The relationship between asthma and bronchiolitis is modified by TLR4, CD14, and IL-13 polymorphisms

Convergent Evidence Supports TH2LCRR as a Novel Asthma Susceptibility Gene

Asthma is a common complex disease with apparent genetic predispositions, and previous genome-wide association studies suggest that rs1295686 within the IL13 (interleukin 13) gene is significantly associated with asthma. Analysis of the data provided by the 1000 Genomes Project indicated that there are additional four SNPs in nearly complete linkage disequilibrium with rs1295686 in Caucasians. However, the causal SNPs and the associated mechanism remain unclear. To investigate this issue, functional genomics approaches were utilized to analyze the functions of these SNPs. Dual-luciferase assays indicated that the functional SNP is not rs1295686 but a haplotype consisting of other three SNPs, rs1295685, rs848 and rs847. Through chromosome conformation capture, it was found that the enhancer containing the three functional SNPs interacts with the promoter of TH2LCRR (T helper type 2 locus control region associated RNA), a recently identified long non-coding RNA. RNA-seq data analysis indicated that TH2LCRR expression is significantly increased in asthma patients and is dependent on the genotype at this locus, indicating that TH2LCRR is a novel susceptibility gene for asthma and that these SNPs confer asthma risk by regulating TH2LCRR expression. By chromatin immunoprecipitation, the related transcription factors that bind in the region surrounding these three SNPs were identified, and their interactions were investigated by functional genomics approaches. Our effort identified a novel mechanism through which genetic variations at this locus could influence asthma susceptibility.

Effect of early-life antibiotic exposure and IL-13 polymorphism on atopic dermatitis phenotype

BACKGROUND

Although atopic dermatitis (AD) is associated with certain gene variants, the rapidly increasing incidence of AD suggests that environmental factors contribute to disease development. In this study, we investigated the association of AD incidence and phenotype with antibiotic exposure within 6 months of age, considering the dose administered and genetic risk.

METHODS

This study included 1637 children from the COCOA cohort. Pediatric allergists assessed the presence of AD at each visit and obtained information about antibiotic exposure for more than 3 days. IL-13 (rs20541) polymorphism was genotyped by the TaqMan method. We stratified the AD phenotypes into four groups and used multinomial logistic regression models for analysis.

RESULTS

Antibiotic exposure within 6 months of age was found to increase the risk of AD within 3 years of life (aOR = 1.40; 95% CI, 1.09-1.81) in dose-dependent manner. Antibiotic exposure more than twice increased the risk of the early-persistent AD phenotype (aOR = 2.50; 95% CI, 1.35-4.63). There was a weak interaction between genetic polymorphisms and environmental factors on the development of AD (p for interaction = 0.06). Children with the IL-13 (rs20541) GA + AA genotype have a higher risk of the early-persistent AD phenotype when exposed to antibiotics more than twice than those with the IL-13 (rs20541) GG genotype and without exposure to antibiotics (aOR = 4.73; 95% CI, 2.01-11.14).

CONCLUSION

Antibiotic exposure within 6 months was related to the incidence of early-persistent AD and a dose-dependent increase in the incidence of AD in childhood, whose effect was modified by the IL-13 (rs20541) genotype.

Association between early bronchiolitis and the development of childhood asthma: a meta-analysis

OBJECTIVE

Early life bronchiolitis has been hypothesised to be associated with the subsequent risk of persistent wheezing or asthma. However, the link remains controversial. The objective of our study was to evaluate the association between bronchiolitis before 2 years of age and the late-onset wheezing/asthma.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, Embase and Web of Science databases were systematically searched for studies published between 1955 and January 2020. Meanwhile, we also checked through the reference lists of relevant articles to see whether these references included reports of other studies that might be eligible for the review. Cohort and case-control studies assessing the association between early-life bronchiolitis and late-onset wheezing/asthma were included in this meta-analysis. Data were extracted by two independent reviewers. Results were pooled using a random-effects model or fixed-effects model according to the heterogeneity among studies.

RESULTS

32 original articles with 292 844 participants, which met the criteria, were included in this meta-analysis. Bronchiolitis before 2 years of age was associated with an increased risk of subsequent wheezing/asthma (relative risk=2.46, 95% CI 2.14 to 2.82, p<0.001). After categorising studies into different groups based on age at the end of follow-up, geographical region and study quality, the association still remained significant.

CONCLUSIONS

The meta-analysis indicates an association between bronchiolitis before 2 years of age and the wheezing/asthma in later life. Well-designed and highly standardised prospective studies that better address bias due to potential confounding factors are needed to validate the risk identified in our meta-analysis.PROSPERO registration numberCRD42018089453.

Toll-like receptor 4: A promising crossroads in the diagnosis and treatment of several pathologies

Toll-like receptor 4 (TLR4) is expressed in a wide variety of cells and is the central component of the mammalian innate immune system. Since its discovery in 1997, TLR4 has been assigned an ever-increasing number of functions that extend from pathogen recognition to tissue damage identification and promotion of the intrinsic "damage repair response" in pain, intestinal, respiratory and vascular disorders. Precisely, the finding of conserved sequence homology among species along with the molecular and functional characterisation of the TLR4 gene enabled researchers to envisage a common operating system in the activation of innate immunity and the initiation of plastic changes at the onset of chronic pain. Malfunctioning in other conditions was conceived in parallel. In this respect, "pivot" proteins and pathway redundancy are not just evolutionary leftovers but essential for normal functioning or cell survival. Indeed, at present, TLR4 single nucleotide polymorphisms (SNP) and their association with certain dysfunctions and diseases are being confirmed in different pools of patients. However, despite its ability to trigger pathogen infection or alternatively tissue injury communications to immune system, TLR4 targeting might not be considered a panacea. This review article represents a compilation of what we know about TLR4 from clinics and basic research on the 20th anniversary of its discovery. Understanding how to fine-tune the interaction between TLR4 and its specific ligands may lead in the next decades to the development of promising new treatments, reducing polypharmacy and probably having an impact on drug use in numerous pathologies.

A low abundance of Bifidobacterium but not Lactobacillius in the feces of Chinese children with wheezing diseases

BACKGROUND

The intestinal microbiota is linked with allergic reaction diseases. However, the difference in the fecal microbiota composition between sensitized wheezy and nonsensitized subjects in Chinese children remains unknown. The aim of this study was to quantitate the amounts of fecal microbiota in wheezy children, and to explore the correlation between fecal microbiota and serum Th1/Th2/Th17-type cytokines and total IgE in these patients.

METHODS

The amounts of Bifidobacterium and Lactobacillus were determined using a 16S-RNA real-time polymerase chain reaction (PCR) method in wheezy children (cases) and nonwheezy controls. Serum Th1/Th2/Th17-type cytokines levels were measured using flow a cytometric bead array assay. In addition, the concentrations of total serum IgE was also determined.

RESULTS

In comparison with that in the healthy control (HC), significantly lower abundance of Bifidobacterium and lower levels of Th1 cytokines (IFN-γ and TNF-α), but higher levels of Th2-type cytokines (IL-4, IL-5) and Th17-type (IL-17A) cytokine were detected in children with bronchiolitis and asthma. But there was no significant difference in the amounts of Lactobacillus. Interestingly, the amounts of fecal Bifidobacterium were correlated positively with serum Th1 cytokines IFN-γ, and correlated negatively with serum Th17 cytokines IL-17A, Th2 cytokines IL-4 and serum total IgE in these patients.

CONCLUSIONS

Our findings demonstrated that lower quantity of Bifidobacterium, but not Lactobacillus, may be correlated with asthma and bronchiolitis in chinese children. These results also may provide guidance in choosing the proper probiotics for wheezing children.

Genetic Mechanisms of Asthma and the Implications for Drug Repositioning

Asthma is a chronic disease that is caused by airway inflammation. The main features of asthma are airway hyperresponsiveness (AHR) and reversible airway obstruction. The disease is mainly managed using drug therapy. The current asthma drug treatments are divided into two categories, namely, anti-inflammatory drugs and bronchodilators. However, disease control in asthma patients is not very efficient because the pathogenesis of asthma is complicated, inducing factors that are varied, such as the differences between individual patients. In this paper, we delineate the genetic mechanisms of asthma, and present asthma-susceptible genes and genetic pharmacology in an attempt to find a diagnosis, early prevention, and treatment methods for asthma. Finally, we reposition some clinical drugs for asthma therapy, based on asthma genetics.

Role of IL-13 Genetic Variants in Signalling of Asthma

Asthma is a chronic inflammatory disease of the lower airways characterised by intermittent airway narrowing and airflow obstruction. The aim of this study was to examine the association of IL-13 Arg 130 Gln (A/G) and -1112C/T cytokine gene polymorphisms and to know the secretion of IL-13 cytokine levels and the interactions between the IL-13 130A/G and IL-13Rα1/IL-4Rα complex cytokine genes. The study population comprised of atopic and non-atopic asthma patients and healthy controls (HC) (N = 120). Single nucleotide polymorphisms (SNPs) were determined by restriction fragment length polymorphism (RFLP). IL-13 cytokine serum levels were measured by enzyme-linked immunosorbent assay (ELISA), and homology modelling of IL-13 A/G cytokine gene was performed through in silico analysis. In IL-13 130A/G cytokine gene AG, GG genotypes (p < 0.0042, OR = 2.87, CI 1.46-5.65; OR = 1.92, CI 1.06-3.48) were found to be significant in atopic asthma patients vs HC. The mean IL-13 serum cytokine levels were found to be significantly high in atopic (38.48 ± 36.54) and non-atopic (36.05 ± 34.54) asthma patients whereas total serum IgE levels were significantly high at p < 0.0001 in atopic and low in non-atopic asthma patients at p < 0.003 compared to HC. In silico analysis indicated that residue IL-13 130 with charge modifying variants was crucial in ligand-receptor interactions. IL-13 cytokine serum levels were significantly high in atopic and non-atopic asthma patients compared to HC. The GG genotype of IL-13 130A/G cytokine gene might be involved in the induced production of total IgE and IL-13 cytokine serum levels suggesting IL-13 may be important in the signalling of asthma.

Acute viral bronchiolitis and risk of asthma in schoolchildren: analysis of a Brazilian newborn cohort

OBJECTIVE

To verify whether the occurrence of acute viral bronchiolitis in the first year of life constitutes a risk factor for asthma at age 6 considering a parental history of asthma.

METHODS

Cross-sectional study in a cohort of live births. A standardized questionnaire of the International Study of Asthma and Allergies in Childhood was applied to the mothers to identify asthma in children at the age of 6 years. Acute viral bronchiolitis diagnosis was performed by maternal report of a medical diagnosis and/or presence of symptoms of coryza accompanied by cough, tachypnea, and dyspnea when participants were 3, 6, 9, and 12 months. Socioeconomic, environmental data, parental history of asthma, and data related to pregnancy were collected in the first 72h of life of the newborn and in prospective home visits by trained interviewers. The association between acute viral bronchiolitis and asthma was evaluated by logistic regression analysis and potential modifier effect of parental history was verified by introducing an interaction term into the adjusted logistic regression model.

RESULTS

Prevalence of acute viral bronchiolitis in the first year of life was 68.6% (461). The occurrence of acute viral bronchiolitis was a risk factor for asthma at 6 years of age in children with parental history of asthma OR: 2.66, 95% CI (1.10-6.40), modifier effect p=0.002. Parental history of asthma OR: 2.07, 95% CI (1.29-3.30) and male gender OR: 1.69, 95% CI, (1.06-2.69) were other identified risk factors for asthma.

CONCLUSION

Acute viral bronchiolitis in the first year of life is a risk factor for asthma in children with parental history of asthma.

Association between IL-13 +1923C/T polymorphism and asthma risk: a meta-analysis based on 26 case-control studies

Asthma is a serious and hereditary respiratory disorder affecting all age groups. Interleukin-13 (IL-13) is a central regulator of allergic inflammation. The purpose of the present study was to estimate the relationship between IL-13 +1923C/T polymorphism and asthma susceptibility. Relevant case-control studies published between January 2000 and July 2016 were searched in the online databases. Review Manage (RevMan) 5.3 was used to conduct the statistical analysis. The pooled odds ratio (OR) with its 95% confidence interval (CI) was employed to calculate the strength of association. A total of 26 articles were retrieved, including 17642 asthma patients and 42402 controls. Overall, our results found that IL-13 +1923C/T polymorphism was significantly associated with increased risk of asthma under each genetic model (P<0.00001). Subgroup analysis by ethnicity showed that alleles and genotypes of this variant correlated with asthma among Asians and Caucasians, but only TT genotype under the homozygote model in Africans. When stratified by age group, this variant highly correlated with asthma in children and moderately in adults. Furthermore, the TT, CT and CC genotypes in asthma group were all significantly associated with increased IgE levels in sera of asthma patients when compared with controls. Our results suggested that IL-13 +1923C/T polymorphism contributed to the development of asthma. Further case-control studies with more ethnicities are still needed.

Pediatric Pulmonology year in review 2015: Part 1

Our journal covers a broad range of research and scholarly topics related to children's respiratory disorders. For updated perspectives on the rapidly expanding knowledge in our field, we will summarize the past year's publications in our major topic areas, as well as selected publications in these areas from the core clinical journal literature outside our own pages. The current review covers articles on neonatal lung disease, pulmonary physiology, and respiratory infection. Pediatr Pulmonol. 2016;51:733-739. © 2016 Wiley Periodicals, Inc.

Genetic association of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C-159T polymorphisms with the risk of severe RSV infection: a meta-analysis

Respiratory syncytial virus (RSV) is the most frequent cause of hospitalization in infants worldwide. It is recognized by Toll‐like receptor 4 (TLR 4) and cluster of differentiation 14 (CD14) in the innate immune response. Previous case–control studies reported the influence of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms on the risk of severe RSV infection. However, a decisive conclusion has not been achieved. Therefore, we performed this meta‐analysis to examine the association between these three polymorphisms and the development of RSV bronchiolitis. A systematic literature search was performed using the PubMed, EMbase, Google Scholar Search, China National Knowledge Infrastructure, China Biological Medicine, and Wanfang Databases. The data were extracted and pooled odds ratios with 95% confidence intervals were calculated under six genetic models. A total of six studies with 1009 cases and 1348 controls, three studies with 473 cases and 481 controls, or four studies with 325 cases and 650 controls relating to each of the three polymorphisms were included in this meta‐analysis. The analyzed data indicated that all of these polymorphisms were not associated with the risk of severe RSV infection. This is the first meta‐analysis to investigate the relationship of TLR4 Asp299Gly, TLR4 Thr399Ile, and CD14 C‐159T polymorphisms with the risk of severe RSV infection. Although the results of this retrospective analysis indicated a lack of the association, more extensive multicentric studies with large sample sizes are necessary to provide a more reliable estimation of the association between these three polymorphisms and RSV bronchiolitis susceptibility.

Association between Dietary Patterns and Atopic Dermatitis in Relation to GSTM1 and GSTT1 Polymorphisms in Young Children

Previous research suggests the association of glutathione S-transferase (GST) gene polymorphisms or diet, but no interactions between these factors in atopic dermatitis (AD). We conducted a community-based case-control study including 194 AD and 244 matched non-AD preschoolers. Glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) present/null genotypes were evaluated uisng a multiplex PCR method. We measured dietary intakes by a validated food frequency questionnaire and constructed three dietary patterns such as “traditional healthy”, “animal foods”, and “sweets” diets. In stratified analyses by GST genotypes, the “traditional healthy” diet and reduced AD showed association only in the GSTM1-present group (odd ratio (OR) 0.31, 95% confidence interval (CI) 0.13–0.75). A similar pattern of the association existed in the combined GSTM1/T1 genotype that indicated the inverse association between the “traditional healthy” diet and AD in the double GSTM1/T1-present genotype group (OR 0.24, 95% CI 0.06–0.93). Results from the multiplicative test analyses showed that the “traditional healthy” diet on reduced AD was significant or borderline significant in the GSTM1-present group (OR 0.71, 95% CI 0.54–0.92 vs. GSTM1-null group) or the GSTM1/T1 double present group (OR 0.63, 95% CI 0.39–1.03 vs. GSTM1/T1 double null group). These findings demonstrate that the present type of GSTM1 may increase susceptibility to the potential effect of the “traditional healthy” diet on AD.

Mold elicits atopic dermatitis by reactive oxygen species: Epidemiology and mechanism studies

Mold has been implicated in the development of atopic dermatitis (AD); however, the underlying mechanisms remain unknown. The aim of the study was to investigate the effects of mold exposure in early life through epidemiologic and mechanistic studies in vivo and in vitro. Exposure to visible mold inside the home during the first year of life was associated with an increased risk for current AD by two population-based cross-sectional human studies. Children with the AG+GG genotype of GSTP1 showed increased risk for current AD when exposed to mold. In the mouse model, treatment with patulin induced and aggravated clinically significant AD and Th2-related inflammation of the affected mouse skin. Additionally, reactive oxygen species (ROS) were released in the mouse skin as well by human keratinocytes. In conclusions, mold exposure increases the risk for AD related to ROS generation mediated by Th2-promoting inflammatory cytokines.

A longitudinal study on early hospitalized airway infections and subsequent childhood asthma

Background

Acute airway infections, including bronchiolitis, are common causes of early childhood hospitalization. The development of later asthma may be related to early airway infections in young children. This study is to investigate the relationship between hospitalized airway infections (HAI) in young children (< 3 years old) and later childhood asthma.

Methods

Hospitalized children (< 3 years old) with bronchiolitis or other acute airway infections (other HAI group) from 1997-2000 were retrieved from the National Health Insurance Research Database of Taiwan, and compared to age- and gender-matched subjects with regards to asthma until 10 years of age; and potential comorbidities and medical care conditions.

Results

In total, 3,264 children (1,981 with bronchiolitis; 1,283 with other HAIs) were compared to 18,527 controls. The incidence of childhood asthma was higher in the study (16.2%) than the control (11.7%) group, and most cases were diagnosed between 3-5 years old. The hazard ratios were 1.583 (95% CI: 1.414-1.772) and 1.226 (95% CI: 1.053-1.428) for the bronchiolitis and other HAI subgroups, respectively, compared to the control group, and 1.228 (95% CI: 1.075-1.542) in the bronchiolitis subgroup compared to the other HAIs subgroup. A significantly higher odds ratio (1.973, 95% CI: 1.193-3.263) for the children with congenital heart disease (CHD) in the bronchiolitis subgroup was found at an age of 3-5 years compared to the control group.

Conclusions and Clinical Relevance

Young children (< 3 years old) hospitalized due to acute HAIs are at a higher risk of developing childhood asthma at age 3 to 10 years. The parents of children with HAIs at age 0 to 2 years should be informed for the higher risk of developing childhood asthma, especially in children with CHD and bronchiolitis.

Association Between Antibiotic Exposure, Bronchiolitis, and TLR4 (rs1927911) Polymorphisms in Childhood Asthma

Purpose

The complex interplay between environmental and genetic factors plays an important role in the development of asthma. Several studies have yielded conflicting results regarding the 2 asthma-related risk factors: antibiotic usage during infancy and/or a history of bronchiolitis during early life and the development of asthma. In addition to these risk factors, we also explored the effects of Toll-like receptor 4 (TLR4) polymorphism on the development of childhood asthma.

Methods

This cross-sectional study involved 7,389 middle school students who were from 8 areas of Seoul, Korea, and completed the International Study of Asthma and Allergies in Childhood questionnaire. The TLR4 polymorphism rs1927911 was genotyped in 1,395 middle school students from two areas using the TaqMan assay.

Results

Bronchiolitis in the first 2 years of life, antibiotic exposure during the first year of life, and parental history of asthma were independent risk factors for the development of asthma. When combined, antibiotic use and a history of bronchiolitis increased the risk of asthma (adjusted odds ratio [aOR]: 4.64, 95% confidence interval [CI]: 3.09-6.97, P value for interaction=0.02). In subjects with CC genotype of TLR4, antibiotic exposure and a history of bronchiolitis during infancy, the risk of asthma was increased, compared to subjects without these risk factors (aOR: 5.72, 95% CI: 1.74-18.87).

Conclusions

Early-life antibiotic exposures and a history of bronchiolitis are risk factors for asthma in young adolescents. Polymorphisms of TLR4 modified the influence of these environmental factors. Reducing antibiotic exposure and preventing bronchiolitis during infancy may prevent the development of asthma, especially in genetically susceptible subjects.