TWEAK/Fn14通路易感基因甲基化与新疆维、哈、汉老年肌少症及与环境因素时空效应交互作用的研究

The levels and patterns of DNA methylation change with aging process. The relationship between DNA methylation and senile disease has aroused the attention, but the correlation is rarely reported in sarcopenia. Sarcopenia is characteristics by t ime distribution and spatial aggregation. The natural and social environment of the southern and northern parts of Xinjiang is different. TWEAK/Fn14 signaling pathway regulates muscle metabolism. The mechanism of pathogenesis for interaction of DNA methylation level and the space-time effect of environmental factors in sarcopenia remains unclear. So, based on an epidemiological investigation which is using multistage random sampling method in the South and North Xinjiang, we carry out a cross-sectional and case-control study. DNA methylation will be detected by pyrophosphate sequencing method. Moreover, we will take a three years prospective follow-up observation (skeletal muscle strength, quality and function, the collection of local natural and social environment factors). Clear the ethnic differences and area characteristics for the prevalence of senile sarcopenia in Xinjiang Uygur, Kazak and Han population. The relationship between senile sarcopenia and gene DNA methylation and its interaction with space-time effect of environmental factors will be studied. Finaly, we will construct and evaluate an multi dimension and three-dimensional early-warning index system of sarcopenia. It is very meaningful to early detection of senile sarcopenia, finding new therapeutic targets, and effective prevention and control of sarcopenia.

机体老化过程伴随着DNA甲基化水平和模式改变，DNA甲基化与老年病的关系已引起重视，但其与肌少症的相关研究鲜有报道。肌少症具有时间分布特征和空间聚集性特征。新疆南北疆自然、社会环境迥异。TWEAK、Fn14调控肌肉代谢过程，其甲基化水平与环境因素的时空效应的交互作用在老年肌少症发病中作用机制尚不清楚。故在新疆南、北疆采用多级随机抽样法进行流行病学调查基础上：开展横断面、病例对照研究，采用焦磷酸测序法检测上述基因DNA甲基化情况；并进行为期3年的前瞻性随访观察（随访骨骼肌力量、质量及活动功能等，收集当地自然、社会环境因素）；明确新疆维、哈、汉族老年肌少症患病率及地区特征、民族差异，分析上述基因DNA甲基化水平及环境因素时空效应的交互作用与老年肌少症的内在联系及民族差异；构建并评价多维度、立体化的肌少症预警指标体系。这对早期发现老年肌少症易感人群、发现新治疗靶点、预防和控制肌少症具有重要意义。

本研究首先采用多级随机抽样法在天山南北各随机入选一个县（南疆洛浦县、北疆木垒县入选）开展流行病学调查，最终共1876例完成调查、数据完整进入统计分析过程（男性853例，女性1023例；洛浦县918例，木垒县958例）；然后在流行病学调查建立的样本库中随机抽取维吾尔、哈萨克、汉族研究对象各200 例，其中对照组、病例组各半；开始随访研究；采用重亚硫酸盐测序、焦磷酸测序鉴定TWEAK、Fn14 基因DNA甲基化水平，分析基因甲基化与肌少症的相关性。流行病学调查结果提示新疆老年自然人群肌少症患病率为16.8%，女性（17.3%）高于男性（16.2%），南疆（22.9%）高于北疆（10.9%），且患病率随增龄而增高；增龄（P<0.001,OR=1.110)、高血压（P<0.05, OR=1.805)是老年自然人群肌少症患病危险因素。分子生物学研究在TWEAK、Fn14基因启动子区分别筛查出38个、30个CpGs岛。TWEAK有6个CpGs岛去甲基化与肌少症相关(CpG4, P=0.011; CpG12, P=0.028; CpG13, P=0.041; CpG20, P=0.008; CpG21, P=0.022; CpG30, P=0.030)； Fn14基因有2个CpGs岛去甲基化与肌少症(CpG24, P=0.031; CpG29, P=0.047)；校正年龄、性别、吸烟、饮酒、肥胖、糖尿病和高血压后，CpG30（TWEAK）和CpG29（Fn14）两个CpGs岛甲基化率在两组间差异无统计学意义。TWEAK、Fn14基因甲基化率在维吾尔族、哈萨克族、汉族间差异无统计学意义。在大样本验证中，校正年龄、性别、吸烟、饮酒、肥胖、糖尿病和高血压后，TWEAK基因的CpG4岛甲基化率对照组高于病例组，差异有统计学意义(F=4.112, P=0.044)；但是，Fn14基因的CpG24岛甲基化率，在两组间差异无统计学意义(F=1.160, P =0.283)。提示TWEAK基因去甲基化与肌少症相关，可能参与肌少症发病。