Genetics and genomics of asthma and allergic diseases

Atopic dermatitis: Correlation of distinct risk factors with age of onset in adulthood compared to childhood

BACKGROUND

Atopic dermatitis (AD) has long been regarded as a primarily pediatric disease. However, there is growing evidence for a high rate of adult-onset AD. We aimed to characterize factors associated with adult-onset versus childhood-onset AD and controls.

METHODS

We analyzed cross-sectional data of the CK-CARE-ProRaD cohorts Bonn, Augsburg, Davos, Zürich of 736 adult patients stratified by age of AD onset (childhood-onset <18 years: 76.4% (subsets: 0 to 2; ≥2 to 6; ≥7 to 11; ≥12 to 18); adult-onset ≥18 years: 23.6% (subsets: ≥18 to 40; ≥41 to 60; ≥61) and 167 controls (91 atopic, 76 non-atopic)).

RESULTS

We identified active smoking to be associated with adult-onset AD versus controls (adjusted Odds Ratio (aOR) = 5.54 [95% Confidence Interval: 1.06-29.01] vs. controlsnon-atopic , aOR = 4.03 [1.20-13.45] vs. controlsatopic ). Conjunctivitis showed a negative association versus controlsatopic (aOR = 0.36 [0.14-0.91]). Food allergy (aOR = 2.93 [1.44-5.96]), maternal food allergy (aOR = 9.43 [1.10-80.95]), palmar hyperlinearity (aOR = 2.11 [1.05-4.25]), and academic background (aOR = 2.14 [1.00-4.54]) increased the odds of childhood-onset AD versus controlsatopic . Shared AD-associated factors were maternal AD (4-34x), increased IgE (2-20x), atopic stigmata (2-3x) with varying effect sizes depending on AD onset and control group. Patients with adult-compared to childhood-onset had doubled odds of allergic rhinitis (aOR = 2.15 [1.12-4.13]), but reduced odds to feature multiple (3-4) atopic comorbidities (aOR = 0.34 [0.14-0.84]). Adult-onset AD, particularly onset ≥61 years, grouped mainly in clusters with low contributions of personal and familial atopy and high frequencies of physical inactivity, childhood-onset AD, particularly infant-onset, mainly in "high-atopic"-clusters.

CONCLUSIONS

The identified associated factors suggest partly varying endo- and exogeneous mechanisms underlying adult-onset versus childhood-onset AD. Our findings might contribute to better assessment of the individual risk to develop AD throughout life and encourage prevention by non-smoking and physical activity as modifiable lifestyle factors.

IL-13, periostin and dipeptidyl-peptidase-4 reveal endotype-phenotype associations in atopic dermatitis

BACKGROUND

The heterogeneous (endo)phenotypes of atopic dermatitis (AD) require precision medicine. Currently, systemic therapy is recommended to patients with an Eczema Area and Severity Index (EASI)≥16. Previous studies have demonstrated an improved treatment response to the anti-interleukin (IL)-13 antibody tralokinumab in AD subgroups with elevated levels of the IL-13-related biomarkers dipeptidyl-peptidase (DPP)-4 and periostin.

METHODS

Herein, 373 AD patients aged≥12 years were stratified by IL-13high , periostinhigh and DPP-4high endotypes using cross-sectional data from the ProRaD cohort Bonn. "High" was defined as >80th quantile of 47 non-atopic controls. We analyzed endotype-phenotype associations using machine-learning gradient boosting compared to logistic regression.

RESULTS

AD severity and eosinophils correlated with IL-13 and periostin levels. Correlations of IL-13 with EASI were stronger in patients with increased (rs=0.482) than with normal (rs=0.342) periostin levels. We identified eosinophilia>6% and an EASI range of 5.5-17 dependent on the biomarker combination to be associated with increasing probabilities of biomarkerhigh endotypes. Also patients with mild-to-low-moderate severity (EASI<16) featured increased biomarkers (IL-13high : 41%, periostinhigh : 48.4%, DPP-4high : 22.3%). Herthoge sign (adjusted Odds Ratio (aOR)=1.89, 95% Confidence Interval (CI) [1.14-3.14]) and maternal allergic rhinitis (aOR=2.79-4.47) increased the probability of an IL-13high -endotype, "dirty neck" (aOR=2.83 [1.32-6.07]), orbital darkening (aOR=2.43 [1.08-5.50]), keratosis pilaris (aOR=2.21 [1.1-4.42]) and perleche (aOR=3.44 [1.72-6.86]) of a DPP-4high -endotype.

CONCLUSIONS

A substantial proportion of patients with EASI<16 featured high biomarker levels suggesting systemic impact of skin inflammation already below the current cut-off for systemic therapy. Our findings facilitate the identification of patients with distinct endotypes potentially linked to response to IL-13-targeted therapy.

Structural Phylogeny of Different Allergens May Reveal Common Epitopic Footprint

BACKGROUND

The incidence of allergy is increasing at an alarming rate for the last few decades.

OBJECTIVE

Our present study is focused on finding out the structurally homologous motifs present in different proteinaceous allergens Methods: Significant number of protein sequences and their corresponding structures of various pollen, fungal, bacterial, and food allergens were retrieved, and the sequence and structural identity were analyzed.

RESULTS

Intra- and inter-sequence and their structural analysis of the proteinaceous allergens, resulted in no significant relationships among them. A few, but not negligible number of high structural similarities were observed within different groups of allergens from fungus, angiosperms, and animals (Aves and Mammalia).

CONCLUSION

Our in silico study on thirty-six different allergens showed a significant level of structural similarities among themselves, regardless of their sequences.

p300 mediates the histone acetylation of ORMDL3 to affect airway inflammation and remodeling in asthma

BACKGROUND

Bronchial asthma is affected by both environmental and genetic factors. The orosomucoid 1-like protein 3 (ORMDL3) gene is related to childhood asthma and is involved in airway inflammation and airway remodeling. The ORMDL3 promoter contains binding sites for the histone acetylase p300. Gene expression can be affected by epigenetic modifications. This study aimed to investigate whether the p300-mediated histone acetylation (HAT) of ORMDL3 gene affects airway inflammation and remodeling in asthma.

METHODS

16HBE14o- cells were transfected with various concentrations of a wild-type p300 plasmid or p300HAT-deletion plasmids. A dual luciferase reporter assay was used to examine the effect of p300-mediated HAT on the ORMDL3 promoter. Thirty BALB/c mice were randomly divided into a control group, an ovalbumin (OVA)-induced asthma group and an asthma + C646 (a selective inhibitor of p300) group. Noninvasive lung function tests were conducted to examine airway hyperreactivity (AHR) in the different groups. HE and Masson's trichrome staining was performed to examine airway remodeling and inflammation. Immunohistochemistry, western blotting and real-time PCR were used to analyze ORMDL3 expression in lung tissues. ELISA and western blotting were used to evaluate the HAT status in lung tissue. The ChIP assay was used to determine the relationship of the ORMDL3 promoter to p300 or acetylated histone H3 (aceH3).

RESULTS

p300 activated transcription from the ORMDL3 promoter, resulting in an increase in endogenous ORMDL3 mRNA levels. ORMDL3 promoter activity was reduced when the HAT activity of p300 was lost. ORMDL3 expression was elevated, and HAT activity was high in the lung tissues of asthmatic mice. p300 and aceH3 bound to the promoter region of ORMDL3. In the asthma group, the amounts of p300 and aceH3 recruited to the ORMDL3 promoter were increased. C646 inhibited p300 expression and reduced HAT activity and aceH3 levels in asthmatic mice, thereby reducing ORMDL3 expression and relieving AHR and airway remodeling.

CONCLUSION

p300-mediated HAT modulates the expression of the asthma susceptibility gene ORMDL3, thereby improving the process of airway inflammation and remodeling in asthma.

Multiomics Data Triangulation for Asthma Candidate Biomarkers and Precision Medicine

Asthma is a common complex disorder and has been subject to intensive omics research for disease susceptibility and therapeutic innovation. Candidate biomarkers of asthma and its precision treatment demand that they stand the test of multiomics data triangulation before they can be prioritized for clinical applications. We classified the biomarkers of asthma after a search of the literature and based on whether or not a given biomarker candidate is reported in multiple omics platforms and methodologies, using PubMed and Web of Science, we identified omics studies of asthma conducted on diverse platforms using keywords, such as asthma, genomics, metabolomics, and epigenomics. We extracted data about asthma candidate biomarkers from 73 articles and developed a catalog of 190 potential asthma biomarkers (167 human, 23 animal data), comprising DNA loci, transcripts, proteins, metabolites, epimutations, and noncoding RNAs. The data were sorted according to 13 omics types: genomics, epigenomics, transcriptomics, proteomics, interactomics, metabolomics, ncRNAomics, glycomics, lipidomics, environmental omics, pharmacogenomics, phenomics, and integrative omics. Importantly, we found that 10 candidate biomarkers were apparent in at least two or more omics levels, thus promising potential for further biomarker research and development and precision medicine applications. This multiomics catalog reported herein for the first time contributes to future decision-making on prioritization of biomarkers and validation efforts for precision medicine in asthma. The findings may also facilitate meta-analyses and integrative omics studies in the future.

Changes in gene expression induced by histamine, fexofenadine and osthole: Expression of histamine H1 receptor, COX-2, NF-κB, CCR1, chemokine CCL5/RANTES and interleukin-1β in PBMC allergic and non-allergic patients

INTRODUCTION

Fexofenadine (FXF) is a third-generation antihistamine drug and osthole is assumed as a natural antihistamine alternative. This paper compares results of histamine, FXF and osthole impact on HRH-1, COX-2, NF-κB-p50, CCR1 mRNA expression. We also measured mRNA expression of IL-1β and CCL5/RANTES in incubated peripheral blood mononuclear cells (PBMC) to compared how histamine, FXF and osthole had influence on expression level and interacts on product secretion.

OBJECTIVE

The purpose was to investigate expression pattern in asthma PBMC.

METHODS

The cultures were treated 72h with FXF and osthole. We measured mRNA expression of histamine HRH-1, COX-2, NF-κB-p50, CCR1, IL-1β and CCL5/RANTES with Real-Time PCR (RT-PCR).

RESULTS

The present study suggest that osthole may be a potential inhibitor of histamine H₁ receptor activity. We also demonstrated that cells cultured with histamine increase COX-2 mRNA expression and osthole reduce it.

CONCLUSION

Allergy remains one of the most common chronic diseases in Europe and it is rapidly approaching epidemic proportions; with current predictions estimating that the number of allergy-afflicted will equal the healthy population by 2020. It is therefore paramount to find new pharmaceuticals which successfully combat allergic disease.

Serum IgE elevation correlates with blood lead levels in battery manufacturing workers

Lead (Pb), an occupational and environmental toxicant, is known to induce immunomodulatory effects resulting in lowered resistance to infectious micro-organisms and altered levels of immunoglobulins in humans. Preferential activation of type-2 helper T cells and inhibition of type-1 T-cell activation is considered a cellular mechanism for the Pb-induced immune alteration, which has not been investigated well in humans. Lead's influence on in vivo balance between type-1 and type-2 activities was assessed among workers exposed to Pb through battery manufacturing in Korea. Serum IgE levels were significantly higher in the workers with a blood Pb level (PbB) of ≤30 μg/dL than in the workers with a PbB of <30 μg/dL. Furthermore, the serum IgE concentrations significantly correlated with PbB although no significant relationship between PbB and serum interleukin-4 or interferon gamma levels was observed. The present study indicates that elevation of IgE levels may be an immunologic index for Pb-induced in vivo toxicities, potentially involved with progression of various allergic diseases in humans.

Effect of Gubenfangxiao decoction on respiratory syncytial virus-induced asthma and expression of asthma susceptibility gene orosomucoid 1-like protein 3 in mice

OBJECTIVE

To investigate the effect of Guben-fangxiao decoction (GBFXD) on respiratory-syncytial-virus (RSV)-induced asthma and the expression of asthma susceptibility gene, orosomucoid 1-like protein 3 (ORMDL3) in mice.

METHODS

Seventy-two female BALB/c mice were randomly assigned to normal, model, GBFXD high dose, GBFXD moderate dose, GBFXD low dose and montelukast groups. An asthma model was induced via intraperitoneal injection and aerosol inhalation of ovalbumin (OVA) and repeated intranasal instillation of RSV in all mice, except those in the normal group. All treatments were administered at the first onset of asthma (within 8 weeks of model establishment) and the mice were euthanized after 28 days of treatment. The levels of transforming growth factor-β (TGF-β) and interleukin-6 (IL-6) in bronchoalveolar lavacie fluid (BALF) of the mice were measured and the expression of asthma susceptibility gene ORMDL3 in lung tissue was determined using real-time polymerase chain reaction (RT-PCR) and western blotting.

RESULTS

Expression of ORMDL3 and levels of TGF-β and IL-6 were significantly higher in the model group (P < 0.05, P < 0.01) compared with the normal mice. Levels of ORMDL3, TGF-β and IL-6 were significantly lower in all three GBFXD treated groups (P < 0.05) compared with the model group. However, the levels in the GBFXD treatment groups did not differ significantly from the montelukast group.

CONCLUSION

GBFXD had a therapeutic effect in this experimental model. The functional mechanism of GBFXD may involve multiple factors, including alleviation of airway inflammation, down-regulation of asthma susceptibility gene ORMDL3 and inhibition of airway remodeling.

Innate IgG molecules and innate B cells expressed by immunoglobulin constant heavy G chain (Fcγ) genetic marker genes are involved in the 'allergic march' of IgE sensitization in children

BACKGROUND

Interindividual variations of immunoglobulin constant heavy G chain (IGHG) genes on chromosome 14q32.3 are identified by alternative genetic markers (GM) of IgG3, IgG1 and IgG2, respectively. They express structurally and functionally innate IgG molecules and B cells, associated with allergic disease, replicated in several studies.

MATERIALS AND METHODS

1-year-old and 10-year-old, IgE-sensitized and non-sensitized children from the German Multicenter Allergy Study birth cohort were assessed by new serological methods for the mendelian IGHG (Fcγ) (GM) genes, as innate IgG molecules and innate B cells.

RESULTS

Food allergy sensitization in thirty-five 1-year-old children (124 not sensitized) was associated with the IGHG*bfn haplotype and B*(bfn) cells (OR 1.9, 95% CI 1.2-3.1; p = 0.010). Aeroallergen sensitization in ninety-nine 10-year-old children (95 not sensitized) was associated with the same genes (OR 1.4, 95% CI 1.02-1.9; p = 0.034). The IgE sensitization was most prominent in the restrictive homozygous IGHG*bfn/*bfn diplotype, 34% at age 1, increasing to 60% at age 10, rating the highest numbers of positive IgE tests, expressing increased levels of IgE and innate IgG2*n.

CONCLUSIONS

The IGHG*bfn haplotype (B*(bfn) cells) and increased innate IgG2*n levels are predictive factors for IgE sensitization in childhood. IGHG genes can be assessed for prognostic and preventive purposes in clinical care.

Integrative genetic analysis of allergic inflammation in the murine lung

Airway allergen exposure induces inflammation among individuals with atopy that is characterized by altered airway gene expression, elevated levels of T helper type 2 cytokines, mucus hypersecretion, and airflow obstruction. To identify the genetic determinants of the airway allergen response, we employed a systems genetics approach. We applied a house dust mite mouse model of allergic airway disease to 151 incipient lines of the Collaborative Cross, a new mouse genetic reference population, and measured serum IgE, airway eosinophilia, and gene expression in the lung. Allergen-induced serum IgE and airway eosinophilia were not correlated. We detected quantitative trait loci (QTL) for airway eosinophilia on chromosome (Chr) 11 (71.802-87.098 megabases [Mb]) and allergen-induced IgE on Chr 4 (13.950-31.660 Mb). More than 4,500 genes expressed in the lung had gene expression QTL (eQTL), the majority of which were located near the gene itself. However, we also detected approximately 1,700 trans-eQTL, and many of these trans-eQTL clustered into two regions on Chr 2. We show that one of these loci (at 147.6 Mb) is associated with the expression of more than 100 genes, and, using bioinformatics resources, fine-map this locus to a 53 kb-long interval. We also use the gene expression and eQTL data to identify a candidate gene, Tlcd2, for the eosinophil QTL. Our results demonstrate that hallmark allergic airway disease phenotypes are associated with distinct genetic loci on Chrs 4 and 11, and that gene expression in the allergically inflamed lung is controlled by both cis and trans regulatory factors.

A study of the association of childhood asthma with HLA alleles in the population of Siliguri, West Bengal, India

Asthma is a heterogeneous disease for which a strong genetic basis is firmly established. It is a complex disorder influenced by gene-environment interaction. Human leukocyte antigen (HLA) genes have been shown to be consistently associated with asthma and its related phenotypes in various populations. The aim of this study was to determine the frequency of the selected HLA classes I and II allelic groups in asthmatic and control groups. HLA typing was performed using polymerase chain reaction-sequence-specific typing (PCR-SSP) method. The allele frequency was estimated by direct counting. Frequency of each HLA allelic group was compared between asthmatic group and control group using χ(2) test. P-value was corrected by multiplying with the number of the allelic groups studied. Odds ratio (OR) and its corresponding 95% confidence interval (CI) for each allelic group were calculated using graphpad instat 3.10. The results of this study showed a significantly higher frequency of HLA-DRB1*03 in asthmatics than in controls (11.43% vs 3.64%, OR = 3.78, 95% CI = 1.61-8.85, P = 0.0025, Pcorr  < 0.05). Analysis of HLA alleles in low and high total serum immunoglobulin E (IgE) level in asthmatics revealed no significant association. HLA-DRB1*03 may be implicated in the susceptibility to asthma in the pediatric population.

Total serum immunoglobulin E in patients with alopecia areata

Context:

Alopecia areata (AA) is a common form of localized, non-scarring hair loss. The pathogenesis of the disease is unknown. Previous evidence suggested the involvement of Th2 cytokines in disease pathogenesis.

Aim:

To determine serum level of total IgE, this is mainly influenced by Th2 cytokines, in Egyptian patients with AA.

Materials and Methods:

Fifty subjects with AA (28 males and 22 females) were selected from Dermatology Outpatient Clinic, Menoufiya University Hospital from February 2012 to December 2012. Subjects with other conditions that might elevate serum IgE were excluded from the study. Fifty age- and sex-matched healthy subjects were selected as a control group. Venous blood samples were taken from cases and controls for measurement of total serum IgE by enzyme-linked immunosorbent assay. Skin biopsy was taken from every case from an active area of hair loss.

Results:

Total serum IgE was elevated in 27 (54%) cases. Its values among patients ranged from 13.5 IU/ml to 780 IU/ml. There was a statistically significant difference between cases and controls with regard to mean value of serum IgE (P < 0.05). Mean value of IgE did not vary significantly with disease severity, patients’ age, patients’ gender, disease duration, site of lesions, and positive family history of AA. No correlation was found between serum IgE levels and histopathological changes detected in examined cases.

Conclusions:

Total serum IgE is elevated in AA. This elevation is not related to age, gender, disease duration, disease severity, site of affection or family history of AA.

Allergic asthma biomarkers using systems approaches

Asthma is characterized by lung inflammation caused by complex interaction between the immune system and environmental factors such as allergens and inorganic pollutants. Recent research in this field is focused on discovering new biomarkers associated with asthma pathogenesis. This review illustrates updated research associating biomarkers of allergic asthma and their potential use in systems biology of the disease. We focus on biomolecules with altered expression, which may serve as inflammatory, diagnostic and therapeutic biomarkers of asthma discovered in human or experimental asthma model using genomic, proteomic and epigenomic approaches for gene and protein expression profiling. These include high-throughput technologies such as state of the art microarray and proteomics Mass Spectrometry (MS) platforms. Emerging concepts of molecular interactions and pathways may provide new insights in searching potential clinical biomarkers. We summarized certain pathways with significant linkage to asthma pathophysiology by analyzing the compiled biomarkers. Systems approaches with this data can identify the regulating networks, which will eventually identify the key biomarkers to be used for diagnostics and drug discovery.

Changing prevalence of allergic diseases in the Asia-pacific region

Asia-Pacific is one of the most densely populated regions of the world and is experiencing rapid economic changes and urbanization. Environmental pollution is a significant problem associated with the rapid modernization of many cities in South Asia. It is not surprising that the prevalences of asthma and allergies are increasing rapidly, although the underlying reasons remain largely unknown. Many studies from this region have documented the changing prevalence of allergic diseases in various parts of the world. However, the methodologies used were neither standardized nor validated, making the results difficult to evaluate. The International Study of Asthma and Allergies in Childhood (ISAAC) has provided a global epidemiology map of asthma and allergic diseases, as well as the trend of changes in the prevalence of these diseases. Allergic sensitization is extremely common in many Asian communities. However, the prevalence of allergic diseases remains relatively rare. The rapid urbanization in the region, which increases environmental pollution and can affect the rural environment, will likely increase the prevalence of asthma and allergies in Asia.

L. plantarum, L. salivarius, and L. lactis attenuate Th2 responses and increase Treg frequencies in healthy mice in a strain dependent manner

Many studies on probiotics are aimed at restoring immune homeostasis in patients to prevent disease recurrence or reduce immune-mediated pathology. Of equal interest is the use of probiotics in sub-clinical situations, which are characterized by reduced immune function or low-grade inflammation, with an increased risk of infection or disease as a consequence. Most mechanistic studies focus on the use of probiotics in experimental disease models, which may not be informative for these sub-clinical conditions. To gain better understanding of the effects in the healthy situation, we investigated the immunomodulatory effects of two Lactobacillus probiotic strains, i.e. L. plantarum WCFS1 and L. salivarius UCC118, and a non-probiotic lactococcus strain, i.e. L. lactis MG1363, in healthy mice. We studied the effect of these bacteria on the systemic adaptive immune system after 5 days of administration. Only L. plantarum induced an increase in regulatory CD103⁺ DC and regulatory T cell frequencies in the spleen. However, all three bacterial strains, including L. lactis, reduced specific splenic T helper cell cytokine responses after ex vivo restimulation. The effect on IFN-γ, IL5, IL10, and IL17 production by CD4⁺ and CD8⁺ T cells was dependent on the strain administered. A shared observation was that all three bacterial strains reduced T helper 2 cell frequencies. We demonstrate that systemic immunomodulation is not only observed after treatment with probiotic organisms, but also after treatment with non-probiotic bacteria. Our data demonstrate that in healthy mice, lactobacilli can balance T cell immunity in favor of a more regulatory status, via both regulatory T cell dependent and independent mechanisms in a strain dependent manner.

Probiotics, prebiotics, and synbiotics: gut and beyond

The human intestinal tract has been colonized by thousands of species of bacteria during the coevolution of man and microbes. Gut-borne microbes outnumber the total number of body tissue cells by a factor of ten. Recent metagenomic analysis of the human gut microbiota has revealed the presence of some 3.3 million genes, as compared to the mere 23 thousand genes present in the cells of the tissues in the entire human body. Evidence for various beneficial roles of the intestinal microbiota in human health and disease is expanding rapidly. Perturbation of the intestinal microbiota may lead to chronic diseases such as autoimmune diseases, colon cancers, gastric ulcers, cardiovascular disease, functional bowel diseases, and obesity. Restoration of the gut microbiota may be difficult to accomplish, but the use of probiotics has led to promising results in a large number of well-designed (clinical) studies. Microbiomics has spurred a dramatic increase in scientific, industrial, and public interest in probiotics and prebiotics as possible agents for gut microbiota management and control. Genomics and bioinformatics tools may allow us to establish mechanistic relationships among gut microbiota, health status, and the effects of drugs in the individual. This will hopefully provide perspectives for personalized gut microbiota management.

Association of Hepatitis A exposure and TIM-1 with childhood allergic asthma

BACKGROUND

Hepatitis A virus (HAV) receptor (TIM-1) polymorphism plays an important role in asthma and autoimmune diseases. Objective. To analyze the association of TIM-1 polymorphism and HAV infection with childhood allergic asthma in Southwest China.

METHODS

TIM-1 exon 4 (157insMTTTVP) and two polymorphism loci, -416G>C and -1454G>A, in the HAV receptor promoter region were studied. Polymerase chain reaction (PCR) was used to test the genotypes of three polymorphism loci among 579 cases of asthma and 524 controls. The HAV infection status was determined in a case-control study with stratified analysis.

RESULTS

HAV exposure associated with childhood allergic asthma in the study population was compared with controls (odds ratio (OR) = 0.181, 95% confidence interval (CI) 0.126-0.260, p < .001). The -416G>C polymorphism was associated with asthma (OR = 1.384, 95% CI 1.148-1.669, p < .001), but the insertion variant 157delMTTTVP of exon 4 and the -1454G>A polymorphism were not.

CONCLUSION

Our results indicated that the -416G>C polymorphism of the TIM-1 gene is associated with childhood allergic asthma, providing a better understanding of the pathogenesis of the allergic asthma among children aged below 15 years in Southwest China.

From genotypes of immunoglobulin constant heavy G chains (Fcγ) (GM) genes (IGHG) to phenotypes in childhood asthma

BACKGROUND

IgE-mediated allergy is associated with immunoglobulin heavy constant G chain (Fcγ) (GM) genes (IGHG) on chromosome 14q32.3. Investigation of the alternative GM allotypes of γ3, γ1 and γ2 chains has disclosed new structural and functional IgG subclasses and B-cell variants, with possible effects on childhood asthma.

OBJECTIVE

To investigate different IGHG (GM) gene complexes in a childhood asthma population for allergy parameters.

METHODS

IGHG alleles and correlated allotypic (allelic) IgG subclass levels were analyzed with a sensitive indirect competitive ELISA in 10-year-old children with bronchial asthma. Individual IGHG diplotype-, genotype- and haplotype-related B cells were compared for allelic IgG subclass levels, IgE sensitization, IgE, IgA and IgM levels, and numbers of peripheral blood eosinophils and lymphocytes.

RESULTS

The group with homozygous IGHG*bfn/*bfn (B1/B1 cells) demonstrated low IgG1*f levels (p < 0.001) but increased IgG2*n levels (p < 0.001) together with increasd IgE and IGHG2*n gene dose-dependent IgE sensitization (atopic phenotype). The IGHG*bf-n/*bf-n (B2/B2 cells) demonstrated low IgG1*f (p < 0.05) and IgG2*-n (p < 0.001) and the IGHG*ga-n/*ga-n (B4/B4 cells) low IgG1*a (p < 0.001) and IgG2*-n (p < 0.02) together with low IgE sensitization (non-atopic phenotype). B*(bfn) (B1) and B*(bf-n) (B2) demonstrated increased numbers of peripheral blood eosinophils, compared to B*(gan) (B4) cells, which demonstrated increased peripheral blood CD8 lymphocytes instead.

CONCLUSION

IGHG diplotypes present different phenotypes in childhood asthma. The IGHG2*n dose relationship to IgE sensitization and increased IgG2*n levels in IgE sensitized are risk markers for IgE-mediated asthma. The opposite IGHG2*-n presents non-IgE-mediated asthma and IgG subclass deficiencies.

Identifying Polymorphisms in IL-31 and Their Association with Susceptibility to Asthma

BACKGROUND

Interleukin 31 (IL-31) is a T helper type 2 effector cytokine that plays an important role in the pathogenesis of atopic and allergic diseases. IL-31 may be involved in promoting allergic inflammation and in inducing airway epithelial responses such as allergic asthma.

METHODS

Single-base extension analysis was used to detect the genotypes of IL-31 single nucleotide polymorphisms (SNPs), and we compared the genotype and allele frequencies of the IL-31 SNPs between patients with asthma and healthy controls.

RESULTS

There were no significant differences in the genotype and allele frequencies of the IL-31 SNPs between patients with asthma and healthy controls. Furthermore we compared the genotype and allele frequencies of IL-31 SNPs between patients with atopic asthma, those with non-atopic asthma and healthy controls. This showed that the SNPs were not associated with the susceptibility to atopic asthma. There were no significant differences in the haplotype frequencies of IL-31 SNPs between patients with asthma and healthy controls. In patients with asthma, the IL-31 SNPs were significantly correlated with total serum levels of IgE (p=0.035).

CONCLUSIONS

Our results indicate that, the IL-31 SNPs may be associated with IgE production in patients with asthma.

Dietary supplements for established atopic eczema

BACKGROUND

Many people with atopic eczema are reluctant to use the most commonly recommended treatments because they fear the long-term health effects. As a result, many turn to dietary supplements as a possible treatment approach, often with the belief that some essential ingredient is 'missing' in their diet. Various supplements have been proposed, but it is unclear whether any of these interventions are effective.

OBJECTIVES

To evaluate dietary supplements for treating established atopic eczema/dermatitis.Evening primrose oil, borage oil, and probiotics are covered in other Cochrane reviews.

SEARCH METHODS

We searched the following databases up to July 2010: the Cochrane Skin Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE (from 2005), EMBASE (from 2007), PsycINFO (from 1806), AMED (from 1985), LILACS (from 1982), ISI Web of Science, GREAT (Global Resource of EczemA Trials) database, and reference lists of articles. We searched ongoing trials registers up to April 2011.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of dietary supplements for the treatment of those with established atopic eczema/dermatitis.

DATA COLLECTION AND ANALYSIS

Two authors independently screened the titles and abstracts, read the full text of the publications, extracted data, and assessed the risk of bias.

MAIN RESULTS

We included 11 studies with a total of 596 participants. Two studies assessed fish oil versus olive oil or corn oil placebo. The following were all looked at in single studies: oral zinc sulphate compared to placebo, selenium versus selenium plus vitamin E versus placebo, vitamin D versus placebo, vitamin D versus vitamin E versus vitamins D plus vitamin E together versus placebo, pyridoxine versus placebo, sea buckthorn seed oil versus sea buckthorn pulp oil versus placebo, hempseed oil versus placebo, sunflower oil (linoleic acid) versus fish oil versus placebo, and DHA versus control (saturated fatty acids of the same energy value). Two small studies on fish oil suggest a possible modest benefit, but many outcomes were explored. A convincingly positive result from a much larger study with a publicly-registered protocol is needed before clinical practice can be influenced.

AUTHORS' CONCLUSIONS

There is no convincing evidence of the benefit of dietary supplements in eczema, and they cannot be recommended for the public or for clinical practice at present. Whilst some may argue that at least supplements do not do any harm, high doses of vitamin D may give rise to serious medical problems, and the cost of long-term supplements may also mount up.

Association of genetic variants in chromosome 17q21 and adult-onset asthma in a Chinese Han population

BACKGROUND

Genome-wide association studies of asthma have identified a novel region containing ORMDL3 at chromosome 17q21 that is strongly associated with childhood-onset asthma and significantly linked to ORMDL3 transcript abundance. These results have been successfully replicated in childhood-onset asthma cohorts in several ethnic groups. In this study, we aimed to evaluate the association of polymorphisms in ORMDL3, GSDMB, ZPBP2 and IKZF3 and adult-onset asthma in a Chinese Han population.

METHODS

We genotyped 5 single nucleotide polymorphisms (SNPs) at chromosome 17q21 in 1,366 Han Chinese people comprising 710 patients with adult-onset asthma and 656 healthy controls. We compared the 2 groups in terms of allele and haplotype frequencies. Transcript levels were measured in leukocytes from 61 asthma patients by quantitative real-time PCR.

RESULTS

We found the 5 SNPs significantly associated with asthma (P<0.05), of which 2, rs11557467 and rs9303277, were strongly associated (P<0.001). Subjects carrying the G allele of rs11557467 or the C allele of rs9303277 showed increased risk of asthma (odds ratio [OR] 1.27, 95% confidence interval 1.07-1.51, P = 0.006, and OR 1.27, 1.07-1.49, P = 0.005, respectively), even after adjusting for age and sex. The risk of asthma was lower for carriers of the haplotype CTGTT (OR 0.81, 0.67-0.97, P = 0.02). The risk allele for each SNP was associated with increased expression of ORMDL3 and GSDMB in leukocytes (all p<0.05).

CONCLUSIONS

Our replication study suggests that variants in 17q21 are significantly associated with risk of adult-onset asthma and gene expression in a Chinese Han population.

Pathogenic mechanisms of allergic inflammation: atopic asthma as a paradigm

Prospective studies tracking birth cohorts over periods of years indicate that the seeds for atopic asthma in adulthood are sewn during early life. The key events involve programming of functional phenotypes within the immune and respiratory systems which determine long-term responsiveness to ubiquitous environmental stimuli, particularly respiratory viruses and aeroallergens. A crucial component of asthma pathogenesis is early sensitization to aeroallergens stemming from a failure of mucosal tolerance mechanisms during the preschool years, which is associated with delayed postnatal maturation of a range of adaptive and innate immune functions. These maturational defects also increase risk for severe respiratory infections, and the combination of sensitization and infections maximizes risk for early development of the persistent asthma phenotype. Interactions between immunoinflammatory pathways stimulated by these agents also sustain the disease in later life as major triggers of asthma exacerbations. Recent studies on the nature of these interactions suggest the operation of an infection-associated lung:bone marrow axis involving upregulation of FcERlalpha on myeloid precursor populations prior to their migration to the airways, thus amplifying local inflammation via IgE-mediated recruitment of bystander atopic effector mechanisms. The key participants in the disease process are airway mucosal dendritic cells and adjacent epithelial cells, and transiting CD4(+) effector and regulatory T-cell populations, and increasingly detailed characterization of their roles at different stages of pathogenesis is opening up novel possibilities for therapeutic control of asthma. Of particular interest is the application of genomics-based approaches to drug target identification in cell populations of interest, exemplified by recent findings discussed below relating to the gene network(s) triggered by activation of Th2-memory cells from atopics.

Regulatory T cells and asthma

Airway inflammation in asthma is characterized by activation of T helper type-2 (Th2) T cells, IgE production and eosinophilia. In many cases, this process is related to an inappropriate T cell response to environmental allergens, and other T cell-dependent pathways may also be involved (such as Th17). Regulatory T cells (Tregs) are T cells that suppress potentially harmful immune responses. Two major subsets of Treg are CD25(hi), Foxp3(+)Tregs and IL-10-producing Tregs. There is evidence that the numbers or function of both subsets may be deficient in patients with atopic allergic disease. Recent work has extended these findings into the airway in asthma where Foxp3 expression was reduced and CD25(hi) Treg-suppressive function was deficient. In animal models of allergic airways disease, Tregs can suppress established airway inflammation and airway hyperresponsiveness, and protocols to enhance the development, recruitment and function of Tregs have been described. Together with studies of patients and in vitro studies of human T cells, these investigations are defining potential interventions to enhance Treg function in the airway in asthma. Existing therapies including corticosteroids and allergen immunotherapy act on Tregs, in part to increase IL-10 production, while vitamin D3 and long-acting beta-agonists enhance IL-10 Treg function. Other possibilities may be enhancement of Treg function via histamine or prostanoid receptors, or by blocking pro-inflammatory pathways that prevent suppression by Tregs (activation of Toll-like receptors, or production of cytokines such as IL-6 and TNF-alpha). As Tregs can also suppress the potentially beneficial immune response important for controlling infections and cancer, a therapeutic intervention should target allergen- or site-specific regulation.

A functional polymorphism in the SPINK5 gene is associated with asthma in a Chinese Han Population

BACKGROUND

Mutation in SPINK5 causes Netherton syndrome, a rare recessive skin disease that is accompanied by severe atopic manifestations including atopic dermatitis, allergic rhinitis, asthma, high serum IgE and hypereosinophilia. Recently, single nucleotide polymorphism (SNP) of the SPINK5 was shown to be significantly associated with atopy, atopic dermatitis, asthma, and total serum IgE. In order to determine the role of the SPINK5 in the development of asthma, a case-control study including 669 asthma patients and 711 healthy controls in Han Chinese was conducted.

METHODS

Using PCR-RFLP assay, we genotyped one promoter SNP, -206G>A, and four nonsynonymous SNPs, 1103A>G (Asn368Ser), 1156G>A (Asp386Asn), 1258G>A (Glu420Lys), and 2475G>T (Glu825Asp). Also, we analyzed the functional significance of -206G>A using the luciferase reporter assay and electrophoresis mobility shift assay.

RESULTS

we found that the G allele at SNP -206G>A was associated with increased asthma susceptibility in our study population (p = 0.002, odds ratio 1.34, 95% confidence interval 1.11-1.60). There was no significant association between any of four nonsynonymous SNPs and asthma. The A allele at -206G>A has a significantly higher transcriptional activity than the G allele. Electrophoresis mobility shift assay also showed a significantly higher binding efficiency of nuclear protein to the A allele compared with the G allele.

CONCLUSION

Our findings indicate that the -206G>A polymorphism in the SPINK5 is associated with asthma susceptibility in a Chinese Han population.

What have we learnt from ISAAC phase III in the Asia-Pacific rim?

PURPOSE OF REVIEW

International Study of Asthma and Allergies in Childhood (ISAAC) phase III had provided a worldwide map of epidemiology of asthma and allergic diseases, as well as the changes in prevalence rate of these diseases when compared to data obtained in phase I. The wide variations of environmental factors and ethnic background in Asia provide excellent opportunities for research into the environmental and genetic determinants of asthma and allergies. This review summarizes important lessons learnt from ISAAC phase III results from Asia on asthma and allergy.

RECENT FINDINGS

ISAAC phase III provided epidemiological evidence of the wide variation and increasing prevalence of asthma and allergy in many Asian countries. When compared to other regions of the world, Asia has a relatively lower prevalence of asthma and allergic diseases. Comparative studies of populations of the same ethnic group living in different environments reveal striking disparity in prevalence of asthma and allergic diseases. The established risk factors could not explain the secular trend and variations of asthma prevalence in different Asian countries. Further research is needed in this rapidly changing region of Asia in order to identify the protective or risk factors associated with the development of asthma.

SUMMARY

ISAAC phase III provides standardized data on the prevalence and burden of asthma and allergy in the Asia-Pacific region. Further research is needed to reveal the underlying factors responsible for the wide variations in disease manifestations in the region.

Tobacco smoking, fruit and vegetable intake modify association between -21A>T polymorphism of catalase gene and risk of bronchial asthma

Although oxidative stress is a cardinal feature of bronchial asthma, the role of interactions between environmental oxidant/antioxidant exposures and antioxidant genes in asthma aetiology has yet to be determined. The present study was conducted to investigate whether two common polymorphisms -21A > T and -262C > T of catalase (CAT) gene are associated with susceptibility to asthma in a Russian population and to test the hypothesis that the asthma risk attributed to CAT genotypes could be dependent on both oxidant (tobacco smoking) and antioxidant (fruit and vegetable intake) exposures. A total of 429 unrelated Russian individuals from Central Russia were recruited in the study, including 215 asthmatics and 214 sex- and age-matched healthy controls. Genotyping analysis for the CAT gene polymorphisms was performed by PCR-RFLP assays. The frequencies of both allele -21A (OR 0.73 95%CI 0.55-0.96 p = 0.03) and -21AA CAT genotype (OR 0.42 95%CI 0.23-0.76 p = 0.004) were higher among asthmatics than among healthy controls. The frequency of -21AA genotype of the CAT gene was significantly higher in patients with allergic (OR 0.47 95%CI 0.25-0.92 p = 0.024) and nonallergic (OR 0.32 95%CI 0.14-0.71 p = 0.004) asthma in comparison with controls (at the Bonferroni corrected p value less than 0.025). Polymorphisms -21A > T and -262C > T of the catalase gene were in a positive linkage disequilibrium (p < 0.0001). Smokers who carried -21AA genotype had an increased risk of nonallergic asthma (p = 0.002), whereas nonsmoker carriers of this genotype did not have the risk of any variant of the disease. Notably, no association of CAT genotype -21AA with asthma was found in high fruit and vegetable consumers, whereas low fruit and vegetable consumers (one time per day or less often) possessing this genotype were at increased risk of both allergic (p = 0.013) and nonallergic (p = 0.008) asthma. This is the first study reporting an association of polymorphism -21A > T of the catalase gene with allergic and nonallergic asthma. We also found, for the first time, that cigarette smoking and fruit and vegetable intakes have potentially inverse modifying influences on the asthma risk in individuals with -21AA CAT genotype and that the gene-environment interactions that were found support the biologic plausibility of catalase gene for the development of bronchial asthma.

No evidence of an association between polymorphisms in the IRAK-M gene and atopic dermatitis in a German cohort

Atopic dermatitis (AD) is a chronic inflammatory skin disease which affects up to 10-15% of the human population in industrialized countries. A complex interaction of genetic and environmental factors is suggested to be involved in the pathogenesis of this disease. Activation of the innate immune system via toll-like receptors (TLRs) might play a role in this respect. Interleukin-1 receptor associated kinase M (IRAK-M) negatively regulates TLR signalling and inflammation. Recently, the IRAK-M gene was identified to confer linkage to asthma on chromosome 12q13-24 in a Sardinian population, and variation within the IRAK-M gene was associated with early-onset persistent asthma in Sardinian and Italian cohorts. In order to evaluate the possible role of polymorphisms in the IRAK-M gene in the pathogenesis of AD, we investigated six single nucleotide polymorphisms (SNPs) in this gene in a German AD case-control study. Unrelated AD patients (n=361) and healthy controls (n=325) were studied genetically using PCR-coupled methods. Analysis of single SNPs and haplotypes did not reveal a significant association between polymorphisms in the IRAK-M gene and AD in this cohort.

Drug-Induced Psoriasis: An Evidence-Based Overview and the Introduction of Psoriatic Drug Eruption Probability Score

Psoriasis is a common skin disorder that needs a long-term management, not only because, of its prevalence but also because of the profound impact it can have on patients quality of life. Drugs may result in exacerbation of a preexisting psoriasis, in induction of psoriatic lesions on clinically uninvolved skin in patients with psoriasis, or in precipitation of the disease in persons without family history of psoriasis or in predisposed individuals. The knowledge of the drugs that may induce, trigger, or exacerbate the disease is of primary importance in clinical practice. By reviewing the literature, there are many reports on drug-induced psoriasis, but the data are not univocal. We propose, when possible, the use of a probability score from the authors to obtain a better classification and further understanding of drug-induced psoriasis.

Allergy and autoimmunity: parallels and dissimilarity: the yin and yang of immunopathology

The etiopathogenesis of allergy and autoimmune diseases is caused by genetic and acquired (environmental) factors, which might be common to both immunopathologies. Genetic factors play an important role in the development and process of immunopathological diseases. Several studies suggest a close relation between gene polymorphism of HLA and cytokines and development of autoimmunity and allergy. Certain gene polymorphisms act as risk or as protective factors. The infection also plays an important role in the induction of allergy and autoimmunity--as a trigger or as a protective factor. Moreover, similar clinical manifestations of both immunopathologies could result in diagnostic problems. This review summarizes the linkage of mechanisms of etiopathogenesis, clinical manifestations and therapeutic strategy between allergic and autoimmune diseases.

Probiotics for treating eczema

BACKGROUND

Probiotics have been proposed as an effective treatment for eczema, and recently a number of clinical trials have been undertaken.

OBJECTIVES

To assess the effects of probiotics for the treatment of eczema

SEARCH STRATEGY

We searched the Cochrane Skin Group Specialised Register (to April 2008), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2,2008) MEDLINE (from 2003 to April 2008), EMBASE (from 2005 to April 2008), PsycINFO, AMED and LILACS (from inception to April 2008) and ISI Web of Science (to December 2006) and reference lists of articles. We also searched registries of ongoing clinical trials, conference proceedings and searched for adverse events.

SELECTION CRITERIA

Randomised controlled trials of live orally ingested microorganisms for the treatment of eczema.

DATA COLLECTION AND ANALYSIS

Two authors independently applied eligibility criteria, assessed the quality of trials and extracted data. We contacted study authors for more information where necessary. We recorded adverse events from the included studies, and from the separate adverse events search.

MAIN RESULTS

Twelve randomised controlled trials involving 781 participants met the inclusion criteria. All trial participants were children. There was no significant difference in participant or parent-rated symptom scores in favour of probiotic treatment (5 trials, 313 participants). Symptom severity on a scale from 0 to 20 was 0.90 points lower after probiotic treatment than after placebo (95%CI -1.04, 2.84; p = 0.36).There was also no significant difference in participant or parent-rated overall eczema severity in favour of probiotic treatment (3 trials, 150 participants). There was no significant difference in investigator rated eczema severity between probiotic and placebo treatments (7 trials, 588 participants). On a scale from 0 to 102 investigator rated eczema severity was 2.46 points lower after probiotic treatment than after placebo treatment (95%CI -2.53, 7.45 p = 0.33). Significant heterogeneity was noted between the results of individual studies, which may be explained by the use of different probiotic strains. Subgroup analysis by age of participant, severity of eczema, presence of atopy or presence of food allergy did not identify a population with different treatment outcomes to the population as a whole. The adverse events search identified some case reports of infections and bowel ischaemia caused by probiotics.

AUTHORS' CONCLUSIONS

The evidence suggests that probiotics are not an effective treatment for eczema, and probiotic treatment carries a small risk of adverse events.

Immunoglobulin constant heavy G subclass chain genes in asthma and allergy

The IGHG (ImmunoGlobulin constant Heavy G chain) genes are situated close to the IGHE gene on chromosome 14q32, 5'mu, delta, gamma3, gamma1, alpha1, gamma2, gamma4, epsilon, alpha2, 3', in linkage disequilibrium. The polymorphism of gamma3, gamma1 and gamma2 genes, is investigated as alternative allotypes. They are inherited in a Mendelian fashion and are expressed randomly in allelic exclusion. The alternative and functionally different gamma3, gamma1 and gamma2 gene variants, are found in four IGHG haplotypes, coding 4 B-cell variants: IGHG*bfn (=B1-cells), IGHG*bf-n (=B2-cells), IGHG*gan (=B3-cells) and IGHG*ga-n (=B4-cells). The dominance of the IGHG2*n allele from the IGHG*bfn haplotype (=B1-cells) has been shown in repeated investigations, namely in patients with asthma and allergy with increased serum levels of IgE > 600 ku/l and more often so in those with IgE > 1,000 ku/l or IgG4>1 g/l, in childhood asthma patients with mean level of IgE = 1,762 ku/l and in allergen exposed individuals developing laboratory animal allergy. In children with non-atopy and mean IgE level = 9.5 ku/l there is instead a dominance of the alternative allotypes from the IGHG*ga-n (=B4-cells) with IGHG2*-n alleles. In a case-control study allergic children with a family history of allergy, clinically manifest allergy and/or positive SPT, the IGHG*bfn haplotype (=B1-cells) with the IGHG2*n allele dominates, with increased risk of atopy and the IGHG*bf-n haplotype (=B2-cells) with the IGHG2*-n allele is infrequent with low risk, probably protective against atopy. The phenotypic expressions of the IGHG*bfn haplotype (=B1 cells) and IGHG*bfn/*bfn diplotypes (B1/B1-cells) are increased IgG2*n allotype together with increased IgE serum levels and IgE sensitisation in agreement with atopy. The alternative IGHG*ga-n/*ga-n diplotype (B4/B4-cells) express low IgG1*a- and IgG2*-n allotypes, together with low IgE and non-IgE sensitisation, in agreement with non-atopy. Together these studies have given us a greater understanding of the involvement of IGHG genes, IGHG coded B-cells and immunochemical and functional variants of IgG molecules describing different forms of asthma and allergy, which will improve diagnoses and treatment.

Prevalence and associated factors of allergic rhinitis and atopic dermatitis in children

Allergic disorders are the chronic diseases of greatest pediatric morbidity, affecting over 25 % of the pediatric population. Indeed, this situation has been referred to as an "allergic epidemic". In comparison with asthma, atopic dermatitis and allergic rhinitis have been less extensively investigated, although this does not mean that they should be regarded as minor disorders but rather as alterations that affect the quality of life of the patients and their families, which generate considerable direct and indirect costs. Despite an important research effort, the reason for this allergic epidemic is not well known. These are multifactor disorders without a single causal agent, in which the most important component is the genetic predisposition of the patient (atopy), modulated by environmental factors, exposure to allergens, infections and irritants, among others. A confounding element is the fact that the concept of allergic diseases encompasses phenotypes of rhinitis, atopic dermatitis or asthma in which no IgE-mediated atopic mechanism is demonstrated, and which can manifest in a way similar to true allergic phenotypes. Differentiation between the two is difficult to establish on the basis of self-administered questionnaires alone, in the absence of a precise etiological diagnosis. The present article reviews the numerous factors suggested to be responsible for the increase in allergic diseases recorded in the last few decades, and for the differences in prevalence observed among centres. For most of these factors the results published in the literature are contradictory, in some cases due to a lack of control of the associated interacting or confounding factors. Consensus exists for only some of these causal factors, such as the established parallelism between the increase in allergic diseases and the reduction in infectious processes on one hand, and the increase in particles generated by diesel fuel combustion on the other. In addition, the implicated factors could act differently (and in some cases even antagonically) upon atopy and on the different disease phenotypes, thereby complicating the study of these interactions even further.

Childhood asthma epidemiology: insights from comparative studies of rural and urban populations

Asthma is one of the most common chronic respiratory disorders. Many epidemiology studies have suggested an increasing trend of asthma in many different regions of the world but the exact reasons explaining such trend remain unclear. Nevertheless, changing environmental factors are most likely important in explaining the trend of asthma. Studies in the past decade have clearly shown a mark difference in the prevalence between urban and rural regions. The consistent findings of a markedly lower prevalence of asthma in children and adults who have been brought up in a farming environment clearly indicate the importance of environmental influence of asthma development. Although the exact protective environmental factors in the rural region remain to be defined, there have been many studies suggesting that early exposure to microbes or microbial products may play a role in modulating the immune system so as to reduce the future risk of asthma and allergies. Advances in the understanding of the genetic predisposition and how these genetic factors may interact with specific environment factors are of paramount importance for the future development of primary preventive strategies for asthma.

Dietary exclusions for established atopic eczema

BACKGROUND

Atopic eczema (AE) is a non-infective chronic inflammatory skin disease characterised by an itchy red rash.

OBJECTIVES

To assess the effects of dietary exclusions for the treatment of established atopic eczema.

SEARCH STRATEGY

We searched The Cochrane Skin Group Specialised Register (to March 2006), The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 1, 2006), MEDLINE (2003 to March 2006), EMBASE (2003 to March 2006), LILACS (to March 2006), PsycINFO (1806 to March 2006), AMED (1985 to March 2006), ISI Web of Science (March 2006), www.controlled-trials.com, www.clinicaltrials.gov and www.nottingham.ac.uk/ongoingskintrials (March 2006). Pharmaceutical companies were contacted where appropriate for reviews or unpublished trials.

SELECTION CRITERIA

People who have atopic eczema as diagnosed by a doctor.

DATA COLLECTION AND ANALYSIS

Two independent authors carried out study selection and assessment of methodological quality.

MAIN RESULTS

We found 9 RCTs involving a total of 421 participants of which 6 were studies of egg and milk exclusion (N=288), 1 was a study of few foods (N=85) and 2 were studies of an elemental diet (N=48). There appears to be no benefit of an egg and milk free diet in unselected participants with atopic eczema. There is also no evidence of benefit in the use of an elemental or few-foods diet in unselected cases of atopic eczema. There may be some benefit in using an egg-free diet in infants with suspected egg allergy who have positive specific IgE to eggs - one study found 51% of the children had a significant improvement in body surface area with the exclusion diet compared to normal diet (RR 1.51, 95% CI 1.07 to 2.11) and change in surface area and severity score was significantly improved in the exclusion diet compared to the normal diet at the end of 6 weeks (MD 5.50,95% CI 0.19 to 10.81) and end of treatment (MD 6.10, 95% CI 0.06 to12.14). Methodological difficulties have made it difficult to interpret these studies. Poor concealment of randomisation allocation, lack of blinding and high dropout rates without an intention-to-treat analysis indicates that these studies should be interpreted with great caution.

AUTHORS' CONCLUSIONS

There may be some benefit in using an egg-free diet in infants with suspected egg allergy who have positive specific IgE to eggs. Little evidence supports the use of various exclusion diets in unselected people with atopic eczema, but that may be because they were not allergic to those substances in the first place. Lack of any benefit may also be because the studies were too small and poorly reported. Future studies should be appropriately powered focusing on participants with a proven food allergy. In addition a distinction should be made between young children whose food allergies improve with time and older children/adults.

Lack of association between three promoter polymorphisms of PTGDR gene and asthma in a Chinese Han population

The PTGDR gene has been suggested to be an asthma susceptibility gene in previous genome-wide linkage studies as well as in functional studies in a mouse model of asthma. Recently, promoter polymorphisms of the PTGDR gene have been reported to be associated with asthma in American and European populations. In order to determine the association of PTGDR promoter polymorphisms and asthma susceptibility in a Chinese Han population, three promoter single nucleotide polymorphisms (SNP) -549T/C, -441C/T, and -197T/C were genotyped in 336 patients with asthma and 264 healthy controls. Asthma was diagnosed according to the American Thoracic Society (ATS) criteria. SNPs -549T/C and -441C/T were genotyped by Tetra-primer Amplification Refractory Mutation System PCR method and -197T/C by polymerase chain reaction-restriction fragment length polymorphism method. Unlike the results observed in American and European populations, none of the three SNPs nor any haplotypes in the PTGDR promoter region were found to be associated with asthma susceptibility in this Chinese Han population (all P-value > 0.05). The frequencies for both high-transcriptional-efficiency haplotype (CCC) and low-transcriptional-efficiency haplotype (TCT) were lower than 1% in patients and controls, significantly different from those observed in American and European populations. These results suggest that the three PTGDR gene promoter polymorphisms studied are not important risk factors for asthma susceptibility in the Chinese Han population.

Genetic variability of the high-affinity IgE receptor alpha subunit (Fc epsilon RI alpha) is related to total serum IgE levels in allergic subjects

Known susceptibility genes to atopy and asthma have been identified by linkage or associations with clinical phenotypes, including total serum IgE levels. IgE-mediated sensitivity reactions require a high-affinity IgE receptor (FcepsilonRI), which immobilizes the immunoglobulin on the surface of the effector cells, mostly mast cells and basophils. In this mini-review, recent findings are presented on genetic variation of this receptor, as related to atopy. Transcription of FCER1A gene encoding the receptor alpha subunit can be initiated from two separate promoters, the proximal one and the distal one, which results in a transcript containing two novel untranslated exons (1A, 2A). Our knowledge on the role of this mechanism in allergic diseases is still at an infancy stage. Within regulatory elements of FCER1A some common single nucleotide polymorphisms have functional associations, which were recently reported and replicated in different ethnical groups. Interestingly, these associations do not confer susceptibility to allergic diseases, but rather modulate serum concentrations of IgE. Similarly to the previously investigated beta subunit of the receptor, FCER1A is a good candidate for a quantitative trait locus (QTL) in allergic diseases, and appears to participate in the systemic regulation of IgE levels.

Cell type-specific regulation of brain-derived neurotrophic factor in states of allergic inflammation

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is a molecule influencing neuronal proliferation and differentiation. In states of allergy, it may orchestrate inflammatory changes by linking the immune system with the nervous system. Because the precise regulation of gene transcription in mast cells MCs is not clear, the present studies assessed the gene regulation of BDNF in this inflammatory cell type.

METHODS

Transcriptional expression of BDNF in human skin was studied in isolated cells using RT-PCR. In situ lesional MC BDNF protein expression was analysed by immunohistochemistry and related to the differential staining of MCs and functional effects of BDNF on HaCaT keratinocytes.

RESULTS

BDNF mRNA expression was found in isolated human skin MCs, keratinocytes, and fibroblasts. Also, low levels were found in endothelial cells and melanocytes. BDNF protein expression was found in situ in lesional and non-lesional MCs. A significantly decreased expression of BDNF protein was found in atopic dermatitis lesional MCs when compared with control MC expression. Functional in vitro experiments demonstrated that a decrease in BDNF stimulation led to increased secretion rates for stem cell factor and IL-8 in HaCaT keratinocytes.

CONCLUSION

The demonstration of a decreased level of BDNF gene transcription in lesional MCs points to a differential regulation of MC-released neutrotrophins in cutaneous allergic inflammation. Topically administered neurotrophin receptor-modulating compounds should be receptor target specific and not universally acting in diseases such as atopic dermatitis or allergic asthma.

Family history of asthma and atopy: in-depth analyses of the impact on asthma and wheeze in 7- to 8-year-old children

OBJECTIVES

Development of asthma in children is influenced by interactions between genetic and environmental factors. It is unclear whether paternal or maternal histories of disease confer different risks. Previous population-based studies have not stratified analyses by child gender and sensitization status. Our aim was to study in detail the hereditary component of childhood asthma.

METHODS

A population-based cohort of 3430 (97% of invited) 7- to 8-year-old school children participated in an expanded International Study of Asthma and Allergy in Childhood survey, and two thirds were skin-prick tested. Heredity was defined as a family history of (1) asthma and (2) atopy (allergic rhinitis or eczema). Multivariate analyses corrected for known risk factors for asthma.

RESULTS

At ages 7 to 8, prevalence of asthma was 5.3% among the children and 9.0% among the parents. In children without parental asthma or parental atopy, the prevalence of asthma was 2.8%. Corrected for parental asthma, parental atopy was a weak but significant risk factor. There were minor differences in the impact of parental disease between sensitized and nonsensitized children and between boys and girls.

CONCLUSIONS

As risk factors for childhood asthma, there were major differences between parental asthma and parental atopy. Sibling asthma was only a marker of parental disease. Interactions between parental disease and the child's allergic sensitization or gender were not statistically significant. Asthma in both parents conferred a multiplicative risk, whereas the effect of parental atopy was additive, however limited. Asthma and atopy, despite their causal relationship, are separate entities and could be inherited differently. This large, population-based, and well-characterized cohort study does not confirm parent-of-origin effects found in previous studies.

Immunoglobulin constant heavy G chain genes as risk factors in childhood allergies

BACKGROUND

Several candidate genes have been found to be associated with the inflammatory response of IgE-mediated allergy, so also the immunoglobulin constant heavy G chain (IGHG) genes. The IGHG genes are situated close to the IGHE gene on chromosome 14q32, 5'mu, delta, gamma3, gamma1, alpha1, gamma2, gamma4, epsilon, alpha2, 3'. They are inherited in a Mendelian fashion and expressed randomly in allelic exclusion. The alternative and functionally different gamma3, gamma1 and gamma2 gene variants are found in four IGHG haplotypes, coding four B cell variants.

OBJECTIVE

The aim of this study was to assess the frequency of different IGHG genes in relation to phenotypes associated with allergy, in a case-control study.

METHODS

We identified the constant heavy-chain genes of IgG in 198 allergic and non-allergic children participating in the Phase II of the International Study of Asthma and Allergy in Children. The IGHG genes were assessed by the alternative serum IgG subclass allotypes expressing the alternative alleles of gamma3, gamma1 and gamma2 genes, using ELISA and double immunodiffusion.

RESULTS

The IGHG*bfn haplotype (=B1 cells) and IGHG2*n allele dominated (51% vs. 24%, P=0.002) and the IGHG*bf-n haplotype (=B2 cells) was infrequent (16% vs. 52%, P < 0.001) in allergic children with a family history of allergy, clinical manifest allergy and positive skin prick test (SPT). The frequency of IGHG genes was similar in children with maternal and paternal heredity and in children with wheezing, eczema or rhinitis, as well as in children with different positive SPT. The IGHG*bfn haplotype with the IGHG2*n allele was strongly associated with heredity for allergy. The IGHG*bf-n haplotype was inversely related to allergy. Conclusions IgG allotypes, immunochemical and functional variants of IgG molecules from IGHG genes are associated with atopy. The IGHG*bfn haplotype (=B1 cells) with the IGHG2*n allele dominates, associated with an increased risk for atopy. In contrast, the IGHG*bf-n haplotype (=B2 cells) with the IGHG2*-n allele is associated with low risk.

Immunotherapy with allergen peptides

Specific allergen immunotherapy (SIT) is disease-modifying and efficacious. However, the use of whole allergen preparations is associated with frequent allergic adverse events during treatment. Many novel approaches are being designed to reduce the allergenicity of immunotherapy preparations whilst maintaining immunogenicity. One approach is the use of short synthetic peptides which representing dominant T cell epitopes of the allergen. Short peptides exhibit markedly reduced capacity to cross link IgE and activate mast cells and basophils, due to lack of tertiary structure. Murine pre-clinical studies have established the feasibility of this approach and clinical studies are currently in progress in both allergic and autoimmune diseases.

Peptide immunotherapy for allergic diseases

Specific allergen immunotherapy has been widely practised for almost 100 years. Whilst this approach is disease-modifying and efficacious, the use of whole allergen preparations is associated with an unacceptably high prevalence of allergic adverse events during treatment. Many approaches to reduce the allergenicity of immunotherapy preparations whilst maintaining immunogenicity are under development. One such approach is the use of short synthetic peptides which represent major T-cell epitopes of the allergen. Major potential advantages of this approach include markedly reduced capacity to cross-link immunoglobulin-E and activate mast cells and basophils, and ease of manufacture and standardization. Promising results in preclinical studies have led to the translation of this approach to clinical studies in humans. Peptide immunotherapy is currently under development for allergic and autoimmune diseases.

Identification of polymorphisms in human interleukin-27 and their association with asthma in a Korean population

Interleukin 27 (IL-27) acts as a versatile cytokine in the early regulation of Th1 initiation and in the negative regulation of the Th2 factor GATA-3. IL-27, which was discovered as a novel heterodimeric cytokine of the IL-12 family, consists of two subunits, the Epstein-Barr virus-induced gene 3 (EBI3) and p28. The IL-27 cytokine is mediated by one of the receptor chains (WSX-1) of the IL-27 receptor that is highly expressed on CD4(+) T lymphocytes and NK cells. Although signaling of IL-27/WSX-1 interactions have been recognized in the down-regulation of airway hyper-reactivity and in lung inflammation during the development of allergic asthma, little is known about the role of single nucleotide polymorphisms (SNPs) of IL-27 and individual susceptibility to asthma. To address this question, we have examined the five exons and the boundary intron sequences of IL-27P28, including the promoter regions, with the aim of identifying sites of variation that may be useful for understanding the genetic influences of this gene. We identified four SNPs, g.-964A > G, g.2905T > G, g.4603G > A and g.4730T > C, and analyzed the genotype and allele frequencies between asthma patients and healthy controls. Our results strongly suggest that the g.-964A > G polymorphism of IL-27p28 is most likely associated with susceptibility to asthma. Moreover, we elucidate the haplotype frequencies of g.2905T > G, g.4603G > A and g.4730T > C in terms of their relative correlation with asthma patients and healthy controls.

Dermatite atópica: uma doença cutânea ou uma doença sistêmica? A procura de respostas na história da dermatologia

A dermatite atópica é doença inflamatória cutânea associada à atopia, predisposição a produzir resposta IgE a alérgenos ambientais, constituindo uma das manifestações das doenças atópicas, junto com a asma e a rinite alérgica. A dermatite atópica é caracterizada por episódios recorrentes de eczema associado a prurido, acometendo superfície cutânea geneticamente alterada, induzindo, por fenômenos imunológicos, a presença de inflamação. Trata-se de doença multifatorial, com enfoque nas alterações sistêmicas e alérgicas ou nas manifestações cutâneas, de acordo com diferentes visões da doença. A conceituação da dermatite atópica é importante, porque a conduta terapêutica pode variar segundo essas duas formas diferentes de analisá-la. Autores modernos discutem extensivamente esses aspectos sem, contudo, alcançar uma conclusão sobre a dermatite atópica como doença sistêmica ou cutânea. A procura dos conceitos sobre a doença, desde os primeiros relatos, associada à evolução do pensamento na dermatologia, poderia esclarecer a origem dessas dúvidas. Uma análise histórica demonstra que a dermatite atópica tem seus conceitos atuais oriundos dos estudos de diversos pensadores, que, em diferentes momentos históricos, descreveram a doença, e que muito do que acreditamos atualmente tem, nesses escritos, seus fundamentos.

AluyMICB dimorphism within the class I region of the major histocompatibility complex is associated with asthma and airflow obstruction in the Busselton population

AIM

To examine the association between the Alu dimorphism within the first intron of the MICB gene and asthma and airflow obstruction. Background The highly polymorphic non-classical MHC class I polypeptide-related (MIC) genes, MICA and MICB, encode stress inducible glycoproteins, which are expressed on a variety of epithelial cells, including those of the lungs.

METHODS

AluyMICB genotyping was performed on 1109 subjects from the Busselton Health Study. From a standard questionnaire, 359 individuals indicated that they had been diagnosed by a doctor with asthma. Lung function was assessed by the forced expired volume in 1 second (FEV1) and expressed as a percent of the predicted value. Airflow obstruction was defined as FEV1<80% predicted.

RESULTS

In men, a dominant relationship was found between the AluyMICB DD genotype and asthma (P=0.006; chi2(2)=7.65). Furthermore, multivariate analysis adjusted for age, height, weight and body mass index (BMI) showed a relationship between DD genotype and asthma in men in a dominant model (odds ratio (OR)=1.97; 95% confidence interval (CI)=1.11-3.51; P=0.021). In women, an association was found between the AluyMICB II genotype and FEV1 percent predicted as a continuous variable (P=0.001). When adjusted for age and BMI, it showed a significant relationship between AluyMICB and airflow obstruction in a dominant model (OR=14.11%, 95% CI 3.29-60.57, P<0.001). However, no association was found between the AluyMICB II genotypes and airflow obstruction in men.

CONCLUSION

These findings suggest the possible involvement of a MHC class I gene in abnormal airway structure in women and airway function in men.

Family based association analysis of the IL2 and IL15 genes in allergic disorders

Allergic diseases affect an increasing number of individuals and are a major global health problem. A substantial genetic contribution in the aetiology of allergic diseases is well documented. We have previously reported linkage of allergic diseases and atopy to the region harbouring the IL2 gene (4q27). IL15 is located approximately 20 Mb distal to IL2. The two genes encode cytokines that are structurally and functionally related, both inducing T-cell activation and proliferation. We screened the two genes for sequence variation and applied the seven single-nucleotide polymorphisms (SNPs) identified in a family based association study of two Danish samples comprising a total of 235 families with allergic diseases. None of the IL15 SNPs showed significant association and the haplotype analysis yielded inconsistent results in the two samples. In contrast, the two IL2 SNPs showed association both separately and in haplotypes with several atopic phenotypes, most significantly with IgE-mediated allergy. (single SNP P-value 0.0005 for positive skin prick test, haplotype P-value 0.019 for positive RAST test). To our knowledge, this is the first study reporting association between IL2 and IgE-mediated allergy, asthma and atopic eczema. The SNP (rs2069762) that showed the most consistent results is located in the promoter and has previously been shown to influence the level of IL2 expression. We suggest that the observed overtransmission of the T allele of this SNP may convey increased susceptibility to allergic disease by skewing the Th1/Th2 balance towards Th2.

Plasma soluble human leukocyte antigen G levels in asthmatic children

BACKGROUND

Human leukocyte antigen G (HLA-G) is a nonclassical major histocompatibility complex class I gene. HLA-G stimulates Th2 cytokine secretion by peripheral blood mononuclear cells. The role of soluble HLA-G (sHLA-G) in bronchial asthma is incompletely understood and the plasma level of sHLA-G in asthmatic children has not been investigated.

OBJECTIVE

It was the aim of this study to investigate the plasma level of sHLA-G in asthmatic children.

METHODS

Asthmatic (n = 53) and healthy children (n = 16) were included in the study. Levels of sHLA-G were determined in plasma using ELISA. Spirometry, total immunoglobulin E and eosinophil counts were obtained and skin testing done with a battery of 25 antigens with appropriate positive and negative controls.

RESULTS

No significant difference was observed in the plasma level of sHLA-G between the asthmatic and healthy children (p > 0.05). When we compared atopic asthmatics with healthy controls, we found significantly higher levels of sHLA-G in atopic asthmatics (p < 0.05). There was a significant difference in the peripheral blood eosinophil counts and total immunoglobulin E levels among the groups (p < 0.001).

CONCLUSION

Our study shows that plasma sHLA-G levels do not differ between asthmatic children and healthy controls. However, higher plasma levels of sHLA-G in atopic asthmatics may suggest a role for sHLA-G in atopy. Further investigations are required to better define the mechanism of the production and the role of sHLA-G molecules observed in patients with asthma.

Asthma, genes, and air pollution

OBJECTIVE

The objective of this article is to evaluate genetic risks associated with the pulmonary response to air pollutants, including particulates and ozone.

METHODS

A comprehensive review of articles related to the genetics of asthma with particular attention to air pollution was conducted through a search of the National Library of Medicine's PubMed database.

RESULTS

Asthma, which affects over 15 million people in the United States, is characterized by inflammation leading to reversible airflow obstruction. Triggered by exposure to numerous occupational and environmental agents, asthma has long been considered to occur more frequently in families, with upwards of a 50% higher rate in the offspring of parents with asthma. Asthma genetic studies have used two major methods: mapping techniques that pinpoint gene loci and studies that identify genes and polymorphisms associated with various asthma mechanisms such as inflammatory mediators. The most consistently replicated chromosomal regions associated with asthma have been chromosomes 2q, 5q, 6p, 12 q, and 13q. Because the formation of reactive oxygen species is a major aspect of the inflammatory process of asthma, genetic aberrations associated with antioxidants such as glutathione S-transferase (GST) may shed light on reasons why some people with asthma seem more at risk of exacerbations as a result of air pollution. People with a polymorphism at the GSTP 1 locus, which codes for GST, one of a family of pulmonary antioxidants, have higher rates of asthma. Children in Mexico City with the GSTM1 null genotype demonstrated significant ozone-related decrements in lung function. Animal studies support the key role of antioxidants in reducing the inflammatory response associated with exposure to diesel exhaust particles.

CONCLUSIONS

Oxidative stress is a key mechanism underlying the toxic effects of exposure to some types of air pollution. Asthmatics with the null genotype for the antioxidant, GST, seem more at risk of the pulmonary effects of air pollution.