Xiao Quan Mao

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 (∼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 77th 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.

Functional promoter polymorphism in the TBX21 gene associated with aspirin-induced asthma

Asthma is a phenotypically heterogeneous disorder with many etiologic factors and clinical characteristics. T-bet, a Th1-specific transcription factor of T-box family, has been found to control interferon-γ (IFN-γ) expression in T cells. Mice lacking the T-bet gene (tbx21) demonstrate multiple physiological and inflammatory features reminiscent of human asthma. In order to examine whether polymorphisms in the candidate gene, TBX21, located on chromosome 17q21.32, are related to the risk of human asthma phenotypes, we have searched for genetic variations in the human TBX21 gene and identified 24 single nucleotide polymorphisms (SNPs), including five novel SNPs, by direct sequencing in Japanese subjects. Among asthma phenotypes, a promoter −1993T→C SNP, which is in linkage disequilibrium with a synonymous coding 390A→G SNP in exon 1, is significantly associated with a risk of aspirin-induced asthma (AIA; P=0.004, Pc=0.016). This association has also been confirmed in additional independent samples of asthma with nasal polyposis (P=0.008), regardless of aspirin hypersensitivity. Furthermore, our data indicate that the −1993T→C substitution increases the affinity of a particular nuclear protein to the binding site of TBX21 covering the −1993 position, resulting in increased transcriptional activity of the TBX21 gene. Thus, in addition to the antigen-driven excess Th2 response, increased T-bet (and subsequent IFN-γ) production in human airways of individuals with the −1993T→C polymorphism could contribute to the development of certain asthma-related phenotypes, such as AIA.

Lack of Association between the IL13 Variant Arg110Gln and Susceptibility to Cedar Pollinosis in a Japanese Population

Background:Interleukin (IL)-13 has come to be appreciated as a molecule critically involved in allergic inflammatory responses. Recent studies revealed that a common variant in the coding region of the IL13 gene, Arg110Gln, has been implicated in the development of asthma and atopy. Methods:To assess whether the IL13 variant Arg110Gln is associated with cedar pollinosis, one of the most common atopic diseases in the Japanese population, we examined the Arg110Gln variant using PCR-RFLP to compare the genotype and allele frequencies between 95 patients with cedar pollinosis and 95 healthy control subjects. Relationships between the Arg110Gln variant and the pollinosis-related traits, e.g. rhinitis severity, eosinophil counts in nasal secretion and serum total and allergen-specific IgE levels, were also investigated. Results: The frequencies of the minor allele Gln110 were 25.8% in patients with cedar pollinosis and 30.9% in healthy control subjects (p > 0.05). There was also no significant difference in the genotype frequencies between cases and controls (p > 0.05). In addition, we found no significant association of the Arg110Gln variant with any of the pollinosis-related phenotypes (p > 0.05). Conclusions: Our data suggest lack of evidence for identifying the variant Arg110Glnat the IL13 locus as a genetic risk factor involved in the development of Japanese cedar pollinosis.

Erratum: An asthma-associated genetic variant of STAT6 predicts low burden of ascaris worm infestation (Genes and Immunity (2004) vol. 5 (58-62) 10.1038/sj.gene.6364030)

Correction to: Genes and Immunity (2004) 5, 58–62. doi:10.1038/sj.gene.6364030 Since the publication of the above paper, the authors have identified that the second author was not included in the original paper. The correct listing of the authors should be as follows: G Peisong, A Yamasaki, X-Q Mao,T Enomoto, Z Feng, F Gloria-Bottini, E Bottini, T Shirakawa, D Sun and JM Hopkin