Association of IFN-gamma and IFN regulatory factor 1 polymorphisms with childhood atopic asthma

TH2-driven manifestations of inborn errors of immunity

Monogenic lesions in pathways critical for effector functions responsible for immune surveillance, protection against autoinflammation, and appropriate responses to allergens and microorganisms underlie the pathophysiology of inborn errors of immunity (IEI). Variants in cytokine production, cytokine signaling, epithelial barrier function, antigen presentation, receptor signaling, and cellular processes and metabolism can drive autoimmunity, immunodeficiency, and/or allergic inflammation. Identification of these variants has improved our understanding of the role that many of these proteins play in skewing toward TH2-related allergic inflammation. Early-onset or atypical atopic disease, often in conjunction with immunodeficiency and/or autoimmunity, should raise suspicion for an IEI. This becomes a diagnostic dilemma if the initial clinical presentation is solely allergic inflammation, especially when the prevalence of allergic diseases is becoming more common. Genetic sequencing is necessary for IEI diagnosis and is helpful for early recognition and implementation of targeted treatment, if available. Although genetic evaluation is not feasible for all patients with atopy, identifying atopic patients with molecular immune abnormalities may be helpful for diagnostic, therapeutic, and prognostic purposes. In this review, we focus on IEI associated with TH2-driven allergic manifestations and classify them on the basis of the affected molecular pathways and predominant clinical manifestations.

Calpeptin may reverse glucocorticoid-resistance of allergic rhinitis associated with cigarette smoke exposure by down-regulating interferon regulatory factor 1

Cigarette smoke exposure is an important factor in chronic inflammation in patients with allergic rhinitis (AR); however, the relationship between cigarette smoke and AR-related glucocorticoid resistance requires further study. In mice, calpeptin significantly reduces inflammation of the lower respiratory tract caused by cigarette smoke, but whether it can treat glucocorticoid-resistant AR caused by cigarette smoke requires further research. In this study, we confirmed that cigarette smoke exposure can aggravate the Th2 inflammatory response in AR leading to glucocorticoid resistance. The underlying mechanism may be related to decreased expression of DNA methyltransferase 3a (Dnmt3a), and increased expression of interferon regulatory factor 1 (IRF1). In addition, we found that calpeptin can inhibit the expression of IRF1 and thus treat AR-associated glucocorticoid resistance in rats exposed to cigarette smoke. These data suggest that calpeptin may downregulate IRF1 and therefore treat glucocorticoid resistance in AR-associated with cigarette smoke exposure.

Beyond Unconventional: What Do We Really Know about Group 2 Innate Lymphoid Cells?

Group 2 innate lymphoid cells (ILC2s) are a set of effectors that mediate the expulsion of helminthic parasites but also drive allergic lung inflammation. As innate agents, they do not recognize Ag, instead, they are sensitive to alarmin engagement, upon which they produce type 2 cytokines that amplify adaptive immunity. Their lymphoid identity appoints them as an intriguing group of unconventional cells; however, increasing evidence is unraveling a series of unprecedented functions that <5 years ago were unthinkable for ILC2s, such as acquiring a proinflammatory identity that enables them to support TH1 immune responses. Their plastic nature has allowed the characterization of ILC2s in more detail than ever; however, the novelty of ILC2 biology requires constant updates and recapitulations. This review provides an overview of ILC2s and describes memory ILC2, regulatory ILC2, inflammatory ILC2, and type 1 ILC2 subsets based on activation status, tissue environments, and function.

Sensing and signaling of immunogenic extracellular RNAs restrain group 2 innate lymphoid cell-driven acute lung inflammation and airway hyperresponsiveness

Repeated exposures to environmental allergens in susceptible individuals drive the development of type 2 inflammatory conditions such as asthma, which have been traditionally considered to be mainly mediated by Th2 cells. However, emerging evidence suggest that a new innate cell type, group 2 innate lymphoid cells (ILC2), plays a central role in initiating and amplifying a type 2 response, even in the absence of adaptive immunity. At present, the regulatory mechanisms for controlling ILC2 activation remain poorly understood. Here we report that respiratory delivery of immunogenic extracellular RNA (exRNAs) derived from RNA- and DNA-virus infected cells, was able to activate a protective response against acute type 2 lung immunopathology and airway hyperresponsiveness (AHR) induced by IL-33 and a fungal allergen, A. flavus, in mice. Mechanistically, we found that the innate immune responses triggered by exRNAs had a potent suppressive effect in vivo on the proliferation and function of ILC2 without the involvement of adaptive immunity. We further provided the loss-of-function genetic evidence that the TLR3- and MAVS-mediated signaling axis is essential for the inhibitory effects of exRNAs in mouse lungs. Thus, our results indicate that the host detection of extracellular immunostimulatory RNAs generated during respiratory viral infections have an important function in the regulation of ILC2-driven acute lung inflammation.

DNA methylation profile is a quantitative measure of biological aging in children

DNA methylation changes within the genome can be used to predict human age. However, the existing biological age prediction models based on DNA methylation are predominantly adult-oriented. We established a methylation-based age prediction model for children (9-212 months old) using data from 716 blood samples in 11 DNA methylation datasets. Our elastic net model includes 111 CpG sites, mostly in genes associated with development and aging. The model performed well and exhibited high precision, yielding a 98% correlation between the DNA methylation age and the chronological age, with an error of only 6.7 months. When we used the model to assess age acceleration in children based on their methylation data, we observed the following: first, the aging rate appears to be fastest in mid-childhood, and this acceleration is more pronounced in autistic children; second, lead exposure early in life increases the aging rate in boys, but not in girls; third, short-term recombinant human growth hormone treatment has little effect on the aging rate of children. Our child-specific methylation-based age prediction model can effectively detect epigenetic changes and health imbalances early in life. This may thus be a useful model for future studies of epigenetic interventions for age-related diseases.

IRF-1 SNPs influence the risk for childhood allergic asthma: A critical role for pro-inflammatory immune regulation

BACKGROUND

Allergic and non-allergic childhood asthma has been characterized by distinct immune mechanisms. While interferon regulating factor 1 (IRF-1) polymorphisms (SNPs) influence atopy risk, the effect of SNPs on asthma phenotype-specific immune mechanisms is unclear. We assessed whether IRF-1 SNPs modify distinct immune-regulatory pathways in allergic and non-allergic childhood asthma (AA/NA).

METHODS

In the CLARA study, asthma was characterized by doctor's diagnosis and AA vs NA by positive or negative specific IgE. Children were genotyped for four tagging SNPs within IRF-1 (n = 172). mRNA expression was measured with qRT-PCR. Gene expression was analyzed depending on genetic variants within IRF-1 and phenotype including haplotype estimation and an allelic risk score.

RESULTS

Carrying the risk alleles of IRF-1 in rs10035166, rs2706384, or rs2070721 was associated with increased risk for AA. Carrying the non-risk allele in rs17622656 was associated with lower risk for AA but not NA. In AA carrying the risk alleles, an increased pro-inflammatory expression of ICAM3, IRF-8, XBP-1, IFN-γ, RGS13, RORC, and TSC2 was observed. NOD2 expression was decreased in AA with risk alleles in rs2706384 and rs10035166 and with risk haplotype. Further, AA with risk haplotype showed increased IL-13 secretion. NA with risk allele in rs2070721 compared to non-risk allele in rs17622656 showed significantly upregulated calcium, innate, mTOR, neutrophil, and inflammatory-associated genes.

CONCLUSION

IRF-1 polymorphisms influence the risk for childhood allergic asthma being associated with increased pro-inflammatory gene regulation. Thus, it is critical to implement IRF-1 genetics in immune assessment for childhood asthma phenotypes.

Reciprocal regulation of the Il9 locus by counteracting activities of transcription factors IRF1 and IRF4

The T helper 9 (Th9) cell transcriptional network is formed by an equilibrium of signals induced by cytokines and antigen presentation. Here we show that, within this network, two interferon regulatory factors (IRF), IRF1 and IRF4, display opposing effects on Th9 differentiation. IRF4 dose-dependently promotes, whereas IRF1 inhibits, IL-9 production. Likewise, IRF1 inhibits IL-9 production by human Th9 cells. IRF1 counteracts IRF4-driven Il9 promoter activity, and IRF1 and IRF4 have opposing function on activating histone modifications, thus modulating RNA polymerase II recruitment. IRF1 occupancy correlates with decreased IRF4 abundance, suggesting an IRF1-IRF4-binding competition at the Il9 locus. Furthermore, IRF1 shapes Th9 cells with an interferon/Th1 gene signature. Consistently, IRF1 restricts the IL-9-dependent pathogenicity of Th9 cells in a mouse model of allergic asthma. Thus our study reveals that the molecular ratio between IRF4 and IRF1 balances Th9 fate, thus providing new possibilities for manipulation of Th9 differentiation.

IFN-γ signalling inhibits production of IL-9, the defining cytokine of the Th9 cell subset. Here the authors show that IFN-γ does this by driving IRF1 to compete with IRF4 for Il9 promoter binding and skewing these cells towards a Th1 phenotype, an effect that reduces asthmatic inflammation in mice.

Abnormal corticosteroid signalling in airway smooth muscle: mechanisms and perspectives for the treatment of severe asthma

Growing in vivo evidence supports the concept that airway smooth muscle produces various immunomodulatory factors that could contribute to asthma pathogenesis via the regulation of airway inflammation, airway narrowing and remodelling. Targeting ASM using bronchial thermoplasty has provided undeniable clinical benefits for patients with uncontrolled severe asthma who are refractory to glucocorticoid therapy. The present review will explain why the failure of glucocorticoids to adequately manage patients with severe asthma could derive from their inability to affect the immunomodulatory potential of ASM. We will support the view that ASM sensitivity to glucocorticoid therapy can be blunted in severe asthma and will describe some of the factors and mechanisms that could be responsible for glucocorticoid insensitivity.

IL-1 is a critical regulator of group 2 innate lymphoid cell function and plasticity

Group 2 innate lymphoid cells (ILC2 cells) are important for type 2 immune responses and are activated by the epithelial cytokines interleukin 33 (IL-33), IL-25 and thymic stromal lymphopoietin (TSLP). Here we demonstrated that IL-1β was a critical activator of ILC2 cells, inducing proliferation and cytokine production and regulating the expression of epithelial cytokine receptors. IL-1β also governed ILC2 plasticity by inducing low expression of the transcription factor T-bet and the cytokine receptor chain IL-12Rβ2, which enabled the conversion of these cells into an ILC1 phenotype in response to IL-12. This transition was marked by an atypical chromatin landscape characterized by the simultaneous transcriptional accessibility of the locus encoding interferon-γ (IFN-γ) and the loci encoding IL-5 and IL-13. Finally, IL-1β potentiated ILC2 activation and plasticity in vivo, and IL-12 acted as the switch that determined an ILC2-versus-ILC1 response. Thus, we have identified a previously unknown role for IL-1β in facilitating ILC2 maturation and plasticity.

Effect of the plant derivative Compound A on the production of corticosteroid-resistant chemokines in airway smooth muscle cells

Preclinical models of human conditions including asthma showed the therapeutic potential of Compound A (CpdA), a dissociated glucocorticoid (GC) receptor (GRα) ligand. Whether CpdA inhibits GC resistance, a central feature of severe asthma, has not been addressed. We investigated whether CpdA modulates cytokine-induced GC resistance in human airway smooth muscle (ASM) cells. Healthy and asthmatic ASM cells were treated with TNF-α/IFN-γ for 24 hours in the presence or absence of CpdA. ELISA and quantitative PCR assays were used to assess the effect of CpdA on chemokine expression. Activation of GRα by CpdA was assessed by quantitative PCR, immunostaining, and receptor antagonism using RU486. An effect of CpdA on the transcription factor interferon regulatory factor 1 (IRF-1) was investigated using immunoblot, immunostaining, and small interfering RNA (siRNA) knockdown. CpdA inhibited production of fluticasone-resistant chemokines CCL5, CX3CL1, and CXCL10 at protein and mRNA levels in both asthmatic and healthy cells. CpdA failed to induce expression of GC-induced Leucine Zipper while transiently inducing mitogen-activated protein kinase phosphatase 1 (MKP-1) at both mRNA and protein levels. CpdA inhibitory action was not associated with GRα nuclear translocation, nor was it prevented by RU486 antagonism. Activation of IRF-1 by TNF-α/IFN-γ was inhibited by CpdA. IRF-1 siRNA knockdown reduced cytokine-induced CCL5 and CX3CL1 production. siRNA MKP-1 prevented the inhibitory effect of CpdA on cytokine-induced CXCL10 production. For the first time, we show that CpdA inhibits the production of GC-resistant chemokines via GRα-independent mechanisms involving the inhibition of IRF-1 and up-regulation of MKP-1. Thus, targeting CpdA-sensitive pathways in ASM cells represents an alternative therapeutic approach to treat GC resistance in asthma.

Peripheral blood IRF1 expression as a marker for glucocorticoid sensitivity

OBJECTIVE

Despite of the common usage of glucocorticoids (GCs), a significant portion of asthma patients exhibit GC insensitivity. This could be mediated by diverse mechanisms, including genomics. Recent work has suggested that measuring changes in gene expression may provide more predictive information about GC insensitivity than baseline gene expression alone, and that expression changes in peripheral blood may be reflective of those in the airway.

METHODS

We performed in silico discovery using gene expression omnibus (GEO) data that evaluated GC effect on gene expression in multiple tissue types. Subsequently, candidate genes whose expression levels are affected by GC were examined in cell lines and in primary cells derived from human airway and blood.

RESULTS

Through gene expression omnibus analysis, we identified interferon regulator factor 1 (IRF1), whose expression is affected by GC treatment in airway smooth muscle cells, normal human bronchial epithelial (NHBE) cells, and lymphoblastoid cell lines (LCLs). Significant IRF1 downregulation post GC exposure was confirmed in two cultured airway epithelial cell lines and primary NHBE cells (P<0.05). We observed large interindividual variation in GC-induced IRF1 expression changes among primary NHBE cells tested. Significant downregulation of IRF1 was also observed in six randomly selected LCLs (P<0.05), with variable degrees of downregulation among different samples. In peripheral blood mononuclear cells obtained from healthy volunteers, variable downregulation of IRF1 by GC was also shown. NFKB1, a gene whose expression is known to be downregulated by GC and the degree of downregulation of which is reflective of GC response, was used as a control in our study. IRF1 shows more consistent downregulation across tissue types when compared with NFKB1.

CONCLUSION

Our results suggest that GC-induced IRF1 gene expression changes in peripheral blood could be used as a marker to reflect GC response in the airway.

Untargeted Proteomics and Systems-Based Mechanistic Investigation of Artesunate in Human Bronchial Epithelial Cells

The antimalarial drug artesunate is a semisynthetic derivative of artemisinin, the principal active component of a medicinal plant Artemisia annua. It is hypothesized to attenuate allergic asthma via inhibition of multiple signaling pathways. We used a comprehensive approach to elucidate the mechanism of action of artesunate by designing a novel biotinylated dihydroartemisinin (BDHA) to identify cellular protein targets of this anti-inflammatory drug. By adopting an untargeted proteomics approach, we demonstrated that artesunate may exert its protective anti-inflammatory effects via direct interaction with multiple proteins, most importantly with a number of mitochondrial enzymes related to glucose and energy metabolism, along with mRNA and gene expression, ribosomal regulation, stress responses, and structural proteins. In addition, the modulatory effects of artesunate on various cellular transcription factors were investigated using a transcription factor array, which revealed that artesunate can simultaneously modulate multiple nuclear transcription factors related to several major pro- and anti-inflammatory signaling cascades in human bronchial epithelial cells. Artesunate significantly enhanced nuclear levels of nuclear factor erythroid-2-related factor 2 (Nrf2), a key promoter of antioxidant mechanisms, which is inhibited by the Kelch-like ECH-associated protein 1 (Keap1). Our results demonstrate that, like other electrophilic Nrf2 regulators, artesunate activates this system via direct molecular interaction/modification of Keap1, freeing Nrf2 for transcriptional activity. Altogether, the molecular interactions and modulation of nuclear transcription factors provide invaluable insights into the broad pharmacological actions of artesunate in inflammatory lung diseases and related inflammatory disorders.

Genetic association of key Th1/Th2 pathway candidate genes, IRF2, IL6, IFNGR2, STAT4 and IL4RA, with atopic asthma in the Indian population

Asthma is a complex, multifactorial disease resulting due to dysregulated immune responses. Genetic factors contribute significantly to asthma pathogenesis, and identification of these factors is one of the major goals in understanding the disease. Th1/Th2 helper differentiation has a critical role in modulating the phenotypes associated with atopic asthma. This study was aimed at identifying genetic modifiers of asthma in selected genes involved in T helper differentiation. A total of 354 single-nucleotide polymorphisms (SNPs) in 33 candidate genes were genotyped in a case-control cohort (cases=147, controls=199) and families (n=247) using Illumina's Golden Gate Assay. Five SNPs, rs3733475A/C (IRF2), rs2069832A/G (IL6), rs2012075G/A (IFNGR2) and rs1400656G/A (STAT4) and rs1805011C/A (IL4RA) were found to be associated with asthma in family based as well as in case-control analyses (P=0.002, P=0.001, P=0.004, P=0.003 and P=0.001, respectively). Interestingly, the minor alleles at these loci showed a protective effect. A five loci haplotype, TAACG, in IRF2 gene, was significantly associated with asthma in families (P=1.1 × 10(-6)) and in case-control cohort (P=0.01). In conclusion, our studies led to identification of some key candidate genes, namely IRF2, IL6, IFNGR2, STAT4 and IL4RA that modulate genetic susceptibility to asthma in the Indian population. Also, this is the first report of independent association of IL6 gene polymorphism with atopic asthma.

Genome-wide interaction studies reveal sex-specific asthma risk alleles

Asthma is a complex disease with sex-specific differences in prevalence. Candidate gene studies have suggested that genotype-by-sex interaction effects on asthma risk exist, but this has not yet been explored at a genome-wide level. We aimed to identify sex-specific asthma risk alleles by performing a genome-wide scan for genotype-by-sex interactions in the ethnically diverse participants in the EVE Asthma Genetics Consortium. We performed male- and female-specific genome-wide association studies in 2653 male asthma cases, 2566 female asthma cases and 3830 non-asthma controls from European American, African American, African Caribbean and Latino populations. Association tests were conducted in each study sample, and the results were combined in ancestry-specific and cross-ancestry meta-analyses. Six sex-specific asthma risk loci had P-values < 1 × 10(-6), of which two were male specific and four were female specific; all were ancestry specific. The most significant sex-specific association in European Americans was at the interferon regulatory factor 1 (IRF1) locus on 5q31.1. We also identify a Latino female-specific association in RAP1GAP2. Both of these loci included single-nucleotide polymorphisms that are known expression quantitative trait loci and have been associated with asthma in independent studies. The IRF1 locus is a strong candidate region for male-specific asthma susceptibility due to the association and validation we demonstrate here, the known role of IRF1 in asthma-relevant immune pathways and prior reports of sex-specific differences in interferon responses.

IFNG+874A/T polymorphisms and IFNG CA repeat polymorphism associated with asthma in Asian--a meta-analysis

INTRODUCTION

Asthma is an etiologically complex disease and develops by the interaction of multiple genes and environmental factors. Previous studies suggested a linkage between the interferon-gamma (INFG) gene cluster in the chromosome 12q region and susceptibility to asthma.

METHODS

This meta-analysis was undertaken to examine the relationship between +874A/T and CA-repeat polymorphisms in INFG gene and asthma. Eligible articles were accumulated via online databases in October 2013. A total of nine articles were included that were associated with the +874A/T polymorphism, involving 470 cases and 574 controls, as well as articles involving CA-repeat polymorphisms, which included 365 cases and 517 controls. The meta-analysis was performed for heterogeneity and calculation of pooled odds ratio and evaluation of publication bias by Egger's linear regression test.

RESULTS

The differences between IFNG polymorphism and the susceptibility to asthma may vary across ethnicities and ages, and also that the allelic frequencies of the AA genotypes in IFNG at +874 is associated with an increased risk of asthma in the Chinese Han adult population; additionally, CA14 occurrence in the first intron can increase the risk of asthma in the Japanese population.

CONCLUSION

Our findings suggested that some polymorphisms in the IFNG gene could act as high prevalence-susceptibility markers of asthma. Larger scale studies are warranted to address these associations among different ethnic populations, ages and the severity of asthma prognosis.

Polymorphism of the rs1800896 IL10 promoter gene protects children from post-bronchiolitis asthma

Viral bronchiolitis is a major cause of hospitalization in infancy, with increased asthma risk in later childhood. However, the principal mechanisms behind post-bronchiolitic asthma have remained unclear. Previously, different cytokine polymorphisms have been associated with asthma occurrence, but no previous follow-up study has investigated cytokine polymorphisms in relation to post-bronchiolitic asthma. We hypothesized that former bronchiolitis patients with cytokine gene variants associating with Th2 cell up-regulation are at asthma risk at preschool age. Our emphasis was in IL10 rs1800896, since IL-10 has an important role in immune tolerance, and lower production of IL-10 has been associated with Th2-type immunology, and accordingly, with increased asthma risk. IL10 rs1800896, IFNG rs2430561, and IL18 rs1872387 polymorphims and their associations with asthma and allergy were studied in 135 preschool-aged children hospitalized for bronchiolitis at age 0-6 months. Parents were interviewed to record asthma and allergy from infancy to present. At age 6.4 years (mean), asthma was present in 17(12.6%), atopic eczema in 47(34.8%) and allergic rhinitis in 36(26.7%) children. IL10 rs1800896 SNP associated significantly with asthma; only 1/32 (3.1%) of those with G/G genotype had asthma (P = 0.04). In logistic regression adjusted for gender, age and atopy, the carriage of allele A (rs1800896) was a significant risk factor for preschool asthma. IFNG rs2430561 or IL18 rs1872387 SNP's had no associations with asthma or allergy. In conclusion, IL10 rs1800896 SNP was significantly associated with preschool asthma after severe lower respiratory tract infection in early infancy.

Functional polymorphisms of interferon-gamma affect pneumonia-induced sepsis

OBJECTIVE

Sepsis is an inflammatory syndrome caused by infection, and both its incidence and mortality are high. Because interferon-gamma (IFN-γ) plays an important role in inflammation, this work assessed IFN-γ single nucleotide polymorphism (SNPs) that may be associated with sepsis.

METHODS

A total of 196 patients with pneumonia-induced sepsis and 213 age- and sex-matched healthy volunteers participated in our study from July 2012 to July 2013 in Guangzhou, China. Patient clinical information was collected. Clinical pathology was assessed in subgroups defined based on clinical criteria, APACHE II (acute physiology and chronic health evaluation) and SOFA (sepsis-related organ failure assessment) scores and discharge rate. Four functional SNPs, -1616T/C (rs2069705), -764G/C (rs2069707), +874A/T (rs2430561) and +3234C/T (rs2069718), were genotyped by Snapshot in both sepsis patients and healthy controls. Pearson's chi-square test or Fisher's exact test were used to analyze the distribution of the SNPs, and the probability values (P values), odds ratios (OR) and 95% confidence intervals (CIs) were calculated.

RESULTS

No mutations in the IFN-γ -764G/C SNP were detected among the participants in our study. The +874A/T and +3234C/T SNPs were in strong linkage disequilibrium (LD) (r(2) = 0.894). The -1616 TC+TT, +874 AT+AA genotype and the TAC haplotype were significantly associated with sepsis susceptibility, while the CTT haplotype was associated with protection against sepsis incidence. Genotype of -1616 TT wasn't only protective against severity of sepsis, but also against higher APACHE II and SOFA scores as +874 AA and +3234 CC. The TAC haplotype was was protective against progression to severe sepsis either.

CONCLUSION

Our results suggest that functional IFN-γ SNPs and their haplotypes are associated with pneumonia-induced sepsis.

Targeting airway smooth muscle in airways diseases: an old concept with new twists

Airway smooth muscle (ASM) manifests a hyper-responsive phenotype in airway disorders such as asthma. ASM also modulates immune responses by secreting mediators and expressing cell-surface molecules that promote recruitment of inflammatory cells to the lungs. The aim of the current article is to highlight therapeutics that may modulate ASM responses in airway disorders and exacerbations.

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

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

Airway smooth muscle and immunomodulation in acute exacerbations of airway disease

Airway smooth muscle (ASM) manifests a hyperresponsive phenotype in airway disorders such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. Current evidence also suggests that ASM modulates immune responses by secreting mediators and expressing cell surface molecules. Such processes amplify or dampen inflammation by inflammatory cells in the airways or by altering cellular responses to viruses, bacteria, or pathogens known to exacerbate airways diseases.

IFNG genotype and sex interact to influence the risk of childhood asthma

BACKGROUND

Asthma is a complex disease characterized by sex-specific differences in incidence, prevalence, and severity, but little is known about the molecular basis of these sex-based differences.

OBJECTIVE

To investigate the genetic architecture of sex differences in asthma risk, we evaluated (1) associations between polymorphisms in the IFNG gene and childhood-onset asthma in combined and sex-specific samples and (2) interactions between polymorphisms and sex on asthma risk.

METHODS

Main and sex-interaction effects of IFNG genetic diversity on asthma risk and IFN-γ levels were examined in a birth cohort of children at high risk for asthma and allergic diseases. Replication of the genetic association was assessed in an independent sample of asthma cases.

RESULTS

Significant genotype-sex interactions on asthma were observed for 2 IFNG single nucleotide polymorphisms, rs2069727 and rs2430561, which were in strong linkage disequilibrium with each other. In contrast, none of the 10 IFNG single nucleotide polymorphisms showed significant main effects on asthma. The observed genotype-sex interaction on asthma was characterized by nonadditivity; that is, heterozygous boys had the highest risk for asthma, and heterozygous girls had the lowest risk. The interaction effect was robust to other asthma risk factors but was limited to children who experienced wheezing illnesses with viral infections during the first 3 years of life. Genotype-sex interactions were also observed in the IFN-γ response to LPS in the first year of life. Finally, the sex-interaction effect was replicated in an independent population of childhood asthma cases.

CONCLUSIONS

These results provide insight into the genetic basis of sex differences in asthma and highlight the potential importance of interactions among sex, genotype, and environmental factors in asthma pathogenesis.

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

BACKGROUND

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

METHODOLOGY/PRINCIPAL FINDINGS

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

CONCLUSIONS/SIGNIFICANCE

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

Genetic studies of the etiology of asthma

Asthma is a heterogeneous disease for which a strong genetic basis is firmly established. Although the generally accepted definition includes three domains of symptoms (variable airway obstruction, airway hyper-responsiveness, and airway inflammation), there is general agreement that, rather than being a single disease entity, asthma consists of related, overlapping syndromes. A considerable proportion of asthma is IgE-mediated, but the observation that not all individuals with asthma are atopic adds to the heterogeneity. Although a genetic basis for asthma is undeniable, elucidation of polymorphisms that are "causal" is greatly hampered by variability in the clinical phenotype, which is likely due to the multiple molecular mechanisms underlying the complex pathological processes involved in disease development and progression. One objective of this review is to consider progress that has been made to date in gene discovery in the field of asthma, with a focus on the evolution of molecular genetic methods that have led to the discoveries thus far, and with a particular focus on the major advances owed to the published genome-wide association studies (GWAS) on asthma to date. A second objective is to consider a Darwinian approach toward understanding the genetic underpinnings of asthma, including evidence supporting a modified Hygiene Hypothesis, which suggests that there are co-associations between asthma risk polymorphisms and polymorphisms associated with another IgE-mediated disease, schistosomiasis. The overall conclusion is that the huge research efforts and expense committed to asthma genetics have changed the perception about disease etiology in general and the functional relevance of the asthma genes identified thus far in particular.

Emerging roles of T helper subsets in the pathogenesis of asthma

The cardinal features of asthma include pulmonary inflammation and airway hyperresponsiveness (AHR). Classically, asthma, specifically allergic asthma, has been attributed to a hyperactive Th2 cell immune response. However, the Th2 cell-mediated inflammation model has failed to adequately explain many of the clinical and molecular aspects of asthma. In addition, the outcomes of Th2-targeted therapeutic trials have been disappointing. Thus, asthma is now believed to be a complex and heterogeneous disorder, with several molecular mechanisms underlying the airway inflammation and AHR that is associated with asthma. The original classification of Th1 and Th2 pathways has recently been expanded to include additional effector Th cell subsets. These include Th17, Th9 and Treg cells. Emerging data highlight the involvement of these new Th cell subsets in the initiation and augmentation of airway inflammation and asthmatic responses. We now review the roles of these recently classified effector Th cell subsets in asthmatic inflammation and the insights they may provide in addition to the traditional Th2 paradigm. The hope is that a clearer understanding of the inflammatory pathways involved and the mediators of inflammation will yield better targeted therapeutics.

Natural killer T cells regulate the development of asthma

Studies in mice, monkeys and humans suggest that invariant natural killer (iNK) T cells play a very important role in the pathogenesis of asthma, a heterogeneous disease associated with airway inflammation and airway hyper-reactivity. The requirement for iNK T cells in multiple mouse models of asthma is novel and surprising, challenging the prevailing dogma that CD4(+) T cells responding to environmental allergens are the key cell type in asthma. In this article, we examine the recent studies of iNK T cells and asthma, and discuss how different subsets of NK T cells function in different forms of asthma, including forms that are independent of adaptive immunity and Th2 cells. Together, these studies suggest that iNK T cells, which can interact with many other cell types including Th2 cells, eosinophils and neutrophils, provide a unifying pathogenic mechanism for many distinct forms of asthma.

Functional analysis of naturally occurring amino acid substitutions in human IFN-gammaR1

IFN-gamma plays an essential role in the IL-12/IL-23/IFN-gamma pathway that is required for the defense against intracellular pathogens. In the IFN-gammaR1 several amino acid substitutions have been reported that abrogate IFN-gamma signaling. These substitutions can lead to a null phenotype and enhanced susceptibility to infection by poorly pathogenic mycobacteria, a disorder known as Mendelian Susceptibility to Mycobacterial Disease (MSMD). More common amino acid variations in the IFN-gammaR1 may also influence IFN-gammaR function, albeit more subtle. To determine the effect of various amino acid substitutions on IFN-gammaR1 expression and function we cloned two newly identified amino acid substitutions (S149L, I352M), four common variations (V14M, V61I, H335P, L467P), seven reported missense mutations (V61Q, V63G, Y66C, C77Y, C77F, C85Y, I87T) and the 818delTTAA mutation in a retroviral expression vector. IFN-gammaR1 expression was determined as well as responsiveness to IFN-gamma stimulation. The two newly discovered variants, and the four common polymorphisms could be detected on the cell surface, however, the V14M, H335P and I352M variants were significantly lower expressed at the cell membrane, compared to the wild type receptor. Despite the variance in cell surface expression, these IFN-gammaR1 variants did not affect function. In contrast to literature, in our model the expression of the V63G variant was severely reduced and its function was severely impaired but not completely abrogated. In addition, we confirmed the severely reduced function of the I87T mutant receptor, the completely abrogated expression and function of the V61E, V61Q, C77F, C77Y and the C85Y mutations, as well as the overexpression pattern of the 818delTTAA mutant receptor. The Y66C mutation was expressed at the cell surface, it was however, not functional. We conclude that the V14M, V61I, S149L, H335P, I352M and L467P are functional polymorphisms. The other variants are deleterious mutations with V61E, V61Q, Y66C, C77F, C77Y and C85Y leading to complete IFN-gammaR1 deficiency, while V63G and I87T lead to partial IFN-gammaR1 deficiency.

Glucocorticoid receptor interacting protein-1 restores glucocorticoid responsiveness in steroid-resistant airway structural cells

Glucocorticoid (GC) insensitivity represents a profound challenge in managing patients with asthma. The mutual inhibition of transcriptional activity between GC receptor (GR) and other regulators is one of the mechanisms contributing to GC resistance in asthma. We recently reported that interferon regulatory factor (IRF)-1 is a novel transcription factor that promotes GC insensitivity in human airway smooth muscle (ASM) cells by interfering with GR signaling (Tliba et al., Am J Respir Cell Mol Biol 2008;38:463-472). Here, we sought to determine whether the inhibition of GR function by IRF-1 involves its interaction with the transcriptional co-regulator GR-interacting protein 1 (GRIP-1), a known GR transcriptional co-activator. We here found that siRNA-mediated GRIP-1 depletion attenuated IRF-1-dependent transcription of the luciferase reporter construct and the mRNA expression of an IRF-1-dependent gene, CD38. In parallel experiments, GRIP-1 silencing significantly reduced GR-mediated transactivation activities. Co-immunoprecipitation and GST pull-down assays showed that GRIP-1, through its repression domain, physically interacts with IRF-1 identifying GRIP-1 as a bona fide transcriptional co-activator for IRF-1. Interestingly, the previously reported inhibition of GR-mediated transactivation activities by either TNF-alpha and IFN-gamma treatment or IRF-1 overexpression was fully reversed by increasing cellular levels of GRIP-1. Together, these data suggest that the cellular accumulation of IRF-1 may represent a potential molecular mechanism mediating altered cellular response to GC through the depletion of GRIP-1 from the GR transcriptional regulatory complexes.

Noncontractile functions of airway smooth muscle cells in asthma

Although pivotal in regulating bronchomotor tone in asthma, airway smooth muscle (ASM) also modulates airway inflammation and undergoes hypertrophy and hyperplasia, contributing to airway remodeling in asthma. ASM myocytes secrete or express a wide array of immunomodulatory mediators in response to extracellular stimuli, and in chronic severe asthma, increases in ASM mass may render the airway irreversibly obstructed. Although the mechanisms by which ASM secretes cytokines and chemokines are the same as those regulating immune cells, there exist unique ASM signaling pathways that may provide novel therapeutic targets. This review provides an overview of our current understanding of the proliferative as well as the synthetic properties of ASM.

Natural killer T cells and the regulation of asthma

A crucial role has been suggested for invariant natural killer T cells (iNKT) in regulating the development of asthma, a complex and heterogeneous disease characterized by airway inflammation and airway hyperreactivity (AHR). iNKT cells constitute a unique subset of T cells responding to endogenous and exogenous lipid antigens, rapidly secreting a large amount of cytokines, which amplify both innate and adaptive immunity. Herein, we review recent studies showing a requirement for iNKT cells in various models of asthma in mice and monkeys as well as studies in human patients. Surprisingly, in several different murine models of asthma, distinct subsets of iNKT cells were required, suggesting that iNKT cells serve as a common critical pathogenic element for many different forms of asthma. The importance of iNKT cells in both allergic and non-allergic forms of asthma, which are independent of adaptive immunity and associated with airway neutrophils, may explain situations previously found to be incompatible with the Th2 paradigm of asthma.

Human interferon regulatory factor-1 gene and its promoter sequences revealed by population-based complete gene sequencing

Interferon regulatory factor-1 (IRF-1) plays important roles in host immunity, cell proliferation and apoptosis. The current GenBank sequence for human IRF-1 (accession number: L05072) was derived from a human placenta DNA library and reported in 1992. In one recent population-based sequence study, we observed consistent discrepancies between our IRF-1 sequence data and GenBank reference sequences suggesting that, current IRF-1 reference sequence was not representative for all populations. By complete gene sequencing, we obtained a representative full-length IRF-1 sequence from a single subject. Compared to submission L05072, our population-based data contains: 35 nucleotide additions, 8 nucleotide removals and another 12 nucleotide replacements. A single nucleotide difference was observed in the IRF-1 promoter sequence compared to GenBank sequence (X53095). These changes were confirmed in 350 Kenyans and 28 non-African donors. The accuracy of a reference sequence is crucial for downstream genetic and functional studies and this study provides more complete and accurate data on the sequence of the human IRF-1 gene and its immediate promoter region.

Transcriptional regulation of cytokine function in airway smooth muscle cells

The immuno-modulatory properties of airway smooth muscle have become of increasing importance in our understanding of the mechanisms underlying chronic inflammation and structural remodeling of the airway wall in asthma and chronic obstructive pulmonary disease (COPD). ASM cells respond to many cytokines, growth factors and lipid mediators to produce a wide array of immuno-modulatory molecules which may in turn orchestrate and perpetuate the disease process in asthma and COPD. Despite numerous studies of the cellular effects of cytokines on cultured ASM, few have identified intracellular signaling pathways by which cytokines modulate or induce these cellular responses. In this review we provide an overview of the transcriptional mechanisms as well as intracellular signaling pathways regulating cytokine functions in ASM cells. The recent discovery of toll-like receptors in ASM cells represents a significant development in our understanding of the immuno-modulatory capabilities of ASM cells. Thus, we also review emerging evidence of the inflammatory response to toll-like receptor activation in ASM cells.

Airway smooth muscle as an immunomodulatory cell

Although pivotal in regulating bronchomotor tone in asthma, airway smooth muscle (ASM) also modulates airway inflammation in asthma. ASM myocytes secrete or express a wide array of immunomodulatory mediators in response to extracellular stimuli, and in chronic severe asthma, increases in ASM mass may also render the airway irreversibly obstructed. Although the mechanisms by which ASM secretes cytokines and chemokines are shared with those regulating immune cells, there exist unique ASM signaling pathways that may provide novel therapeutic targets. This review provides an overview of our current understanding of the proliferative as well as synthetic properties of ASM.

Relationships between specific serum IgE, IgG, IFN-gamma level and IFN-gamma, IFNR1 polymorphisms in patients with penicillin allergy

OBJECTIVE

The findings of numerous studies have suggested that both genetic and environmental influences are involved in the pathogenesis of allergic disease and atopy. We studied the polymorphisms in the interferon (IFN)-gamma (gamma) and IFN-gamma receptor 1 (IFNR1) gene with the aim of clarifying the relationships among these polymorphisms, penicillin allergy and anti-penicillin antibodies.

METHODS

A restriction endonuclease fragment length polymorphism (RFLP)-PCR analysis and sequencing were used to study the IFNR1 and IFN-gamma polymorphisms. The presence and level of eight specific immunoglobulin (Ig)E and IgG antibodies were determined by the radioallergosorbent test (RAST) and enzyme-linked immunosorbent assay (ELISA), respectively.

RESULTS

The positive rates of specific IgE and IgG were 61.11 and 53.92%, respectively. There was no significant difference in the whole-allele of IFN-gamma distribution between patients with a penicillin allergy and control subjects. Allele 7 (18CA repeat) was significantly less frequent in the urticaria group (3.19 vs. 11.93%) than in the controls. There was no difference in IFN-gamma production among different alleles in IFN-gamma. The frequency of G/A (Val/Met) in the IFNR1 gene in allergic patients was significantly less than that in the controls (P < 0.05). There were no significant differences in the positive rate of IgE among different alleles of IFN-gamma. The same was true for the positive rate of IgG.

CONCLUSIONS

The Met/Val allele in IFNR1 gene may have a protective role in the non-penicillin allergic population. The allele 18CA repeat in IFN-gamma gene may be associated with urticaria.

A single nucleotide polymorphism (A --> G) in intron 3 of IFNgamma gene is associated with asthma

Interferon-gamma (IFNgamma) is located on chromosome 12, and a number of studies have detected very strong linkage signals around this gene and asthma. The aim of this study was to analyze the association of a (CA)n repeat in intron 1 and six single nucleotide polymorphisms (((rs2069705, T/C) (promoter)), ((rs1861494, A/G), (rs1861493, T/C), (rs2069718, C/T) (intron 3)), ((rs2069727, A/G) and (rs2069728, G/A) (3' untranslated region))) spanning the whole gene with asthma. We report here the association of rs1861494 A/G with atopic asthma in a case-control cohort (n=189 and n=270 cases and controls, respectively) (P=0.0006), which was replicated (P=0.006) in a family study (n=137) as well. Allele G was found to be negatively associated (odds ratio=0.50, 95% confidence interval, P=0.0006). A five-locus haplotype also showed significant association with asthma in the case-control (P=0.002) and the family studies (P=0.0004). In our three-locus sliding window haplotypic analysis, we found the (CA)n repeat, rs1861494 A/G and rs2069718 C/T to be of high priority (P=0.0003). Using electrophoretic mobility shift assay, we provide evidence that the alleles of rs1861494 A/G have differential affinity to bind to putative nuclear factor(s). In conclusion, we report for the first time association of rs1861494 A/G polymorphism with asthma, which may regulate the IFNgamma levels and, hence, modulate asthma pathogenesis.

IRF-1 gene variations influence IgE regulation and atopy

RATIONALE

The development of atopic diseases is characterized by skewed immune responses to common allergens. Only recently, interferons have been identified to play a crucial role in these mechanisms.

OBJECTIVES

Because interferon regulatory factor (IRF)-1 is critical for interferon expression, we tested the hypotheses that genetic changes in this essential transcription factor may have consequences for the development of atopy.

METHODS

The IRF-1 gene locus was resequenced in 80 human chromosomes. Association and haplotype analyses were performed in a cross-sectional study population of German children from Dresden (n = 1,940), and results were replicated in a second population sample from Munich (n = 1,159), both part of the ISAAC (International Study of Asthma and Allergy in Childhood) phase II. Promoter polymorphism effects were studied using electrophoretic mobility shift assay and colorimetric binding assays. Allele-specific IRF-1 gene expression was studied in vitro using luciferase reporter assays, whereas we assessed ex vivo expression of IRF-1 by real-time polymerase chain reaction and IFN-gamma protein by Luminex technology (Bio-Rad, Hercules, CA). Statistical analyses were performed using SAS/Genetics (SAS 9.1.3; SAS Institute, Cary, NC).

MEASUREMENTS AND MAIN RESULTS

By resequencing, 49 polymorphisms were identified within the IRF-1 gene. Four blocks containing 11 polymorphisms were significantly associated with atopy, total IgE levels, or specific IgE levels in both populations (P < 0.05). Two polymorphisms changed transcription factor binding of nuclear factor (NF)-kappaB and EGR1 (early growth response 1) to the IRF-1 promoter, altered gene expression in vitro (P = 0.0004), and altered IRF-1 mRNA and IFN-gamma protein expression ex vivo.

CONCLUSIONS

Our results suggest that functionally relevant IRF-1 polymorphisms influence atopy risk, potentially by altering transcription factor binding, IRF-1 gene expression, and IFN-gamma regulation.

Cytokines induce an early steroid resistance in airway smooth muscle cells: novel role of interferon regulatory factor-1

We have previously shown that long-term treatment of airway smooth muscle (ASM) cells with a combination of TNF-alpha and IFN-gamma impaired steroid anti-inflammatory action through the up-regulation of glucocorticoid receptor beta isoform (GRbeta) (Mol Pharmacol 2006;69:588-596). We here found that steroid actions could also be suppressed by short-term exposure of ASM cells to TNF-alpha and IFN-gamma (6 h) as shown by the abrogated glucocorticoid responsive element (GRE)-dependent gene transcription; surprisingly, neither GRalpha nuclear translocation nor GRbeta expression was affected by cytokine mixture. The earlier induction of CD38, a molecule recently involved in asthma, seen with TNF-alpha and IFN-gamma combination but not with cytokine alone, was also completely insensitive to steroid pretreatment. Chromatin-immunoprecipitation (IP) and siRNA strategies revealed not only increased binding of interferon regulatory factor 1 (IRF-1) transcription factor to CD38 promoter, but also its implication in regulating CD38 gene transcription. Interestingly, the capacity of fluticasone to completely inhibit TNF-alpha-induced IRF-1 expression, IRF-1 DNA binding, and transactivation activities was completely lost in cells exposed to TNF-alpha and IFN-gamma in combination. This early steroid dysfunction seen with cytokine combination could be reproduced by enhancing IRF-1 cellular levels using constitutively active IRF-1, which dose-dependently inhibited GRE-dependent gene transcription. Consistently, reducing IRF-1 cellular levels using siRNA approach significantly restored steroid transactivation activities. Collectively, our findings demonstrate for the first time that IRF-1 is a novel alternative GRbeta-independent mechanism mediating steroid dysfunction induced by pro-asthmatic cytokines, in part via the suppression of GRalpha activities.

Associations between interferon regulatory factor–1 polymorphisms and Behçet’s disease

Interferon regulatory factor-1 (IRF-1) is a transcription factor that regulates the functions of type I and II interferons and plays a role in host protection. Behçet's disease (BD) is an idiopathic systemic vasculitis that is often complicated with thrombotic features, and infectious agents have long been postulated to be a disease-triggering factor in its pathogenesis. The authors investigated the distributions of IRF-1 promoter -415 C/A, -410 A/G, and -300 A/G, and 3'-untranslated region (UTR) A/G polymorphisms in 105 BD patients (mean age 41.7 +/- SEM 1.1 years, 44 male and 61 female) and in 105 gender- and age-matched healthy controls. The frequencies of individual alleles and genotypes were not different between the control and BD groups. However, the frequency of AGGG haplotype was significantly higher (73.5% vs 60.2%, odds ratio [OR] = 1.842, 95% confidence interval [95% CI] = 1.219-2.783, p(c) = 0.036) and that of the CAAG haplotype was significantly lower (2.2% vs 9.5%, OR = 0.195, 95% CI = 0.068-0.559, p(c) = 0.02) in BD patients than in healthy controls. In addition, the frequency of the AGGG haplotype was significantly higher (80.3% vs 57.4%, OR = 3.033, 95% CI = 1.716-5.360, p(c) = 0.001) and that of the CAAG haplotype was significantly lower (0.8% vs 12.3%; OR = 0.059, 95% CI = 0.010-0.357, p(c) = 0.005) in female BD patients than female controls. By subgroup analyses, the CAAA haplotype tended to be more common in BD patients with moderate or severe disease than in those with mild disease (25.4% vs 13.6%, OR = 2.158, 95% CI = 1.046-4.440, p = 0.037 before Bonferroni correction). When BD patients were subclassified by a history of deep vein thrombosis (DVT), the CAAA haplotype was found to be significantly increased the risk of DVT (42.1% vs 15.7%, OR = 3.906, 95% CI = 1.836-8.324, p(c) = 0.0015) and the AGGG haplotype tended to reduce this risk (57.9% vs 77.3%, OR = 0.403, 95% CI = 0.195-0.834, p(c) = 0.0685). Furthermore, the frequency of the CAAA haplotype was significantly higher in BD patients that had experienced a thrombotic event than in those that had not (40.5% vs 15.5%, OR = 3.7147, 95% CI = 1.778-7.770, p(c) = 0.0015). These results suggest that IRF-1 is a novel susceptibility gene in BD, especially in women, and furthermore, that IRF-1 polymorphisms may be related to thrombosis in BD patients.

Association of interferon-gamma and interferon regulatory factor 1 polymorphisms with asthma in a family-based association study in Taiwan

BACKGROUND

Asthma is a multi-factorial disorder caused by complex interactions between genetic and environmental factors. IFN-gamma and IFN regulatory factor 1 (IRF-1) affect Th1/Th2 cytokine balance, and influence the differentiation of Th2 cells, which influence the development of asthma.

OBJECTIVE

This study investigated CA repeats polymorphism of the IFN-gamma gene and GT repeats polymorphism of the IRF-1 gene, which may predispose individuals to asthma pathogenesis.

METHODS

In the present study, we used the transmission/disequilibrium test (TDT) to investigate the relationship between asthma and the IFN-gamma and IRF-1 polymorphisms by studying 348 subjects composed of 232 parents and 116 asthmatic children.

RESULTS

For global TDT test, IFN-gamma CA repeats and IRF-1 GT repeat polymorphisms showed a significant association with asthma in children (P=0.009 and 0.017, respectively). We demonstrated that 13 CA repeats (138 bp) of IFN-gamma gene and 11 GT repeats (306 bp) of IRF-1 gene are significantly preferentially transmitted to asthmatic children (T/NT=89/61, chi2=8.43, P<0.005 and T/NT=75/49, chi2=8.18, P<0.005, respectively). The offspring will have an increased risk of asthma when their parents transmit IFN-gamma 13 CA repeats (OR=1.83, P=0.009) and IRF1 11 GT repeats (OR=1.88, P=0.007) to them. But we observed that the IFN-gamma and IRF-1 polymorphisms are not associated with IgE concentrations.

CONCLUSION

These findings provide strong evidence of which IFN-gamma CA repeat and IRF-1 GT repeat polymorphisms influence the risk of asthma for children in Taiwan.

IL-12-induced T-bet expression and IFNgamma release in lymphocytes from asthmatics--role of MAPkinases ERK-1/-2, p38(MAPK) and effect of dexamethasone

The transcription factor T-box-expressed-in-T-cells (T-bet) is required for T(H)1 lymphocyte differentiation, regulates the IL-12-induced expression of the T(H)1-specific cytokine IFNgamma and may be dysregulated in asthmatics. The modulatory role of extracellular signal-regulated kinase (ERK)-1/-2, p38mitogen-activated protein kinase (MAPK) and dexamethasone on IL-12 induced T-bet and IFNgamma expression was assessed in peripheral blood lymphocytes of 10 atopic asthmatics and 10 nonatopic normals. IFNgamma production was dependent on phosphorylation of ERK-1/-2 and p38MAPK, as examined by PD098059, an inhibitor of the upstream activator of MAPKkinase (MKK-1), and SB203580, an inhibitor of p38MAPK. The inhibitory effect of PD098059 on IFNgamma release was decreased in asthmatic T-cells compared with normals. The IL-12-induced T-bet expression and the inhibitory effect of SB203580 were increased in asthmatic T-cells compared with normals. Dexamethasone blocked the IL-12-induced T-bet expression in asthmatic T-cells completely and decreased IL-12-induced IFNgamma release by approximately 50%, which occurred to the same extent in asthmatic and normal T-cells. In conclusion, (1) p38MAPK-pathway rather than ERK-pathway may play a more basic role in the regulation of the increased T-bet expression in asthma, and (2) ERK- and p38MAPK-activation modulate IFNgamma expression independently of T-bet and this regulatory role of ERK-1/-2 on IFNgamma release is impaired in asthma. The therapeutic benefit of dexamethasone on T-bet and IFNgamma production seems to be critical.

Functional polymorphism in the suppressor of cytokine signaling 1 gene associated with adult asthma

Suppressor of cytokine signaling (SOCS) 1 is an essential physiologic regulator of the IFN-gamma signaling that is crucial to lead appropriate immune responses, and impaired IFN-gamma production is considered a hallmark of atopic diseases. Recent study has shown that SOCS1 is also crucial in attenuating type 1 IFN signaling and in limiting the host response to viral infection. Clinical and experimental evidence suggest an important role for respiratory viral infections in the development of asthma. To assess genetic functional variants of SOCS1 related to susceptibility and clinical phenotypes in adult asthma in a Japanese population, we conducted association and haplotype analyses of 462 subjects with adult asthma and 639 control subjects. After screening for polymorphisms, we identified a total of 13 variants and characterized the linkage disequilibrium (LD) mapping of the gene. Three variants were selected for genotyping with regard to the LD pattern, and we found a significant association between an SOCS1 promoter polymorphism -1478CA > del and adult asthma (P = 0.0063). The three-locus haplotype of SOCS1 using these three polymorphisms also showed a positive association with a haplotype T-C-del (-5388T, -3969C, and -1478 del; P = 0.0097). Furthermore, reporter gene analysis revealed that related promoter variant -1478 del enhanced the transcriptional level of SOCS1 in human lung epithelial cells, and induced higher levels of protein expression of SOCS1 and lower phosphorylation of STAT1 stimulated with IFN-beta. These findings suggest that the SOCS1 gene might be involved in the development of adult asthma through functional genetic polymorphism.

Pharmacogenomics of beta2-agonist: key focus on signaling pathways

Asthma is one of the most common respiratory diseases, where inhalation and exhalation are obstructed due to narrowing of the airways by broncho-constriction or by inflammation. Among all the available anti-asthma therapies, beta2-agonists are the most effective bronchodilators available, and give rapid relief of asthma symptoms. Evidence suggests that the degree of beta2-agonist response varies greatly between patients and genetic factors have a major role in it. Despite several studies on the beta2-agonist pharmacogenetics, significant gaps in knowledge still remain and need to be resolved before the pharmacotyping of beta2-agonist responsiveness comes to clinical practice. As we know, beta2-agonists show their influence by targeting beta2-adrenergic receptors, leading to the activation of beta2-adrenergic receptors and its downstream cascade. Signaling through beta2-adrenergic receptors mediates numerous airway functions by regulating broncho-constriction and dilation pathways. Therefore, it is an important prerequisite to understand these pathways, which will assist in defining the variability in therapeutic responses for beta2-agonists. Owing to the complexity of the action of a beta2-agonist and its therapeutic response, a broader genomics approach will help in optimizing therapy for the individual patient. This might be achieved by considering and focusing on receptor/s at which the drug binds directly, signal transduction cascades or downstream proteins and proteins involved in the relaxation and constriction of the airway smooth muscle. Considering that a drug response may involve a large number of proteins, it seems unlikely that a single polymorphism or haplotype in a single gene would explain a high degree of drug response variability in a consistent fashion. Thus, it shows that a polygenic approach will be more appropriate. In order to follow this, the mode of action of the beta2-agonist and its downstream signaling cascade should essentially be assessed to resolve the beta2-agonist enigma.

Roles of apoptosis in airway epithelia

The airway epithelium functions primarily as a barrier to foreign particles and as a modulator of inflammation. Apoptosis is induced in airway epithelial cells (AECs) by viral and bacterial infections, destruction of the cytoskeleton, or by exposure to toxins such as high oxygen and polycyclic hydrocarbons. Various growth factors and cytokines including TGF-beta, IFN-gamma, or the activators of the death receptors, TNF-alpha and FasL, also induce apoptosis in AECs. However, cell death is observed in maximally 15% of AECs after 24 h of treatment. Preincubation with IFN-gamma or a zinc deficiency increases the percentage of apoptotic AECs in response to TNF-alpha or FasL, suggesting that AECs have mechanisms to protect them from cell death. Apoptosis of AECs is a major mechanism in reducing cell numbers after hyperplastic changes in airway epithelia that may arise due to major injuries in response to LPS or allergen exposures. Resolution of hyperplastic changes or changes during prolonged exposure to an allergen is primarily regulated by the Bcl-2 family of proteins. Fas and FasL are both expressed in AECs, and their main function may be to control inflammation by inducing Fas-induced death in inflammatory cells without inducing apoptosis in neighboring cells. Furthermore, AECs engulf dying eosinophils to clear them by phagocytosis. Therefore, in the airway epithelium apoptosis serves three main roles: (1) to eliminate damaged cells; (2) to restore homeostasis following hyperplastic changes; and (3) to control inflammation, and thereby support the barrier and anti-inflammatory functions.

Interferon gamma polymorphisms and their interaction with smoking are associated with lung function

Interactions between genetic and environmental determinants are likely to be important in the pathogenesis of chronic obstructive pulmonary disease. We hypothesized that interferon gamma (IFNG) single nucleotide polymorphisms (SNPs) and their interaction with smoking are associated with the rate of decline or level of lung function in smokers. We studied four SNPs in IFNG in 585 non-Hispanic whites (NHW) who had the fastest (n =280) or the slowest (n=305) decline of FEV(1)% predicted selected from among continuous smokers followed for 5 years in the NHLBI Lung Health Study. We also studied 1061 NHW with the lowest (n=530) or the highest (n=531) baseline lung function at the beginning of the LHS. Two SNPs were associated with baseline levels of lung function and the p values were 0.008 for +2197T/C in a dominant model and 0.002 for +5171A/G in a recessive model. However, after adjusting for confounding factors, only +5171A/G was still significant (p=0.001 for the recessive model). In addition, there was a significant genotype and smoking interaction with p=0.006 for the +5171A/G (GG vs.GA + AA) for the baseline lung function. When comparing individuals with GG versus individuals with AG + AA for low lung function, the adjusted odds ratios decreased significantly as pack-years increased. No association was found in the rate of decline study. There was an association between IFNG genotype and baseline of lung function and this association was modified by cigarette smoking.

Viral infections, cytokine dysregulation and the origins of childhood asthma and allergic diseases

BACKGROUND

The origins of asthma and allergic disease begin in early life for many individuals. It is vital to understand the factors and/or events leading to their development.

METHODS

The Childhood Origins of Asthma project evaluated children at high risk for asthma to study the relationships among viral infections, environmental factors, immune dysregulation, genetic factors, and the development of atopic diseases. Consequently wheezing illnesses, viral respiratory pathogen identification, and in vitro cytokine response profiles were comprehensively evaluated from birth to 3 years of age, and associations of the observed phenotypes with genetic polymorphisms were investigated.

RESULTS

For the entire cohort, cytokine responses did not develop according to a strict T helper cell 1 or T helper cell 2 polarization pattern during infancy. Increased cord blood mononuclear cell phytohemagglutin-induced interferon-gamma responses of mononuclear cells were associated with decreased numbers of moderate to severe viral infections during infancy, especially among subjects with the greatest exposure to other children. In support of the hygiene hypothesis, an increased frequency of viral infections in infancy resulted in increased mitogen-induced interferon-gamma responses at 1 year of age. First year wheezing illnesses caused by respiratory viral infection were the strongest predictor of subsequent third year wheezing. Also, genotypic variation interacting with environmental factors, including day care, was associated with clinical and immunologic phenotypes that may precede the development of asthma.

CONCLUSIONS

Associations between clinical wheezing, viral identification, specific cytokine responses and genetic variation provide insight into the immunopathogenesis of childhood asthma and allergic diseases.

Association study between the IL4, IL13, IRF1 and UGRP1 genes in chromosomal 5q31 region and Chinese Graves' disease

Graves' disease (GD) was believed to be a polygenic disease. Several chromosomal regions were linked to GD, and the 5q31 chromosome regions containing several interleukin genes cluster were worth observing. In this study, IL4, IL13, IRF1 and UGRP1 genes were sequenced, and 5, 3, 7 and 7 polymorphisms respectively were discovered. Then an extended association study for the attracting polymorphisms was performed with 146 sporadic Graves' patients, 142 unrelated controls and the 54 multiplex Graves' families. However, the genotype and allele frequency distribution of these polymorphisms had similar distribution between the Graves' patients and unrelated controls, and transmission disequilibrium tests indicated that none of them showed dominant transmission from heterozygous parents to the affected offsprings. Comparison of the clinical variables of the Graves' patients indicated that the onset ages of the patients carrying TT at IRF1 6477 T/G locus were younger than those having variant allele (TG, GG); the difference was of statistical significance (P=0.005, Pc=0.020). Our association study revealed that, IL4, IL13, IRF1 and UGRP1 genes in chromosomal 5q31 regions might not confer susceptibility to Chinese GD. But those individuals who were TT homozygous at IRF1 6477 T/G locus seemed to be attacked by GD much earlier than others.

Genetic polymorphism of the interferon-gamma gene in cervical carcinogenesis

Beyond human papillomavirus (HPV) infection, host genetic factors may contribute to cervical carcinogenesis. This study aims to test the hypothesis that CA-dinucleotide repeat polymorphism in the first intron of the interferon-gamma (IFN-gamma) gene is associated with HPV-initiated cervical carcinogenesis. A hospital-based case-control study including patients with low-grade squamous intraepithelial lesions (LSILs; n = 93), high-grade squamous intraepithelial lesions (HSILs; n = 123) and invasive carcinomas (n = 153) of the uterine cervix, as well as 1:1 age-matched controls, was conducted. The IFN-gamma genotype was determined by PCR and capillary electrophoresis with internal standards. HPV genotype was determined by consensus PCR and reverse line blot hybridization. Genotypes containing the 12 or 14 allele (12 or 14 CA repeats) were significantly more common in patients with HSILs than in controls (46% vs. 22%; OR = 3.0; 95% CI = 1.7-5.2; p < 0.0001). In contrast, genotypes containing 13 and 18 were significantly more common in controls than in patients with HSILs (76% vs. 53%; OR = 0.3; 95% CI = 0.2-0.6; p = 0.0001) or squamous cell carcinomas (74% vs. 63%; OR = 0.6; 95% CI = 0.4-1.0; p = 0.037). The frequency of the 12 and 14 genotypes increased significantly in accordance with the severity of cervical carcinogenesis (p(test for trend) = 0.0002), whereas the 13 and 18 genotypes showed the opposite trend (p(test for trend) = 0.007). Comparing IFN-gamma genotype and HPV status, 18-containing genotypes were more frequently found in HPV(+) LSILs, and 12-containing genotypes were less frequently found in HPV(+) HSILs. Compared with non-13 genotypes, 13 genotype HSILs were more frequently infected with HPV58 (70% vs. 45%) and less frequently infected with HPV18 (0% vs. 16%; p= 0.007). Genetic polymorphism of the IFN-gamma gene is associated with individual susceptibility to cervical carcinogenesis. This polymorphism correlates with HPV infection in a disease- and type-specific manner.

Roles of interferon-regulatory factors in T-helper-cell differentiation

Members of the interferon-regulatory factor family of transcription factors have long been known to be intracellular mediators of the effects of interferons. In recent years, interferon-regulatory factors have also been shown to have an essential role in the differentiation of T helper cells, both by modulating the functions of antigen-presenting cells and by having direct effects on the T helper cells themselves. Depending on the interferon-regulatory factor involved, the differentiation of T helper cells to either T helper 1 cells or T helper 2 cells can be influenced. In this article, we provide an overview of this relatively new and still underappreciated role of interferon-regulatory factors.