A common FCER1B gene promoter polymorphism influences total serum IgE levels in a Japanese population

Fc Receptor Variants and Disease: A Crucial Factor to Consider in the Antibody Therapeutics in Clinic

The fragment crystallizable (Fc) domain of antibodies is responsible for their protective function and long-lasting serum half-life via Fc-mediated effector function, transcytosis, and recycling through its interaction with Fc receptors (FcRs) expressed on various immune leukocytes, epithelial, and endothelial cells. Therefore, the Fc-FcRs interaction is a control point of both endogenous and therapeutic antibody function. There are a number of reported genetic variants of FcRs, which include polymorphisms in (i) extracellular domain of FcRs, which change their affinities to Fc domain of antibodies; (ii) both cytoplasmic and intracellular domain, which alters the extent of signal transduction; and (iii) the promoter region of the FcRs gene, which affects the expression level of FcRs, thus being associated with the pathogenesis of disease indications. In this review, we firstly describe the correlation between the genetic variants of FcRs and immunological disorders by individual differences in the extent of FcRs-mediated regulations. Secondly, we discuss the influence of the genetic variants of FcRs on the susceptibility to infectious diseases or cancer in the perspective of FcRs-induced effector functions. Overall, we concluded that the genetic variants of FcRs are one of the key elements in the design of antibody therapeutics due to their variety of clinical outcomes among individuals.

Interaction between antibiotic use and MS4A2 gene polymorphism on childhood eczema: a prospective birth cohort study

Background

Eczema is usually the first allergic manifestation to appear in life attributed to gene–environment interactions. IL13, IL4, MS4A2 and ILR4A are four key inflammatory genes associated with atopy. This study aimed to explore gene-environment interactions on eczema in early life among the above four genes and environmental factors in Chinese Han children.

Methods

Five hundred ninety-seven children from a birth cohort who completed two-year follow-up were enrolled and their cord blood was collected. Subjects were genotyped for six polymorphisms in the aforementioned four genes. The children were followed at 6, 12 and 24 months, with epidemiologic information and medical history of eczema collected by questionnaire and eczema assessed by dermatologists.

Results

Among the 597 children, 168 were diagnosed with eczema and the others were not after 2 years of follow-up. MS4A2 rs569108 GG genotype (P = 1.68E-02, odds ratio (OR) = 4.66) and antibiotic use (P = 3.75E-4, OR = 2.02) were found independently associated with development of childhood eczema. Children with both antibiotic use and MS4A2 rs569108 GG genotype were more likely to develop eczema than those with only antibiotic use or GG homozygote (OR = 6.24 VS. 2.04 or 4.68).

Conclusions

MS4A2 rs569108 polymorphism and antibiotic use were solely associated with eczema, and they interacted with each other to increase the risk of developing the disease in Chinese Han toddlers. Long-term follow-up along with functional and replication studies are still needed.

Gene-gene and gene-environment interactions on cord blood total IgE in Chinese Han children

Background

IL13, IL4, IL4RA, FCER1B and ADRB2 are susceptible genes of asthma and atopy. Our previous study has found gene–gene interactions on asthma between these genes in Chinese Han children. Whether the interactions begin in fetal stage, and whether these genes interact with prenatal environment to enhance cord blood IgE (CBIgE) levels and then cause subsequent allergic diseases have yet to be determined. This study aimed to determine whether there are gene–gene and gene-environment interactions on CBIgE elevation among the aforementioned five genes and prenatal environmental factors in Chinese Han population.

Methods

989 cord blood samples from a Chinese birth cohort were genotyped for nine single-nucleotide polymorphisms (SNPs) in the five genes, and measured for CBIgE levels. Prenatal environmental factors were collected using a questionnaire. Gene–gene and gene-environment interactions were analyzed with generalized multifactor dimensionality methods.

Results

A four-way gene–gene interaction model (IL13 rs20541, IL13 rs1800925, IL4 rs2243250 and ADRB2 rs1042713) was regarded as the optimal one for CBIgE elevation (testing balanced accuracy = 0.5805, P = 9.03 × 10^–4). Among the four SNPs, only IL13 rs20541 was identified to have an independent effect on elevated CBIgE (odds ratio (OR) = 1.36, P = 3.57 × 10^–3), while the other three had small but synergistic effects. Carriers of IL13 rs20541 TT, IL13 rs1800925 CT/TT, IL4 rs2243250 TT and ADRB2 rs1042713 AA were estimated to be at more than fourfold higher risk for CBIgE elevation (OR = 4.14, P = 2.69 × 10^–2). Gene-environment interaction on elevated CBIgE was found between IL4 rs2243250 and maternal atopy (OR = 1.41, P = 2.65 × 10^–2).

Conclusions

Gene–gene interaction between IL13 rs20541, IL13 rs1800925, IL4 rs2243250 and ADRB2 rs1042713, and gene-environment interaction between IL4 rs2243250 and maternal atopy begin in prenatal stage to augment IgE production in Chinese Han children.

Potential Metabolic Biomarkers in Adult Asthmatics

Asthma is the most common chronic airway inflammation, with multiple phenotypes caused by complicated interactions of genetic, epigenetic, and environmental factors. To date, various determinants have been suggested for asthma pathogenesis by a new technology termed omics, including genomics, transcriptomics, proteomics, and metabolomics. In particular, the systematic analysis of all metabolites in a biological system, such as carbohydrates, amino acids, and lipids, has helped identify a novel pathway related to complex diseases. These metabolites are involved in the regulation of hypermethylation, response to hypoxia, and immune reactions in the pathogenesis of asthma. Among them, lipid metabolism has been suggested to be related to lung dysfunction in mild-to-moderate asthma. Sphingolipid metabolites are an important mediator contributing to airway inflammation in obese asthma and aspirin-exacerbated respiratory disease. Although how these molecular variants impact the disease has not been completely determined, identification of new causative factors may possibly lead to more-personalized and precise pathway-specific approaches for better diagnosis and treatment of asthma. In this review, perspectives of metabolites related to asthma and clinical implications have been highlighted according to various phenotypes.

Association of a four-gene model with allergic diseases: Two-year follow-up of a birth cohort study

Background

Our previous study has developed a four‐gene model involving IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108 associated with asthma and atopy in Chinese Han children. However, whether the gene model is associated with allergies in early life has yet to be determined. This study aimed to apply the gene model in a birth cohort to investigate its associations with the development of allergic diseases in Chinese Han toddlers.

Methods

Five hundred and ninety‐seven children from a birth cohort completing 2‐year follow‐up were included. Epidemiologic information and cord blood were collected. Children were genotyped for the above polymorphisms and divided into high or low genetic risk groups based on the genotypes. Subjects were followed at 6, 12, and 24 months, with information on allergic diseases collected via standard questionnaires and assessed by specialists.

Results

Two hundred and eighty‐four children were divided into a high‐risk group and 313 into a low‐risk group. Between the two groups, a significant difference was only found in delivery mode among all the subject characteristics (p = .025). After stratification for delivery mode, children at high risk were more likely to develop eczema (relative risk [RR] = 1.46, p = .040) over 2 years of follow‐up compared with those at low risk. No significant associations were found between genetic risk and food allergy, wheezing and allergic rhinitis (p > .05).

Conclusion

The gene model was significantly associated with the development of eczema in Chinese Han toddlers. Long‐term follow‐up along with functional and replication studies on the gene model are still needed in future.

Association of FcεRIβ polymorphisms with risk of asthma and allergic rhinitis: evidence based on 29 case-control studies

Purpose: Accumulating evidence has shown that allergic diseases are caused by a complex interaction of genetic and environmental factors, some single nucleotide polymorphisms (SNPs) existing in high-affinity IgE receptor β chain (FcεRIβ) are potential risk factors for allergic diseases. However, the results have been inconsistent and inconclusive due to the limited statistical power in individual study. Thus, we conducted a meta-analysis to systematically evaluate the association between FcεRIβ SNPs and allergic diseases risk.

Methods: Eligible studies were collected from PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure, and WanFang databases. Pooled odd ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated to assess the strength of the relationships between five polymorphisms (E237G, -109 C/T, RsaI_in2, RsaI_ex7, and I181L) and the risk of allergic diseases by using five genetic models. In addition, the stability of our analysis was evaluated by publication bias, sensitivity, and heterogeneity analysis.

Results: Overall, a total of 29 case–control studies were included in this meta-analysis. We found that E237G (B vs. A: OR = 1.28, 95% CI = 1.06–1.53, P<0.001, I² = 63.1%) and -109 C/T (BB vs. AA + AB: OR = 1.58, 95%CI = 1.26–1.98, P<0.001, I² = 66.4%) were risk factors for allergic diseases.

Conclusion: Our meta-analysis suggests that polymorphisms in FcεRIβ may be associated with the development of allergic diseases.

Four-locus gene interaction between IL13, IL4, FCER1B, and ADRB2 for asthma in Chinese Han children

RATIONALE

IL13, IL4, IL4RA, FCER1B, and ADRB2 are important inflammatory genes associated with immunoglobulin E levels. This study attempts to determine whether there are gene-gene interactions in the five genes among asthmatic children of Chinese Han nationality.

METHODS

Nine single-nucleotide polymorphisms (SNPs) in the five genes were genotyped in 1,000 asthmatic children and 1,000 healthy controls using TaqMan real-time quantitative polymerase chain reaction. Multifactor-dimensionality reduction method was applied for the analysis.

RESULTS

A four-way gene-gene interaction model consisting of IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108 was chosen as the optimal one for determining asthma susceptibility (testing balanced accuracy = 0.6089, cross-validation consistency = 10/10, P = 6.98E-05). Each of the four SNPs was identified to have an independent association with childhood asthma (G allele of rs20541, odds ratio (OR) = 1.24, P = 1.23E-03; T allele of rs2243250, OR = 1.25, P = 3.81E-03; A allele of rs1042713, OR = 1.29, P = 6.75E-05; G allele of rs569108, OR = 1.27, P = 3.86E-03). Individuals homozygous for the risk alleles at all the four loci (rs20541 GG, rs2243250 TT, rs1042713 AA, and rs569108 GG) had a significantly higher risk of asthma compared with those without any risk homozygotes (OR = 13.55, P = 4.28E-03), and also greater than those with less than four risk homozygotes (OR = 10.09, P = 6.51E-03).

CONCLUSIONS

Our results suggest that IL13 rs20541, IL4 rs2243250, ADRB2 rs1042713, and FCER1B rs569108, four SNPs with significant sole effect on asthma, interact to confer a higher risk for the disease in Chinese Han children.

IgE FcɛR1β polymorphism and risk of developing chronic spontaneous urticaria: A study in an ethnic Kashmiri population

BACKGROUND

The pathogenesis of chronic spontaneous urticaria involves interplay between the genetic and environmental factors, most of which is still poorly understood. It is well-recognized that 30-40% of chronic spontaneous urticaria is autoimmune in nature. Chronic autoimmune urticaria is caused by anti-FcɛR1β and less frequently, by anti-IgE auto antibodies that lead to mast cell and basophil activation, thereby giving rise to the release of histamine and other proinflammatory mediators. We investigated the association between SNP loci in FcɛR1β and chronic spontaneous urticaria and to see its relation with serum IgE levels in Kashmiri population.

METHODS

The autologous serum skin test was used as a screening test for chronic autoimmune urticaria. PCR-RFLP was used to detect the genotype of the SNP loci. Serum IgE levels were assessed by ELISA kit.

RESULTS

No significant difference was found between the study population and control group in genotype distribution (wild and variant) among FcɛR1β loci (P value=0.06, odds ratio=0.29). The frequency of FcɛR1β (C109T) in autologous serum skin test positive chronic autoimmune urticaria patients with the CT genotype was found to be statistically non-significant when compared with the wild genotype (P=0.35). Carriers of FcɛR1β (T allele) had a more significant risk of developing CAU than those with C allele (P=0.01). In our population serum total IgE levels did not find any statistical significance with regard to ASST positive & ASST negative patients (P=0.26).

CONCLUSIONS

There is statistically no significant association between FcɛR1β gene polymorphism and CSU in Kashmiri population; however, there is a probability of developing CSU in patients carrying FcɛR1β T allele. Furthermore, serum total IgE levels had no significant association with the development of CAU.

Human FcR polymorphism and disease

Fc receptors play a central role in maintaining the homeostatic balance in the immune system. Our knowledge of the structure and function of these receptors and their naturally occurring polymorphisms, including single nucleotide polymorphisms and/or copy number variations, continues to expand. Through studies of their impact on human biology and clinical phenotype, the contributions of these variants to the pathogenesis, progression, and/or treatment outcome of many diseases that involve immunoglobulin have become evident. They affect susceptibility to bacterial and viral pathogens, constitute as risk factors for IgG or IgE mediated inflammatory diseases, and impact the development of many autoimmune conditions. In this chapter, we will provide an overview of these genetic variations in classical FcγRs, FcRLs, and other Fc receptors, as well as challenges in achieving an accurate and comprehensive understanding of the FcR polymorphisms and genomic architecture.

Association of the MS4A2 gene promoter C-109T or the 7th exon E237G polymorphisms with asthma risk: a meta-analysis

BACKGROUND AND OBJECTIVE

A large number of studies have examined the association between the Membrane-spanning 4 domains, superfamily A, number 2 (MS4A2) gene C-109T (rs1441586) or E237G (rs569108) variants and asthma risk. However, the results are inconsistent and inconclusive. To derive a more precise estimation, a meta-analysis was performed.

METHODS

Meta-analyses were conducted with the data from case-control association studies (24 studies with 4496 asthmatics and 4571 controls for E237G variant and 9 studies including 2005 cases and 1868 control for C-109T polymorphisms, respectively). Random-effects model was used to calculate summary odds ratios (ORs).

RESULTS

For the MS4A2 gene E237G variant, no significant associations with asthma were found in overall population; we observed an elevated risk of atopic asthma among subjects with the 237G allele (OR=1.341, 95% CI: 1.039-1.732 for G versus E and OR=1.374, 95% CI: 1.032-1.828 for EG+GG versus EE) in the stratified meta-analysis. As for the MS4A2 gene C-109T polymorphism, no significant associations with asthma risk were observed in the total population; in subgroup analysis by ethnicity of subjects we found increased asthma risk among Asians carrying T allele (OR=1.140, 95% CI: 1.019-1.276 for T versus C and OR=1.359, 95% CI: 1.029-1.794 for TT versus CC).

CONCLUSIONS

Data indicated that the MS4A2 gene E237G variant may be a risk factor for developing atopic asthma and the promoter -109T allele is a potential risk factor of asthma in Asians.

Genome-wide association study for levels of total serum IgE identifies HLA-C in a Japanese population

Most of the previously reported loci for total immunoglobulin E (IgE) levels are related to Th2 cell-dependent pathways. We undertook a genome-wide association study (GWAS) to identify genetic loci responsible for IgE regulation. A total of 479,940 single nucleotide polymorphisms (SNPs) were tested for association with total serum IgE levels in 1180 Japanese adults. Fine-mapping with SNP imputation demonstrated 6 candidate regions: the PYHIN1/IFI16, MHC classes I and II, LEMD2, GRAMD1B, and chr13∶60576338 regions. Replication of these candidate loci in each region was assessed in 2 independent Japanese cohorts (n = 1110 and 1364, respectively). SNP rs3130941 in the HLA-C region was consistently associated with total IgE levels in 3 independent populations, and the meta-analysis yielded genome-wide significance (P = 1.07×10⁻¹⁰). Using our GWAS results, we also assessed the reproducibility of previously reported gene associations with total IgE levels. Nine of 32 candidate genes identified by a literature search were associated with total IgE levels after correction for multiple testing. Our findings demonstrate that SNPs in the HLA-C region are strongly associated with total serum IgE levels in the Japanese population and that some of the previously reported genetic associations are replicated across ethnic groups.

Links between allergy and cardiovascular or hemostatic system

In addition to a well-known immunologic background of atherosclerosis and influences of inflammation on arterial and venous thrombosis, there is growing evidence for the presence of links between allergy and vascular or thrombotic disorders. In this interpretative review, five pretty well-documented areas of such overlap are described and discussed, including: (1) links between atherosclerosis and immunoglobulin E or atopy, (2) mutual effects of blood lipids and allergy, (3) influence of atopy and related disorders on venous thromboembolism, (4) the role of platelets in allergic diseases, and (5) the functions of protein C system in atopic disorders.

Identifying genetic susceptibility to sensitization to cephalosporins in health care workers

Exposure to cephalosporins could cause occupational allergic diseases in health care workers (HCWs). We evaluated the prevalence of serum specific IgE and IgG antibodies to cephalosporin-human serum albumin (HSA) conjugate and to identify potential genetic risk factors associated with sensitization to cephalosporins in exposed HCWs. The study population consisted of 153 HCWs who had been exposed to antibiotics in a single university hospital and 86 unexposed healthy controls. A questionnaire survey of work-related symptoms (WRS) was administered. A skin-prick test (SPT) was performed, and serum-specific IgE and IgG antibodies to 3 commonly prescribed cephalosporins were measured by ELISA. Four single-nucleotide polymorphisms of the candidate genes related to IgE sensitization were genotyped. The prevalence of WRS to cephalosporins was 2.6%. The prevalence rates of serum-specific IgE and IgG antibodies to cephalosporins were 20.3% and 14.7%, respectively. The FcεR1β-109T > C polymorphism was significantly associated with IgE sensitization to cephalosporins in HCWs (P = 0.036, OR = 3.553; CI, 1.324-9.532). The in vitro functional assay demonstrated that the T allele of FcεR1β-109T had greater promoter activity than did the C allele (P < 0.001). The FcεR1β-109T > C polymorphism may be a potential genetic risk factor for increased IgE sensitization to cephalosporins.

FCεRI gene promoter polymorphisms and total IgE levels in susceptibility to atopic dermatitis in Korea

IgE-dependent activation of mast cells and basophils through the high-affinity IgE receptor (FcεRI) is involved in the pathogenesis of allergen-induced immune responsiveness in atopic diseases like atopic dermatitis (AD). We sought to determine FcεRI gene polymorphisms are associated with AD in Korean patients, and analyzed the relevance of FcεRI gene polymorphisms and serum IgE levels. We conducted a case-control association analysis (175 patients and 56 controls) of Korean subjects. Genotyping was performed using the TaqMan fluorogenic 5' nuclease assay, and serum levels of IgE were measured using a fluorescence enzyme immunoassay. We found that there were no significant relationships between FcεRI and AD, although there were trends towards an association between the 66T>C (rs2251746) polymorphism and total serum IgE levels in the Korean AD patients. In conclusion, while the 66T>C (rs2251746) of the FcεRIα polymorphism may be linked to AD and higher serum IgE levels, polymorphisms in the FcεRIβ gene did not confer susceptibility to AD in our patient sample.

Unraveling the genetic basis of asthma and allergic diseases

Asthma and allergic diseases are believed to be complex genetic diseases which may result from the interaction of multiple genetic factors and environmental stimuli. In past decades, great efforts have been exerted in unraveling their genetic basis. The strategies in discovering genes and genetic variants, confirming their importance in pathogenesis of asthma and allergic diseases, as well as their strengths and limitations are summarized comprehensively and concisely. The current consensus about the genetic basis of asthma and allergic diseases is briefly described as well.

Genetic variability of the high-affinity IgE receptor alpha-subunit (FcepsilonRIalpha)

Our knowledge on the variability of FCER1A gene encoding for alpha-subunit of the high-affinity immunoglobulin E receptor (FcepsilonRI) that plays a central role in the pathogenesis of allergy and related disorders, has been recently much extended. Last findings from FCER1A mutational screening and genetic association studies, followed by functional analyses of the polymorphisms, are briefly summarized in this mini-review. The association between FCER1A gene variants and total serum IgE levels seems especially interesting and, supported by functional analyses of polymorphisms, may provide a rationale for pharmacogenetic studies on anti-IgE therapy that indirectly suppresses FcepsilonRI expression.

Association Between Serum IgE Levels and the CTLA4 +49A/G and FCER1B -654C/T Polymorphisms in Korean Children With Asthma

PURPOSE

T cells play a central role in cell-mediated immunity, atopic disease, and asthma. The balance of CD28/cytotoxic T-lymphocyte antigen 4 (CTLA4)-derived signal transduction plays an important role in the activation of T cells and an increased immunoglobulin E (IgE) response. The aim of the current study was to investigate the association between polymorphisms in the genes encoding both CTLA4 and the high-affinity IgE receptor 1B (FCER1B) and serum IgE levels in Korean children with asthma.

METHODS

We enrolled 238 controls and 742 children with asthma. The CTLA4 +49A/G and FCER1B -654C/T polymorphisms were genotyped by PCR-restriction fragment length polymorphism analysis.

RESULTS

We observed no difference in the distribution of CTLA4 +49A/G among controls, children with asthma, and those with atopic asthma. In contrast, the GA genotype of CTLA4 +49A/G in children with atopic asthma was significantly higher compared to that in those with non-atopic asthma. Moreover, significantly higher log Dp/Df-specific IgE levels were found in children with asthma and those with atopic asthma carrying one or two copies of the CTLA4 +49A versus those homozygous for +49G. Gene-gene interactions between CTLA4 and FCER1B with the heterozygote and homozygote of variant genotypes were associated with the log Dp/Df-specific IgE levels, but not asthma development. In addition, children with Dp/Df (+) asthma carried an elevated combined genotype of risk allele compared to those with Dp/Df (-) asthma.

CONCLUSIONS

The CTLA4 +49A/G polymorphism may contribute to the production of IgE in Korean children with asthma, especially in Dp/Df-specific IgE levels, but not in the direct development of asthma. In addition, Dp/Df-specific IgE levels with a FCER1B -654C/T polymorphism may involve additive effects.

Involvement of Fc(epsilon)R1beta gene polymorphisms in susceptibility to atopy in Korean children with asthma

INTRODUCTION

IgE-dependent activation of mast cells and basophils through the high-affinity IgE receptor (Fc(epsilon)R1) is involved in the pathogenesis of allergen-induced immune responsiveness in atopic disease including bronchial asthma.

MATERIALS AND METHODS

We genotyped 650 children for allelic determinants at two polymorphic sites, -109T/C and E237G, in the Fc(epsilon)R1beta gene by SNP-IT assays using the SNP stream 25K system.

RESULTS

Distributions of the genotype and allele frequencies of Fc(epsilon)R1beta -109T/C and E237G polymorphisms were significantly associated with atopy (P < 0.05) and elevated serum IgE levels. However, differences in the E237G polymorphism did not reach statistical significance after adjustment for multiple comparisons. The genotypes TC or CC at -109T/C were associated with decreased forced expiratory flow(25-75%) in children with asthma (P < 0.05), but this did not reach statistical significance after correction for multiple comparisons. In addition, haplotype 1 (T-A) was associated with atopy susceptibility (P = 0.0069). Analysis of genotype distributions of haplotypes demonstrated a significantly lower PC(20) for homozygous -/- diploids compared with homozygous Ht1/Ht1 (P = 0.0261).

CONCLUSION

Polymorphisms in the Fc(epsilon)R1beta gene confer susceptibility to atopy in Korean children and may have a disease-modifying effect on airways of asthmatic patients.

No evidence of association between interleukin-13 gene polymorphism in aspirin intolerant chronic urticaria

Aspirin-intolerant chronic urticaria (AICU) is a common condition among the chronic urticaria population, but the genetic mechanism is not yet understood. In this study, the genotypes and haplotypes of three interleukin (IL)-13 polymorphisms, -1510 A>C, -1055C>T, and Arg110Gln (110G>A), as well as their respective clinical phenotypes were examined to determine whether genetic variants of IL-13 play a role in AICU. Single-nucleotide polymorphism (SNP) genotyping was used to compare IL-13 genotype and allele frequencies among 135 patients with AICU, 146 with aspirin-tolerant chronic urticaria (ATCU), and 430 normal controls (NC). Relationships among the AICU phenotype, atopy, and total IgE level were also investigated. The results failed to show a significant difference in the allele or genotype frequencies between the AICU group and either the ATCU or NC group (P>0.05, respectively). Haplotype analysis confirmed that there was no significant difference among the three study groups (P>0.05), nor was there a significant difference in atopy or total IgE level according to the three genetic polymorphisms (P>0.05, respectively). Our data lead to the conclusion that there is no evidence supporting genetic polymorphisms in IL-13 as a genetic risk factor for the development of AICU.

Functional and clinical consequences of Fc receptor polymorphic and copy number variants

Receptors for immunoglobulins (Fc receptors) play a central role during an immune response, as they mediate the specific recognition of antigens of almost infinite diversity by leucocytes, thereby linking the humoral and cellular components of immunity. Indeed, engagement of Fc receptors by immunoglobulins initiates a range of immunoregulatory processes that might also play a role in disease pathogenesis. In the circulation, five main types of immunoglobulins (Ig) exist - namely IgG, IgA, IgE, IgM and IgD and receptors with the ability to recognize and bind to IgG (Fc gamma receptor family), IgE (Fc epsilon RI and CD23), IgA (CD89; Fc alpha/microR) and IgM (Fc alpha/microR) have been identified and characterized. However, it is astonishing that nearly all the known human Fc receptors display extensive genetic variation with clear implications for their function, thus representing a substantial genetic risk factor for the pathogenesis of a range of chronic inflammatory disorders.

Complexities of diagnosis and treatment of allergic respiratory disease in the elderly

Atopic diseases such as rhinitis and asthma are relatively common in children and young adults. However, many patients aged >65 years are also affected by these disorders. Indeed, the literature suggests that between 3-12% and 4-13% of individuals in this age range have allergic rhinitis and asthma, respectively. However, these numbers are most likely underestimates because atopic diseases are frequently not considered in older patients. The diagnosis of both allergic rhinitis and asthma in older patients is more difficult than in younger patients because of a wide differential diagnosis of other diseases that can produce similar symptoms and must be excluded. Furthermore, treatment of these disorders is complicated by the potential for drug interactions, concern about the adverse effects of medications, in particular corticosteroids, and the lack of drug trials specifically targeting treatment of older patients with allergic rhinitis and asthma.

Genome-wide scan on total serum IgE levels identifies FCER1A as novel susceptibility locus

High levels of serum IgE are considered markers of parasite and helminth exposure. In addition, they are associated with allergic disorders, play a key role in anti-tumoral defence, and are crucial mediators of autoimmune diseases. Total IgE is a strongly heritable trait. In a genome-wide association study (GWAS), we tested 353,569 SNPs for association with serum IgE levels in 1,530 individuals from the population-based KORA S3/F3 study. Replication was performed in four independent population-based study samples (total n = 9,769 individuals). Functional variants in the gene encoding the alpha chain of the high affinity receptor for IgE (FCER1A) on chromosome 1q23 (rs2251746 and rs2427837) were strongly associated with total IgE levels in all cohorts with P values of 1.85 x 10(-20) and 7.08 x 10(-19) in a combined analysis, and in a post-hoc analysis showed additional associations with allergic sensitization (P = 7.78 x 10(-4) and P = 1.95 x 10(-3)). The "top" SNP significantly influenced the cell surface expression of FCER1A on basophils, and genome-wide expression profiles indicated an interesting novel regulatory mechanism of FCER1A expression via GATA-2. Polymorphisms within the RAD50 gene on chromosome 5q31 were consistently associated with IgE levels (P values 6.28 x 10(-7)-4.46 x 10(-8)) and increased the risk for atopic eczema and asthma. Furthermore, STAT6 was confirmed as susceptibility locus modulating IgE levels. In this first GWAS on total IgE FCER1A was identified and replicated as new susceptibility locus at which common genetic variation influences serum IgE levels. In addition, variants within the RAD50 gene might represent additional factors within cytokine gene cluster on chromosome 5q31, emphasizing the need for further investigations in this intriguing region. Our data furthermore confirm association of STAT6 variation with serum IgE levels.

Association of three sets of high-affinity IgE receptor (FcepsilonR1) polymorphisms with aspirin-intolerant asthma

BACKGROUND AND OBJECTIVE

The high-affinity IgE receptor comprises a tetramer of the ligand-binding alpha chain, a signal-augmenting beta chain, and a signal-transducing gamma chain dimer on mast cells. We hypothesized that the three subsets of the FCER1 gene may play a role in the development of the aspirin-intolerant asthma (AIA) phenotype and analyzed these genetic polymorphisms in association with clinical parameters in AIA patients.

SUBJECTS AND METHODS

Six polymorphisms of FCER1 (FCERIA-344C>T, FCER1A-95T>C, MS4A2-109T>C, MS4A2 E237G, FCER1G-237A>G, FCER1G-54G>T) were genotyped in 126 AIA patients compared to 177 patients with aspirin-tolerant asthma (ATA) and 222 normal health controls (NC).

RESULTS

A significant difference in the genotype frequencies of FCER1G-237A>G was detected between AIA and ATA patients (p<0.05) both in co-dominant and recessive analysis models, whereas no significant relationships were identified between the frequencies of the other five single-nucleotide polymorphisms and AIA, ATA, and NC subjects. In addition, AIA patients carrying the homozygous AA genotype of FCER1G-237A>G exhibited significantly higher total serum IgE levels than did those with the GG/AG genotype (p=0.012). AIA patients expressing the CT/TT genotype at FCERIA-344C>T showed a higher prevalence of serum IgE specific to Staphylococcal enterotoxin A than did those with the CC genotype (p=0.008).

CONCLUSION

The FCER1G-237A>G and FCERIA-344C>T polymorphisms may contribute to the development of AIA in a Korean population.

A polymorphism of MS4A2 (- 109T > C) encoding the beta-chain of the high-affinity immunoglobulin E receptor (FcepsilonR1beta) is associated with a susceptibility to aspirin-intolerant asthma

BACKGROUND AND OBJECTIVE

The MS4A2 gene, the beta chain of the high-affinity receptor for immunoglobulin (Ig)E, has previously been linked to atopy and asthma. The beta-chain of FcepsilonR1 enhances receptor maturation and signal transduction capacity, leading to the release of proinflammatory mediators and cytokines that can exacerbate the symptom of asthma. This study was performed to evaluate whether two genetic polymorphisms of the FcepsilonR1beta gene (FcepsilonR1beta-109T > C and FcepsilonR1beta E237G) are associated with aspirin-intolerant asthma (AIA). The MS4A2 gene polymorphisms (FcepsilonR1beta-109T > C and FcepsilonR1beta E237G) were determined by SNP-IT assays in patients with AIA (N = 164), aspirin-tolerant asthma (ATA, N = 144) and normal controls (NC, N = 264) recruited from a Korean population.

RESULTS

The genotype frequencies of FcepsilonR1beta-109T > C and E237G polymorphisms were not significantly associated with the pathogenesis of AIA. However, FcepsilonR1beta-109T > C polymorphism was significantly associated with the presence of specific IgE to Staphylococcal enterotoxin B (SEB); the number of subjects carrying both homozygous TT genotype of FcepsilonR1beta-109T > C and specific IgE to SEB was significantly higher in the AIA group when compared with the other control groups (P = 0.01, odds ratio (OR) = 7.723, 95% confidence interval (CI) = 1.327-39.860 for AIA vs. ATA; P = 0.02, OR = 6.364, 95% CI = 1.149 approximately 35.229 for AIA vs. NC). In addition, luciferase reporter assays also showed that the FcepsilonR1beta-109T allele was associated with higher promoter activity of MS4A2 in both RBL-2H3 and A549 cell lines.

CONCLUSION

FcepsilonR1beta-109T > C polymorphism may increase expression of MS4A2 by mast cells, leading to enhanced release of proinflammatory mediators in the asthmatic airway, contributing to increased susceptibility to AIA.

Genetic polymorphisms at FCER1B and PAI-1 and asthma susceptibility

BACKGROUND

We previously detected a promoter polymorphism (- 109C/T) in the gene for the beta-chain of the high-affinity receptor for IgE (FCER1B), which was associated with total serum IgE levels but not with asthma in a Japanese population. A genetic interaction is biologically plausible between FcepsilonRI-beta and the plasminogen activator inhibitor 1 (PAI-1), which is highly expressed in mast cells in asthmatics and plays an essential role in airway remodelling. We hypothesized that FCER1B promoter polymorphisms, by modifying the intensity of mast cell activation signals, modulate the genetic effects of a functional 4G/5G polymorphism in the PAI-1 gene on asthma. OBJECTICIVE: To examine whether FCER1B promoter polymorphisms (- 109C/T and - 654C/T) influence the genetic effects of the functional polymorphism (4G/5G) at the PAI-1 promoter region on asthma susceptibility using a case-control analysis.

METHODS

Subjects (374 asthmatic patients and 374 non-asthmatic controls) were divided into combined genotype groups based on the presence of FCER1B - 109TT and - 654CC genotypes and the PAI-1 4G allele. Logistic regression analysis was used to estimate adjusted odds ratios for asthma associated with the different genotype groups.

RESULTS

Individuals homozygous for the FCER1B - 109T/ - 654C haplotype and the PAI - 1 5G allele had a reduced susceptibility to asthma; the odds ratio for the development of asthma was 0.20 (95% confidence interval, 0.084 - 0.46; P = 0.00015) for them, compared with individuals also homozygous for the - 109T/- 654C haplotype at FCER1B but carrying the 4G allele at PAI-1. The regression model also showed an interaction of the PAI-1 4G/5G genotype with the FCER1B-109C/T (P for interaction = 0.0017) or FCER1B-654C/T (P for interaction = 0.031) on asthma.

CONCLUSION

The present findings suggest a synergistic interaction between FCER1B and PAI-1 genes in asthma susceptibility.

Multilocus analysis of atopy in Korean children using multifactor-dimensionality reduction

BACKGROUND

Atopy is considered to be a complex genetic trait and does not follow a simple mendelian pattern of inheritance. It is now well recognised that gene-gene interactions are important in complex genetic disease.

AIM

To analyse the influence of gene-gene interactions in the development of atopy.

METHODS

A total of 2055 ethnically identical participants aged 10-18 years living in rural areas on Jeju Island, Korea, were randomly recruited. Atopy was defined as a positive skin prick test response to one or more common inhalant allergens. Gene-gene interactions among 12 polymorphic loci were analysed in the seven candidate genes of atopy using the multidimensionality-reduction method.

RESULTS

A significant interaction was found between V297I in the gene coding vascular endothelial growth factor receptor 2 (KDR) and -308G-->A in the gene coding tumour necrosis factor (TNF)alpha on the risk of atopy, with a cross-validation consistency of 10 out of 10 and a prediction error of 35.9% (p = 0.001). Conventional logistic regression also revealed significant interactions between KDR and TNF for atopy. Individuals with the variant allele of -308G-->A in TNF (GA or AA) and V297I in KDR (VI or II) had a significantly higher risk of atopy (OR 2.23; 95% CI 1.48 to 3.57).

CONCLUSION

KDR and TNF may synergistically influence the development of atopy through gene-gene interaction in Korean children and adolescents.

Sequence variants of the secreted phosphoprotein 1 gene are associated with total serum immunoglobulin E levels in a Japanese population

BACKGROUND

Secreted phosphoprotein 1 (SPP1) is a cytokine with pleiotrophic immunological activities, including activation of macrophage chemotaxis and T-helper type 1 (Th1) immune responses. SPP1 gene polymorphisms have been shown to be associated with several immune inflammatory diseases including multiple sclerosis (MS), which is characterized by fewer allergic symptoms and lower numbers of allergen sensitizations.

OBJECTIVE

The present study examined whether SPP1 gene polymorphisms are associated with total serum IgE levels, atopy and asthma in a Japanese population.

METHODS

This case-control association analysis examined 611 subjects, including 268 subjects with asthma. We genotyped three promoter and two exon polymorphisms at SPP1: -1687A/G; -381T/C; -94 deletion/G; 5891C/T; and 7052T/C. Results Association analyses of SPP1 polymorphisms showed that homozygosities for the 5891T allele (P=0.009) and 7052C allele (P=0.001) were significantly associated with increased levels of total IgE in non-asthmatic subjects. However, these variants were not associated with asthma and atopy. Interestingly, individuals carrying the 5891C allele, which is more prevalent in patients with MS in Japanese populations, displayed significantly lower levels of total serum IgE. Individuals homozygous for the 7052C allele, which is associated with development of systemic lupus erythematosus, displayed significantly higher total serum IgE levels.

CONCLUSION

These findings suggest that genetic polymorphisms in SPP1 may play a role in controlling basal levels of total serum IgE, independent of atopy.

CD28/CTLA-4--CD80/CD86 and ICOS--B7RP-1 costimulatory pathway in bronchial asthma

Costimulatory molecules are cell surface glycoproteins that can direct, modulate and fine-tune T-cell receptor signals. The B7-1/B7-2--CD28/CTLA-4 and ICOS-B7RP-1 pathway provides key second signals that can regulate the activation, inhibition and fine-tuning of T-lymphocyte responses. The expression of B7-1/B7-2--CD28/CTLA-4 molecules on clinical samples from patients with asthma have been well studied, and the results indicate that different extents of these molecules are expressed on the surface of various cells, and that the concentrations of soluble form of these molecules are elevated in the sera of patients with asthma. There is a burst of papers describing an important role for B7-1/B7-2--CD28/CTLA-4 pathway in the Th1/Th2 balance. Similarly, ICOS stimulates both Th1 and Th2 cytokine production but may have a preferential role in Th2 cell development. Moreover, The B7-1/B7-2-CD28/CTLA-4 and ICOS-B7RP-1 pathway has been suggested of being involved in the development of airway inflammation and airway hyperresponsiveness. Further study of the functions of the pathways within the CD28/CTLA-4--CD80/CD86 and ICOS--B7RP-1 superfamily individually and their interplay should provide insights into the pathogenesis of asthma, and has great therapeutic potential for treatment of asthma.

Polymorphisms of high-affinity IgE receptor and histamine-related genes in patients with ASA-induced urticaria/angioedema

The pathogenic mechanism of ASA-induced urticaria/angioedema (AIU) is still poorly understood, but it has been known that histamine releasing by cutaneous mast cell activation is considered to be an important role. Considering the importance of histamine in AIU, we speculated that a genetic abnormality of histamine-related genes such as a high-affinity IgE receptor, a metabolic enzyme of histamines and histamine receptors, may be involved in the development of AIU. Enrolled in the study were 110 patients with AIU, 53 patients without ASA hypersensitivity who had various drug allergies presenting as exanthematous skin symptoms, and 99 normal healthy controls (NC). Eleven single nucleotide polymorphisms (SNPs) of the beta chain of the high-affinity IgE receptor (FCER1B) and three histamine-related genes-histamine N-methyltransferase (HNMT), histamine H1 receptor (HRH1), histamine H2 receptor (HRH2)-were screened using the SNP-IT assay based on a single base extension method. No significant differences were observed in allele and genotype frequencies, and haplotype frequencies of all the SNPs of FCER1B, HNMT, HRH1, and HRH2 among the three groups (p>0.05, respectively). These results suggest that the polymorphisms of FCER1B and the three histamine-related genes may not contribute to the development of AIU phenotype in the Korean population.

The E237G polymorphism of the high-affinity IgE receptor beta chain and asthma

BACKGROUND

The beta chain of high-affinity IgE receptor (FcepsilonRI beta) has been proposed as a candidate gene for asthma and atopic diseases.

OBJECTIVES

To determine the prevalence of the E237G polymorphism of the FcepsilonRI beta gene and to investigate its association with asthma and total IgE levels in 3 Asian populations.

METHODS

A total of 291 asthmatic patients (141 Chinese, 68 Malay, and 82 Indian) and 355 asymptomatic blood donors (157 Chinese, 100 Malay, and 98 Indian) were recruited. The E237G genotype was determined by allele-specific polymerase chain reaction. Total serum IgE level was measured by enzyme-linked immunosorbent assay.

RESULTS

The G allele was more common in Chinese controls (17.9%) than in Malay (11.5%) (P = .05) and Indian (9.2%) (P = .01) controls. Genotypes with the G allele were more prevalent in asthmatic patients in the Chinese population (odds ratio, 1.97; 95% confidence interval, 1.05-3.77; P = .04).

CONCLUSIONS

There were interethnic differences in the frequencies of the G variant among Chinese, Malay, and Indian populations. The E237G polymorphism of FcsRI beta may be a risk factor for asthma in the Chinese population.

Association studies for asthma and atopic diseases: a comprehensive review of the literature

Hundreds of genetic association studies on asthma-related phenotypes have been conducted in different populations. To date, variants in 64 genes have been reported to be associated with asthma or related traits in at least one study. Of these, 33 associations were replicated in a second study, 9 associations were not replicated either in a second study or a second sample in the same study, and 22 associations were reported in just a single published study. These results suggest the potential for a great amount of heterogeneity underlying asthma. However, many of these studies are methodologically limited and their interpretation hampered by small sample sizes.

A functional polymorphism in the RANTES gene promoter is associated with the development of late-onset asthma

The CC chemokine regulated upon activation, normal T-cell expressed and secreted (RANTES) attracts eosinophils, basophils, and T cells during inflammation and immune response, indicating a possible role for this chemokine in asthma. Both the -403A and -28G alleles of the RANTES promoter region exhibit significantly enhanced promoter activity in reporter constructs in vitro. We therefore investigated the genetic influence of these alleles on the development of asthma using case-control analysis in a Japanese population (298 patients with asthma and 311 control subjects). Given the evidence for heterogeneity of asthma according to age at onset, we divided patients with asthma into three subgroups: 117 late-onset patients with asthma (onset at more than 40 years of age), 83 middle-onset patients with asthma (onset at 20 to 40 years of age), and 98 early-onset patients with asthma (onset at less than 20 years of age). The -28G allele was significantly associated with late-onset asthma (odds ratio = 2.033; 95% confidence interval, 1.379-2.998; corrected p < 0.0025) but was not associated with the other two asthma subgroups. The -403A allele was not associated with any of the asthma subgroups. Further evidence of the importance of the -28G allele was a significant increase in the production of RANTES in vitro in individuals who carried this allele. Our findings suggest that, among Japanese, the -28G allele of the RANTES promoter region confers susceptibility to late-onset asthma.

Interactions between genes and environmental factors in asthma and atopy: new developments

Asthma and associated phenotypes are complex traits most probably caused by an interaction of multiple disease susceptibility genes and environmental factors. Major achievements have occurred in identifying chromosomal regions and polymorphisms in candidate genes linked to or associated with asthma, atopic dermatitis, IgE levels and response to asthma therapy. The aims of this review are to explain the methodology of genetic studies of multifactorial diseases, to summarize chromosomal regions and polymorphisms in candidate genes linked to or associated with asthma and associated traits, to list genetic alterations that may alter response to asthma therapy, and to outline genetic factors that may render individuals more susceptible to asthma and atopy due to environmental changes.

Allelic frequencies and patterns of single-nucleotide polymorphisms in candidate genes for asthma and atopy in Iceland

Numerous asthma and atopy loci have been reported in studies demonstrating associations of the asthma-related phenotypes atopy, elevated IgE levels, and bronchial hyperresponsiveness with alleles of microsatellite markers and single-nucleotide polymorphisms (SNPs) within specific cytokine/chemokine and IgE-regulating genes. Although the studies reporting these observations are compelling, most of them lack statistical power. We assessed the nature, pattern, and frequency of SNPs in 24 candidate genes in Iceland and looked for associations with asthma and atopy. We identified 42 SNPs with an average minor allele frequency of 20.3% (asthma) and 20.7% (control). Twenty SNPs (48%) were within coding sequences and 90% of those led to a predicted change in protein sequence. No differences were detected in the allelic frequencies of SNPs in any of these candidate genes between control subjects and the patients with atopic asthma. Moreover, linkage analysis that included 269 patients with atopic asthma uncovered no evidence of linkage to markers associated with these genes. We conclude that this study has failed to produce evidence in support of the notion that variations within these 24 candidate atopy and asthma genes significantly influence the expression of the atopic asthmatic phenotype or contribute to the susceptibility of atopic asthma.

(CCTTT)n repeat polymorphism in the NOS2 gene promoter is associated with atopy

BACKGROUND

Several studies have shown that nitric oxide (NO) plays a role in the regulation of the T(H)1/T(H)2 balance, indicating the potential for NO to contribute to the development of atopy and several other allergic diseases, including bronchial asthma. NO synthase 2 (NOS2) is critically involved in the synthesis of NO during several inflammatory states, and the gene encoding NOS2 is located at chromosome 17q11.2-q12, where 2 genome scans have identified a candidate locus for atopy and asthma.

OBJECTIVE

The 14-repeat allele of the (CCTTT)(n) repeat polymorphism in the NOS2 promoter region is a powerful enhancer of promoter activity in reporter constructs in vitro. We tested whether this potentially functional allele in the NOS2 gene influences the development of atopy and asthma.

METHODS

We studied a total of 497 unrelated Japanese subjects (141 nonatopic healthy controls, 102 atopic healthy controls, 56 nonatopic asthmatic subjects, and 198 atopic asthmatic subjects). The odds ratio (OR) was calculated for atopy and asthma in carriers of the 14-repeat allele through use of logistic regression models. Atopy was defined as a positive specific IgE level to at least 1 of 10 common inhaled allergens.

RESULTS

The 14-repeat allele was inversely associated with atopy (OR = 0.42, P < .01). The association remained significant when the model was controlled for asthmatic status (OR = 0.36, P < .01). This allele, however, was associated neither with the development of asthma nor with total serum IgE levels.

CONCLUSION

Our findings suggest that the (CCTTT)(n) repeat polymorphism in the promoter of the NOS2 gene that affects promoter activity is a risk factor for the development of atopy, and this genetic effect seems independent of asthma.

Current concepts on the genetics of asthma

Asthma is a complex genetic disorder with variable phenotype, largely attributed to the interactions of the environment and multiple genes, each potentially having small effects. Numerous asthma and atopy loci have been reported in studies demonstrating associations and/or linkage of the asthma-associated phenotypes, atopy, elevated IgE levels, and bronchial hyperresponsiveness to alleles of microsatellite markers and single nucleotide polymorphisms within specific cytokine/chemokine and IgE regulating genes. Although the studies reporting these observations are compelling, most of them lack statistical power. This review compiles the evidence that supports linkage and associations to the various genetic loci and candidate genes. Whereas significant progress has been made in the field of asthma genetics in the past decade, the roles of the genes and genetic variations within the numerous candidate asthma genes that have been found to associate with the expression of the asthmatic phenotype remain to be determined.