p-value = 2.70 × 10⁻⁷) while increasing the risk of vasomotor rhinitis (IVW OR = 1.30[1.04, 1.62], p-value = 0.022). Besides, no other risk factors could affect the risk of either allergic or vasomotor rhinitis. After adjusting for age of smoking initiation and alcohol intake, the cigarettes per day could still decrease the risk of allergic rhinitis (IVW OR = 4.66 × 10⁻³ [1.99 × 10⁻⁴, 0.11], p-value = 0.003) while not affecting the risk of vasomotor rhinitis (IVW OR = 0.92[0.44, 1.96], p-value = 0.834).

Conclusion

Smoking can affect the risk of allergic and vasomotor rhinitis differently where it decreases the risk of allergic rhinitis and increases the risk of vasomotor rhinitis.

Individual characteristics and associated factors of hay fever: A large-scale mHealth study using AllerSearch

BACKGROUND

The prevalence of hay fever, a multifactorial allergic disease, is increasing. Identifying individual characteristics and associated factors of hay fever is essential for predictive, preventive, personalized, and participatory (P4) medicine. This study aimed to identify individual characteristics and associated factors of hay fever using an iPhone application AllerSearch.

METHODS

This large-scale mobile health-based cross-sectional study was conducted between February 2018 and May 2020. Individuals who downloaded AllerSearch in Japan and provided a comprehensive self-assessment (general characteristics, medical history, lifestyle habits, and hay fever symptoms [score range 0-36]) were included. Associated factors of hay fever (vs. non-hay fever) and severe hay fever symptoms were identified using multivariate logistic and linear regression analyses, respectively.

RESULTS

Of the included 11,284 individuals, 9041 had hay fever. Factors associated with hay fever (odds ratio) included age (0.98), female sex (1.33), atopic dermatitis (1.40), history of dry eye diagnosis (1.36), discontinuation of contact lens use during hay fever season (3.34), frequent bowel movements (1.03), and less sleep duration (0.91). The factors associated with severe hay fever symptoms among individuals with hay fever (coefficient) included age (-0.104), female sex (1.329), history of respiratory disease (1.539), history of dry eye diagnosis (0.824), tomato allergy (1.346), discontinuation of contact lens use during hay fever season (1.479), smoking habit (0.614), and having a pet (0.303).

CONCLUSIONS

Our large-scale mobile health-based study using AllerSearch elucidated distinct hay fever presentation patterns, characteristics, and factors associated with hay fever. Our study establishes the groundwork for effective individualized interventions for P4 medicine.

Atopic Dermatitis: Disease Characteristics and Comorbidities in Smoking and Nonsmoking Patients from the TREATgermany Registry

BACKGROUND

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a multifactorial genesis including genetic predispositions and environmental risk and trigger factors. One of the latter possibly is smoking, indicated by an increased prevalence of AD in adults and children that are actively or passively exposed to cigarette smoke.

OBJECTIVES

In this study AD characteristics and its atopic comorbidities are compared in smoking and nonsmoking AD patients.

METHODS

TREATgermany is a non-interventional clinical registry which includes patients with moderate to severe AD in Germany. Baseline data of patients included into TREATgermany from inception in June 2016 to April 2020 in 39 sites across Germany was analyzed comparing AD disease characteristics and comorbidities in smokers versus non-smokers.

RESULTS

Of 921 patients, 908 (male: 58.7%) with a mean age of 41.9 ± 14.4 reported their smoking status. The objective Scoring of Atopic Dermatitis (oSCORAD) did not differ between smokers (n=352; 38.8%) and nonsmokers, however lesions' intensity of oozing/crusts and excoriations as well as patient global assessment scores (PGA) of AD severity were higher in smoking as opposed to nonsmoking patients. Smokers reported a lower number of weeks with well-controlled AD and more severe pruritus than nonsmokers. Total IgE levels were more elevated in smokers and they displayed a younger age at initial diagnosis of bronchial asthma. After adjustment for potential confounders, the increased intensity of oozing/crusts, the reduced number of weeks with well-controlled AD and the greater pruritus remained different in smokers compared to nonsmokers. In addition, smoking patients with adult-onset AD showed a 2.5 times higher chance of involvement of the feet.

CONCLUSIONS

German registry data indicate that AD patients who smoke have a higher disease burden with a different distribution pattern of lesions in adult-onset AD.

Management of adult asthma and chronic rhinitis as one airway disease

Introduction: Chronic rhinitis is defined as nasal inflammation with the presence of minimum two symptoms such as nasal obstruction, rhinorrhea, sneezing and/or itching one hour daily for a minimum of 12 weeks/year. According their etiology, four groups of rhinitis are described: allergic, infectious, non-allergic non-infectious and mixed.Chronic rhinitis is frequently associated with asthma, shares similar mechanisms of the pathogenesis and has a negative impact of its outcomes sustaining the concept of unified airways disease.Areas covered: The present review summarizes the complex relationship between chronic rhinitis and asthma on the basis of recent epidemiological data, clinical characteristics, diagnosis and therapeutic management. All four groups are discussed with the impact of their specific treatment on asthma outcomes. Some medications are common for chronic rhinitis and asthma while others are more specific but able to treat the associated comorbidity.Expert opinion: The systematic assessment of chronic rhinitis in patients with asthma and its specific treatment improves both disease outcomes. Conversely, several therapies of asthma demonstrated beneficial effects on chronic rhinitis. Treating both diseases at the same time by only one medication is an interesting option to explore in the future in order to limit drugs administration, related costs and side effects.

Scutellaria baicalensis and Their Natural Flavone Compounds as Potential Medicinal Drugs for the Treatment of Nicotine-Induced Non-Small-Cell Lung Cancer and Asthma

Flavonoids as the largest group of natural phytochemical compounds have received significant attention, as demonstrated by clinical trials, due to their chemotherapeutic and/or pharmacological effects against non-small-cell lung cancer (NSCLC) and asthma. Scutellaria baicalensis (S. baicalensis), known as one of the most popular medicinal plants and used in several countries, contains natural active flavone constituents, with the major compounds of the roots being baicalein, baicalin, wogonin, wogonoside and oroxylin A. S. baicalensis and their compounds are proven to have inhibitory effects on NSCLC cells when used at different concentrations. However, the exact mechanisms by which these compounds exert their therapeutic effects against asthma remain unexplored. Indeed, the mechanisms by which S. baicalensis and its flavone compounds exert a protective effect against nicotine-induced NSCLC and asthma are not yet fully understood. Therefore, this review explores the mechanisms involved in the therapeutic potential of flavone-rich extracts from S. baicalensis in nicotine-induced NSCLC and asthma.

Proxy gene-by-environment Mendelian randomization study confirms a causal effect of maternal smoking on offspring birthweight, but little evidence of long-term influences on offspring health

Background

A lack of genetic data across generations makes transgenerational Mendelian randomization (MR) difficult. We used UK Biobank and a novel proxy gene-by-environment MR to investigate effects of maternal smoking heaviness in pregnancy on offspring health, using participants’ (generation one: G1) genotype (rs16969968 in CHRNA5) as a proxy for their mothers’ (G0) genotype.

Methods

We validated this approach by replicating an established effect of maternal smoking heaviness on offspring birthweight. Then we applied this approach to explore effects of maternal (G0) smoking heaviness on offspring (G1) later life outcomes and on birthweight of G1 women’s children (G2).

Results

Each additional smoking-increasing allele in offspring (G1) was associated with a 0.018 [95% confidence interval (CI): -0.026, -0.009] kg lower G1 birthweight in maternal (G0) smoking stratum, but no meaningful effect (-0.002 kg; 95% CI: -0.008, 0.003) in maternal non-smoking stratum (interaction P-value = 0.004). The differences in associations of rs16969968 with grandchild’s (G2) birthweight between grandmothers (G0) who did, versus did not, smoke were heterogeneous (interaction P-value = 0.042) among mothers (G1) who did (-0.020 kg/allele; 95% CI: -0.044, 0.003), versus did not (0.007 kg/allele; 95% CI: -0.005, 0.020), smoke in pregnancy.

Conclusions

Our study demonstrated how offspring genotype can be used to proxy for the mother’s genotype in gene-by-environment MR. We confirmed the causal effect of maternal (G0) smoking on offspring (G1) birthweight, but found little evidence of an effect on G1 longer-term health outcomes. For grandchild’s (G2) birthweight, the effect of grandmother’s (G0) smoking heaviness in pregnancy may be modulated by maternal (G1) smoking status in pregnancy.

The relationship between asthma diagnosis and E-Cigarette use among youth and young adults: the mediation effects of anxiety, depression, and impulsivity and the moderation effects of substance use

INTRODUCTION

Youth and young adults with asthma use electronic cigarettes (e-cigarettes) at a higher rate than those without asthma. However, the factors that influence e-cigarette use in this vulnerable population are scarce. Therefore, the study aim was to assess the effects of anxiety, depression, impulsivity, and substance use in the relationship between e-cigarette use and youth and young adults with asthma status.

METHOD

We enrolled youth and young adults (15-25 years old) in Alabama with a clinical diagnosis of asthma (n = 151) or without a diagnosis of any chronic pulmonary disease (n = 132; reference group). Validated questionnaires were administered to collect demographic data and assess susceptibility to e-cigarette use, current use of e-cigarettes, anxiety, depression, impulsivity, and substance use (alcohol and cannabis). We then conducted parallel mediation analyses to test the mediational effects of anxiety, depression, and impulsivity, and moderation analyses to assess the moderation effects of substance use in the relationship between asthma and e-cigarette use.

RESULTS

Susceptibility to e-cigarette use and current use of e-cigarettes were both lower among youth and young adults with asthma. After controlling for covariates, anxiety, depression, and impulsivity were not significant mediators of the relationships between asthma and susceptibility to e-cigarette use and current use of e-cigarettes. However, the frequency of cannabis use in the past 30 days moderated the relationship between asthma and susceptibility to e-cigarette use (Unstandardized beta = - 2.03, p = 0.046), such that more frequent cannabis use was associated with less susceptibility.

CONCLUSION

Among youth and young adults with asthma, cannabis use was associated with reduced susceptibility to e-cigarette use. Longitudinal assessments of this population are needed to better assess the temporal relationship between asthma, comorbid substance use, and e-cigarette use among young people with asthma to avoid pulmonary complications.

Maternal and childhood exposure to inorganic arsenic and airway allergy - A 15-Year birth cohort follow-up study

BACKGROUND

The prevalence of allergic diseases in children has increased globally. Early-life exposure to inorganic arsenic has been found to be associated with impaired immune function and decreased lung function in children; however, the results are inconsistent. We aimed to evaluate the effect of prenatal and childhood exposure to inorganic arsenic on allergic diseases in children, through a 15-year follow-up birth cohort study, conducted in central Taiwan.

METHODS

Children born to women enrolled in the Taiwan Maternal and Infant Cohort Study (TMICS-pilot) from December 2000 to November 2001 were recruited and followed every 2-3 years until the age of 14 years. Urinary specimens were collected in the pregnant women during the 3rd trimester and the followed children. Diagnoses of allergic diseases were based on physician diagnoses using the International Study of Asthma and Allergies in Childhood questionnaire. Urinary arsenic speciation was performed using high-performance liquid chromatography and inductively coupled plasma dynamic reaction cell mass spectrophotometry.

RESULTS

Of the 261 children from 358 mother-infant pairs for this study, those with asthma and allergic rhinitis reported a higher prevalence of maternal allergy (49.47%) than did non-allergic children (29.81%). In the fully adjusted model, levels of maternal urine (iAs + MMA + DMA) greater than the median were found to be significantly associated with an increased risk of asthma (OR = 4.28; 95% CI 1.32, 13.85). Levels of urinary (iAs + MMA + DMA) in children higher than the median were associated with an increased risk of allergic rhinitis (OR = 2.26; 95% CI 1.20, 4.26).

CONCLUSION

Prenatal and childhood exposure to inorganic arsenic were found to be significantly associated with the occurrence of asthma and allergic rhinitis in children, respectively. Further large cohort follow-up studies are important to validate the association between inorganic arsenic exposure and allergic diseases in children.

Mental Health and the Association between Asthma and E-cigarette Use among Young Adults in The United States: A Mediation Analysis

Background: Asthma is associated with a greater likelihood of e-cigarette use among young adults, which may increase the risk of pulmonary complications. Because substance use trajectories emerge in early adulthood, it is important to identify factors that may be important in addressing this new public health threat. One such factor may be poor mental health. Methods: Data were extracted from the 2018 Behavioral Risk Factor Surveillance System (BRFSS). Current and former asthma status was measured by self-reported lifetime and current asthma status; mental health functioning was measured by the number of self-reported bad mental health days during the past 30 days; e-cigarette use was measured by self-reported current e-cigarette use. We tested the hypothesis that mental health mediates the association between asthma status and e-cigarette use among young adults using structural equation modeling. Results: The prevalence of e-cigarette use was significantly higher among young adults with current (9.90%) or former asthma (13.09%) than those without asthma (9.58%). Furthermore, the number of bad mental health days in the past 30 days was significantly greater among young adults with current or former asthma than among those without asthma (Mean (Standard Deviation): 6.85 (0.42), 4.18 (0.85) versus 3.83 (0.17)), respectively. Finally, we found a statistically significant indirect effect of asthma on the likelihood of e-cigarette use through mental health such that the higher prevalence of e-cigarette use among those with current or former asthma was statistically accounted for by a greater number of bad mental health days in the past 30 days. Conclusions: Consistent with mediation, poorer mental health accounted for the higher prevalence of e-cigarette use among those with asthma. However, longitudinal studies are needed to interrogate causal relationships, including the effects of e-cigarette use on mental health. Mental health services may play an important role in improving health and wellbeing in this vulnerable population.

The need for clean air: The way air pollution and climate change affect allergic rhinitis and asthma

Air pollution and climate change have a significant impact on human health and well-being and contribute to the onset and aggravation of allergic rhinitis and asthma among other chronic respiratory diseases. In Westernized countries, households have experienced a process of increasing insulation and individuals tend to spend most of their time indoors. These sequelae implicate a high exposure to indoor allergens (house dust mites, pets, molds, etc), tobacco smoke, and other pollutants, which have an impact on respiratory health. Outdoor air pollution derived from traffic and other human activities not only has a direct negative effect on human health but also enhances the allergenicity of some plants and contributes to global warming. Climate change modifies the availability and distribution of plant- and fungal-derived allergens and increases the frequency of extreme climate events. This review summarizes the effects of indoor air pollution, outdoor air pollution, and subsequent climate change on asthma and allergic rhinitis in children and adults and addresses the policy adjustments and lifestyle changes required to mitigate their deleterious effects.

Lifetime Smoking and Asthma: A Mendelian Randomization Study

Evidence from clinical and epidemiological studies indicates that asthma is associated with allergic diseases including hay fever, allergic rhinitis, and eczema. Genetic analysis demonstrated that asthma had a positive genetic correlation with allergic diseases. A Mendelian randomization (MR) analysis using the rs16969968 single-nucleotide variant as the instrumental variable indicated that smoking was associated with increased risk of asthma. However, in a different MR analysis, smoking was significantly associated with reduced hay fever and reduced allergic sensitization risk. These findings revealed inconsistencies in the association of smoking with asthma and allergic diseases. Hence, we conducted an updated MR analysis to investigate the causal association between lifetime smoking and asthma risk by using 124 genetic variants as the instrumental variables. No significant pleiotropy was detected using the MR-Egger intercept test. We found that increased lifetime smoking was significantly associated with decreased asthma risk by using the inverse variance weighted (IVW) method (OR = 0.97, 95% CI 0.956-0.986, and P = 1.77E-04), the weighted median regression method (OR = 0.976, 95% CI 0.96-0.994, and P = 8.00E-03), and the MR-Egger method (OR = 0.919, 95% CI 0.847-0.998, and P = 4.5E-02). Importantly, MR pleiotropy residual sum and outlier (MR-PRESSO) MR analysis also indicated a significant association between increased lifetime smoking and decreased asthma risk with OR = 0.971, 95% CI 0.956-0.986, and P = 2.69E-04. After the outlier was removed, MR-PRESSO outlier test further supported the significant association with OR = 0.971, 95% CI 0.959-0.984, P = 1.57E-05.

The rising of allergic respiratory diseases in a changing world: from climate change to migration

INTRODUCTION

The rising of allergic respiratory diseases (ARDs) suggests a decisive role of environmental factors, that have dramatically changed in the last decades.

AREAS COVERED

This review addresses various aspects of the external exposome acting on the development, progression, clinical presentation and severity of ARDs. Climate change, air pollution and biodiversity loss act directly and through their complex interactions on atopic risk: reacent foundings on these aspects are discussed herein. The review also focuses on migration studies, underling the possible role of migrant status as an experimental model to study environment effects on atopy onset and progression.

EXPERT OPINION

Future perspective on this topic include prevention and mitigation strategies in regard to pollution and climate change, improvement of environmental monitoring methods, implementation of public health policies, further advances in 'omics' research and knowledge, prospective and immunological research on migrant populations and new policies to face human mobility.

[Vulnerability of women to tobacco: The broncho-pulmonary consequences (asthma, COPD)]

Smoking remains common, with an exposure that begins early during pregnancy. It induces epigenetic changes, with a trans-generational transmission. Smoking increases the risk of uncontrolled asthma during childhood and adult life. Asthma is also associated with increased risk of a decline of lung function and chronic obstructive pulmonary disease (COPD). Women are more at risk of developing early and severe COPD. The mechanisms are currently poorly known.

Is smoking heaviness causally associated with alcohol use? A Mendelian randomization study in four European cohorts

Background

Observational studies have shown that tobacco and alcohol use co-occur, but it is not clear whether this relationship is causal.

Methods

Using data from the Avon Longitudinal Study of Parents and Children (ALSPAC) and UK Biobank, we used observational methods to test the hypothesis that smoking heaviness increases alcohol consumption. Mendelian randomization (MR) analyses were then used to test the causal relationship between smoking heaviness and alcohol consumption using 55 967 smokers from four European studies [ALSPAC, The Nord-Trøndelag Health Study (HUNT), the Copenhagen General Population Study (CGPS) and UK Biobank]. MR analyses used rs1051730/rs16969968 as a genetic proxy for smoking heaviness.

Results

Observational results provided evidence of an association between cigarettes per day and weekly alcohol consumption (increase in units of alcohol per additional cigarette smoked per day = 0.10, 95% confidence interval (CI) 0.05 to 0.15, P ≤ 0.001 in ALSPAC; and 0.48, 95% CI 0.45 to 0.52, P ≤ 0.001 in UK Biobank). However, there was little evidence for an association between rs1051730/rs16969968 and units of alcohol consumed per week across ALSPAC, HUNT, CGPS and UK Biobank (standard deviation increase in units of alcohol per additional copy of the risk allele = –0.004, 95% CI –0.023 to 0.016, P=0.708, I² = 51.9%). We had 99% and 88% power to detect a change of 0.03 and 0.02 standard deviation units of alcohol per additional copy of the risk allele, respectively.

Conclusions

Previously reported associations between smoking and alcohol are unlikely to be causal, and may be the result of confounding and/or reverse causation. This has implications for public health research and intervention research.

Genetic Architectures of Childhood- and Adult-Onset Asthma Are Partly Distinct

The extent to which genetic risk factors are shared between childhood-onset (COA) and adult-onset (AOA) asthma has not been estimated. On the basis of data from the UK Biobank study (n = 447,628), we found that the variance in disease liability explained by common variants is higher for COA (onset at ages between 0 and 19 years; h²_g = 25.6%) than for AOA (onset at ages between 20 and 60 years; h²_g = 10.6%). The genetic correlation (r_g) between COA and AOA was 0.67. Variation in age of onset among COA-affected individuals had a low heritability (h²_g = 5%), which we confirmed in independent studies and also among AOA-affected individuals. To identify subtype-specific genetic associations, we performed a genome-wide association study (GWAS) in the UK Biobank for COA (13,962 affected individuals) and a separate GWAS for AOA (26,582 affected individuals) by using a common set of 300,671 controls for both studies. We identified 123 independent associations for COA and 56 for AOA (37 overlapped); of these, 98 and 34, respectively, were reproducible in an independent study (n = 262,767). Collectively, 28 associations were not previously reported. For 96 COA-associated variants, including five variants that represent COA-specific risk factors, the risk allele was more common in COA- than in AOA-affected individuals. Conversely, we identified three variants that are stronger risk factors for AOA. Variants associated with obesity and smoking had a stronger contribution to the risk of AOA than to the risk of COA. Lastly, we identified 109 likely target genes of the associated variants, primarily on the basis of correlated expression quantitative trait loci (up to n = 31,684). GWAS informed by age of onset can identify subtype-specific risk variants, which can help us understand differences in pathophysiology between COA and AOA and so can be informative for drug development.

The Effects of Dietary Supplements on Asthma and Lung Cancer Risk in Smokers and Non-Smokers: A Review of the Literature

Smoking is one of the major global causes of death. Cigarette smoke and secondhand (passive) smoke have been causally related to asthma and lung cancer. Asthma is a potential risk factor for developing lung cancer in both smokers and non-smokers. Prospective studies and randomized control trials (RCTs) of dietary supplements and lung cancer risk in adult smokers and non-smokers have yielded inconsistent results. A few prospective studies have shown that long-term use of high doses of some supplements, such as retinol, β-carotene, B vitamins, and vitamin E, increase lung cancer risk in current and former smokers. Limited evidence from RCTs suggests that vitamin D supplementation is effective in improving lung function and reducing asthma risk in current/former smokers. The relationship between dietary supplements and lung cancer risk has never before been examined in asthmatic smokers and non-smokers. This short review aims to examine the evidence from existing studies for the effects of dietary supplements on asthma/lung cancer risk and mortality in smokers and non-smokers.

The potential impact and cost-effectiveness of tobacco reduction strategies for tuberculosis prevention in Canadian Inuit communities

BACKGROUND

Tuberculosis (TB) remains a significant public health problem in Canadian Inuit communities. In 2016, Canadian Inuit had an incidence rate 35 times the Canadian average. Tobacco use is an important risk factor for TB, and over 60% of Inuit adults smoke. We aimed to estimate changes in TB-related outcomes and costs from reducing tobacco use in Inuit communities.

METHODS

Using a transmission model to estimate the initial prevalence of latent TB infection (LTBI), followed by decision analysis modelling, we conducted a cost-effectiveness analysis that compared the current standard of care for management of TB and LTBI without additional tobacco reduction intervention (Status Quo) with (1) increased tobacco taxation, (2) pharmacotherapy and counselling for smoking cessation, (3) pharmacotherapy, counselling plus mass media campaign, and (4) the combination of all these. Projected outcomes included the following: TB cases, TB-related deaths, quality-adjusted life years (QALYs), and health system costs, all over 20 years.

RESULTS

The combined strategy was projected to reduce active TB cases by 6.1% (95% uncertainty range 4.9-7.0%) and TB deaths by 10.4% (9.5-11.4%) over 20 years, relative to the status quo. Increased taxation was the only cost-saving strategy.

CONCLUSIONS

Currently available strategies to reduce commercial tobacco use will likely have a modest impact on TB-related outcomes in the medium term, but some may be cost saving.

Active and passive smoking impacts on asthma with quantitative and temporal relations: A Korean Community Health Survey

This study aimed to evaluate the relations of smoking with asthma and asthma-related symptoms, considering quantitative and temporal influences. The 820,710 Korean adults in the Korean Community Health Survey in 2009, 2010, 2011, and 2013 were included and classified as non-smoker, past smoker or current smoker. Total smoking years, total pack-years, and age at smoking onset were assessed. Information on wheezing, exercise wheezing, and aggravation of asthma in the past 12 months and asthma diagnosis history and current treatment was collected. Multiple logistic regression analysis with complex sampling was used. Current and former smokers showed significant positive relations with wheezing, exercise wheezing, asthma ever, current asthma, and asthma aggravation. Current smokers demonstrated higher adjusted odd ratios (AORs) for wheezing, exercise wheezing, and asthma aggravation than former smokers. Former smokers showed higher AORs than current smokers for current asthma treatment. Longer passive smoking was related to wheezing and exercise wheezing. Greater age at smoking onset and duration since cessation were negatively related to wheezing, exercise wheezing, and current asthma; total pack-years demonstrated proportional associations with these symptoms. Former, current, and passive smoking was positively correlated with wheezing and exercise wheezing. Total pack-years and early initiation were increasingly related to asthma.

Estimating the causal effect of body mass index on hay fever, asthma and lung function using Mendelian randomization

BACKGROUND

Observational studies have shown that body mass index (BMI) is positively associated with asthma. However, observational data are prone to confounding and reverse causation. In Mendelian randomization, genetic variants are used as unconfounded markers of exposures to examine causal effects. We examined the causal effect of BMI on asthma, hay fever, allergic sensitization, serum total immunoglobulin E (IgE), forced expiratory volume in one-second (FEV1) and forced vital capacity (FVC).

METHODS

We included 490 497 participants in the observational and 162 124 participants in the genetic analyses. A genetic risk score (GRS) was created using 26 BMI-associated single nucleotide polymorphisms (SNPs). Results were pooled in meta-analyses and expressed as odds ratios (ORs) or β-estimates with 95% confidence interval (CI).

RESULTS

The GRS was significantly associated with asthma (OR=1.009; 95% CI: 1.004, 1.013), but not with hay fever (OR= 0.998; 95% CI: 0.994, 1.002) or allergic sensitization (OR=0.999; 95% CI: 0.986, 1.012) per BMI-increasing allele. The GRS was significantly associated with decrease in FEV1: β=-0.0012 (95% CI: -0.0019, -0.0006) and FVC: β=-0.0022 (95% CI: -0.0031, -0.0014) per BMI-increasing allele. Effect sizes estimated by instrumental variable analyses were OR=1.07 (95% CI: 1.03, 1.10) for asthma, a 9 ml decrease in FEV1 (95% CI: 2.0-15 mL decrease) and a 16 ml decrease in FVC (95% CI: 7.0-24 mL decrease) per 1 kg/m² higher BMI.

CONCLUSIONS

The results support the conclusion that increasing BMI is causally related to higher prevalence of asthma and decreased lung function, but not with hay fever or biomarkers of allergy.