目的通过大样本病例与对照研究明确x CT基因功能性SNP与结核病易感性的相关性,明确其调控结核病发生发展的分子机制。方法从健康对照和结核患者的全血样本中提取基因组DNA,采用TaqMan探针技术对x CT基因rs13120371位点进行基因分型并对基因频率进行关联性分析,结核菌特异性抗原IFN-γ斑点形成细胞的数量和放射影像学分数反应不同基因型与临床指标的相关性,Real-time PCR方法检测健康对照和结核患者外周血单个核细胞中x CT基因及其相关的CXCL1、CXCL2、IL1B基因的表达水平。结果等位基因位点基因频率分布符合Hardy-Weinberg平衡定律（χ^2=0.678,P〉0.05）,选择的样本具有群体代表性。rs13120371位点的单核苷酸多态性与结核病的易感性相关,其中结核患者组等位基因A的基因频率为70.2%,等位基因G的基因频率为29.8%;健康对照组等位基因A的基因频率为66.8%,等位基因G的基因频率为33.2%,两组之间的等率基因频率差异具有统计学意义（P=0.02,OR=0.86）。AA基因型患者的结核菌特异性刺激分泌的IFN-r斑点形成细胞数量及炎症反应指标明显高于基因型GG的患者,基因型AA的细胞xCT基因的表达水平也明显上调。结论 xCT基因rs13120371位点的单核苷酸多态性与汉族人群结核感染的易感性相关,并且rs13120371位点是功能性SNP,等位基因A可能增加结核菌感染的风险。
Objective To study the relationship between functional SNP in xCT gene and susceptibility to tuberculosisby analyzing clinical data and investigating large number of case-control studies, and explore the molecular mechanism of SNPregulation. Methods Genomic DNA was extracted from whole blood samples of healthy objects and tuberculosis patients.TaqMan technique was performed to determine genotype. The analysis between different genotype and clinical data wasperformed by SFC and HRCT score. The expression level of xCT/CXCL1/CXCL2/IL1 B gene in PBMCs of healthy objects andpatients were detected by using real-time PCR. Results The frequency distribution of allele loci was in accordance with theHardy-Weinberg equilibrium law（χ~2=0.678, P0.05）. The selected samples were population representative. The singlenucleotide polymorphisms of rs13120371 were associated with the susceptibility to tuberculosis. The frequency of allele A andallele G in the TB group were 70.2% and 29.8% respectively, which frequencies were 66.8% and 33.2% in the healthy controlgroup, and the difference was statistically significant（P=0.02, OR=0.86）. The level of Mtb stimulated specific IFN-r andinflammatory response were higher in the samples with allele A than those with allele G. The expression of xCT gene was alsosignificantly increased in the PBMCs that carrying allele A. Conclusion SNP site rs13120371 in xCT gene is associated withthe susceptibility of tuberculosis in Han Chinese population, and it is a functional SNP. The allele A can increase the risk oftuberculosis infection.
China Tropical Medicine