Upregulating promoter polymorphisms of RANTES relate to atopic dermatitis.

It has been reported that a functional polymorphism in the promoter of the RANTES gene (-403G/A) is associated with atopic dermatitis in a German population. Although there are several reports on the association of RANTES promoter polymorphisms (-403G/A and -28C/G) with asthma, the association of these polymorphisms with atopic dermatitis has not yet been confirmed in other populations. We therefore aimed to test whether the RANTES promoter polymorphisms relate to atopic dermatitis in a well-defined Japanese population. We conducted an association study of upregulating promoter polymorphisms of RANTES (-403G/A and -28C/G) in 389 patients with atopic dermatitis and 177 healthy control subjects. There was a significant association between the upregulating variant of RANTES -28G and atopic dermatitis, while -403A variant showed a significant association with atopic dermatitis with high IgE productivity. These results support a role for RANTES promoter polymorphisms in susceptibility to atopic dermatitis.

Polymorphisms in ADAM33 are associated with allergic rhinitis due to Japanese cedar pollen.

BACKGROUND: A recent report provided evidence that a disintegrin and metalloprotease domain 33 (ADAM33), a member of the ADAM family, is a novel susceptibility gene in asthma linked to bronchial hyper-responsiveness. However, there has been no investigation of the genetic role of ADAM33 variants in nasal allergy. OBJECTIVE: The purpose of this study was to test the association between ADAM33 polymorphisms and Japanese cedar pollinosis (JCPsis), a most common seasonal allergic rhinitis in Japan. METHODS: We conducted a case-control association study among a Japanese population, involving 95 adult individuals with JCPsis and 95 normal healthy controls. A total of 22 single-nucleotide polymorphisms (SNPs) in ADAM33 were genotyped using PCR-based molecular methods. RESULTS: Six SNPs of ADAM33 gene, three in introns (7575G/A, 9073G/A and 12540C/T) and three in the coding region (10918G/C, 12433T/C and 12462C/T), were strongly associated with JCPsis (P = 0.0002-0.022 for absolute allele frequencies) and most of the SNPs were in linkage disequilibrium with each other. A higher frequency of the common alleles of these SNPs was noted for the subjects with JCPsis in comparison with healthy controls. We also identified a haplotype associated with the disease susceptibility. In addition, associations were found between ADAM33 polymorphisms and various cedar pollinosis phenotypes including clinical severity, eosinophil counts in nasal secretion and allergen-specific IgE levels in sera, but not total serum IgE levels. CONCLUSION: These results indicate that polymorphisms in the ADAM33 gene are associated with susceptibility to allergic rhinitis due to Japanese cedar pollen, but the functional relationship still needs clarification.

Genetic variants of FcepsilonRIbeta and Il-4 and atopy in a Polish population.

BACKGROUND: Atopy results from the interaction between genetic and environmental factors. The aim of our study was to clarify the association between the FcRIint2 polymorphic variant, the Glu237Gly mutation in exon 7 of FcepsilonRIbeta and (-590 C/T) Il-4 gene promoter polymorphism with atopy in a randomized Polish sample. SUBJECTS AND METHODS: Unrelated subjects aged 18-45 years who were residents of an urban area (Lodz, Poland) were included in the study: 98 patients with asthma and/or allergic rhinitis, and 87 non-atopic, non-asthmatic controls. We used common criteria for atopy and asthma. Atopic status was determined by positive skin prick tests (SPT) and IgE levels. The severity of asthma was assessed in spirometric measurements; SPTs to house dust mite (HDM) and mixed grass pollen (MGP) were performed. Total and specific IgE were measured in each subject. Genotypic analysis was performed by PCR for FcRIint2 and (590 C/T) Il-4 gene promoter polymorphism and ARMS-PCR was performed for the Glu237Gly mutation. RESULTS: We found a statistically significant association between atopy and FcRIint2 variant polymorphism (OR = 2.96), a correlation between positive skin prick tests to MGP and raised MGP-specific IgE concentrations in patients bearing this variant (OR = 4.0). We did not observe that the FcRIint2 variant was associated with positive SPTs to HDM or high levels of HDM-specific IgE (OR = 1.0). The intronic variant of FcepsilonRIbeta was strongly correlated with elevated total serum IgE (OR = 4.74). No statistically significant association was found between atopy and the Glu237Gly mutation of FcepsilonRIbeta(OR = 1.36) or (-590 C/T) Il-4 gene promoter polymorphism (OR = 0.88). CONCLUSIONS: The results suggest that FcRIint2 polymorphism is related to atopy and may influence its development.

An asthma-associated genetic variant of STAT6 predicts low burden of ascaris worm infestation.

Th-2 immune mechanisms are involved in the pathology of asthma and in the protective immune response to parasitic worms. Common upregulating genetic variants of Th-2 immune signalling are risk factors for asthma, and we tested whether they may confer a counteradvantage in protecting against parasitic worms. We examined the intensity of infection by the parasitic worm, Ascaris lumbricoides, by microsopic counting of ascaris eggs in the stool of 614 schoolchildren from an area of endemic ascaris infection in China. We investigated the relationship between the intensity of ascaris infection and common, asthma-associated genetic variants of Th-2 and Th-1 immune signalling. Ascaris egg counts per gram of stool (epg), mean 1068 epg, ranged from barely detectable (<240 epg) to heavy (approximately 9600 epg) in a skewed distribution. Logistic regression, after exploratory discriminant analysis, showed a major association between a common genetic variant of the 3'-UTR regulatory elements of the signal transducer and transactivating factor (STAT6) (P=0.0002) and egg counts, at the 77 th centile. Linear regression after log transformation of egg counts confirmed a highly significant association with this STAT6 variant (P=0.001). Thus, a common, asthma-associated, genetic variant of the pivotal transduction and transactivating factor for Th-2 immune signalling, STAT6, predicts increased resistance to ascaris worm infection. The evolution of enhanced resistance to parasitic worm infection, through human genetic variation in Th-2 immune signalling, may represent one origin for asthma.

The rise of atopy and links to infection.

Atopy is the state of allergy to common environmental antigens. Genetic and environmental factors promote the disorder. The impressive rise in prevalence, mainly centred on socio-economically developed communities around the world, emphasizes the potent action of environmental factors in moulding this immune disorder which is characterized by inadequately restrained Th-2 immune mechanisms and IgE production. Reversing the epidemiological trend depends on our identifying the major environmental inputs and acting against these. As yet, the nature of these environmental factors remains to be clarified. Candidate factors include changes in diet, chemical air pollution and microbial exposures in developed countries. This article limits its scope to changing microbial exposures as a potential mechanism. (a) It records epidemiological data that have associated atopic status with less natural exposure to pathogens, parasites and commensal micro-organisms, but with more exposure to certain antibiotics and public health immunizations in early life. (b) It records studies in mice that support the concept that certain microbial exposures can inhibit experimental allergy. (c) It considers potential immune mechanisms for such an action, including the possibility that certain natural infections promote immune regulatory processes that can restrain atopy. It is concluded that the hypothesis that changing patterns of microbial exposure may have promoted the rise in atopy is viable, and that exciting possibilities for reversing the rise of atopy may be derived from further studies.

Low molecular weight PTP-IL-4RA interaction in atopy predisposition.

We recently described a protective effect of the low molecular weight protein tyrosine phosphatase (LMPTP) BC genotype, associated with the highest total enzymatic activity, against high serum IgE levels both in the English and the Italian populations. Here we test the hypothesis of a role of LMPTP in the negative modulation of IL-4 signal transduction checking for genetic interaction between interleukin-4 receptor alpha chain (IL-4RA) genetic polymorphisms and LMPTP polymorphism in the predisposition to high total IgE levels in the English population. We find a significant interaction between LMPTP polymorphism and the intracellular Gln/Arg polymorphism in position 551 of IL-4RA. Our data support the hypothesis of a direct or indirect biochemical interaction between LMPTP and IL-4RA resulting in different modulation of IL-4 signal transduction among joint genotypes.

IL-4 receptor alpha chain genetic polymorphism and total IgE levels in the English population: two-locus haplotypes are more informative than individual SNPs.

The IL-4RA locus encodes for the alpha chain of the IL-4 receptor, and is both a functional and positional candidate gene for atopy and allergic disease. Recently Ober et al. have shown that the study of haplotypes at multiple loci in the IL-4RA gene could be more informative than the separate study of single nucleotide polymorphisms (SNPs). One hundred and fifty subjects affected by atopic asthma and 150 healthy control subjects were studied in the English population (Oxford district). Subjects and controls were genotyped for the Ile50Val, Ser478Pro and Gln551Arg polymorphism of the IL-4 receptor alpha chain. The distribution of haplotypes 50-478 shows a highly significant association with IgE levels. In particular, the haplotype Val50/Pro478 is much less frequent in subjects with IgE levels > 100 U mL-1 than in those with IgE levels < 100 U mL-1. Furthermore, the distribution of haplotype 50-551 shows a weak association with IgE levels that is lacking for 478-551 haplotypes. A lower frequency of the Val50/Pro478 haplotype is also observed among asthmatic subjects as compared to healthy controls. With regard to individual SNPs (50 478 and 551), no significant association has been observed with IgE levels or with asthma, thus confirming the higher informative value of the haplotype analysis as compared to separate study on SNPs.

Interleukin-4 and its alternatively spliced variant (IL-4delta2) in patients with atopic asthma.

The interleukin-4 (IL-4) splice variant (IL-4delta2) is known to antagonize many biological activities of IL-4, and this challenges our understanding of the role of IL-4 in asthma. Studies that have used nonspecific antibodies, probes, and/or primers to quantify IL-4 in clinical samples would not have distinguished the expression of IL-4 from IL-4delta2. This is the first study to examine patients with chronic asthma and atopy for IL-4delta2 mRNA in their peripheral blood mononuclear cells without antigen stimulation, using a quantitative nested reverse-transcription polymerase chain reaction (RT-PCR) protocol. The median IL-4 mRNA copy number in cells from the patients with asthma was 2.8 logs higher than in a comparator group of patients with tuberculosis (p = 0.0005) and 4.5 logs higher (p = 0.0004) than in healthy control subjects. In contrast, IL-4delta2 expression in cells from patients with asthma was similar to that seen in cells from patients with tuberculosis. Hence, the median ratio of IL-4 to IL-4delta2 was 500-fold higher in the patients with asthma when compared with either patients with tuberculosis or healthy control subjects. The relative expression of IL-4 and IL-4delta2 may be a reason for the functional diversity of Th2 cells in different clinical conditions, and a hitherto unexplored mechanism for the pulmonary pathology in patients with atopic asthma.

Genetic polymorphisms of CC chemokine receptor 3 in Japanese and British asthmatics.

Whole genome scan analyses have revealed that chromosomal region 3p21-24, which contains a gene cluster of CC chemokine receptors such as CCR3, is possibly linked to asthma. Because CCR3 ligands play a pivotal role in the selective recruitment and activation of inflammatory cells in the asthmatic airway, the authors examined whether there is any association between asthma and the CCR3 gene polymorphisms. Three polymorphisms were identified using the single stranded conformational polymorphism method in Japanese (Asian) and British (Caucasian) subjects; one silent mutation T51C and two missense mutations G824A and T971C. These polymorphisms were examined in 391 Japanese subjects (210 asthmatics and 181 nonasthmatic controls) and 234 British subjects (142 asthmatics and 92 nonasthmatic controls). Asthma diagnosis was based on episodic symptoms, documented wheeze, and the presence of reversible airflow limitation. CCR3 T51C demonstrated a significant association with the diagnosis of asthma in the British population (odds ratio 2.35, p<0.01), but not in the Japanese population. Multiple logistic regression analysis also showed that CCR3 T51C was associated with asthma (odds ratio 2.83, p < 0.02), independent of atopic phenotypes such as high levels of total or house dust mite-specific immunoglobulin-E in serum. In conclusion, a significant association between asthma and CCR3 T51C polymorphism localized on chromosome 3p21 was found.

Imbalance production between interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1Ra) in bronchial asthma.

Genes of the IL-1 family encode three different peptides, IL-1alpha, IL-1beta, and IL-1Ra, respectively. IL-1 operates through IL-1RI, and is involved in airway inflammation in asthmatic subjects, whereas IL-1Ra appears to be a specific competitive inhibitor of IL-1. All genes are on chromosome 2q12-21 where genomewide searches have identified linkage for asthma. To test whether variants of IL-1 relate to asthma, we conducted a genetic association study in a Japanese population. We show that the A2 allele of IL1RN (encoding IL-1Ra) associates with nonatopic asthma [OR = 5.71, 95% CI: 1.63-19. 8, Pc = 0.007]. Both atopic and nonatopic asthmatics with the A2 allele had significantly lower serum IL-1Ra levels in both types of asthmatics. Peripheral blood cells from asthmatics with A2 alleles, however, produced as much IL-1 as did those with A1 homozygotes. Since Th1 and Th2 cytokines differentially regulate the ratio between IL-1beta and IL-1Ra, these findings suggest that dysregulation of IL-1beta/IL-1Ra, probably due to interaction between epithelium and immuno-competent cells in the airway, is important in asthma inflammation.

Atopy and the human IL-4 receptor alpha chain.

BACKGROUND: Atopy is a common inherited disorder characterized by increased IgE responsiveness, but no functional analysis of the candidate genes related to atopy has been performed. IL-4 is important for B-cell production of IgE, and the human IL-4 receptor alpha chain (hIL-4Ralpha) is crucial for the binding and signal transduction of IL-4, so hIL-4Ralpha may be a candidate gene related to atopy. OBJECTIVE: We examined the relationship between the variation at amino acid 50 of hIL-4Ralpha and atopic asthma. METHODS: We performed a genetic study to investigate the relationship between the variation of amino acid 50 (isoleucine [Ile(50)] or valine [Val(50)]) and atopic asthma in a Japanese population and a functional study with the use of transfectants that expressed hIL4Ralpha bearing either Ile(50) or Val(50). Furthermore, we analyzed CD23 expression and IgE synthesis after IL-4 stimulation of peripheral blood mononuclear cells bearing either Ile(50) or Val(50). RESULTS: The prevalence of Ile(50) was higher than that of Val(50) in individuals with atopic asthma, especially during childhood. In transfectants, germline epsilon transcription activity and Stat6 activity were upregulated by the Ile(50) variant, compared with Val(50), but receptor affinity for IL-4 was similar between the two. CD23 expression and IgE synthesis in response to IL-4 were augmented in Ile(50)-expressing peripheral mononuclear blood cells compared to cells expressing Val(50). CONCLUSION: The Ile(50) variant of hIL-4Ralpha may be related to atopic asthma, particularly in children.

Genetic variants of IL-13 signalling and human asthma and atopy.

Asthma and atopy show epidemiological association and are biologically linked by T-helper type 2 (T(h)2) cytokine-driven inflammatory mechanisms. IL-4 operates through the IL-4 receptor (IL-4R, a heterodimer of IL-4Ralpha and either gammac or IL-13Ralpha1) and IL-13 operates through IL-13R (a heterodimer of IL-4Ralpha and IL-13Ralpha1) to promote IgE synthesis and IgE-based mucosal inflammation which typify atopy. Recent animal model data suggest that IL-13 is a central cytokine in promoting asthma, through the stimulation of bronchial epithelial mucus secretion and smooth muscle hyper-reactivity. We investigated the role of common genetic variants of IL-13 and IL-13Ralpha1 in human asthma, considering IgE levels. A novel variant of human IL-13, Gln110Arg, on chromosome 5q31, associated with asthma rather than IgE levels in case-control populations from Britain and Japan [peak odds ratio (OR) = 2.31, 95% CI 1.33-4.00]; the variant also predicted asthma and higher serum IL-13 levels in a general, Japanese paediatric population. Immunohistochemistry demonstrated that both subunits of IL-13R are prominently expressed in bronchial epithelium and smooth muscle from asthmatic subjects. Detailed molecular modelling analyses indicate that residue 110 of IL-13, the site of the charge-modifying variants Arg and Gln, is important in the internal constitution of the ligand and crucial in ligand-receptor interaction. A non-coding variant of IL-13Ralpha1, A1398G, on chromosome Xq13, associated primarily with high IgE levels (OR = 3. 38 in males, 1.10 in females) rather than asthma. Thus, certain variants of IL-13 signalling are likely to be important promoters of human asthma; detailed functional analysis of their actions is needed.

The Ile198Thr and Ala379Val variants of plasmatic PAF-acetylhydrolase impair catalytical activities and are associated with atopy and asthma.

The platelet-activating factor (PAF) represents a phospholipid with complex biological functions, including involvement in inflammatory processes. The degrading enzyme PAF acetylhydrolase (PAFAH) represents a candidate for asthma and other atopic diseases. Two loss-of-function mutations of PAFAH are associated with severe asthma in Japanese individuals. Our aim was to look for further PAFAH variants in white populations, their possible association with atopic and asthmatic phenotypes, and their functional importance. We picked up three common variants in the PAFAH gene: Arg92His (exon 4), Ile198Thr (exon 7), and Ala379Val (exon 11). The known loss-of-function mutations were not seen. The variant allele Thr198 was found to be highly associated with total IgE concentrations in an atopic population (P=.009) and with "atopic asthma" in an asthmatic population (P=.008). The variant allele Val379 was found to be highly associated with "specific sensitization" in the atopic population (P=.002) and with "asthma" in the asthmatic population (P=.003). By use of recombinant PAFAH enzymes, the variant Val379 showed increased (14 microM) and Thr198 markedly increased (42 microM) KM values compared to the wild type (7 microM); furthermore, Vmax of Val379 was highly increased (132%). Thr198 and Val379 influence plasmatic PAFAH toward lower substrate affinities and therefore are very likely to prolong the activities of PAF. At the same time, they are associated with an increased risk to develop asthma and atopy. Thus, two PAFAH variants seem to play a key role in atopic and asthmatic processes in Caucasian populations.

Variants of NOS1, NOS2, and NOS3 genes in asthmatics.

Nitric oxide (NO) gas concentrations are higher in expired air in asthmatics. NO is synthesized by three isoforms of NO synthase (NOS) encoded by three distinct genes, NOS1, NOS2, and NOS3. Genome-wide searches have identified linkages to asthma on chromosomes 7, 12, and 17 where these three genes are localized. No association study, however, has been reported to date. To test whether variants of NOS1, NOS2, and NOS3 relate to asthma, a genetic association study was conducted in a British population (n = 300). Intragenic microsatellite variants of NOS1 were significantly associated with asthma [odds ratio (OR) = 2.08, 95% CI: 1.20-3.57 (95% CI), P = 0.008 (Pc = 0.048)], but not with IgE levels. Neither NOS2 nor NOS3 variants showed any association with asthma nor IgE levels. These findings suggest that NOS1 variants may be a significant contributor to asthma in a British population.