中国人克罗恩病患者易感基因干扰素α-4、10变异型的功能与机制研究

The previous studies have highlighted a strong genetic and mucasal immunologic contribution to the susceptibility of Crohn's disease (CD). However, few reports have identified the specific susceptible genes in Chinese CD patients. In our preliminary study, we performed the whole exome sequencing in Chinese four of individual CD patients and screened 26 of gene variants, then we extended the case numbers to 35 pateints and identified IFNα-4 and IFNα-10 as susceptible genes appling sanger sequencing, and these kinds of mutation types were also related to medical treatment efficacy. In this study, we will extend our case numbers and funthuer identify these 3 of genes and try to find out more susceptibility genes; will check out the secretion amounts of IFNα-4, 10 from serum samples of patients and healthy controls; further explore the functional effects followed by these kinds of mutation types and involved mechanism using in vitro and in vivo study, as whether through induction of Treg or Th17 cells activation or differentiation; to define the associations of genotypes with clinical feature and medical treatment efficacy.The susceptibile genes we identified may server as a vital clue to resolve the genetic heterogenecity of CD, lead to provide experimental evidence for better diagnosis and treatment of the patients.

克罗恩病的发生与遗传及免疫因素密切相关，本病的基因异质性具有种族差异性，但中国人群特异的易感基因尚未明确。本课题组前期对国人4例克罗恩病例进行全外显子高通量测序，筛选出26个共有基因的改变，此后扩大样本量，通过常规Sanger测序验证出IFNα-4和IFNα-10亚型的变异型在病例和对照组之间统计学显著差异，并与内科药物疗效显著相关。因此本课题将：进一步明确IFNα亚型为本病的国人特异易感基因，并确定易感基因与临床特征及药物疗效间的相关性；在患者血清标本中，检测IFNα-4、10的分泌量，明确此突变型对蛋白表达量的影响；建立小鼠急慢性肠炎模型，明确IFNα不同亚型对肠道炎症的作用；通过体外实验验证突变型的功能学差异；并探索易感基因是否介导调节性T (Treg) 或Th17等细胞活化与分化而参与黏膜炎症反应的机制，将通过IFNα亚型个体化治疗国人克罗恩病成为可能，提供可靠的实验依据。

克罗恩病（CD）是炎症性肠病（IBD）的一种。近年来，全基因组关联分析（GWAS）的应用，使许多与CD相关的候选基因得以发现，可在中国大陆汉族人群中尚未发现种族特异性的易感基因。我们对4位CD患者进行了全基因组外显子测序，并在多中心扩大样本中进行验证，发现了干扰素α4（IFNA4）和IFNA10杂合性突变是中国大陆汉族克罗恩病的易感基因。进一步结合临床资料分析，我们发现CD患者血清中IFNA4和IFNA10的表达水平较健康对照组发生了明显变化。此外，具有IFNA4 和IFNA10 二个亚型位点突变时，CD患者对类固醇激素的治疗效率显著降低。我们的结果表明IFNA4和IFNA10突变削弱了HuH-7细胞对HCV病毒复制的抑制能力，并在体外影响Treg细胞的成熟。进一步研究发现重组IFNA10和IFNA4通过诱导Treg细胞改善结肠炎小鼠模型肠粘膜的急性炎症。以上发现有助于更好地理解CD易感基因异质性，并为改进克罗恩病的诊治策略提供线索。