Chen Zhi-tao, Xia Bing, Jiang Ting, Zhou Feng, Zou Kai-fang, Ge Liu-qing
Department of Gastroenterology, Wuhan University Zhongnan Hospital; Clinical Research Center for Intestinal & Colorectal Diseases of Hubei Province and Key Laboratory of Allergy and Immune-related Diseases, Wuhan, Hubei, P.R. China.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2010 Dec;27(6):603-9. doi: 10.3760/cma.j.issn.1003-9406.2010.06.001.
To investigate the effect of (AT)n repeat polymorphism of the 3'untranslated region in cytotoxic T-lymphocyte associated antigen 4 (CTLA-4) gene on CTLA-4 mRNA stability and full length (flCTLA-4) and soluble CTLA4 (sCTLA-4) expression in ulcerative colitis (UC).
flCTLA-4 mRNA in colonic biopsies and sCTLA-4 mRNA stability in peripheral blood mononuclear cells of UC patients were measured by quantitative PCR and half-life, respectively. The protein expression of flCTLA-4 in colonic biopsies and sCTLA-4 in sera of UC patients were determined by immunohistochemistry and enzyme-linked immunosorbent assay, respectively. The polymorphism of CTLA-4 (AT)n repeats in 300 UC and 700 age and sex matched healthy controls was genotyped by fluorescent PCR.
Among the UC patients, sCTLA-4 mRNA expression levels were decreased in active disease compared to non-active disease (P= 0.004). Carriers of the longer alleles of the (AT)n repeats expressed lower levels of flCTLA-4 and sCTLA-4 mRNA and sCTLA-4 protein than those of the shorter alleles in UC (all P< 0.01), and mRNA with long (AT)n repeat alleles has shorter half-life than mRNA with short alleles and, hence, are unstable. The frequency of long allele carriers of CTLA-4 (AT)n repeats was significantly higher in UC patients than in the healthy controls (22.0% vs. 6.3%, P< 0.01, OR= 4.21, 95% CI: 2.79-6.33), and associated with extensive colitis (P= 0.008).
CTLA-4 gene expression levels were associated with (AT)n repeat polymorphisms in UC patients. The expression of CTLA-4 mRNA and protein were decreased in carriers of the longer alleles of the (AT)n repeats of CTLA-4 gene. This study suggests that CTLA-4 plays an important role in genetic risk and pathophysiology for UC in central China.
研究细胞毒性T淋巴细胞相关抗原4（CTLA-4）基因3'非翻译区(AT)n重复多态性对溃疡性结肠炎（UC）患者CTLA-4信使核糖核酸（mRNA）稳定性、全长CTLA-4（flCTLA-4）及可溶性CTLA-4（sCTLA-4）表达的影响。
分别采用定量聚合酶链反应（PCR）和半衰期测定法检测UC患者结肠活检组织中flCTLA-4 mRNA及外周血单个核细胞中sCTLA-4 mRNA的稳定性。分别采用免疫组织化学法和酶联免疫吸附测定法检测UC患者结肠活检组织中flCTLA-4蛋白及血清中sCTLA-4蛋白的表达。采用荧光PCR对300例UC患者及700例年龄和性别相匹配的健康对照者的CTLA-4基因(AT)n重复序列进行基因分型。
在UC患者中，与非活动期疾病相比，活动期疾病的sCTLA-4 mRNA表达水平降低（P=0.004）。在UC患者中，(AT)n重复序列较长等位基因的携带者与较短等位基因的携带者相比，flCTLA-4和sCTLA-4 mRNA及sCTLA-4蛋白表达水平较低（均P<0.01），并且具有长(AT)n重复序列等位基因的mRNA半衰期短于具有短等位基因的mRNA，因此不稳定。UC患者中CTLA-4基因(AT)n重复序列长等位基因携带者的频率显著高于健康对照者（22.0%比6.3%，P<0.01，比值比[OR]=4.21，95%可信区间[CI]：2.79-6.33），并且与广泛性结肠炎相关（P=0.008）。
UC患者的CTLA-4基因表达水平与(AT)n重复多态性相关。CTLA-4基因(AT)n重复序列较长等位基因的携带者中CTLA-4 mRNA和蛋白表达降低。本研究提示，CTLA-4在中国中部地区UC的遗传易感性和病理生理学中起重要作用。
