Gene-environmental interaction in the development of atopic asthma: new developments

Pediatric asthma exacerbation and COVID-19 pandemic: Impacts, challenges, and future considerations

OBJECTIVE

Asthma, a common disease among children and adolescents, poses a great health risk when ignored; therefore, a thorough follow-up to prevent exacerbations is emphasized. The aim of the present study is to investigate asthma exacerbation in children during the Coronavirus disease 2019 (COVID-19) era.

DATA SOURCES

This narrative review has been done by searching the PubMed and Embase databases using Asthma, COVID-19, Pandemic, and Symptom flare up as keywords.

STUDY SELECTIONS

Studies related to asthma exacerbation in COVID-19 pandemic were included.

RESULTS

Based on studies, controlled or mild to moderate asthma has not been considered a risk factor for COVID-19 severity and has not affected hospitalization, intensive care unit (ICU) admission, and mortality. Surprisingly, emergent and non-emergent visits and asthmatic attacks decreased during the pandemic. The three main reasons for decreased incidence and exacerbation of asthma episodes in the COVID-19 era included reduced exposure to environmental allergens, increasing the acceptance of treatment by pediatrics and caregivers, and decreased risk of other respiratory viral infections. Based on the available studies, COVID-19 vaccination had no serious side effects, except in cases of uncontrolled severe asthma, and can be injected in these children. Also, there was no conclusive evidence of asthma exacerbation after the injection of COVID-19 vaccines.

CONCLUSION

Further studies are recommended to follow the pattern of asthma in the post-pandemic situation and to become prepared for similar future conditions.

Differential Quercus spp. pollen-particulate matter interaction is dependent on geographical areas

Particulate matter (PM) and pollen interaction, either airborne or at the respiratory mucosa needs further clarification, as allergic reaction intensification can be related to the PM physical characteristics and toxicity. This study aimed to investigate the physical-chemical properties of PM that can adhere to the pollen wall during its transport or inhalation, using Quercus spp. as a model, in three Portuguese cities with different geographical locations, meteorological influence and urbanization levels. Possible sources were evaluated through air masses trajectory analysis using the HYSPLIT model and correlation with meteorological factors. The sampling was performed using a 7-days Hirst-type volumetric sampler, and the pollen grains were observed using a Field Emission Electron Probe Microanalyser for PM analysis. A secondary electron image of each pollen grain was taken, to determine the adhered particles characteristics and energy dispersive x-ray spectroscopy (EDS) spectra were obtained for individual particles. A total of 484 pollen grains was observed, with 7683 particles counted and 1914 EDS spectra analyzed. The particle's equivalent diameter ranged from 0.3-16 μm, with most having a diameter < 3 μm. For the three cities, there were significant differences in the number of particles per pollen and the % area occupied by the particles. Particles adhered were mainly Si-rich, but variations in other dominant groups were observed. For Évora and Guarda, Ca-rich, SO-rich were second and third more representative, while Porto were Organic and Cl-rich. Metals&Oxides were found in all cities with the highest number in Porto. P-rich particles were only found in Évora. Sea salt particles were observed in Évora, coincide with air mass trajectories possible carrying them from the Mediterranean Sea. In conclusion, the PM physical characteristics are similar between the studied cities, however, the dominant chemical composition is different, certainly impacting the exposome influence and pollen-allergy intensification towards the same pollen type and concentration.

Association between early viral lower respiratory tract infections and subsequent asthma development

BACKGROUND

The association between hospitalization for human respiratory syncytial virus (HRSV) bronchiolitis in early childhood and subsequent asthma is well established. The long-term prognosis for non-bronchiolitis lower respiratory tract infections (LRTI) caused by viruses different from HRSV and rhinovirus, on the other hand, has received less interest.

AIM

To investigate the relationship between infant LRTI and later asthma and examine the influence of confounding factors.

METHODS

The PubMed and Global Index Medicus bibliographic databases were used to search for articles published up to October 2021 for this systematic review. We included cohort studies comparing the incidence of asthma between patients with and without LRTI at ≤ 2 years regardless of the virus responsible. The meta-analysis was performed using the random effects model. Sources of heterogeneity were assessed by stratified analyses.

RESULTS

This review included 15 articles (18 unique studies) that met the inclusion criteria. LRTIs at ≤ 2 years were associated with an increased risk of subsequent asthma up to 20 years [odds ratio (OR) = 5.0, 95%CI: 3.3-7.5], with doctor-diagnosed asthma (OR = 5.3, 95%CI: 3.3-8.6), current asthma (OR = 5.4, 95%CI: 2.7-10.6), and current medication for asthma (OR = 1.2, 95%CI: 0.7-3.9). Our overall estimates were not affected by publication bias (P = 0.671), but there was significant heterogeneity [I² = 58.8% (30.6-75.5)]. Compared to studies with hospitalized controls without LRTI, those with ambulatory controls had a significantly higher strength of association between LRTIs and subsequent asthma. The strength of the association between LRTIs and later asthma varied significantly by country and age at the time of the interview. The sensitivity analyses including only studies with similar proportions of confounding factors (gender, age at LRTI development, age at interview, gestational age, birth weight, weight, height, smoking exposure, crowding, family history of atopy, and family history of asthma) between cases and controls did not alter the overall estimates.

CONCLUSION

Regardless of the causative virus and confounding factors, viral LRTIs in children < 2 years are associated with an increased risk of developing a subsequent asthma. Parents and pediatricians should be informed of this risk.

Correlation between DNA methylation and Thymic Stromal Lymphopoietin expression in asthmatic airway epithelial cells

BACKGROUND

The overexpression of TSLP and DNA methylation in asthma were both risk factors the relationship was not clear.

OBJECTIVE

This study aimed to investigate the relationship between methylation status of TSLP promoter and mRNA/protein expression in asthmatic airway epithelial cells.

METHODS

Human bronchial epithelial cells were cultured in vitro and divided into: Control group, treated with PBS, model group, sensitized with LPS (10 μg/mL) for 12 h (37 °C, 5% CO₂). Other groups were cultured with the pCMV3 plasmid (M + NC/pCMV), pGPH1 plasmid (M + NC/pGPH), DNMT1/pCMV3 plasmid (M + DNMT1/pCMV), and DNMT1/pGPH1 plasmid (M + DNMT1/pGPH) for 48 h. The expression of DNA methyltransferase 1 and TSLP were measured using real-time PCR and western blotting.

RESULTS

Compared with the control group, TSLP mRNA (1.00 ± 0.00 vs. 2.82 ± 0.81 vs. 1, P < 0.001) and protein (1.07 ± 0.04 vs. 1.46 ± 0.11, P < 0.01) were significantly greater, and the methylation of promoter was lower (92.75 ± 1.26 vs. 58.57 ± 3.34, P < 0.05) in the model group. Compared with the model group, TSLP mRNA (2.82 ± 0.81 vs. 1.17 ± 0.10, P < 0.001) decreased, but TSLP promoter methylation increased (58.57 ± 3.34 vs. 92.58 ± 7.30, P < 0.05) in M + DNMT1/pCMV. TSLP mRNA and protein were higher (2.82 ± 0.81 vs. 5.32 ± 0.21, P < 0.001; 1.46 ± 0.11 vs. 1.94 ± 0.11, respectively, P < 0.01), TSLP promoter methylation was lower (58.57 ± 3.34 vs. 33.57 ± 4.29, P < 0.05) in M + DNMT1/pGPH.

CONCLUSIONS

Overexpression of TSLP in asthmatic airway epithelial cells may be regulated by DNA demethylation.

Cross-reactivity between the Betulaceae family and fallout in the real atmospheric aeroallergen load

Betulaceae family is a dominant tree pollen type in the atmosphere at Northwest Spain, being a major cause of allergenic rhinitis or asthma symptoms. Alnus pollen cause symptoms in the 9-20% of the total hay fever sufferers mean while the 41.89% of patients present a positive skin-prick-test for Betula allergens. Aln g1 and Bet v1 aeroallergens belong to PR-10 protein family and are associated to cross-reactivity processes. Airborne pollen and aeroallergens from Alnus and Betula were sampled during their Main Pollen Season from 2016 to 2019. Pollen sampling was conducted by means of a Hirst volumetric trap and aeroallergens were sampled using a Multi Vial Cyclone Sampler. Alnus flowering took place from January to February, with an average duration of 44 days. Betula bloom occurred from April to May with an average pollen season of 33 days. The major innovation of our study was the first detection of Aln g1 allergens in the atmosphere by using Bet v1 antibodies. This fact verified the cross-reactivity between the main allergens of Betula and Alnus pollen. Along the study period, an average of 18 days/year and 14 days/year with high potential risk of allergy due to Alnus pollen and allergen respectively, was registered. For Betula an average of 16 days/year with high potential risk of allergy due to pollen and 22 days for allergen was registered. The main consequence of the successive bloom of both trees would be the so-called "priming effect". Urban population sensitized to Betula pollen could suffer allergic symptoms during winter (as a consequence of Alnus), and in spring with the manifestation of higher symptoms under low birch pollen grain levels in the atmosphere. The traditional information to prevent allergies, such as the airborne pollen concentrations, should be combined with the data of aeroallergen to identify the real allergenic load in the atmosphere.

Rhinovirus and childhood asthma: an update

Asthma is recognized as a complex disease resulting from interactions between multiple genetic and environmental factors. Accumulating evidence suggests that respiratory viral infections in early life constitute a major environmental risk factor for the development of childhood asthma. Respiratory viral infections have also been recognized as the most common cause of asthma exacerbation. The advent of molecular diagnostics to detect respiratory viruses has provided new insights into the role of human rhinovirus (HRV) infections in the pathogenesis of asthma. However, it is still unclear whether HRV infections cause asthma or if wheezing with HRV infection is simply a predictor of childhood asthma. Recent clinical and experimental studies have identified plausible pathways by which HRV infection could cause asthma, particularly in a susceptible host, and exacerbate disease. Airway epithelial cells, the primary site of infection and replication of HRV, play a key role in these processes. Details regarding the role of genetic factors, including ORMDL3, are beginning to emerge. This review discusses recent clinical and experimental evidence for the role of HRV infection in the development and exacerbation of childhood asthma and the potential underlying mechanisms that have been proposed.

Increased seroprevalence of Enterovirus 71 IgE antibodies in asthmatic compared with non-asthmatic children

BACKGROUND

Asthma is a common pediatric chronic inflammatory airway disease. Respiratory viral infections are frequent infectious triggers for exacerbations of asthma.

OBJECTIVE

We sought to determine whether Enterovirus 71 (EV71), a ubiquitous virus that causes systemic inflammatory responses in children but is not a known respiratory pathogen, can also serve as an infectious trigger for asthma.

METHODS

Specific EV71 IgE and IgM antibodies (Abs), total serum IgE, and IL-2 and IL-4 cytokine levels in serum of asthmatic and non-asthmatic children (N = 42, ages 5-19; N = 35, ages 1-20, respectively) were measured (ELISA).

RESULTS

Asthmatic children had higher EV71 IgE Ab levels than non-asthmatic (P < 0.001). Non-asthmatic children had significantly higher EV71 IgM Ab levels than asthmatic (P < 0.001). Despite low serum IgE levels of non-asthmatic, compared with asthmatic (P < 0.001), the non-asthmatic children produced significantly more IL-2 and IL-4 than asthmatic (P < 0.001; P < 0.001). The ages of the asthmatics, but not the non-asthmatics had a significant effect on the levels of EV 71 IgE Abs (P = 0.02; P = 0.356). A test of difference between these two slopes was significant. However, the ages of the non-asthmatic, but not the asthmatic children had a significant effect on the levels of EV 71 IgM Abs; a test of difference between these two slopes was significant.

CONCLUSIONS

Increased specific EV71 IgE Ab responses may indicate that EV71 infection may also be an infectious trigger in asthma. However, the role of specific EV71 IgM Abs, Th2 cytokines, and age in non-asthmatic children should be further studied.

Characterisation of particulate matter on airborne pollen grains

A characterization of the physical-chemical composition of the atmospheric PM adsorbed to airborne pollen was performed. Airborne pollen was sampled using a Hirst-type volumetric spore sampler and observed using a Field Emission Electron Probe Microanalyser for PM analysis. A secondary electron image was taken of each pollen grain and EDS spectra were obtained for individually adsorbed particles. All images were analysed and the size parameters of the particles adsorbed to pollen was determined. The measured particles' equivalent diameter varied between 0.1 and 25.8 μm, mostly in the fine fraction. The dominant particulates identified were Si-rich, Organic-rich, SO-rich, Metals & Oxides and Cl-rich. Significant daily differences were observed in the physical-chemical characteristics of particles adsorbed to the airborne pollen wall. These differences were correlated with weather parameters and atmospheric PM concentration. Airborne pollen has the ability to adsorb fine particles that may enhance its allergenicity.

The evolution of the hygiene hypothesis: the role of early-life exposures to viruses and microbes and their relationship to asthma and allergic diseases

PURPOSE OF REVIEW

Understanding the mechanisms involved in the development of asthma and allergic diseases is expanding, due in part to sequencing advances that have led to the identification of new viral strains such as human rhinovirus strain C (HRV-C) and the human microbiome project.

RECENT FINDINGS

Recent studies have identified new ways in which viral and microbial exposures in early life interact with host genetic background/variants to modify the risk for developing asthma and allergic diseases. Recent research suggests that HRV-C is the main pathogenic agent associated with infant wheeze, hospitalizations and likely the subsequent development of asthma. Pulmonary He MRI suggests that HRV infection in early childhood and subsequent immune responses initiate airway remodeling. Numerous studies of the microbiome indicate that intestinal and airway microbiome diversity and composition contribute to the cause of asthma and allergic diseases.

SUMMARY

Susceptibility to asthma and allergic diseases is complex and involves genetic variants and environmental exposures (bacteria, viruses, smoking, and pet ownership), alteration of our microbiome and potentially large-scale manipulation of the environment over the past century.

Changes of T-lymphocyte subpopulation and differential expression pattern of the T-bet and GATA-3 genes in diffuse large B-cell lymphoma patients after chemotherapy

BACKGROUND AND OBJECTIVE

T cell-mediated immunity plays an important role in enhancing antitumor response.This study aimed to investigate the changes in the T-lymphocyte subpopulation and to characterize the differential expression pattern of corresponding regulatory genes in peripheral blood mononuclear cells (PBMCs) from diffuse large B cell lymphoma (DLBCL) patients before and after chemotherapy.

METHODS

A total of 56 DLBCL patients were recruited for analysis of T-cell subset distribution in the peripheral blood using flow cytometry; serum interferon (IFN)-γ and interleukin (IL)-4 levels using enzyme-linked immunosorbent assays; and early growth response protein 1 (EGR-1), T-bet, GATA-binding protein 3 (GATA-3), and transforming growth factor (TGF)-β mRNA levels using quantitative reverse-transcription polymerase chain reaction. Twenty-six healthy subjects served as controls.

RESULTS

The percentage of CD3(+)CD4(+)T lymphocytes in peripheral blood from DLBCL patients was significantly decreased, whereas the percentages of CD3(+)CD8(+)T and CD4(+)CD25(+)T cells were significantly increased compared to those in controls (p < 0.05). Serum levels of IFN-γ and IL-4 were also significantly lower in DLBCL patients than those in controls (p < 0.05), and the levels of EGR-1, T-bet, and GATA-3 mRNA in PBMCs were lower (2.69 ± 1.48, 9.43 ± 2.14, and 20.83 ± 9.05 fold, respectively) in DLBCL patients than those in controls. Furthermore, there was a positive association between the levels of EGR-1 and T-bet mRNA (p = 0.001). However, the level of TGF-β mRNA was significantly increased in DLBCL patients, which was inversely associated with the T-bet mRNA level (p = 0.008), but positively associated with the percentage of T regulatory cells in PBMCs (p = 0.011). After three cycles of chemotherapy, the distribution of T-lymphocyte subsets in DLBCL patients were changed, and the levels of EGR-1, T-bet, and GATA-3 mRNA were significantly increased (p < 0.05) compared to those before chemotherapy.

CONCLUSIONS

These results demonstrate the changes in T-lymphocyte subpopulations and the altered expression 34 pattern of the corresponding regulatory genes in PBMCs from DLBCL patients after chemotherapy, which are associated with the response of patients to treatment. The preferential expression of the T-bet gene after chemotherapy was closely correlated with the increased expression of the EGR-1 gene and decreased expression of the TGF-β gene.

Gene susceptibility in Iranian asthmatic patients: a narrative review

As environmental factors are important in the development of asthma, genetic factors could have a critical role in the expression of the disease. Hence, we carried out a systematic review to assess the susceptible genes for asthma in Iranian population. We conducted a literature search by using the electronic database PubMed, Biological Abstracts Web of Science, Current Contents Connect, Cinahl, ScienceDirect, Scopus, IranMedex, and Scientific Information Database to identify articles that evaluated the association between genetic variants and the risk of asthma in Iranian population (until April 30, 2012). The search terms were used include: Asthma and gene in combination with Iran for international database. The following criteria were used for selecting literatures in this review: The study should evaluate the association between gene polymorphism and risk of asthma in Iranian population, and the study should be a case-control design with normal subject as ac control group that published in a journal. Finally, 14 case-control studies were extracted from local and international database. In this study, we reviewed 38 polymorphisms in 19 genes. Polymorphism in interleukin-13 (IL-13), IL-10, IL-1, IL-2, IL-12, E-Selectin, S128R and Exon 9 Vitamin D Receptor were susceptible for asthma and polymorphism in chemokine receptor 5, transforming growth factor-a (TGF-a), Intron 8 of the Vitamin D Receptor, angiotensin-converting enzyme gene, IL-6 and interferon-c were not susceptible for asthma in Iranian population. Polymorphism in IL-4, tumor necrosis factor-α and TGF-b had inconsistent findings. This systematic review indicated that three polymorphisms (IL-13, IL-10, and IL-1) are associated with risk of asthma in Iranian population.

Infantile respiratory syncytial virus and human rhinovirus infections: respective role in inception and persistence of wheezing

There is evidence that respiratory viruses play a key role in the development and exacerbation of obstructive respiratory diseases in children. This review attempts to juxtapose the separate profiles and prototypes of pathogenetic mechanisms represented by the two most common amongst such viruses: respiratory syncytial virus (RSV) and human rhinovirus (HRV). RSV represents the most common agent of severe airway disease in infants and young children, and is predominant in winter months. Large epidemiological studies have revealed an unequivocal relationship between RSV infection and subsequent wheezing into childhood, thought to be related to long-term changes in neuroimmune control of the airways rather than allergic sensitisation. HRV is a highly diverse group of viruses that affect subjects of all ages, is ubiquitous and occurs year-round. In contrast to RSV, infections with HRV cause minimal cytotoxicity but induce a rapid production of cytokines and chemokines with amplification of the inflammatory response. The susceptibility to HRV-induced bronchiolitis and subsequent wheezing appears to be linked to individual predisposition since it is often associated with a family or personal history of asthma/atopy. Thus, RSV probably serves as an "inducer" rather than a "trigger". Conversely, HRVs seem to serve as a "trigger" rather than an "inducer" in predisposed individuals.

Prevalence and determinants of atopy and allergic diseases among school-age children in rural Saskatchewan, Canada

BACKGROUND

There have been few investigations of farming-related activities or specific characteristics resulting in the associations between those exposures and atopic disease.

OBJECTIVE

To study the associations between farm-associated exposures and atopic diseases.

METHODS

As part of a longitudinal study of lung health in rural residents, a cross-sectional baseline study was conducted in rural Saskatchewan, Canada. This included an initial survey phase followed by a clinical testing phase. A subsample of 584 children (grades 1-8) completed skin prick testing to assess atopic status. Atopy was defined as a positive reaction to any of 6 allergens (local grasses, wheat dust, cat dander, house dust mite, Alternaria species, or Cladosporium species) of at least 3 mm compared with the negative control.

RESULTS

Of those who completed clinical testing, the prevalence of atopy was 19.4%, that of hay fever was 8.8%, and that of eczema was 27.4%. Based on skin prick testing, sensitization was highest for cat dander (8.6%) followed by local grasses (8.2%) and house dust mite (5.1%). After adjustment for potential confounders, home location (farm vs non-farm) was not associated with atopic status. However, livestock farming was protective against atopy (adjusted odds ratio 0.38, 95% confidence interval 0.17-0.88). In contrast, current residence on a farm was associated with an increase in the likelihood of hay fever in these children (adjusted odds ratio 3.68, 95% confidence interval 1.29-10.45). Also, regular farming activities in the past year were associated with an increased risk of hay fever.

CONCLUSION

In children, livestock exposure has a protective effect on skin prick test positivity, whereas farm living and activities increase the risk of hay fever.

A systematic review of CD14 and toll-like receptors in relation to asthma in Caucasian children

The aetiology of childhood asthma is complex. An early dysfunction in the immunological development of the innate immune system in combination with environmental factors possibly triggers asthma. CD14 and toll-like receptors are important components of the innate immune system. The aim of this systematic review was to obtain a better insight into the relation between CD14 and toll-like receptors and childhood asthma in Caucasians. We searched PubMed and EMBASE for relevant articles. In total, 44 articles were included. The quality of the selected studies was independently assessed by the first two authors using the Newcastle-Ottawa quality assessment scale. Toll-like receptor 2, toll-like receptor 6, toll-like receptor 9, and toll-like receptor 10 appear to have some association with childhood asthma in Caucasians. The evidence for a relation of CD14 with childhood asthma is limited. In conclusion, there is no convincing evidence yet for a role of CD14 and toll-like receptors in relation to childhood asthma. Future studies should include haplotype analysis and take environmental factors into account to further clarify the role of CD14 and toll-like receptors on childhood asthma.

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

The concept of gene-environment (GxE) interactions has dramatically evolved in the last century and has now become a central theme in studies that assess the causes of human disease. Despite the numerous efforts to discover genes associated in asthma and allergy through various approaches, including the recent genome-wide association studies, investigation of GxE interactions has been mainly limited to candidate genes, candidate environmental exposures, or both. This review discusses the various strategies from hypothesis-driven strategies to the full agnostic search of GxE interactions with an illustration from recently published articles. Challenges raised by each piece of the puzzle (ie, phenotype, environment, gene, and analysis of GxE interaction) are put forward, and tentative solutions are proposed. New perspectives to integrate various types of data generated by new sequencing technologies and to progress toward a systems biology approach of disease are outlined. The future of a molecular network-based approach of disease to which GxE interactions are related requires space for innovative and multidisciplinary research. Assembling the various parts of a puzzle in a complex system could well occur in a way that might not necessarily follow the rules of logic.

Epigenetic regulation of DNMT1 gene in mouse model of asthma disease

Asthma is a complex genetic disease, which arises from the interaction of multiple genes and environmental stimuli. These influences are important to asthma pathogenesis. These can be mechanically explained by the Epigenetic phenomenon, which consists of the chromatin and its modifications, as well as a covalent modification of cytosines residing at the dinucleotide sequence CG in DNA by methylation. This reaction is catalyzed by a family of DNA methyltransferase enzyme (DNMTs). DNMT1 is one of them which maintained the methylation status during replication and also critical for the development, differentiation and regulation of Th1 and Th2 cells. Therefore we studied the DNMT1 mRNA expression profiling as well as CpG methylation status in promoter region. For these studies we developed asthma mouse model, and used Flow cytometer, qRT(2)-PCR, Methylation specific PCR, bisulfate conversion and BiQ analyzer. We found that DNMT1 expression level was low in all the tissues (lung, trachea and BALF cells) of asthmatic in comparison to normal mice. This was due to the methylation of regulatory sites of DNMT1 promoter region at cytosine residue. As the incidence of asthma is increasing globally and in world, this study assumes greater significance in designing and developing therapeutic means.

Downregulation of Hlx closely related to the decreased expressions of T-bet and Runx3 in patients with gastric cancer may be associated with a pathological event leading to the imbalance of Th1/Th2

T-bet plays an important role in immunoregulation; it induces the differentiation of Th1 together with the homeobox transcription factor gene Hlx. Recent studies show that T-bet and Th1-associated factors are critical in regulating tumor development. However, the contributions of Hlx in the occurrence and development of cancer remain unknown. In this study, the Hlx, T-bet, Runx3, and IFN-γ were measured in PBMC from patients with gastric cancer and the correlation between Hlx and T-bet or IFN-γ was assessed. The expression levels of Hlx, T-bet, and IFN-γwere significantly decreased, and there was a positive correlation between Hlx and T-bet or IFN-γ. In addition, the Runx3 expression was also downregulated with the lower T-bet mRNA level. These results suggested that the decreased Hlx expression was closely associated with T-bet and Runx3 downregulations and may contribute to the development of gastric cancer.

Associations and interactions of genetic polymorphisms in innate immunity genes with early viral infections and susceptibility to asthma and asthma-related phenotypes

BACKGROUND

The innate immune system is essential for host survival because of its ability to recognize invading pathogens and mount defensive responses.

OBJECTIVES

We sought to identify genetic associations of innate immunity genes with atopy and asthma and interactions with early viral infections (first 12 months of life) in a high-risk birth cohort.

METHODS

Three Canadian family-based studies and 1 Australian population-based case-control study (n = 5565) were used to investigate associations of 321 single nucleotide polymorphisms (SNPs) in 26 innate immunity genes with atopy, asthma, atopic asthma, and airway hyperresponsiveness. Interactions between innate immunity genes and early viral exposure to 3 common viruses (parainfluenza, respiratory syncytial virus, and picornavirus) were examined in the Canadian Asthma Primary Prevention Study by using both an affected-only family-based transmission disequilibrium test and case-control methods.

RESULTS

In a joint analysis of all 4 cohorts, IL-1 receptor 2 (IL1R2) and Toll-like receptor 1 (TLR1) SNPs were associated with atopy after correction for multiple comparisons. In addition, an NFKBIA SNP was associated with atopic asthma. Six SNPs (rs1519309 [TLR3], rs740044 [ILIR2], rs4543123 [TLR1], rs5741812 [LBP], rs917998 [IL18RAP], and rs3136641 [NFKBIB]) were significant (P < .05, confirmed with 30,000 permutations) in both the combined analysis of main genetic effects and SNP-virus interaction analyses in both case-control and family-based methods. The TLR1 variant (rs4543123) was associated with both multiple viruses (respiratory syncytial virus and parainfluenza virus) and multiple phenotypes.

CONCLUSION

We have identified novel susceptibility genes for asthma and related traits and interactions between these genes and early-life viral infections.

Impact of asthma and comorbid allergic rhinitis on quality of life and control in patients of Italian general practitioners

OBJECTIVE

Asthma is a disease with elevated prevalence within the general population. Although general practitioners (GPs) are among the first health-care professionals to whom patients refer for their symptoms, there are few evaluations of this disease based on data provided by the GPs. The aim of this observational study is to assess the impact of asthma and comorbid allergic rhinitis on individual/social burden, quality of life, and disease control in asthmatic patients of Italian GPs.

METHODS

Throughout Italy, 107 GPs enrolled 995 patients diagnosed with asthma and using anti-asthmatic drug prescriptions, or with asthma-like symptoms during the previous 12 months. Data were collected through questionnaires filled out by GPs and patients.

RESULTS

Of the 995 asthmatic patients, 60.6% had concomitant allergic rhinitis (R+A), 39.4% had asthma alone. The latter, compared to those with R+A, showed significantly lower prevalence of intermittent asthma (37.5% vs. 55.6%) and higher prevalence of mild, moderate, and severe persistent asthma (28.4% vs. 23.2%, 28.7% vs. 18.8%, and 5.4% vs 2.4%, respectively). Individual/social burden due to asthma was frequent and increased with disease severity: 87.5% of severe persistent asthma patients reported at least one medical consultation in the last 12 months, 37.5% emergency department visits, 26.7% hospitalization, and 62.5% limitations in daily activities. Control and quality of life were inversely associated with disease severity and were worse in patients with R+A than in those with asthma alone.

CONCLUSIONS

This study showed the negative impact of high severity levels and comorbid allergic rhinitis on quality of life of asthmatic patients and on individual/social burden due to asthma in an Italian GPs setting.

Evidence of association between interferon regulatory factor 5 gene polymorphisms and asthma

Asthma is a heterogeneous disorder hallmarked by chronic inflammation in the respiratory system. Exacerbations of asthma are correlated with respiratory infections. Considering the implication of interferon regulatory factor 5 (IRF5) in innate and adaptive immunity, we investigated the preferential transmission patterns of ten IRF5 gene polymorphisms in two asthmatic family cohorts. A common IRF5 haplotype was found to be associated with asthma and the severity of asthmatic symptoms. Stratified analysis of subgroups of asthmatic individuals revealed that the associations were more pronounced in nonatopic asthmatic individuals. In addition, the risk alleles of IRF5 polymorphisms for asthma were almost completely opposite to those for autoimmune disorders. Our study provides the first evidence of association between IRF5 and asthma, and sheds light on the related but potentially distinct roles of IRF5 alleles in the pathogenesis of asthma and autoimmune disorders.

The association between IFN-γ and IL-4 genetic polymorphisms and childhood susceptibility to bronchial asthma

The present study aims to investigate the association between the genetic polymorphisms of interferon (IFN)-γ and interleukin (IL)-4 with childhood susceptibility to asthma and the levels of IFN-γ, IL-4, and immunoglobulin (Ig) E among asthmatic children. A total of 100 asthmatic children and 122 control children were enrolled in the present study. The genotypes of the IFN-γ gene at the -179G/T locus and the IL-4 gene at the -33C/T and -589C/T loci were detected using polymerase chain reaction with restriction fragment length polymorphism. The IFN-γ gene at the +874A/T locus and the IFN-γ CA repeats were tested using allele-specific and capillary electrophoresis, respectively, whereas the IFN-γ, IL-4, and total IgE levels were measured using enzyme-linked immunosorbent assays. The 100 asthmatic children and the 122 control children were all GG homozygous in the -179 locus of the IFN-γ gene, which shows that the IFN-γ gene is not mutated at the -179 locus. No significant differences were found in terms of genotypic and allelic frequency distribution in the IFN-γ gene or the CA repeat at the +874A/T locus between the asthmatic children and the control (P>0.05). An association was found between the polymorphism of the IFN-γ gene at +874A/T and IFN-γ levels. IFN-γ expression was lower among patients with the AA genotype than those with the AT genotype (P<0.05); the genotypic and allelic frequency distributions of the IL-4 gene at -33C/T and -589C/T were significantly different between the asthmatic children and the control (P<0.05). The levels of IL-4 and IgE among children with TT genotype at the -33 and -589 loci were higher than those with the CT genotype, but only the polymorphism at -33C/T was associated with IL-4 levels (P<0.05). The polymorphisms of the IFN-γ gene at +874A/T or the CA repeats are not correlated with susceptibility to asthma. Thus, the polymorphism at +874A/T is correlated with IFN-γ level. The TT genotypes of the IL-4 gene at the -33 and -589 loci are associated with asthma susceptibility in children, and polymorphism at the -33 locus may be associated with IL-4 level.

TLR2 polymorphisms influence neonatal regulatory T cells depending on maternal atopy

BACKGROUND

Toll-like receptor (TLR) polymorphisms have been associated with atopic diseases in children and adults. Development of atopic diseases may be modified by TLR-mediated signals that modulate T-regulatory cells (Tregs) early in life when maternal influences are still present and relevant. The aim of this study was to assess whether genetic TLR variants influence Tregs in neonates.

METHODS

Twelve single nucleotide polymorphisms located in TLR1, TLR2, TLR4, TLR6, and TLR10 were genotyped in 200 cord blood samples (72 samples from atopic, 128 from nonatopic mothers). Cord blood mononuclear cells were cultured without or with stimulation [lipid A (LpA), peptidoglycan (Ppg), phytohemagglutinin, house dust mite]. mRNA expression of Treg marker genes [forkhead box protein P3 (FOXP3), glucocorticoid-induced tumor necrosis factor receptor (GITR), lymphocyte activation gene 3 (LAG3)], TLR2, Th1/Th2 cytokines, and tumor necrosis factor alpha (TNF-α) was measured.

RESULTS

In children with the AA genotype of the TLR2 promoter variant rs4696480, gene expression of FOXP3 and Treg marker genes GITR and LAG3 as well as Th2 cytokines and TNF-α secretion was significantly increased in the presence of maternal atopy and Tregs decreased without maternal atopy. In carriers of the GG genotype for TLR2 rs1898830, gene expression of Treg marker genes was significantly decreased with and increased without maternal atopy. FOXP3 expression was also modified by TLR1 rs4833095 (P ≤ 0.03) and trendwise by TLR10 rs4129009 after LpA and Ppg stimulation.

CONCLUSIONS

Genetic variations of TLR2, TLR1, and TLR10 affect Treg marker gene expression in cord blood. Gene-immunological interactions of the TLR pathway influence Tregs early in life, modulated by maternal atopy. This may be relevant for immune maturation in the development of atopic diseases in childhood.

Genetic polymorphisms of innate immunity-related inflammatory pathways and their association with factors related to type 2 diabetes

Background

Type 2 diabetes mellitus (T2DM) has been linked to a state of pre-clinical chronic inflammation resulting from abnormalities in the innate immune pathway. Serum levels of pro-inflammatory cytokines and acute-phase proteins, collectively known as 'inflammatory network', are elevated in the pre-, or early, stages of T2DM and increase with disease progression. Genetic variation can affect the innate immune response to certain environmental factors, and may, therefore, determine an individual's lifetime risk of disease.

Methods

We conducted a cross-sectional study in 6,720 subjects from the TwinsUK Registry to evaluate the association between 18 single nucleotide polymorphisms (SNPs) in five genes (TLR4, IL1A, IL6, TNFA, and CRP) along the innate immunity-related inflammatory pathway and biomarkers of predisposition to T2DM [fasting insulin and glucose, HDL- and LDL- cholesterols, triglycerides (TGs), amyloid-A, sensitive C-reactive protein (sCRP) and vitamin D binding protein (VDBP) and body mass index (BMI)].

Results

Of 18 the SNPs examined for their association with nine metabolic phenotypes of interest, six were significantly associated with five metabolic phenotypes (Bonferroni correction, P ≤ 0.0027). Fasting insulin was associated with SNPs in IL6 and TNFA, serum HDL-C with variants of TNFA and CRP and serum sCRP level with SNPs in CRP. Cross-correlation analysis among the different metabolic factors related to risk of T2DM showed several significant associations. For example, BMI was directly correlated with glucose (r = 0.11), insulin (r = 0.15), sCRP (r = 0.23), LDL-C (r = 0.067) and TGs (r = 0.18) but inversely with HDL-C (r = -0.14). sCRP was also positively correlated (P < 0.0001) with insulin (r = 0.17), amyloid-A (r = 0.39), TGs (r = 0.26), and VDBP (r = 0.36) but inversely with HDL-C (r = -0.12).

Conclusion

Genetic variants in the innate immunity pathway and its related inflammatory cascade is associated with some metabolic risk factors for T2DM; an observation that may provide a rationale for further studying their role as biomarkers for disease early risk prediction.

Pathways activated during human asthma exacerbation as revealed by gene expression patterns in blood

BACKGROUND

Asthma exacerbations remain a major unmet clinical need. The difficulty in obtaining airway tissue and bronchoalveolar lavage samples during exacerbations has greatly hampered study of naturally occurring exacerbations. This study was conducted to determine if mRNA profiling of peripheral blood mononuclear cells (PBMCs) could provide information on the systemic molecular pathways involved during asthma exacerbations.

METHODOLOGY/PRINCIPAL FINDINGS

Over the course of one year, gene expression levels during stable asthma, exacerbation, and two weeks after an exacerbation were compared using oligonucleotide arrays. For each of 118 subjects who experienced at least one asthma exacerbation, the gene expression patterns in a sample of peripheral blood mononuclear cells collected during an exacerbation episode were compared to patterns observed in multiple samples from the same subject collected during quiescent asthma. Analysis of covariance identified genes whose levels of expression changed during exacerbations and returned to quiescent levels by two weeks. Heterogeneity among visits in expression profiles was examined using K-means clustering. Three distinct exacerbation-associated gene expression signatures were identified. One signature indicated that, even among patients without symptoms of respiratory infection, genes of innate immunity were activated. Antigen-independent T cell activation mediated by IL15 was also indicated by this signature. A second signature revealed strong evidence of lymphocyte activation through antigen receptors and subsequent downstream events of adaptive immunity. The number of genes identified in the third signature was too few to draw conclusions on the mechanisms driving those exacerbations.

CONCLUSIONS/SIGNIFICANCE

This study has shown that analysis of PBMCs reveals systemic changes accompanying asthma exacerbation and has laid the foundation for future comparative studies using PBMCs.

Interactions between glucocorticoid treatment and cis-regulatory polymorphisms contribute to cellular response phenotypes

Glucocorticoids (GCs) mediate physiological responses to environmental stress and are commonly used as pharmaceuticals. GCs act primarily through the GC receptor (GR, a transcription factor). Despite their clear biomedical importance, little is known about the genetic architecture of variation in GC response. Here we provide an initial assessment of variability in the cellular response to GC treatment by profiling gene expression and protein secretion in 114 EBV-transformed B lymphocytes of African and European ancestry. We found that genetic variation affects the response of nearby genes and exhibits distinctive patterns of genotype-treatment interactions, with genotypic effects evident in either only GC-treated or only control-treated conditions. Using a novel statistical framework, we identified interactions that influence the expression of 26 genes known to play central roles in GC-related pathways (e.g. NQO1, AIRE, and SGK1) and that influence the secretion of IL6.

Genome-virome interactions: examining the role of common viral infections in complex disease

New technologies have widened our view of 'complex diseases': those with both genetic and environmental risk factors. In this Review, we explore recent genetic and virological evidence implicating host-virus interactions in three diseases: type 1 diabetes, inflammatory bowel disease and asthma. The viruses implicated in these diseases cause mucosal infections that affect most of the population but are asymptomatic or mild in many hosts. These findings place a new emphasis on common viral infections as important environmental factors in the pathogenesis of complex diseases, and they compel the field to pursue a better understanding of host interactions with the human virome.

Effect of area of residence on patterns of aeroallergen sensitization in atopic patients

BACKGROUND

An association with sensitization to inhaled allergens and allergic rhinitis and asthma has been established. A recent study concluded that the disparity in allergen sensitization might primarily be caused by environmental factors rather than genetic differences. The primary objective was to identify potential differences in sensitization among subjects with the same ethnicity in South India who reside in different environments.

METHODS

Five hundred forty-six patients presenting to a tertiary allergy center with allergic rhinitis and or asthma underwent evaluation using a structured questionnaire, skin-prick testing to common aeroallergens, and spirometry and were categorized according to area of residence.

RESULTS

The most common allergens causing sensitization were house-dust mite (range, 65-70%), trees (range, 52-56%), and cockroaches (range, 39-53%). There was lower risk of sensitization to cockroach allergens for subjects <21 years old living in suburban (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.12-0.81) and rural environments (OR, 0.33; 95% CI, 0.11-0.96) compared with subjects <21 years old living in urban areas. There was higher risk of sensitization to fungi in subjects <21 years old living in suburban areas (OR, 1.51; 95% CI, 0.60-3.77) and rural environments (OR, 2.71; 95% CI, 0.98-7.48) compared with subjects <21 years old living in urban environments.

CONCLUSION

Sensitization patterns are similar in different areas of residence except in younger subjects. Sensitization to fungi was higher in younger subjects from the rural area and cockroach sensitization were higher in younger subjects from urban areas. Sensitization is an important precursor of clinical allergic disease and further studies to unravel the complex gene-environment interactions of aeroallergen sensitization in different environments are needed.

Type 2 diabetes mellitus and inflammation: Prospects for biomarkers of risk and nutritional intervention

Obesity is a major risk factor for type 2 diabetes mellitus (T2DM), which is a significant health problem worldwide. Active disease is associated with low-grade chronic inflammation resulting in part from the activation of the innate immune system. In obesity, this activation leads to the release of pro-inflammatory cytokines such as tumor necrosis factor-α, interleukin-1β and interleukin-6 that block major anabolic cascades downstream of insulin signaling and thus disrupt insulin homeostasis and action. Cytokines also trigger the production of acute-phase reactants such as C-reactive protein, plasminogen activator inhibitor-1, serum amyloid-A, and haptoglobin. The elevated synthesis of pro-inflammatory cytokines and acute-phase proteins (inflammatory network) characterizes the early (or pre-clinical) stages of T2DM and exhibits a graded increase with the disease progression. Current evidence suggests that understanding inflammatory networks can point to new biomarkers that may permit capturing the interaction between genetic and environmental risk factors in the pathogenesis of T2DM. Such biomarkers have a significant public health potential in the prediction of disease occurrence beyond risk factors presently monitored, such as family history, lifestyle assessment and standard clinical chemistry profiles. Furthermore, inflammatory markers may assist in the evaluation of novel strategies for prevention, particularly in relation to micronutrients. This review discusses the current knowledge linking T2DM risk to inflammatory signaling pathways interacting with the innate immunity system and the prospect of inflammatory markers serving as molecular targets for prevention and/or biomarkers for early risk prediction of T2DM. The potential of micronutrients replenishment to improve insulin action by attenuating inflammation is also evaluated in the context of the public health relevance of this approach.