Leveraging gene-environment interactions and endotypes for asthma gene discovery

Revealing the mechanism and efficacy of natural products on treating the asthma: Current insights from traditional medicine to modern drug discovery

Asthma remains a significant global health challenge, demanding innovative approaches to treatment. Traditional medicine has a rich history of using natural products to alleviate asthmatic symptoms. However, transitioning from these traditional remedies to modern drug discovery approaches has provided fresh insights into the mechanisms and effectiveness of these natural products. This study provides our comprehensive review, which examines the current state of knowledge in the treatment of asthma. It delves into the mechanisms through which natural products ameliorate asthma symptoms, and it discusses their potential in the development of novel therapeutic interventions. Our analysis reveals that natural products, traditionally employed for asthma relief, exhibit diverse mechanisms of action. These include anti-inflammatory, bronchodilatory, immunomodulatory effects, and reducing gene expression. In the context of modern drug discovery, these natural compounds serve as valuable candidates for the development of novel asthma therapies. The transition from traditional remedies to modern drug discovery represents a promising avenue for asthma treatment. Our review highlights the substantial efficacy of natural products in managing asthma symptoms, underpinned by well-defined mechanisms of action. By bridging the gap between traditional and contemporary approaches, we contribute to the growing body of knowledge in the field, emphasizing the potential of natural products in shaping the future of asthma therapy.

Unraveling the Molecular Landscape of Neutrophil Extracellular Traps in Severe Asthma: Identification of Biomarkers and Molecular Clusters

Neutrophil extracellular traps (NETs) play a central role in chronic airway diseases. However, the precise genetic basis linking NETs to the development of severe asthma remains elusive. This study aims to unravel the molecular characterization of NET-related genes (NRGs) in severe asthma and to reliably identify relevant molecular clusters and biomarkers. We analyzed RNA-seq data from the Gene Expression Omnibus database. Interaction analysis revealed fifty differentially expressed NRGs (DE-NRGs). Subsequently, the non-negative matrix factorization algorithm categorized samples from severe asthma patients. A machine learning algorithm then identified core NRGs that were highly associated with severe asthma. DE-NRGs were correlated and subjected to protein-protein interaction analysis. Unsupervised consensus clustering of the core gene expression profiles delineated two distinct clusters (C1 and C2) characterizing severe asthma. Functional enrichment highlighted immune-related pathways in the C2 cluster. Core gene selection included the Boruta algorithm, support vector machine, and least absolute contraction and selection operator algorithms. Diagnostic performance was assessed by receiver operating characteristic curves. This study addresses the molecular characterization of NRGs in adult severe asthma, revealing distinct clusters based on DE-NRGs. Potential biomarkers (TIMP1 and NFIL3) were identified that may be important for early diagnosis and treatment of severe asthma.

Modulating Th1/Th2 drift in asthma-related immune inflammation by enhancing bone mesenchymal stem cell homing through targeted inhibition of the Notch1/Jagged1 signaling pathway

Asthma, a disease intricately linked to immune inflammation, is significantly influenced by the immune regulatory effect of bone mesenchymal stem cells (BMSCs). This study aims to investigate changes in the homing of BMSCs in bronchial asthma, focusing on the Notch homolog (Notch)1/Jagged1 signaling pathway's role in regulating T helper 1(Th1)/T helper 2(Th2) drift. Additionally, we further explore the effects and mechanisms of homologous BMSCs implantation in asthma-related immune inflammation. Following intervention with BMSCs, a significant improvement in the pathology of rats with asthma was observed. Simultaneously, a reduction in the expression of inflammatory cells and inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin(IL)-4, and IL-13 was observed in bronchoalveolar lavage fluid (BALF). Furthermore, there was an increase in the expression of Th1 cytokine Interferon-γ（IFN-γ）and the transcription factor T-box expressed in T cell (T-bet), while the expression of Th2 cytokine IL-13 and transcription factor GATA binding protein (GATA)-3 decreased in lung tissue. This indicates that the Th1/Th2 drift leans towards Th1, which a crucial in ameliorating asthma inflammation. Importantly, inhibition of the Notch1 signaling pathway led to an increased expression of the Stromal cell-derived factor-1(SDF-1)/C-X-C motif chemokine receptor (CXCR)4 chemokine axis. Consequently, the homing ability of bone marrow mesenchymal stem cells to asthma-affected lung tissue was significantly enhanced. BMSCs demonstrated heightened efficacy in regulating the cytokine/chemokine network and Th1/Th2 balance, thereby restoring a stable state during the immune response process in asthma. In conclusion, inhibiting the Notch signaling pathway enhances the expression of the SDF-1 and CXCR4 chemokine axis, facilitating the migration of allogeneic BMSCs to injured lung tissues. This, in turn, promotes immune regulation and improves the Th1/Th2 imbalance, thereby enhancing the therapeutic effect on asthmatic airway inflammation.

Association between urine uranium and asthma prevalence

Background

Previous studies showed that urine uranium (U) is associated with asthma prevalence in adults. However, the association between them among the general population is unclear. Therefore, this study aimed to explore this unclear association.

Methods

The data of the participants were collected from the 2007-2016 National Health and Nutrition Examination Survey (NHANES) performed in the United States. Continuous variables with a skewed distribution were analyzed using Ln-transformation. The association between urine U and asthma prevalence was analyzed by multiple regression analysis, and the linear association between them was evaluated by smoothed curve fitting. The subgroup analysis was performed using the hierarchical multivariate regression analysis.

Results

A total of 13,581 participants were included in our analysis. The multivariate regression analysis showed that LnU was independently and positively correlated with asthma prevalence in the general population (OR = 1.12; 95% CI: 1.04-1.20; p = 0.002). The subgroup analysis revealed that college graduate or above showed a stronger association between LnU and asthma prevalence (<9th grade: OR = 0.84; 95% CI: 0.61-1.14; 9-11th grade: OR = 1.23; 95% CI: 0.99-1.52; high school grade: OR = 1.00; 95% CI: 0.84-1.19; college: OR = 1.04; 95% CI: 0.91-1.19; ≥college graduate: OR = 1.32; 95% CI: 1.11-1.57; P for interaction = 0.0389).

Conclusion

Our research suggested that urinary U levels are positively associated with asthma prevalence among the general population of the United States, and the association is especially strong among people with high levels of education.

Association of Matrix Metalloproteinase-1 Promoter Polymorphisms With Asthma Risk

BACKGROUND/AIM

Matrix metalloproteinase-1 (MMP-1) expression has been documented as an influential contributor to the intricate milieu of allergic airway inflammation, tissue remodeling, and the exacerbation of asthma's severity. However, the genetic role underlying MMP-1 in the context of asthma has remained enigmatic, with its full implications yet to be unveiled. Considering this, our research was designed to investigate the association of MMP-1 -1607 rs1799750 and the propensity for asthma severity.

PATIENTS AND METHODS

As a case-control investigation, our study enrolled 198 individuals diagnosed with asthma and age- and sex-matched 453 non-asthmatic controls. The genotypes of MMP-1 rs1799750 were determined utilizing the polymerase chain reaction-restriction fragment length polymorphism methodology.

RESULTS

The frequency distributions of 2G/2G, 1G/2G and 1G/1G genotypes at MMP-1 rs1799750 were 49, 42.9, and 8.1%, respectively, among the patients with asthma. This pattern was not different from that of controls (43.7, 46.8, and 9.5%, respectively) (p for trend=0.4486). The allelic frequency pertaining to the variant 1G allele within the asthma group was 29.5%, with a non-significant disparity compared to the 32.9% in the control group (p=0.2596). Noticeably, there was a positive association between MMP-1 rs1799750 2G/1G and 1G/1G genotypes with asthma severity (p=0.0060).

CONCLUSION

Our research indicated that the presence of MMP-1 rs1799750 1G allele might not be the sole arbiter of an individual's susceptibility to asthma, yet its potential to function as a discerning prognostic marker for the severity of asthma emerged as a noteworthy finding deserving attention and further exploration.

Extracellular vesicles from BALF of pediatric cystic fibrosis and asthma patients increase epithelial sodium channel activity in small airway epithelial cells

Extracellular Vesicles (EVs) are nanosized vesicles derived from all cell types. EV cargo allows for intercellular communication, intracellular signaling, and regulation of proteins in recipient cells. We tested the hypothesis that EVs isolated from the bronchoalveolar-lavage fluid (BALF) of pediatric cystic fibrosis (CF) or pediatric asthma patients increase epithelial sodium channel (ENaC) activity in normal human small airway epithelial cells (SAECs) and the mechanism involves specific EV lipids. We characterized EVs from BALF of pediatric CF and pediatric asthma patients by nanoparticle tracking analysis, transmission electron microscopy, and Western blotting. The CF and asthma pediatric groups were similar in BALF electrolytes concentration and cell count, except for neutrophils, which were higher in the CF group. Lipidomic analyses for each group of EVs were performed using targeted mass spectrometry. Phosphatidylethanolamine, sphingomyelins, and triacylglycerol were enriched in both groups, but phosphatidylcholine and phosphatidylinositol concentrations were greater in the CF group compared to the asthma group, and the opposite trend was found for phosphatidylserine. Endogenous ENaC activity, measured by the single-channel patch-clamp technique, increased in normal human SAECs after challenging SAEC with EVs from either the CF or asthma groups compared to control EVs. In conclusion, EVs isolated from BALF of pediatric patients with CF or asthma have unique lipid profiles. Despite the differences, both types of EVs increase ENaC activity in normal human SAECs compared to control EVs isolated from the conditioned media of these cells.

Metabolomics Applied to Pediatric Asthma: What Have We Learnt in the Past 10 Years?

Background: Asthma is the most common chronic condition in children. It is a complex non-communicable disease resulting from the interaction of genetic and environmental factors and characterized by heterogeneous underlying molecular mechanisms. Metabolomics, as with the other omic sciences, thanks to the joint use of high-throughput technologies and sophisticated multivariate statistical methods, provides an unbiased approach to study the biochemical-metabolic processes underlying asthma. The aim of this narrative review is the analysis of the metabolomic studies in pediatric asthma published in the past 10 years, focusing on the prediction of asthma development, endotype characterization and pharmaco-metabolomics. Methods: A total of 43 relevant published studies were identified searching the MEDLINE/Pubmed database, using the following terms: "asthma" AND "metabolomics". The following filters were applied: language (English), age of study subjects (0-18 years), and publication date (last 10 years). Results and Conclusions: Several studies were identified within the three areas of interest described in the aim, and some of them likely have the potential to influence our clinical approach in the future. Nonetheless, further studies are needed to validate the findings and to assess the role of the proposed biomarkers as possible diagnostic or prognostic tools to be used in clinical practice.

Exploration and Validation of Potential Biomarkers and Therapeutic Targets in Ferroptosis of Asthma

Purpose

Asthma is a chronic inflammatory airway disease involving multiple mechanisms, of which ferroptosis is a form of programmed cell death. Recent studies have shown that ferroptosis may play a crucial role in the pathogenesis of asthma, but no specific ferroptosis gene has been found in asthma, and the exact mechanism is still unclear. The present study aimed to screen ferroptosis genes associated with asthma and find therapeutic targets, in order to contribute a new clue for the diagnosis and therapy of asthma.

Methods

Ferroptosis-related differentially expressed genes (FR-DEGs) in asthma were selected by the GSE41861, GSE43696 and ferroptosis datasets. Next, the FR-DEGs were subjected by GO and KEGG enrichment, and the mRNA-miRNA network was constructed. Then, GSEA and GSVA enrichment analysis and Immune infiltration analysis were performed, followed by targeted drug prediction. Finally, the expression of FR-DEGs was confirmed using GSE63142 dataset and RT-PCR assay.

Results

We found 13 FR-DEGs by the GSE41861, GSE43696 and ferroptosis database. Functional enrichment analysis revealed that the 13 FR-DEGs were enriched in oxidative stress, immune response, ferroptosis, lysosome, necrosis, apoptosis etc. Moreover, our results revealed the mRNA-miRNA network of the FR-DEGs and identified candidate drugs. Also, immune infiltration revealed that ELAVL1, CREB5, CBR1 and NR1D2 are associated with the immune cells and may be potential targets in asthma. Finally, 10 FR-DEGs were validated by the GSE63142 database. It was verified that 7 FR-DEGs were differentially expressed by collecting asthma patients and healthy controls.

Conclusion

This study ultimately identified 7 FR-DEGs for the diagnosis and therapy of asthma. These 7 FR-DEGs contribute to oxidative stress and immune responses. This study provides potential therapeutic targets and biomarkers for asthma patients, shedding further light on the pathogenesis of asthma as well as providing new insights into the treatment of asthma.

Application of Metabolomics in Obesity-Related Childhood Asthma Subtyping: A Narrative Scoping Review

Obesity-related asthma is a heterogeneous childhood asthma phenotype with rising prevalence. Observational studies identify early-life obesity or weight gain as risk factors for childhood asthma development. The reverse association is also described, children with asthma have a higher risk of being obese. Obese children with asthma have poor symptom control and an increased number of asthma attacks compared to non-obese children with asthma. Clinical trials have also identified that a proportion of obese children with asthma do not respond as well to usual treatment (e.g., inhaled corticosteroids). The heterogeneity of obesity-related asthma phenotypes may be attributable to different underlying pathogenetic mechanisms. Although few childhood obesity-related asthma endotypes have been described, our knowledge in this field is incomplete. An evolving analytical profiling technique, metabolomics, has the potential to link individuals' genetic backgrounds and environmental exposures (e.g., diet) to disease endotypes. This will ultimately help define clinically relevant obesity-related childhood asthma subtypes that respond better to targeted treatment. However, there are challenges related to this approach. The current narrative scoping review summarizes the evidence for metabolomics contributing to asthma subtyping in obese children, highlights the challenges associated with the implementation of this approach, and identifies gaps in research.

Environmental influences on childhood asthma: Allergens

Allergen exposure is associated with the development of allergen-specific sensitization, but their relationship is influenced by other contemporaneous exposures (such as microbial exposure) and the genetic predisposition of the host. Clinical outcomes of the primary prevention studies that tested the effectiveness of allergen avoidance in pregnancy and early life on the subsequent development of sensitization and asthma published to date are inconsistent. Therefore, we cannot provide any evidence-based advice on the use of allergen avoidance for the primary prevention of these conditions. The evidence about the impact of allergen exposure among and among sensitized children with asthma is more consistent, and the combination of sensitization and high exposure to sensitizing allergen increases airway inflammation, triggers symptoms, adversely impacts upon disease control, and is associated with poorer lung function in preschool age. However, there are differing opinions about the role of inhalant allergen avoidance in asthma management, and recommendations differ in different guidelines. Evidence from more recent high-quality trials suggests that mite allergen-impermeable bed encasings reduce hospital attendance with asthma attacks and that multifaceted targeted environmental control improves asthma control in children. We therefore suggest a pragmatic approach to allergen avoidance in the management of childhood asthma for clinical practice, including the recommendations to: (1) tailor the intervention to the patient's sensitization and exposure status by using titer of allergen-specific IgE antibodies and/or the size of the skin test as indicators of potential response; (2) use a multifaceted allergen control regime to reduce exposure as much as possible; and (3) start intervention as early as possible upon diagnosis.

Novel genetic variants in long non-coding RNA MEG3 are associated with the risk of asthma

Background

Asthma is the most common chronic inflammatory airway disease worldwide. Asthma is a complex disease whose exact etiologic mechanisms remain elusive; however, it is increasingly evident that genetic factors play essential roles in the development of asthma. The purpose of this study is to identify novel genetic susceptibility loci for asthma in Taiwanese. We selected a well-studied long non-coding RNA (lncRNA), MEG3, which is involved in multiple cellular functions and whose expression has been associated with asthma. We hypothesize that genetic variants in MEG3 may influence the risk of asthma.

Methods

We genotyped four single nucleotide polymorphisms (SNPs) in MEG3, rs7158663, rs3087918, rs11160608, and rs4081134, in 198 patients with asthma and 453 healthy controls and measured serum MEG3 expression level in a subset of controls.

Results

The variant AG and AA genotypes of MEG3 rs7158663 were significantly over-represented in the patients compared to the controls (P = 0.0024). In logistic regression analyses, compared with the wild-type GG genotype, the heterozygous variant genotype (AG) was associated with a 1.62-fold [95% confidence interval (CI) [1.18-2.32], P = 0.0093] increased risk and the homozygous variant genotype (AA) conferred a 2.68-fold (95% CI [1.52-4.83], P = 0.003) increased risk of asthma. The allelic test showed the A allele was associated with a 1.63-fold increased risk of asthma (95% CI [1.25-2.07], P = 0.0004). The AG plus AA genotypes were also associated with severe symptoms (P = 0.0148). Furthermore, the AG and AA genotype carriers had lower serum MEG3 expression level than the GG genotype carriers, consistent with the reported downregulation of MEG3 in asthma patients.

Conclusion

MEG3 SNP rs7158663 is a genetic susceptibility locus for asthma in Taiwanese. Individuals carrying the variant genotypes have lower serum MEG3 level and are at increased risks of asthma and severe symptoms.

LncRNAs ENST00000499459 and TCONS_00004989 enhance asthma progression in children with house dust mite-induced allergic asthma

BACKGROUND

Long non-coding RNAs (lncRNAs) have been extensively reported to play critical roles in the pathogenesis of various disease, especially in cancer. However, little is known about the role of lncRNAs in the pathogenesis of pediatric allergic asthma.

METHODS

High-throughput sequencing analysis was performed to identify differentially expressed mRNAs and lncRNAs in peripheral blood mononuclear cells (PBMCs) from 3 children with allergic asthma and 3 matched healthy controls. Bioinformatics analysis was used to select candidate lncRNAs and mRNAs that may be involved in the pathogenesis of asthma. Candidate lncRNAs were validated in a larger size of asthma patients and healthy controls. Finally, lncRNAs and molecular pathways associated with the pathogenesis of allergic asthma were identified by competing endogenous RNA (ceRNA) analysis.

RESULTS

Five differentially expressed lncRNAs were identified after high-throughput sequencing and verified by real-time PCR. LncRNAs ENST0000631797, TCONS_00004989 and ENST00000499459 were verified to be differentially expressed in allergic asthma. Besides, ENST00000499459/DIXDC1 axis was identified to play a crucial role in allergic asthma after comprehensive ceRNA network analysis.

CONCLUSION

ENST00000499459 and TCONS_00004989 are potential biomarkers for house dust mite-induced allergic asthma.

Asthma and Wheeze Severity and the Oropharyngeal Microbiota in Children and Adolescents

Rationale: There is a major unmet need for improving the care of children and adolescents with severe asthma and wheeze. Identifying factors contributing to disease severity may lead to improved diagnostics, biomarkers, or therapies. The airway microbiota may be such a key factor. Objectives: To compare the oropharyngeal airway microbiota of children and adolescents with severe and mild/moderate asthma/wheeze. Methods: Oropharyngeal swab samples from school-age and preschool children in the European U-BIOPRED (Unbiased BIOmarkers in the PREDiction of respiratory disease outcomes) multicenter study of severe asthma, all receiving severity-appropriate treatment, were examined using 16S ribosomal RNA gene sequencing. Bacterial taxa were defined as amplicon sequence variants. Results: We analyzed 241 samples from four cohorts: A) 86 school-age children with severe asthma; B) 39 school-age children with mild/moderate asthma; C) 65 preschool children with severe wheeze; and D) 51 preschool children with mild/moderate wheeze. The most common bacteria were Streptococcus (mean relative abundance, 33.5%), Veillonella (10.3%), Haemophilus (7.0%), Prevotella (5.9%), and Rothia (5.5%). Age group (school-age vs. preschool) was associated with the microbiota in β-diversity analysis (F = 3.32, P = 0.011) and in a differential abundance analysis (28 significant amplicon sequence variants). Among all children, we found no significant difference in the microbiota between children with severe and mild/moderate asthma/wheeze in univariable β-diversity analysis (F = 1.99, P = 0.08, N = 241), but a significant difference in a multivariable model (F = 2.66, P = 0.035), including the number of exacerbations in the previous year. Age was also significant when expressed as a microbial maturity score (Spearman Rho, 0.39; P = 4.6 × 10^-10); however, this score was not associated with asthma/wheeze severity. Conclusions: There was a modest difference in the oropharyngeal airway microbiota between children with severe and mild/moderate asthma/wheeze across all children but not in individual age groups, and a strong association between the microbiota and age. This suggests the oropharyngeal airway microbiota as an interesting entity in studying asthma severity, but probably without the strength to serve as a biomarker for targeted intervention.

Identification of Novel Metabolic Subtypes Using Multi-Trait Limited Mixed Regression in the Chinese Population

The aggregation and interaction of metabolic risk factors leads to highly heterogeneous pathogeneses, manifestations, and outcomes, hindering risk stratification and targeted management. To deconstruct the heterogeneity, we used baseline data from phase II of the Fangshan Family-Based Ischemic Stroke Study (FISSIC), and a total of 4632 participants were included. A total of 732 individuals who did not have any component of metabolic syndrome (MetS) were set as a reference group, while 3900 individuals with metabolic abnormalities were clustered into subtypes using multi-trait limited mixed regression (MFMR). Four metabolic subtypes were identified with the dominant characteristics of abdominal obesity, hypertension, hyperglycemia, and dyslipidemia. Multivariate logistic regression showed that the hyperglycemia-dominant subtype had the highest coronary heart disease (CHD) risk (OR: 6.440, 95% CI: 3.177-13.977) and that the dyslipidemia-dominant subtype had the highest stroke risk (OR: 2.450, 95% CI: 1.250-5.265). Exome-wide association studies (EWASs) identified eight SNPs related to the dyslipidemia-dominant subtype with genome-wide significance, which were located in the genes APOA5, BUD13, ZNF259, and WNT4. Functional analysis revealed an enrichment of top genes in metabolism-related biological pathways and expression in the heart, brain, arteries, and kidneys. Our findings provide directions for future attempts at risk stratification and evidence-based management in populations with metabolic abnormalities from a systematic perspective.

Airway inflammation in adolescents and elderly women: Chronic air pollution exposure and polygenic susceptibility

BACKGROUND AND AIM

The fractional exhaled nitric oxide (FeNO) concentration in the exhaled breath is a biomarker for eosinophilic airway inflammation. We explored the interplay between chronic air pollution exposure and polygenic susceptibility to airway inflammation at different critical age stages.

METHODS

Adolescents (15 yr) enrolled in the GINIplus/LISA birth cohorts (n = 2434) and 220 elderly women (75 yr on average) enrolled in the SALIA cohort with FeNO measurements available were investigated. Environmental main effects of the mean of ESCAPE land-use regression air pollutant concentrations within a time window of 15 years and main effects of the polygenic risk scores (PRS) using internal weights from elastic net regression of genome-wide derived single nucleotide polymorphisms were investigated. Furthermore, we examined gene-environment interaction (GxE) effects on natural log-transformed FeNO levels by adjusted linear regression models.

RESULTS

While we observed no significant environmental and polygenic main effects on airway inflammation in either age group, we found robust harmful effects of chronic nitrogen dioxide (NO₂) exposure in the GxE models for elderly women (16.2 % increase in FeNO, p-value = 0.027). Stratified analyses found GxE effects between the PRS and chronic NO₂ exposure in never-smoker elderly women and in adolescents without any inflammatory respiratory conditions.

CONCLUSIONS

FeNO measurement is a useful biomarker to detect higher risk of NO₂-induced eosinophilic airway inflammation in the elderly. There was limited evidence for GxE effects on airway inflammation in adolescents or the elderly. Further GxE studies in subpopulations should be conducted to investigate the assumption that susceptibility to airway inflammation differs between age stages.

Identification of Hub Genes and Potential Biomarkers for Childhood Asthma by Utilizing an Established Bioinformatic Analysis Approach

Childhood asthma represents a heterogeneous disease resulting from the interaction between genetic factors and environmental exposures. Currently, finding reliable biomarkers is necessary for the clinical management of childhood asthma. However, only a few biomarkers are being used in clinical practice in the pediatric population. In the long run, new biomarkers for asthma in children are required and would help direct therapy approaches. This study aims to identify potential childhood asthma biomarkers using a genetic-driven biomarkers approach. Herein, childhood asthma-associated Single Nucleotide Polymorphisms (SNPs) were utilized from the GWAS database to drive and facilitate the biomarker of childhood asthma. We uncovered 466 childhood asthma-associated loci by extending to proximal SNPs based on r2 > 0.8 in Asian populations and utilizing HaploReg version 4.1 to determine 393 childhood asthma risk genes. Next, the functional roles of these genes were subsequently investigated using Gene Ontology (GO) term enrichment analysis, a Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and a protein−protein interaction (PPI) network. MCODE and CytoHubba are two Cytoscape plugins utilized to find biomarker genes from functional networks created using childhood asthma risk genes. Intriguingly, 10 hub genes (IL6, IL4, IL2, IL13, PTPRC, IL5, IL33, TBX21, IL2RA, and STAT6) were successfully identified and may have been identified to play a potential role in the pathogenesis of childhood asthma. Among 10 hub genes, we strongly suggest IL6 and IL4 as prospective childhood asthma biomarkers since both of these biomarkers achieved a high systemic score in Cytohubba’s MCC algorithm. In summary, this study offers a valuable genetic-driven biomarker approach to facilitate the potential biomarkers for asthma in children.

Subtyping children with asthma by clustering analysis of mRNA expression data

Background: Asthma is a heterogeneous disease. There are several phenotypic classifications for childhood asthma.

Methods: Unsupervised consensus cluster analysis was used to classify 36 children with persistent asthma from the GSE65204 dataset. The differentially expressed genes (DEGs) between different asthma subtypes were identified, and weighted gene co-expression network analysis (WGCNA) was carried out. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis was performed for DEGs and critical gene modules. Protein–protein interactions (PPI) were constructed to obtain the hub genes. Finally, differences in the immune microenvironment were analyzed between different subtypes.

Results: Two subtypes (C1, C2) were identified using unsupervised consensus clustering. The DEGs between different asthma subtypes were mainly enriched in immune regulation and the release of inflammatory mediators. The important modular genes screened by WGCNA were mainly enriched in aspects of inflammatory mediator regulation. PPI analysis found 10 hub genes (DRC1, TTC25, DNALI1, DNAI1, DNAI2, PIH1D3, ARMC4, RSPH1, DNAAF3, and DNAH5), and ROC analysis demonstrated that 10 hub genes had a reliably ability to distinguish C1 from C2. And we observed differences between C1 and C2 in their immune microenvironment.

Conclusion: Using the gene expression profiles of children’s nasal epithelium, we identified two asthma subtypes that have different gene expression patterns, biological characteristics, and immune microenvironments. This will provide a reference point for future childhood asthma typing and personalized therapy.

Genetic variants in miR-145 gene are associated with the risk of asthma in Taiwan

Asthma is a chronic airway inflammation disease and the diagnosis and treatment strategies remain difficult. MicroRNAs play important roles in many biological and pathological processes including asthma development. There is no study confirming the contribution of genetic variants in miR-145 to asthma etiology. We hypothesize that single nucleotide polymorphisms (SNPs) in the promoter region of miR-145 may be associated with the risk of asthma in Taiwanese. We used a case–control study to test this hypothesis. In 198 asthma patients and 453 healthy controls, the genotypes of miR-145 rs4705342 and rs4705343 were determined, and the associations of miR-145 genotypes with asthma risk and severity were evaluated. The distribution of miR-145 rs4705342 genotypes between asthma patients and non-asthmatic control groups were significantly different (p = 0.0187). In multivariable logistic regression analysis, compared with the wild-type TT genotype, individuals carrying the variant genotypes had progressively decreased risks of asthma: the odds ratio (OR) for the heterogeneous variant genotype (CT) and homozygous variant genotype (CC) was 0.77 (95% CI 0.55–1.10, p = 0.1788) and 0.41 (95% CI 0.21–0.79, p = 0.0102), respectively (p for trend = 0.0187). In allelic test, the C allele was associated with a 31% reduced risk of asthma (OR = 0.69, 95% CI 0.53–0.90, p = 0.0070). In addition, the rs4705342 variant genotypes were correlated with the symptom severity (p = 3 × 10^–5). Furthermore, the variant genotypes correlated with lower miR-145-5p expression level in serum (p = 0.0001). As for rs4705343, there was no differential distribution of genotypes between cases and controls. Our data provide evidence for miR-145 rs4705342 to serve as a novel biomarker for asthma risk prediction.

The Role of Polygenic Susceptibility on Air Pollution-Associated Asthma between German and Japanese Elderly Women

Polygenic susceptibility likely influences individual responses to air pollutants and the risk of asthma. We compared the role of polygenic susceptibility on air pollution-associated asthma between German and Japanese women. We investigated women that were enrolled in the German SALIA cohort (n = 771, mean age = 73 years) and the Japanese Shika cohort (n = 847, mean age = 67 years) with known asthma status. Adjusted logistic regression models were used to assess the associations between (1) particulate matter with a median aerodynamic diameter ≤ 2.5μm (PM2.5) and nitrogen dioxide (NO2), (2) polygenic risk scores (PRS), and (3) gene-environment interactions (G × E) with asthma. We found an increased risk of asthma in Japanese women after exposure to low pollutant levels (PM2.5: median = 12.7µg/m3, p-value < 0.001, NO2: median = 8.5µg/m3, p-value < 0.001) and in German women protective polygenic effects (p-value = 0.008). While we found no significant G × E effects, the direction in both groups was that the PRS increased the effect of PM2.5 and decreased the effect of NO2 on asthma. Our study confirms that exposure to low air pollution levels increases the risk of asthma in Japanese women and indicates polygenic effects in German women; however, there was no evidence of G × E effects. Future genome-wide G × E studies should further explore the role of ethnic-specific polygenic susceptibility to asthma.

A Meta-Analysis on Vitamin D Supplementation and Asthma Treatment

Background

Vitamin D, as an immunomodulator, may be related to the therapeutic effect of asthma patients, but the research in this area is still controversial. The aim of this meta-analysis was to analyze the role of vitamin D supplementation in the treatment of asthma patients.

Materials and Methods

Randomized Controlled Trials (RCTs) of vitamin D supplementation in asthma were searched in PubMed, EMBASE, and the Cochrane library. Primary outcomes were forced expiratory volume in one second (FEV1), asthma exacerbations, Asthma Control Test scores (ACT scores), and fractional exhaled nitric oxide (FENO).

Results

A total of 10 RCTs were included, including 1,349 patients. Vitamin D supplementation didn't affect the ACT scores (SMD = 0.04, 95% CI = -0.13 to 0.21, P = 0.87), FEV1 (SMD = 0.04, 95% CI = -0.35 to 0.43, P < 0.01) and FENO (SMD = -0.01, 95% CI = -0.22 to 0.20, P = 0.27), but reduced the rate of asthma exacerbations (RR = 0.69, 95% CI = 0.41 to 0.88, P < 0.01), especially in subgroups of children (RR = 0.46, 95% CI = 0.30 to 0.70, P = 0.83) and follow up time less than 6 months (RR = 0.45, 95% CI = 0.32 to 0.63, P = 0.95). Additionally, though there was only one study included in the subgroup, it significantly enhanced FEV1 at the last visit for patients whose FEV1 baseline value was less than 70% (SMD = 0.94, 95% CI = 0.47 to 1.41).

Conclusion

Vitamin D supplementation can reduce asthma exacerbations, especially in children, and within 6 months of follow up time. In addition, vitamin D has a positive effect on improving FEV1 of patients whose FEV1 baseline value is less than 70%, but more RCTs are still needed to support this conclusion.

Systematic Review Registration

[https://inplasy.com], identifier [10.37766/inplasy20 22.6.0049].

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.

Association between Interleukin-4-590C>T Polymorphism and the Susceptibility to Asthma: A Meta-Analysis of Case-Control Study

This study was aimed to investigate the relationship between the interleukin-4-590C > T gene polymorphism and the susceptibility to asthma by meta-analysis. To explore the underlying relationship between the polymorphism of IL-4-590C > T and the susceptibility to asthma, this study systematically retrieved the literature including cohort studies and case-control studies published before June 2019 in PubMed, Embase, and Cochrane Library. Data on the odds ratio (OR) and 95% confidence interval (CI) of the literature were included in the relative studies. Subsequently, the included data were weighted by an inverse variance and then analyzed by the fixed or random effects model. Overall, 818 asthma patients and 831 healthy individuals participated in the 8 independent case-control studies in the current meta-analysis. There was no correlation between IL-4-590C > T TT genotype and the increased susceptibility to asthma (dominant model: OR = 1.31, 95% CI = 0.68-2.53). Subgroup analysis by ethnicity showed no significant results in the Asians (OR = 1.28, 95% CI = 0.24-6.80); however, IL-4-590C > T TT genotype significantly elevated the susceptibility to asthma in the Caucasians (OR = 1.43, 95%CI = 1.03-1.98). Meanwhile, subgroup analysis was performed by source of control. A statistically significant result was found in the population-based control group (OR = 1.33, 95% CI = 1.01-1.76), but not in the hospital-based control group (OR = 1.22, 95% CI = 0.27-5.46). The results demonstrated that IL-4-590C > T TT genotype could significantly enhance the susceptibility to asthma in Caucasians without increasing that in Asian populations. However, it still required a large sample of high-quality studies in multicentral hospital to further confirm its reliability.

Genome-wide association study identifies TNFSF15 associated with childhood asthma

BACKGROUND

Genome-wide association studies (GWASs) of asthma have identified several risk alleles and loci, but most have been conducted in individuals with European-ancestry. Studies in Asians, especially children, are still lacking. We aimed to identify susceptibility loci by performing the first GWAS of asthma in Korean children with persistent asthma.

METHODS

We used a discovery set of 741 children with persistent asthma as cases and 589 healthy children and 551 healthy adults as controls to perform a GWAS. We validated our GWAS findings using UK Biobank data. We then used the Genotype-Tissue Expression database to identify expression quantitative trait loci of candidate variants. Finally, we quantified proteins of genes associated with asthma.

RESULTS

Variants at the 17q12-21 locus and SNPs in CYBRD1 and TNFSF15 genes were associated with persistent childhood asthma at genome-wide thresholds of significance. Four SNPs in the TNFSF15 gene were also associated with childhood-onset asthma in British white participants in the UK Biobank data. The asthma-associated rs7856856-C allele, the lead SNP, was associated with decreased TNFSF15 expression in whole blood and in arteries. Korean children with asthma had lower serum TNFSF15 levels than controls, and those with the asthma risk rs7856856-CC genotype exhibited the lowest serum TNFSF15 levels overall, especially asthmatic children.

CONCLUSIONS

Our GWAS of persistent childhood asthma with allergic sensitization identified a new susceptibility gene, TNFSF15, and replicated associations at the 17q12-21 childhood-onset asthma locus. This novel association may be mediated by reduced expression of serum TNFSF15 and loss of suppression of angiogenesis.

The A118G single-nucleotide polymorphism in OPRM1 is a risk factor for asthma severity

BACKGROUND

Although population studies have implicated emotional burden in asthma severity, the underlying genetic risk factors are not completely understood. We aimed to evaluate the genetic influence of a functional single-nucleotide polymorphism (SNP) in the stress-related μ-opioid receptor gene (OPRM1; A118G SNP, rs1799971) on asthma severity.

METHODS

We initially assessed disease severity in asthmatic outpatients carrying A118G. Using an ovalbumin-induced experimental asthma rodent model harboring the functionally equivalent SNP, we investigated the mechanism by which this SNP influences the allergic immune response.

RESULTS

Among 292 outpatients, 168 underwent airway hyperresponsiveness (AHR) to methacholine testing. Compared with patients carrying the AA and AG genotypes, those carrying the GG genotype exhibited enhanced AHR. The stress levels were presumed to be moderate among patients and were comparable among genotypes. Compared with Oprm1 AA mice, GG mice demonstrated aggravated asthma-related features and increased pulmonary interleukin-4⁺CD4⁺ effector and effector memory T cells under everyday life stress conditions. Intraperitoneal naloxone methiodide injection reduced effector CD4⁺ T cell elevation associated with increased eosinophil numbers in bronchoalveolar lavage fluid of GG mice to the levels in AA mice, suggesting that elevated Th2 cell generation in the bronchial lymph node (BLN) of GG mice induces enhanced eosinophilic inflammation.

CONCLUSIONS

Without forced stress exposure, patients with asthma carrying the OPRM1 GG genotype exhibit enhanced AHR, attributable to enhanced Th2 cell differentiation in the regional lymph node. Further research is necessary to elucidate the role of the OPRM1 A118G genotype in the Th2 cell differentiation pathway in the BLN.

Metabolic Reprogramming of Nasal Airway Epithelial Cells Following Infant Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is a seasonal mucosal pathogen that infects the ciliated respiratory epithelium and results in the most severe morbidity in the first six months of life. RSV is a common cause of acute respiratory infection during infancy and is an important early-life risk factor strongly associated with asthma development. While this association has been repeatedly demonstrated, limited progress has been made on the mechanistic understanding in humans of the contribution of infant RSV infection to airway epithelial dysfunction. An active infection of epithelial cells with RSV in vitro results in heightened central metabolism and overall hypermetabolic state; however, little is known about whether natural infection with RSV in vivo results in lasting metabolic reprogramming of the airway epithelium in infancy. To address this gap, we performed functional metabolomics, 13C glucose metabolic flux analysis, and RNA-seq gene expression analysis of nasal airway epithelial cells (NAECs) sampled from infants between 2-3 years of age, with RSV infection or not during the first year of life. We found that RSV infection in infancy was associated with lasting epithelial metabolic reprogramming, which was characterized by (1) significant increase in glucose uptake and differential utilization of glucose by epithelium; (2) altered preferences for metabolism of several carbon and energy sources; and (3) significant sexual dimorphism in metabolic parameters, with RSV-induced metabolic changes most pronounced in male epithelium. In summary, our study supports the proposed phenomenon of metabolic reprogramming of epithelial cells associated with RSV infection in infancy and opens exciting new venues for pursuing mechanisms of RSV-induced epithelial barrier dysfunction in early life.

Multi-omics colocalization with genome-wide association studies reveals a context-specific genetic mechanism at a childhood onset asthma risk locus

BACKGROUND

Genome-wide association studies (GWASs) have identified thousands of variants associated with asthma and other complex diseases. However, the functional effects of most of these variants are unknown. Moreover, GWASs do not provide context-specific information on cell types or environmental factors that affect specific disease risks and outcomes. To address these limitations, we used an upper airway epithelial cell (AEC) culture model to assess transcriptional and epigenetic responses to rhinovirus (RV), an asthma-promoting pathogen, and provide context-specific functional annotations to variants discovered in GWASs of asthma.

METHODS

Genome-wide genetic, gene expression, and DNA methylation data in vehicle- and RV-treated upper AECs were collected from 104 individuals who had a diagnosis of airway disease (n=66) or were healthy participants (n=38). We mapped cis expression and methylation quantitative trait loci (cis-eQTLs and cis-meQTLs, respectively) in each treatment condition (RV and vehicle) in AECs from these individuals. A Bayesian test for colocalization between AEC molecular QTLs and adult onset asthma and childhood onset asthma GWAS SNPs, and a multi-ethnic GWAS of asthma, was used to assign the function to variants associated with asthma. We used Mendelian randomization to demonstrate DNA methylation effects on gene expression at asthma colocalized loci.

RESULTS

Asthma and allergic disease-associated GWAS SNPs were specifically enriched among molecular QTLs in AECs, but not in GWASs from non-immune diseases, and in AEC eQTLs, but not among eQTLs from other tissues. Colocalization analyses of AEC QTLs with asthma GWAS variants revealed potential molecular mechanisms of asthma, including QTLs at the TSLP locus that were common to both the RV and vehicle treatments and to both childhood onset and adult onset asthma, as well as QTLs at the 17q12-21 asthma locus that were specific to RV exposure and childhood onset asthma, consistent with clinical and epidemiological studies of these loci.

CONCLUSIONS

This study provides evidence of functional effects for asthma risk variants in AECs and insight into RV-mediated transcriptional and epigenetic response mechanisms that modulate genetic effects in the airway and risk for asthma.

The impact of age on genetic risk for common diseases

Inherited genetic variation contributes to individual risk for many complex diseases and is increasingly being used for predictive patient stratification. Previous work has shown that genetic factors are not equally relevant to human traits across age and other contexts, though the reasons for such variation are not clear. Here, we introduce methods to infer the form of the longitudinal relationship between genetic relative risk for disease and age and to test whether all genetic risk factors behave similarly. We use a proportional hazards model within an interval-based censoring methodology to estimate age-varying individual variant contributions to genetic relative risk for 24 common diseases within the British ancestry subset of UK Biobank, applying a Bayesian clustering approach to group variants by their relative risk profile over age and permutation tests for age dependency and multiplicity of profiles. We find evidence for age-varying relative risk profiles in nine diseases, including hypertension, skin cancer, atherosclerotic heart disease, hypothyroidism and calculus of gallbladder, several of which show evidence, albeit weak, for multiple distinct profiles of genetic relative risk. The predominant pattern shows genetic risk factors having the greatest relative impact on risk of early disease, with a monotonic decrease over time, at least for the majority of variants, although the magnitude and form of the decrease varies among diseases. As a consequence, for diseases where genetic relative risk decreases over age, genetic risk factors have stronger explanatory power among younger populations, compared to older ones. We show that these patterns cannot be explained by a simple model involving the presence of unobserved covariates such as environmental factors. We discuss possible models that can explain our observations and the implications for genetic risk prediction.

The genes we inherit from our parents influence our risk for almost all diseases, from cancer to severe infections. With the explosion of genomic technologies, we are now able to use an individual’s genome to make useful predictions about future disease risk. However, recent work has shown that the predictive value of genetic information varies by context, including age, sex and ethnicity. In this paper we introduce, validate and apply new statistical methods for investigating the relationship between age and the contributions of genetic risk. These methods allow us to ask questions such as whether relative risk is constant over time, precisely how relative risk changes over time and whether all genetic risk factors have similar age profiles. By applying the methods to data from the UK Biobank, a prospective study of 500,000 people, we show that there is a tendency for genetic relative risk to decline with increasing age. We consider a series of possible explanations for the observation and conclude that there must be processes acting that we are currently unaware of, such as distinct phases of life in which genetic risk manifests itself, or interactions between genes and the environment.

Thermosensory Transient Receptor Potential Ion Channels and Asthma

Asthma is a widespread chronic disease of the bronchopulmonary system with a heterogeneous course due to the complex etiopathogenesis. Natural-climatic and anthropogenic factors play an important role in the development and progression of this pathology. The reception of physical and chemical environmental stimuli and the regulation of body temperature are mediated by thermosensory channels, members of a subfamily of transient receptor potential (TRP) ion channels. It has been found that genes encoding vanilloid, ankyrin, and melastatin TRP channels are involved in the development of some asthma phenotypes and in the formation of exacerbations of this pathology. The review summarizes modern views on the role of high and low temperatures in airway inflammation in asthma. The participation of thermosensory TRP channels (vanilloid, ankyrin, and melastatin TRP channels) in the reaction to high and low temperatures and air humidity as well as in the formation of bronchial hyperreactivity and respiratory symptoms accompanying asthma is described. The genetic aspects of the functioning of thermosensory TRP channels are discussed. It is shown that new methods of treatment of asthma exacerbations caused by the influence of temperature and humidity should be based on the regulation of channel activity.

Indoor environmental quality in households of families with infant twins under 1 year of age living in Porto

Exposure to air pollution in early years can exacerbate the risk of noncommunicable diseases throughout childhood and the entire life course. This study aimed to assess temperature, relative humidity (RH), carbon dioxide (CO₂) and monoxide (CO), particulate matter (PM_2.5, PM₁₀), ultrafine particles, nitrogen dioxide (NO₂), ozone (O₃), formaldehyde, acetaldehyde and volatile organic compounds (VOC) levels in the two rooms where infant twins spend more time at home (30 dwellings, Northern Portugal). Findings showed that, in general, the worst indoor environmental quality (IEQ) settings were found in bedrooms. In fact, although most of the bedrooms surveyed presented adequate comfort conditions in terms of temperature and RH, several children are sleeping in a bedroom with improper ventilation and/or with a significant degree of air pollution. In particular, mean concentrations higher than recommended limits were found for CO₂, PM_2.5, PM₁₀ and total VOC. Additionally, terpenes and decamethylcyclopentasiloxane were identified as main components of emissions from indoor sources. Overall, findings revealed that factors related to behaviors of the occupants, namely related to a conscientious use of cleaning products, tobacco and other consumer products (air-fresheners, incenses/candles and insecticides) and promotion of ventilation are essential for the improvement of air quality in households and for the promotion of children's health.

Genetic Influences on Disease Subtypes

Disease classification, or nosology, was historically driven by careful examination of clinical features of patients. As technologies to measure and understand human phenotypes advanced, so too did classifications of disease, and the advent of genetic data has led to a surge in genetic subtyping in the past decades. Although the fundamental process of refining disease definitions and subtypes is shared across diverse fields, each field is driven by its own goals and technological expertise, leading to inconsistent and conflicting definitions of disease subtypes. Here, we review several classical and recent subtypes and subtyping approaches and provide concrete definitions to delineate subtypes. In particular, we focus on subtypes with distinct causal disease biology, which are of primary interest to scientists, and subtypes with pragmatic medical benefits, which are of primary interest to physicians. We propose genetic heterogeneity as a gold standard for establishing biologically distinct subtypes of complex polygenic disease. We focus especially on methods to find and validate genetic subtypes, emphasizing common pitfalls and how to avoid them.

Glutathione S-Transferase Gene Associations and Gene-Environment Interactions for Asthma

PURPOSE OF REVIEW

Asthma is one of the most common chronic inflammatory airway diseases. Airway oxidative stress is defined as an imbalance between oxidative and antioxidative processes in the airways. There is evidence that chronic damage caused by oxidative stress may be involved in asthmatic inflammation and reduced lung function. Given their biological antioxidant function, the antioxidant genes in the glutathione S-transferase (GST) family are believed to be associated with development and progression of asthma. This review aims to summarize evidence on the relationship between GST gene polymorphisms and asthma and interactions with environmental exposures.

RECENT FINDINGS

The current evidence on the association between GST genes and asthma is still weak or inconsistent. Failure to account for environmental exposures may explain the lack of consistency. It is highly likely that environmental exposures interact with GST genes involved in the antioxidant pathway. According to current knowledge, carriers of GSTM1(rs366631)/T1(rs17856199) null genotypes and GSTP1 Val105 (rs1695) genotypes are more susceptible to environmental oxidative exposures and have a higher risk of asthma. Some doubt remains regarding the presence or absence of interactions with different environmental exposures in different study scenarios. The GST-environment interaction may depend on exposure type, asthma phenotype or endotype, ethnics, and other complex gene-gene interaction. Future studies could be improved by defining precise asthma endotypes, involving multiple gene-gene interactions, and increasing sample size and power. Although there is evidence for an interaction between GST genes, and environmental exposures in relation to asthma, results are not concordant. Further investigations are needed to explore the reasons behind the inconsistency.

The axis of the receptor for advanced glycation endproducts in asthma and allergic airway disease

Asthma is a generalized term that describes a scope of distinct pathologic phenotypes of variable severity, which share a common complication of reversible airflow obstruction. Asthma is estimated to affect almost 400 million people worldwide, and nearly ten percent of asthmatics have what is considered "severe" disease. The majority of moderate to severe asthmatics present with a "type 2-high" (T2-hi) phenotypic signature, which pathologically is driven by the type 2 cytokines Interleukin-(IL)-4, IL-5, and IL-13. However, "type 2-low" (T2-lo) phenotypic signatures are often associated with more severe, steroid-refractory neutrophilic asthma. A wide range of clinical and experimental studies have found that the receptor for advanced glycation endproducts (RAGE) plays a significant role in the pathogenesis of asthma and allergic airway disease (AAD). Current experimental data indicates that RAGE is a critical mediator of the type 2 inflammatory reactions which drive the development of T2-hi AAD. However, clinical studies demonstrate that increased RAGE ligands and signaling strongly correlate with asthma severity, especially in severe neutrophilic asthma. This review presents an overview of the current understandings of RAGE in asthma pathogenesis, its role as a biomarker of disease, and future implications for mechanistic studies, and potential therapeutic intervention strategies.

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.

Association of Hemoglobin and Hematocrit Levels during Pregnancy and Maternal Dietary Iron Intake with Allergic Diseases in Children: The Japan Environment and Children's Study (JECS)

Few epidemiologic studies have examined the role of maternal iron status in allergic diseases in offspring and findings have been inconsistent. We used a large birth cohort in Japan to explore the association of the markers for maternal iron status (maternal hemoglobin, hematocrit and dietary iron intake during pregnancy) with allergy development in offspring during early childhood. We analyzed information on children age 0–3 years from the Japan Environment and Children’s Study (JECS). We used logistic models and generalized estimating equation models to evaluate the effect of maternal hemoglobin and hematocrit levels and dietary iron intake on allergies in children. Models were also fitted with propensity score-matched datasets. Data were collected for a total of 91,247 mother–child pairs. The prevalence (95% confidence interval) of low hemoglobin and hematocrit was 14.0% (13.7–14.2%) and 12.5% (12.3–12.8%), respectively. After adjusting confounders, low hemoglobin and hematocrit during pregnancy were not associated with childhood allergic outcomes. Findings from models with propensity score-matched datasets also indicated that children born to mothers with low hemoglobin or hematocrit levels during pregnancy did not have a higher risk of developing allergic conditions at 3 years old. We found no meaningful associations between low energy adjusted maternal dietary iron intake and allergies in children. In conclusion, using birth cohort data, we found no evidence supporting an association of low maternal hemoglobin, hematocrit and low dietary iron intake with allergy symptoms during early childhood. Further studies with more suitable proxy markers for blood iron status are needed.

Allergy and immunology in young children of Japan: The JECS cohort

BACKGROUND

Capturing epidemiological signatures is essential to document burdens of disease and to design health care services, including prevention measures, clinical interventions, and policies. There are large geographical and ethnic variations in the epidemiology of allergic and immunological diseases. Various data are available from North America and Europe, but the epidemiology of allergic and immunological diseases in Asia is not well documented.

OBJECTIVE

To characterize epidemiological signatures of allergic and immunological disease in young children in Japan.

METHODS

This was a national, multicenter, prospective birth cohort study: Japan Environment and Children's Study (JECS). A general population of 103,060 women was enrolled during pregnancy. Allergic and immunological outcomes were assessed among young children using questionnaire data.

RESULTS

The prevalence of caregiver-reported immediate food allergy was 7.6%, 6.7%, and 4.9% at age 1, 2, and 3 years, respectively. Hen egg allergy was most common (5.4% prevalence at age 1 year) followed by allergies to cow milk and wheat. Several patterns of allergic symptom clusters were identified. Physician diagnosed, as reported by the caregiver, non-IgE mediated gastrointestinal food allergy affected 0.5% of infants. By contrast, caregiver-reported gastrointestinal food allergies affected 1.4% of children. Kawasaki disease affected 0.3% and 0.4% children, respectively, at age 1 and 3 years. Primary immunodeficiency disorders affected 0.005% children at age 3 years.

CONCLUSION

These data provide important epidemiological signatures of allergy and immunology in young Japanese children including the age-specific prevalence of allergic disease, Kawasaki disease, and primary immune deficiency.

Role of biomarkers and effect of FIP-fve in acute and chronic animal asthma models

BACKGROUND

Asthma is a consequence of complex gene-environment interactions. Exploring the heterogeneity of asthma in different stages is contributing to our understanding of its pathogenesis and the development of new therapeutic strategies, especially in severe cases.

OBJECTIVE

This study aimed to further understand the relationship between manifestations of acute and chronic asthma and various endotypes, and explore the severity of lung inflammation, cell types, cytokine/chemokine differences, and the effects of FIP-fve.

MATERIALS AND METHODS

Acute and chronic OVA-sensitization mouse asthma models, based on our previously published method, were used and FIP-fve was used to evaluate the effect on these two models. BALF cytokines/chemokines were detected according to the manufacturer's protocol.

RESULTS

Seventeen cytokine/chemokine secretions were higher in the chronic stage than in the acute stage. Whether in acute stage or chronic stage, the FIP-fve treatment groups had reduced airway hyperresponsiveness, infiltration of airway inflammatory cells, secretion of cytokines, chemokines by Th2 cells, and TNF-α, IL-8, IL-17, CXCL-1, CXCL-10, CCL-17, and CCL-22, and it was also found that the Treg cell cytokine IL-10 had increased significantly. PCA (Principal Component Analysis) was also used to compare statistics and laboratory data to find the important biomarkers in different stages and after treatment with FIP-fve.

CONCLUSIONS

There are many different immune responses in the different stages of the asthma process. Drug treatment at the appropriate times might help reduce the worsening of asthma.

Environmental and Endogenous Acids Can Trigger Allergic-Type Airway Reactions

Inflammatory allergic and nonallergic respiratory disorders are spreading worldwide and often coexist. The root cause is not clear. This review demonstrates that, from a biochemical point of view, it is ascribable to protons (H+) released into cells by exogenous and endogenous acids. The hypothesis of acids as the common cause stems from two considerations: (a) it has long been known that exogenous acids present in air pollutants can induce the irritation of epithelial surfaces, particularly the airways, inflammation, and bronchospasm; (b) according to recent articles, endogenous acids, generated in cells by phospholipases, play a key role in the biochemical mechanisms of initiation and progression of allergic-type reactions. Therefore, the intracellular acidification and consequent Ca2+ increase, induced by protons generated by either acid pollutants or endogenous phospholipases, may constitute the basic mechanism of the multimorbidity of these disorders, and environmental acidity may contribute to their spread.

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.

Extracellular vesicles and asthma: A review of the literature

Asthma is a chronic, recurrent and incurable allergy-related respiratory disease characterized by inflammation, bronchial hyperresponsiveness and narrowing of the airways. Extracellular vesicles (EVs) are a universal feature of cellular function and can be detected in different bodily fluids. Recent evidence has shown the possibility of using EVs in understanding the pathogenesis of asthma, including their potential as diagnostic and therapeutic tools. Studies have reported that EVs released from key cells involved in asthma can induce priming and activation of other asthma-associated cells. A literature review was conducted on all current research regarding the role and function of EVs in the pathogenesis of asthma via the PRISMA statement method. An electronic search was performed using EMBASE and PubMed through to November 2018. The EMBASE search returned 76 papers, while the PubMed search returned 211 papers. Following duplicate removal, titles and abstracts were screened for eligibility with a total of 34 studies included in the final qualitative analysis. The review found evidence of association between the presence of EVs and physiological changes characteristic of asthma, suggesting that EVs are involved in the pathogenesis, with the weight of evidence presently favouring deleterious effects of EVs in asthma. Numerous studies highlighted differences in exosomal contents between EVs of healthy and asthmatic individuals, which could be employed as potential diagnostic markers. In some circumstances, EVs were also found to be suppressive to disease, but more often promote inflammation and airway remodelling. In conclusion, EVs hold immense potential in understanding the pathophysiology of asthma, and as diagnostic and therapeutic markers. While more research is needed for definitive conclusions and their application in medical practice, the literature presented in this review should encourage further research and discovery within the field of EVs and asthma.

Role of genomics in asthma exacerbations

PURPOSE OF REVIEW

Asthma exacerbations have been suggested to result from complex interactions between genetic and nongenetic components. In this review, we provide an overview of the genetic association studies of asthma exacerbations, their main results and limitations, as well as future directions of this field.

RECENT FINDINGS

Most studies on asthma exacerbations have been performed using a candidate-gene approach. Although few genome-wide association studies of asthma exacerbations have been conducted up to date, they have revealed promising associations but with small effect sizes. Additionally, the analysis of interactions between genetic and environmental factors has contributed to better understand of genotype-specific responses in asthma exacerbations.

SUMMARY

Genetic association studies have allowed identifying the 17q21 locus and the ADRB2 gene as the loci most consistently associated with asthma exacerbations. Future studies should explore the full spectrum of genetic variation and will require larger sample sizes, a better representation of racial/ethnic diversity and a more precise definition of asthma exacerbations. Additionally, the analysis of important environmental gene-environment analysis and the integration of multiple omics will allow understanding the genetic factors and biological processes underlying the risk for asthma exacerbations.

Childhood Asthma: Advances Using Machine Learning and Mechanistic Studies

A paradigm shift brought by the recognition that childhood asthma is an aggregated diagnosis that comprises several different endotypes underpinned by different pathophysiology, coupled with advances in understanding potentially important causal mechanisms, offers a real opportunity for a step change to reduce the burden of the disease on individual children, families, and society. Data-driven methodologies facilitate the discovery of "hidden" structures within "big healthcare data" to help generate new hypotheses. These findings can be translated into clinical practice by linking discovered "phenotypes" to specific mechanisms and clinical presentations. Epidemiological studies have provided important clues about mechanistic avenues that should be pursued to identify interventions to prevent the development or alter the natural history of asthma-related diseases. Findings from cohort studies followed by mechanistic studies in humans and in neonatal mouse models provided evidence that environments such as traditional farming may offer protection by modulating innate immune responses and that impaired innate immunity may increase susceptibility. The key question of which component of these exposures can be translated into interventions requires confirmation. Increasing mechanistic evidence is demonstrating that shaping the microbiome in early life may modulate immune function to confer protection. Iterative dialogue and continuous interaction between experts with different but complementary skill sets, including data scientists who generate information about the hidden structures within "big data" assets, and medical professionals, epidemiologists, basic scientists, and geneticists who provide critical clinical and mechanistic insights about the mechanisms underpinning the architecture of the heterogeneity, are keys to delivering mechanism-based stratified treatments and prevention.

Exercise and Asthma

Asthma is a chronic lower respiratory disease that is very common worldwide, and its incidence is increasing year by year. Since the 1970s, asthma has become widespread, with approximately 300 million people affected worldwide and about 250,000 people have lost their lives. Asthma seriously affects people's physical and mental health, resulting in reduced learning efficiency, limited physical activities, and decreased quality of life. Therefore, raising awareness of the risk of asthma and how to effectively treat asthma have become important targets for the prevention and management of asthma in recent years. For patients with asthma, exercise training is a widely accepted adjunct to drug-based and non-pharmacological treatment. It has been recommended abroad that exercise prescriptions are an important part of asthma management.

Phenotypic and Molecular Characterization of Risk Loci Associated With Asthma and Lung Function

Purpose

Respiratory diseases have a highly multifactorial etiology where different mechanisms contribute to the individual's susceptibility. We conducted a deep characterization of loci associated with asthma and lung function by previous genome-wide association studies (GWAS).

Methods

Sixteen variants were selected from previous GWAS of childhood/adult asthma and pulmonary function tests. We conducted a phenome-wide association study of these loci in 4,083 traits assessed in the UK Biobank (n = 361,194 participants). Data from the Genotype-Tissue Expression (GTEx) project were used to conduct a transcriptomic analysis with respect to tissues relevant for asthma pathogenesis. A pediatric cohort assessed with the International Study of Asthma and Allergies in Children (ISAAC) Phase II tools was used to further explore the association of these variants with 116 traits related to asthma comorbidities.

Results

Our phenome-wide association studies (PheWAS) identified 206 phenotypic associations with respect to the 16 variants identified. In addition to the replication of the phenotypes tested in the discovery GWAS, we observed novel associations related to blood levels of immune cells (eosinophils, neutrophils, monocytes, and lymphocytes) for the asthma-related variants. Conversely, the lung-function variants were associated with phenotypes related to body fat mass. In the ISAAC-assessed cohort, we observed that risk alleles associated with increased fat mass can exacerbate allergic reactions in individuals affected by allergic respiratory diseases. The GTEx-based analysis showed that the variants tested affect the transcriptomic regulation of multiple surrounding genes across several tissues.

Conclusions

This study generated novel data regarding the genetics of respiratory diseases and their comorbidities, providing a deep characterization of loci associated with asthma and lung function.

Whole Genome Sequencing Identifies CRISPLD2 as a Lung Function Gene in Children With Asthma

BACKGROUND

Asthma is a common respiratory disorder with a highly heterogeneous nature that remains poorly understood. The objective was to use whole genome sequencing (WGS) data to identify regions of common genetic variation contributing to lung function in individuals with a diagnosis of asthma.

METHODS

WGS data were generated for 1,053 individuals from trios and extended pedigrees participating in the family-based Genetic Epidemiology of Asthma in Costa Rica study. Asthma affection status was defined through a physician's diagnosis of asthma, and most participants with asthma also had airway hyperresponsiveness (AHR) to methacholine. Family-based association tests for single variants were performed to assess the associations with lung function phenotypes.

RESULTS

A genome-wide significant association was identified between baseline FEV1/FVC ratio and a single-nucleotide polymorphism in the top hit cysteine-rich secretory protein LCCL domain-containing 2 (CRISPLD2) (rs12051168; P = 3.6 × 10-8 in the unadjusted model) that retained suggestive significance in the covariate-adjusted model (P = 5.6 × 10-6). Rs12051168 was also nominally associated with other related phenotypes: baseline FEV1 (P = 3.3 × 10-3), postbronchodilator (PB) FEV1 (7.3 × 10-3), and PB FEV1/FVC ratio (P = 2.7 × 10-3). The identified baseline FEV1/FVC ratio and rs12051168 association was meta-analyzed and replicated in three independent cohorts in which most participants with asthma also had confirmed AHR (combined weighted z-score P = .015) but not in cohorts without information about AHR.

CONCLUSIONS

These findings suggest that using specific asthma characteristics, such as AHR, can help identify more genetically homogeneous asthma subgroups with genotype-phenotype associations that may not be observed in all children with asthma. CRISPLD2 also may be important for baseline lung function in individuals with asthma who also may have AHR.

How a farming environment protects from atopy

It is now well established that the exposure to certain environments such as farms has the potential to protect from the development of allergies later in life. This protection is achieved when repeated exposure to the farming environment occurs early in life, but persists when children spend sufficient amount of time in contact with livestock and hay, and drink unpasteurized milk. The capacity of farm dust to protect from allergy development lies, amongst others, in the microbe composition in the farm. These protective microbes release various metabolites and cell wall components that change farmers' home dust composition, when compared to urbanized home dust. Additionally, they can colonize various barrier sites (skin, lung, intestine) in farmers' children, leading to persistent changes in the way their immune system and their barrier cells respond to environmental allergens.

Advancing the symptom science model with environmental health

OBJECTIVE

Globally, indoor and outdoor pollutants are leading risk factors for death and reduced quality of life. Few theories explicitly address environmental health within the nursing discipline with a focus on harmful environmental exposures. The objective here is to expand the National Institutes of Health Symptom Science Model to include the environmental health concepts of environmental endotype (causative pathway) and environmental exposure.

DESIGN

Meleis' research to theory strategy for theory refinement was used. Research workshop proceedings, environmental health nursing research expert consensus, panelist research trajectories, and review of the literature were utilized as data sources.

RESULTS

Ongoing emphasis on the physical environment as a key determinant of health and theoretical perspectives for including environmental exposures and endotypes in symptom science are presented. Definitions of these concepts, further developed, are provided. Recommendations to strengthen environmental health nursing research and practice through capacity building/infrastructure, methods/outcomes, translational/clinical research, and basic/mechanistic research are included.

CONCLUSION

The revised model deepens theoretical support for clinical actions that include environmental modification, environmental health education, and exposure reduction. This modification will enable a middle-range theory and shared mental model to inspire the prioritization of environmental health in nursing leadership, research, practice, and education.

Cadherin-related Family Member 3 Genetics and Rhinovirus C Respiratory Illnesses

RATIONALE

Experimental evidence suggests that CDHR3 (cadherin-related family member 3) is a receptor for rhinovirus (RV)-C, and a missense variant in this gene (rs6967330) is associated with childhood asthma with severe exacerbations.

OBJECTIVES

To determine whether rs6967330 influences RV-C infections and illnesses in early childhood.

METHODS

We studied associations between rs6967330 and respiratory infections and illnesses in the COPSAC₂₀₁₀ (Copenhagen Prospective Studies on Asthma in Childhood 2010) and COAST (Childhood Origins of Asthma Birth Cohort Study) birth cohorts, where respiratory infections were monitored prospectively for the first 3 years of life. Nasal samples were collected during acute infections in both cohorts and during asymptomatic periods in COAST and analyzed for RV-A, RV-B, and RV-C, and other common respiratory viruses.

MEASUREMENTS AND MAIN RESULTS

The CDHR3 asthma risk allele (rs6967330-A) was associated with increased risk of respiratory tract illnesses (incidence risk ratio [IRR] = 1.14 [95% confidence interval, 1.05-1.23]; P = 0.003). In particular, this variant was associated with risk of respiratory episodes with detection of RV-C in COPSAC₂₀₁₀ (IRR = 1.89 [1.14-3.05]; P = 0.01) and in COAST (IRR = 1.37 [1.02-1.82]; P = 0.03) children, and in a combined meta-analysis (IRR = 1.51 [1.13-2.02]; P = 0.006). In contrast, the variant was not associated with illnesses related to other viruses (IRR = 1.07 [0.92-1.25]; P = 0.37). Consistent with these observations, the CDHR3 variant was associated with increased detection of RV-C, but not of other viruses during scheduled visits at specific ages.

CONCLUSIONS

The CDHR3 asthma risk allele is associated specifically with RV-C illnesses in two birth cohorts. This clinical evidence supports earlier molecular evidence indicating that CDHR3 functions as an RV-C receptor, and raises the possibility of preventing RV-C infections by targeting CDHR3.

ORMDL3 knockdown in the lungs alleviates airway inflammation and airway remodeling in asthmatic mice via JNK1/2-MMP-9 pathway

Orosomucoid-like protein 3 (ORMDL3) is a common mutation in many asthma patients and its effects on the specific pathogenesis of asthma are still unclear. Therefore, in this study, we used a mouse that specifically knockout the mouse ORDML3 gene to further study the mechanism. We used ovalbumin (OVA) to induce asthma in wild-type mice and ORMDL3 knockout mice. Lung ventilation resistance, airway inflammation, mucus hypersecretion, collagen deposition, the levels of inflammatory factors and the expression of ORDML3 and JNK1/2-MMP-9 pathway were detected. The results showed that ORMDL3 gene was highly expressed in clinical asthmatic children and mouse asthma model. Knocking down the ORMDL3 gene in the lung tissue of asthmatic mice can reduce airway hyperresponsiveness, airway inflammation, mucus secretion, and collagen deposition around the airway. After knocking down the lung tissue of mice, the IL-4, IL-5 and IL-13 concentrations in broncho alveolar lavage fluid of asthmatic mice were significantly decreased, and the activation of JNK1/2-MMP-9 pathway was inhibited in mouse lung tissue. Collectively, our results demonstrate that the ORMDL3 gene may aggravate asthma symptoms by activating the JNK1/2-MMP-9 pathway, which indicates that the ORMDL3 gene may be the key molecule for the next step of asthma targeted therapy.

Allergy Development in Adulthood: An Occupational Cohort Study of the Manufacturing of Industrial Enzymes

BACKGROUND

Occupational allergy may serve as a model of allergy development in adults.

OBJECTIVE

We aimed at describing respiratory allergy and IgE sensitization across different exposure strata defined by time, technology, and exposure control.

METHODS

In a retrospective (1970-2017) cohort of industrial enzyme production employees, monitored by an occupational medical center, 5024 individuals were surveyed. Five exposure groups and risk levels for sensitization and allergic disease were analyzed on the basis of demographic characteristics, hiring decade, and smoking status.

RESULTS

Of all persons entering the company 47 years from 1970, 149 developed occupational allergy (incidence rate, 2.72/1000 person-years). In a multivariate cause-specific Cox proportional hazards model, the hazard of allergy was significantly related to decade of recruitment. Compared with the 1970s, the hazard ratio (HR) uniformly decreased from 0.85 (95% CI, 0.57-1.27) in the 1980s to 0.16 (95% CI, 0.05-0.52) in the 2010s. Compared with expected highest exposed group, the HRs were 0.48 (95% CI, 0.31-76) and 0.13 (95% CI, 0.06-0.30) in less exposed production areas and 0.92 (95% CI, 0.48-1.73) and 0.23 (95% CI, 0.10-0.53) in different laboratory areas. The HR of smoking was 2.03 (95% CI, 1.41-2.93). The pattern of sensitizations also showed clear associations to recruitment decade, exposure, and smoking. Among individuals sensitized but not yet allergic, a high IgE level was the only risk factor (HR, 3.03; 95% CI, 1.82-5.04) for subsequent allergy development.

CONCLUSIONS

The impact of exposure is dose-related and linked to the sensitization step, which may subsequently lead to allergy development. For primary prevention of enzyme allergy, exposure control is mandatory and achievable despite increasing production volumes.