No association of toll-like receptor 2 polymorphisms with Alzheimer's disease in Han Chinese

Toll-like receptor 2 (TLR2) represents a reasonable functional and positional candidate gene for Alzheimer's disease (AD) as it is located under the linkage region of AD on chromosome 4q, and is functionally involved in the microglia-mediated inflammatory response and amyloid β (Aβ) clearance. In the current study, 7 single nucleotide polymorphisms (SNPs) that span the TLR2 were selected and their associations with late-onset AD (LOAD) risk were assessed in a case-control sample comprising 785 individuals in a Han Chinese population. No significant differences in the frequency of TLR2 alleles, genotypes, and haplotypes in the AD cases were detected compared with the controls. TLR2 gene might not play a major role in the genetic predisposition to late-onset Alzheimer's disease in this population.     

Extensive polymorphism in the porcine Toll-like receptor 10 gene

The great importance of the Toll-like receptors (TLRs) in innate immunity is well established, but one family member--TLR10--remains elusive. TLR10 is expressed in various tissues in several species, but its ligand is not known and its function is still poorly understood. The open reading frame of TLR10 was sequenced in 15 wild boars, representing three populations, and in 15 unrelated domestic pigs of Hampshire, Landrace and Large White origin. Amino acid positions corresponding to detected nonsynonymous single nucleotide polymorphisms (SNPs) were analysed in the crystal structures determined for the human TLR1-TLR2-lipopeptide complex and the human TLR10 Toll/Interleukin 1 receptor (TIR) dimer. SNP occurrence in wild boars and domestic pigs was compared, and haplotypes for the TLR10 gene and the TLR6-1-10 gene cluster were reconstructed. Despite the limited number of animals sequenced in the present study (N = 30), a larger number of SNPs were found in TLR10 than recently reported for TLR1, TLR6 and TLR2. Thirty-three SNPs were detected, of which 20 were nonsynonymous. The relative frequency of nonsynonymous (d(N) ) and synonymous (d(S) ) SNPs between wild boars and domestic pigs was higher in TLR10 than recently reported for TLR1, TLR6 and TLR2. However, the polymorphism reported in the present study seems to leave the function of the TLR10 molecule unaffected. Furthermore, no nonsynonymous SNPs were detected in the part of the gene corresponding to the hinge region of the receptor, probably reflecting rigorously acting functional constraint. The total number of SNPs and the number of nonsynonymous SNPs were significantly lower (P < 0.05) in the wild boars than in the domestic pigs, and fewer TLR10 haplotypes were present in the wild boars. The majority of the TLR6-1-10 haplotypes were specific for either wild boars or domestic pigs, probably reflecting differences in microbial environment and population history.     

A comprehensive evaluation of IL4 variants in ethnically diverse populations: association of total serum IgE levels and asthma in white subjects

BACKGROUND: The role of variation in the IL4 gene in asthma and allergy susceptibility is controversial. This cytokine is important in IgE isotype switching and the regulation of allergic inflammation; however, published studies have not delineated the specific role of variation in this gene in allergic disorders. OBJECTIVE: We sought to identify single nucleotide polymorphisms (SNPs) in IL4 and to evaluate the association of SNPs and haplotypes with asthma and allergic phenotypes (total serum IgE) in white, African American, and Hispanic asthmatic populations. METHODS: Sixteen individuals were resequenced, and 19 SNPs were identified; 2 novel and 17 SNPs were previously reported. Eleven of the SNPs were used to evaluate association in the 3 groups. RESULTS: Nine polymorphisms were associated with total serum IgE levels in white subjects (.0012 < or = P < or =.034), and 5 of these were also associated with asthma in this population (.010 < or = P < or =.031). Three common haplotypes were observed, and all were associated with either high or low serum IgE levels in white subjects (.00008 < or = P < or =.004). Inspection of the haplotypes revealed that 3017 G/T in intron 2 was the only SNP concordant with serum IgE levels (G allele with lower levels and T allele with higher levels). CONCLUSIONS: After a comprehensive genetic evaluation, our data suggest that the 3017 G/T variant or the haplotype it identifies influences IL4's ability to modulate total serum IgE levels. Inconsistencies with previously reported IL4 associations might be due to population differences in allele frequencies, the extent of linkage disequilibrium with this SNP or haplotype, or both.     

TLR4基因多态性在中国人群中的初步研究

目的检测中国人Toll样受体4(Toll—like receptor 4．TLR4)基因调控区和编码区的单核苷酸多态性(single nucleotide polymorphisms，SNPs)．寻找TLR4基因的遗传标记。方法采用直接测序的方法检测基因的5′区、编码区、部分内含子区和3′区，以确定中国人群中TLR4基因SNP的位置和类型，并用聚合酶链反应-限制性片段长度多态性对重庆汉族样本进行了抽样调查。结果在4．98kb的测序范围内，发现5个新的SNP，3个位于5′区．2个位于3′非翻译区。在重庆地区汉族样本中．两个高频分布SNP的等位基因频率分别是0．266和0．404。结论在TLR4基因新发现的两个高频多态性位点在我国人群中比较常见，可以作为关联分析的遗传标记。     

Atopy and new-onset asthma in young Danish farmers and CD14, TLR2, and TLR4 genetic polymorphisms: a nested case-control study

BACKGROUND: Evidence exists that exposure to high levels of microbial agents such as endotoxin in the farm environment decreases the risk of atopic sensitization. Genetic variation in innate immunity genes may modulate the response to microbial agents and thus influence susceptibility to asthma and atopy. OBJECTIVE: To study potential associations between single nucleotide polymorphisms (SNPs) in CD14, Toll-like receptor 2 (TLR2), and TLR4 genes, and atopy and new-onset asthma in young farmers. METHODS: A nested case-control study was conducted within a cohort of 1901 young Danish farmers. We genotyped 100 new-onset asthma cases and 88 control subjects for three CD14 SNPs, three TLR2 SNPs, and two TLR4 SNPs. Atopy at baseline (defined as a positive skin prick test to one or more common inhalant allergens) was found in 17 asthma cases (17.0%) and in 17 controls (19.3%). RESULTS: The CD14/-260T allele was significantly associated with less atopy [odds ratio (OR) 0.39; 95% confidence interval (CI) 0.21-0.72, additive genetic model], whereas the CD14/-651T allele was positively associated with atopy (OR 2.53; 95% CI 1.33-4.80). Similar results were obtained by haplotype analysis. Stratified analysis by farm childhood showed stronger effects of both CD14 SNPs on atopy among farmers who were born and raised on a farm, although no significant interaction was found. No associations between CD14, TLR2, or TLR4 genotypes and new-onset asthma were found. CONCLUSION: The CD14/-260 and CD14/-651 promoter polymorphisms are associated with atopy prevalence among young adults exposed to farm environments.     

广东汉族正常人群TLR4基因单核苷酸多态性研究(英)

目的：人类Toll样受体4（TLR4）是先天免疫系统中一个重要的病原微生物识别受体。本研究将建立中国汉族正常人群TLR4基因座位的单核苷酸多态性图谱。方法：收集191例健康、无亲缘关系的中国广东汉族人外周血液,通过对TLR4基因的启动子区、3个外显子区以及它们周围的内含子区进行PCR扩增和测序,得到汉族正常人群TLR4基因座位单核苷酸多态性图谱及其频率分布特点。结果：共发现8个单核苷酸多态性位点,其中5个是首次发现的新位点。分布频率最高（0.283）的单核苷酸多态性位点是-1607 C/T。常见于高加索人中的2个非同义突变Asp299Gly和Thr399Ile在汉族人中没有被发现。中性检验显示汉族人群TLR4基因符合中性进化模型。结论：本研究建立了汉族正常人群TLR4基因座位的单核苷酸多态性图谱,发现了一些种族特异性的单核苷酸多态性位点,这些工作将为今后开展汉族人基因多态性与疾病相关性研究以及人群进化研究提供一定的帮助。     

Lack of association between genetic variation in G-protein-coupled receptor for asthma susceptibility and childhood asthma and atopy

G-protein-coupled receptor for asthma susceptibility (GPRA or GPR154) was identified as an asthma and atopy candidate gene by positional cloning. Some subsequent studies suggest associations of GPRA single nucleotide polymorphisms (SNPs) and haplotypes with asthma or atopy susceptibility. However, the associated SNPs or haplotypes vary among studies. The role of GPRA genetic variation in asthma and atopy remains unsolved. Published data on GRPA variants and asthma come exclusively from Caucasian and Asian populations. We examined whether GPRA SNPs and haplotypes are associated with asthma and atopy in a Mexican population. We genotyped and analyzed 27 GPRA SNPs in 589 nuclear families consisting of asthmatic children aged 4-17 years of age and their parents in Mexico City. Atopy was determined by skin prick tests to 25 aeroallergens. The 27 SNPs examined provided excellent coverage of the GPRA gene. GPRA SNPs and haplotypes were not associated with childhood asthma and the degree of atopy to aeroallergens in a Mexican population. Our review of studies of GPRA variants in relation to asthma phenotypes shows considerable heterogeneity. Accordingly, our results suggest that GPRA variants are not an important contributor to childhood asthma and atopy susceptibility in a Mexican population.     

Integrin beta 3 genotype influences asthma and allergy phenotypes in the first 6 years of life

BACKGROUND: The integrin beta3 gene (ITGB3) encodes a subunit of the platelet and monocyte-specific fibrinogen receptor and the widely expressed vitronectin receptor, which have diverse roles in cell migration, adhesion, and signaling. Previous work from our laboratory reported associations between single nucleotide polymorphisms (SNPs) in ITGB3 and asthma and allergic sensitization in 4 populations. OBJECTIVE: To examine whether SNPs in ITGB3 are associated with the development of asthma and allergic phenotypes in early life. METHODS: We typed 13 SNPs in 206 children participating in a birth cohort study and tested for associations with asthma and allergy phenotypes in the first 6 years of life. RESULTS: Our study revealed significant associations between SNPs in ITGB3 and asthma, wheezing, and IgE levels, suggesting an early role for this gene in the development of asthma and allergy. In particular, SNPs at the 3' end of the gene were significantly associated with IgE levels beginning at 1 year of age, whereas a SNP in intron 1 showed significant interaction effects with viral respiratory illness in infancy on asthma susceptibility. CONCLUSION: Our results suggest that genetic variation in ITGB3 contributes to asthma susceptibility and allergic sensitization, and that the effects of this gene begin early in life. Similar to our earlier study, different SNPs in the gene are associated with asthma and IgE. CLINICAL IMPLICATIONS: ITGB3 may play an important role in the development of asthma and allergy and may represent a potential therapeutic target for the treatment of these disorders.     

Genetic impact of functional single nucleotide polymorphisms in the 3'-UTR region of the chemoattractant receptor expressed on Th2 cells (CRTH2) gene on asthma and atopy in a Japanese population

BACKGROUND: The human chemoattractant receptor expressed on Th2 cells (CRTH2), the receptor for prostaglandin D2, induces cell migration in eosinophils, basophils, and Th2 cells. The gene encoding CRTH2 is located on chromosome 11q13. Several groups, including ours, have reported significant associations between this region and various traits associated with allergic diseases such as asthma and atopy. Two single nucleotide polymorphisms in the 3'-UTR of the CRTH2 gene (1544G-->C and 1651G-->A) are associated with the mRNA stability of the gene; they have also been associated with asthma in both African American and Chinese populations. METHODS: Because CRTH2 is a biologically important candidate gene on chromosome 11q13, we conducted a case-control analysis using 787 Japanese subjects (384 asthmatics and 403 controls) to evaluate the genetic impact of the CRTH2 gene on asthma and asthma-related traits. Four polymorphisms [1544G-->C (rs11571288), 1651G-->A (rs545659), 11336T-->C (rs2074422), and 12375G-->T (rs561285)] were studied. RESULTS: The allele, genotype, or haplotype frequencies for 2 functional polymorphisms in our Japanese population were significantly different from those in the Chinese or African American populations. No association was found between any polymorphisms or haplotypes in the CRTH2 gene and asthma, atopy, or total serum IgE levels in a Japanese population. CONCLUSIONS: Our data failed to support previous associations of functional polymorphisms at the 3'-UTR of the CRTH2 gene implicated in asthma. We did show a significant difference in the allele and genotype frequencies as well as different haplotype frequencies among African American, Chinese, and Japanese populations, suggesting that the genetic impacts of these functional polymorphisms on asthma and asthma-related phenotypes may vary in different populations.     

Chromosome 7p linkage and GPR154 gene association in Italian families with allergic asthma

BACKGROUND: Several genome scans have reported linkage of markers on chromosome 7p with asthma and related phenotypes in different populations. A fine mapping in Finnish and French-Canadian populations has associated the GPR154 gene (also known as G-protein-coupled receptor for asthma susceptibility, GPRA) with elevated IgE or asthma. OBJECTIVE: To confirm chromosome 7p linkage and candidate gene association in Italian families with atopic asthma. METHODS: In a two-phase approach, we first performed a linkage analysis of chromosome 7, and then a family-based association study on the GPR154 gene for allergic asthma phenotypes in the Italian population. RESULTS: The screening of 117 families with 19 microsatellite markers showed potential linkage for elevated IgE (P<0.002 at 22 cM from p-ter), asthma (P<0.005 at 44 cM), or atopy (P<0.005 at 54 cM). In the second phase of the present study, candidate gene GPR154, which is located in the phase one-linked region, was investigated in 211 families with seven single nucleotide polymorphisms (SNPs) that tag most haplotype variability, by the pedigree disequilibrium test. Elevated IgE levels were associated with two GPR154 gene SNPs (SNP 546333, P=0.0046; rs740 347, P=0.006), and with haplotypes in the global test (P=0.013). Haplotype analysis performed in nuclear families having at least 1 asthmatic parent showed a significant association with asthma (P=0.0173), atopy (P=0.0058), SPT (P=0.0025), and bronchial hyper reactivity (P=0.0163). CONCLUSION: These results support a susceptibility locus for asthma and related phenotypes on chromosome 7, and are in agreement with recent reports suggesting that a common susceptibility factor for atopic manifestations in asthma is likely conferred by the locus containing the GPR154 gene.     

Childhood allergic rhinitis predicts asthma incidence and persistence to middle age: a longitudinal study

BACKGROUND: The association between allergic rhinitis and asthma is well documented, but the temporal sequence of this association has not been closely examined. OBJECTIVE: We sought to assess the associations between childhood allergic rhinitis and (1) asthma incidence from preadolescence to middle age and (2) asthma persistence to middle age. METHODS: Data were gathered from the 1968, 1974, and 2004 surveys of the Tasmanian Asthma Study. Cox regression was used to examine the association between childhood allergic rhinitis and asthma incidence in preadolescence, adolescence, and adult life. Binomial regression was used to examine the association between childhood allergic rhinitis and asthma beginning before the age of 7 years and persisting at age 44 years. RESULTS: Childhood allergic rhinitis was associated with a significant 2- to 7-fold increased risk of incident asthma in preadolescence, adolescence, or adult life. Childhood allergic rhinitis was associated with a 3-fold increased risk of childhood asthma persisting compared with remitting by middle age. CONCLUSIONS: Childhood allergic rhinitis increased the likelihood of new-onset asthma after childhood and the likelihood of having persisting asthma from childhood into middle age. CLINICAL IMPLICATIONS: Asthma burden in later life might be reduced by more aggressive treatment of allergic rhinitis in early life.     

湖北汉族变应性哮喘患者GPR154基因单倍型分析

目的探讨G蛋白偶联受体154(Gprotein-coupled receptor154,GPR154)基因多态性与湖北汉族变应性哮喘易感性间的关系。方法用聚合酶链反应和限制性片段长度多态性对145例变应性哮喘患者和120名健康人群GPR154基因的SNP563704和SNP522363位点的多态性进行分析。结果(1)变应性哮喘患者SNP563704 CC、CT和TT基因型频率是0.324、0.524和0.152;与对照组相比差异无统计学意义(χ2=1·880,P>0.05);变应性哮喘组不同基因型间血清总IgE水平差异无统计学意义(F=0.714,P>0.05)。(2)变应性哮喘患者SNP522363CC、CG和GG基因型频率是0.289、0.521和0.190;与对照组相比差异无统计学意义(χ2=0.700,P>0.05);变应性哮喘组不同基因型间血清总IgE水平差异无统计学意义(F=0·083,P>0.05)。(3)对SNP522363和SNP563704进行单倍型分析,4种频率大于0.03的单倍型在哮喘组和对照组间差异有统计学意义(χ2=16.50,P<0.01)。哮喘组CT和GT单倍型频率显著高于对照组,差异有统计学意义(P=0.015;P=0.002)。结论湖北汉族变应性哮喘易感性与单个的单核甘酸多态性无关,但与SNP522363和SNP563704组成的单倍型显著相关。     

Genetic polymorphisms of viral infection-associated Toll-like receptors in Chinese population

Toll-like receptors (TLRs) play a pivotal role in an innate immunity system, which controls inflammation responses and further instructs development of adaptive immunity. We enrolled 250 Han Chinese in Taiwan screening for the single nucleotide polymorphisms (SNPs) in TLRs associated with viral infection, including TLR2, TLR3, TLR4, TLR7, TLR8, and TLR9. The 6 SNPs not hitherto identified in Chinese populations, including TLR3 1377 C>T, TLR3 -7 C>A, TLR7 Gln11Leu, TLR7 IVS1+1817 G>T, TLR8 Met1Val, and TLR8 -129 G>C, had minor allele frequencies of 38%, 23%, 22.3%, 3%, 16.0%, and 16.0%, respectively. The frequencies of 2 common SNPs, TLR9, -1486 T>C and 2848 G>A, were 28% and 44%, respectively. As compared with other ethnic populations, Chinese displayed an opposite allele frequency of TLR8 Met1Val and TLR8 -129 G>C to Caucasians and African Americans. In addition, TLR2 Arg677Try, TLR2 Arg753Gln, TLR4 Asp299Gly, and TLR4 Thr399Ile that were apparent in approximately 10% of Caucasians were not detected in Chinese. In conclusion, obvious ethnic differences in TLR polymorphisms may in part reflect the ethnic diversity of host viral susceptibility.     

Fine mapping and positional candidate studies on chromosome 5p13 identify multiple asthma susceptibility loci

BACKGROUND: Genome-wide linkage scans to identify asthma susceptibility loci have revealed many linked regions, including a broad region on chromosome 5p. OBJECTIVE: To identify a 5p-linked asthma or bronchial hyperresponsiveness (BHR) locus. METHODS: We performed fine mapping and positional candidate studies of this region in the Hutterites and an outbred case-control sample from Germany by genotyping 89 single nucleotide polymorphisms (SNPs) in 22 genes. SNP and haplotype analyses were performed. RESULTS: Three genes in a distal region (zinc finger RNA binding protein [ZFR], natriuretic peptide receptor C, and a disintegrin and metalloproteinase domain with thrombospondin type 1 motif [ADAMTS12]) were associated with BHR, whereas 4 genes in a proximal region (prolactin receptor, IL-7 receptor [IL7R], leukemia inhibitory factor receptor [LIFR], and prostaglandin E4 receptor [PTGER4]) were associated with asthma symptoms in the Hutterites. Furthermore, nearly the entire original linkage signal in the Hutterites was generated by individuals who had the risk-associated alleles in ZFR3, natriuretic peptide receptor C, ADAMTS12, LIFR, and PTGER4. Variation in ADAMTS12, IL7R, and PTGER4 were also associated with asthma in the outbred Germans, and the frequencies of long-range haplotypes composed of SNPs at ZFR, ADAMTS12, IL7R, LIFR, and PTGER4 were significantly different between both the German and Hutterite cases and controls. There is little linkage disequilbrium between alleles in these 2 regions in either population. CONCLUSION: These results suggest that a broad region on 5p, separated by >9 Mb, harbors at least 2 and possibly 5 asthma or BHR susceptibility loci. These findings are consistent with the hypothesis that regions providing evidence for linkage in multiple populations may, in fact, house more than 1 susceptibility locus, as appears to be the case for the linked region on 5p. CLINICAL IMPLICATIONS: Identifying asthma or BHR genes could lead to novel therapeutic approaches.     

Association analysis of Toll-like receptor 7 gene polymorphisms and Behçet's disease in Japanese patients

Action of Toll-like receptors (TLRs) is deeply associated with defense mechanisms of the innate and adaptive immune responses to microbial pathogens. There have been reports of genetic polymorphisms within the TLR7 gene being closely related to a variety of inflammatory and infectious diseases. Behçet's disease (BD) is an autoinflammatory disease, and the pathogenesis has yet to be fully discovered. We investigated whether polymorphisms of Toll-like receptor 7 (TLR7) are associated with BD by analyzing the frequency of eight single nucleotide polymorphisms (SNPs) within 200 Japanese BD patients and 102 randomized controls. We genotyped nine SNPs in the TLR7 gene and assessed the allele/genotype diversity between cases and controls for all SNPs. In all eight SNPs, statistically significant differences were not observed between cases and controls.     

Toll-like receptor 6 gene (TLR6): single-nucleotide polymorphism frequencies and preliminary association with the diagnosis of asthma

Toll-like receptor 6 (TLR6) is one of a series of highly conserved innate immune receptors. We resequenced TLR6 in DNA samples from 24 African Americans, 23 European Americans, and 24 Hispanic Americans, identifying 53 SNPs, 22 with an allele frequency >5%. Significant differences in SNP frequencies among the three populations were noted. In all, 11 SNPs caused amino-acid changes, including one with a frequency >5% in all three populations. Utilizing this SNP (Ser249Pro), we performed exploratory nested case-control disease-association studies, including one involving 56 African Americans with asthma and 93 African American controls. The minor allele of this SNP was associated with decreased risk for asthma (odds ratio 0.38, 95% CI 0.16-0.87, P=0.01), an effect consistent with the known biology of the toll-like receptors. Although replication of this finding in other, larger samples is needed, variation in TLR6 may have relevance to the pathogenesis of immunologically mediated diseases.     

G protein-coupled receptor 154 gene polymorphism is associated with airway hyperresponsiveness to methacholine in a Chinese population

BACKGROUND: A new asthma susceptibility gene, the G protein-coupled receptor for asthma susceptibility (GPRA, GPR154), has recently been identified and the association was replicated in 2 white populations, but not in a Korean population. OBJECTIVE: To test the association between GPR154 gene polymorphisms and airway responsiveness to methacholine in a Chinese population. METHODS: Eight single nucleotide polymorphisms (SNPs) in the GPR154 gene were genotyped in 451 cases and 232 controls in stage I. The association of 1 SNP, rs324981, was tested in an additional 264 case and 241 control subjects in stage II. Both single marker and haplotype associations were tested. RESULTS: In stage I, we found that airway hyperresponsiveness to methacholine was associated with 2 single SNPs, rs324981 and rs324987, but not with the haplotypes of GPR154. The minor allele homozygotes of rs324981 (AA) and rs324987 (TT) were at a significantly lower risk of hyperresponsiveness to methacholine with odds ratios of 0.59 (P=.02) and 0.56 (P=.01), respectively. In stage II, we found a similar trend of association between rs324981 and airway hyperresponsiveness (P=.09). In the pooled analysis, the odds ratio of the AA homozygote of rs324981 was 0.61 (P=.004). The permutation test resulted in a study-wide empirical P value of .023, which meant that the association remained significant after adjustment for multiple tests. CONCLUSIONS: Our study supports a role of the GPR154 gene in asthma susceptibility and suggests that the AA homozygote of rs324981 is a protective factor for airway hyperresponsiveness to methacholine in a Chinese population. CLINICAL IMPLICATIONS: Our findings confirmed a role of GPR154 in the genetic susceptibility of asthma and suggest that GPR154 polymorphism should be taken into consideration to improve the assessment of an individual's risk of asthma.     

支气管哮喘易感区域5q31-33内Tim-3基因单体型分析

目的： 探讨染色体上支气管哮喘易感区域5q31-33内Tim-3基因多态性与支气管哮喘的关系。方法：应用限制性片段长度多态性技术方法,分析了118个儿童变应性哮喘核心家系Tim-3基因4个SNPs(rs10053538、rs10515746、rs13170556和rs9313441)的基因型;采用基于家系传递不平衡检验（TDT）,分析基因分型数据;应用TRANSMIT软件构建单体型并进行单体型关联分析。结果：①基于家系的TDT分析显示,Tim-3基因的4个SNPs由杂合子父母传递给患病子代的等位基因频率不比预期值高,与哮喘无关（P>0.05）。②Transmit多个位点单体型分析结果显示由Tim-3基因rs10053538、 rs13170556、 rs9313441构建的单体型与支气管哮喘有关联（Global 2=10.83,P<0.05）。父母传递给患病子女GGG单体型的观察值小于期望值,差异显著（2=8.24,P<0.01）。结论：中国汉族人群中,位于染色体5q31-33区域的Tim-3基因本身或其附近的基因可能与儿童变应性哮喘的易感性相关。