Toll样受体9基因启动子单核苷酸多态性与儿童变应性哮喘的相关性

摘要

Objective To investigate the distribution characteristics of the single nucleotide polymorphisms (SNPs) in the promoter region of the toll-like receptor 9 gene (TLR9)in Chinese Han children from Zhejiang province, and their associations with asthma susceptibility and phenotypes. Methods A case-control study was conducted. A total of 312 asthmatic children aged between 1.9 and 11.6 and 339 age matched healthy controls were enrolled in this study from April 2007 to November 2008. The -1486 C/T in rs187084 and -1237 C/T in rs5743836 loci of the TLR9 gene were genotyped by direct DNA sequencing of the PCR products. Serum levels of IFN-γ, IL-12 and IL-4 were detected by enzyme linked immunosorbent assay. Serum levels of total IgE were detected by chemiluminescence, and serum levels of ildren (P＜0.01). The CC genotype had the lowest levels of serum IFN-γand the highest levels of serum IL-4 among the three genotypes. There were no significant differences in these cytokines among the healthy controls (P＞0.05). No statistical differences of serum IL-12 were found among the three genotypes in the two groups (P＞0.05). (4) There were no significant differences of total IgE (log-transformed) among the three genotypes in the asthmatic children (P＞0. 05). Conclusion The -1237 C/T polymorphism of TLR9 gene was not detected in Chinese Han children in this study. The - 1486 C/T polymorphism was associated with the levels of serum IFN-γ and IL-4 in children with asthma.However, there were no correlations between the -1486C/T polymorphism and serum IL-12 levels, total IgE levels or asthmatic susceptibility.%目的 研究Toll样受体9(toll-like receptor 9,TLR9)基因启动子区单核苷酸多态性在浙江汉族儿童中的分布,探讨其与哮喘易感性及其表型之间的相关性.方法 对312例变应性哮喘患儿(哮喘组)和339名健康儿童(对照组)采用DNA直接测序法检测TLR9基因-1486(rs187084)和-1237(rs5743836)单核苷酸多态性;采用ELISA法检测两组不同基因型血清干扰素γ(interferon-γ,IFN-γ)、白细胞介素12(interleukin-12,IL-12)和白细胞介素4(interleukin-4,IL-4)水平;采用化学发光法检测血清总免疫球蛋白E(immunoglobulin E,IgE)水平;采用酶免疫荧光法检测血清变应原特异IgE.结果 (1)哮喘组和对照组均存在-1486位点T→C突变,哮喘组TT、TC和CC 3种基因型的频率分别是3 8.8%、48.4%和12.8%,对照组分别是41.0%、44.3%和14.7%;未发现-1237位点存在多态性.(2)哮喘组和对照组-1486位点各基因型的频率分布差异无统计学意义(P＞0.05),年龄分层后比较差异也无统计学意义(P＞0.05).(3)哮喘组-1486位点3种基因型的血清IFN-γ和IL-4水平差异有统计学意义(P＜0.01),CC基因型的IFN-γ水平较低而IL-4水平较高;对照组2种细胞因子的差异无统计学意义(P＞0.05).哮喘组和对照组血清IL-12水平在3种基因型间差异均无统计学意义(P＞0.05).(4)哮喘组-1486位点不同基因型血清总IgE水平差异无统计学意义(P＞0.05).结论 浙江汉族儿童不存在TLR9基因-1237位点多态性.TLR9基因-1486 C/T位点单核苷酸多态性与浙江汉族儿童哮喘易感性、血清IL-12及总IgE水平无关;-1486 C/T位点多态性与哮喘患儿血清IFN-γ和IL-4水平有关联,CC基因型的IFN-γ水平较低而IL-4水平较高.