儿童肥胖相关基因、脂肪因子谱和代谢表型关系的探索

发布时间：2018-03-01 10:06

  本文关键词： 遗传因素 肥胖 代谢异常 维生素D 脂肪因子谱 代谢正常型肥胖 儿童青少年　出处：《北京协和医学院》2017年硕士论文　论文类型：学位论文

【摘要】：[背景]肥胖已成为全球性危机,由肥胖所诱发的代谢综合征、2型糖尿病、心血管疾病和肿瘤等多种严重疾病形式严峻。近年来,儿童和青少年的肥胖也呈现逐年增长的趋势,由于轨迹现象,儿童期肥胖会延续至成人期,成为成人慢性病后备军。肥胖由遗传和环境因素共同导致。目前,通过全基因组关联分析(Genome-wide Association Study,GWAS)等研究,已发现了FTO等近百个肥胖易感基因或关联位点,然而,大多数GWAS研究都在欧洲成人中进行,亚洲儿童青少年的相关研究相对缺乏。近期研究发现并不是所有的肥胖人群都会发生代谢异常,这使得代谢正常型肥胖(Metabolically healthy obesity,MHO)这一肥胖亚型备受关注,MHO较代谢异常肥胖人群(Metabolically unhealthy obesity,MUO)具有更健康的代谢指标,但目前仍无法有效的区分这两种肥胖亚型。在儿童青少年中找到区分代谢正常和代谢异常肥胖的生物标志物对于早期干预代谢异常的发生具有重要作用。脂肪组织不仅是能量存储器而且还是功能强大的内分泌器官,通过分泌数十种脂肪因子参与糖脂代谢、能量平衡、免疫、炎症和血管稳态等众多生理功能的调节。而瘦素、脂联素、抵抗素、成纤维细胞生长因子21(Fibroblast growth factor 21,FGF21)和视黄醇结合蛋白4(Retinol binding protein 4,RBP4)等通过中枢神经系统调节体重的脂肪因子,在代谢中更加起到了不可忽视的作用。近年来,一个新的脂肪因子betatrophin,又被称为脂蛋白酯酶抑制因子(Lipasin),是一个在肝脏丰富表达并受到营养调节的脂肪因子。近年研究发现肥胖人群在发生代谢异常之前通常会出现脂肪因子谱的紊乱,因此探究能早期预测代谢异常的脂肪因子谱对于肥胖人群的针对性干预具有重要意义。本研究在北京儿童和青少年代谢综合征(BCAMS)研究队列的基线人群及10年后随访人群的基础上探索儿童肥胖相关基因、脂肪因子谱和代谢表型的关系。[目的](1)探讨成人肥胖相关基因位点对北京地区6-18岁儿童青少年肥胖和代谢相关指标的影响。(2)脂肪因子谱在儿童青少年两种肥胖亚型中差异及预警作用。(3)探讨betatrophin和心血管风险因子的关系。[方法]本研究纳入2004年北京儿童和青少年代谢综合征研究(Beijing children and adolescents metabolic syndrome study,BCAMS)调查总样本中3506名6-18岁儿童青少年,和BCAMS队列10年后随访人群559名。肥胖和代谢综合征(Metabolic Syndrom,MS)的定义分别采用中国儿童青少年BMI分类标准和修正后的美国国家胆固醇教育计划成人治疗小组第3次报告标准(Adult Treatment Panel Ⅲ guidelines,ATPⅢ)。采用胰岛素抵抗指数(Homeostasis model of assessment-insulin resistance,HOMA-IR)对胰岛素抵抗(Insulin Resistance,IR)进行评价。MHO采用心血管代谢危险因素(Cardio-metabolic risk factors,CR)和HOMA-IR两种定义相结合进行评价。运动和饮食数据采用问卷调查方式进行收集。采用质谱法对单核苷酸多态性(Single nucleotide polymorphism,SNP)位点进行检测。采用酶联免疫分析法(Enzyme-linked immunosorbent assay,ELISA)测定血清脂肪因子和胰岛素水平。采用化学发光免疫分析法检测血清25羟基维生素D(25-hydroxy-vitamin-D,25(OH)D)。组间比较采用t-检验,方差分析和卡方检验,多因素分析采用多元Logistic回归和多元线性逐步回归。[结果](1)成人肥胖相关基因位点与儿童青少年肥胖和代谢相关指标的关系:①成人肥胖相关基因位点与儿童肥胖及脂肪因子的关系:校正多因素后,在儿童中重复出6个亚洲成人肥胖相关基因位点与儿童肥胖显著相关,分别是:MC4R-rs2331841(P= 2.8×10-7)、FTO-rs1558902(P= 5.6×10-5)、GNPDA2-rs16858082(P= 3.4×10-1),PCSK1-rs261967(P = 0.001)、SEC16B-rs516636(P = 0.004)和MAP2K5-rs4776970(P=0.004),比值比(odds ratio,OR)范围从 1.211 到 1.421;另有2个位点与儿童肥胖临界相关:ITIH4-rs2535633和BDNF-rs2030323与(F0.05)。同样地,上述8个位点与其他肥胖相关指标,如体质指数(body mass index,BMI)、腰围、FAT%和UAC也呈现显著或临界相关关系。而且我们发现,其中6个SNP的风险位点 FTO-rs1558902(P= 0.002)、MC4R-rs2331841(P=0.003)、MAP2K5-rs4776970(P= 0.003)、GNPDA2-rs16858082(P= 0.007)、PCSK1-rs261967(P=0.009)和BDNF-rs2030323(P=0.027)与瘦素水平正相关,而且上述6个位点的基因风险评分(genetic predisposition score,GPS2)与瘦素水平的关系更显著(P=6.2 ×10-11)。同时也发现,MC4R-rs2331841和BDNF-rs2030323与脂联素水平临界相关(P0.05)。②成人肥胖相关基因位点与儿童代谢相关指标的关系:在儿童中验证的上述8个成人肥胖相关基因位点与儿童代谢相关指标也存在一定的相关性。校正BMI后,多数相关性消失,但KCNQ1-rs2237892仍与HDL-C负相关(P = 3.7×10-4),MC4R-rs2331841仍与空腹血糖正相关(P = 0.012)。(2)代谢正常型肥胖及代谢异常型肥胖儿童青少年的脂肪因子谱:联合两种最常用MHO/MUO定义方法,定义MHO和MUO人群:MUO:存在≥1项MS组分或HOMA-IR≥3;MHO:肥胖但不存在MS组分且HOMA-IR3。MHO在肥胖儿童中所占的比例为20.4%。MHO较MUO儿童具有更高的脂联素(P=0.002)水平,更低的瘦素(P0.001),RBP-4(P= 0.001)和SPARC(P=0.011)水平。肥胖人群中,低水平的SPARC(OR = 0.821 per SD,95 CI = 0.695-0.971,P=0.021),RBP-4(OR=0.772,95%CI = 0.644-0.926,P=0.005),和瘦素脂联素比值(OR = 0.576,95%CI = 0.433-0.765,P0.001)是MHO的独立预测因子。以上述3种脂肪因子(瘦素/脂联素比值、RBP-4和SPARC)异常为标准,存在3种脂肪因子异常较无脂肪因子异常的肥胖人群发生MHO的可能性降低80%(OR = 0.201,95%CI = 0.097-0.415),而发生MS的风险升高近3倍(OR = 2.880,95%CI = 1.584-5.237)。(3)Betatrophin和心血管风险因子的关系:Betatrophin 水平和 TC(P0.001),TG0.001)及 LDL-C(P0.001)正相关,和维生素D水平负相关(P = 0.003)。按维生素D水平分组,维生素D15ng/ml人群中,betatrophin和心血管风险因子,如高血压、高血脂和高血糖正相关,而在维生素D≥15ng/ml人群中,betatrophin和空腹胰岛素,2小时胰岛素及HOMA-IR负相关。[结论](1)GWAS获得的亚洲成人肥胖相关位点部分与中国儿童青少年肥胖及代谢指标相关,这些与儿童肥胖相关的基因主要在中枢表达,并与瘦素水平增加相关,提示这些基因影响儿童肥胖的机制可能和中枢的瘦素抵抗有关,同时也体现了中枢调控对儿童肥胖的重要作用。(2)采用严格的CR和IR两种方式联合定义MHO,MHO约占肥胖儿童的1/5。以RBP-4、SPARC以及瘦素脂联素比值为代表的脂肪因子谱可作为区分MHO和MUO两种肥胖表型的新型生物标志物,存在上述3种脂肪因子(瘦素/脂联素比值、RBP-4和SPARC)异常较无脂肪因子异常的肥胖人群发生MHO的可能性降低80%,而发生MS的风险升高近3倍。(3)青年人群中高水平的betatrophin和心血管风险因素相关,首次揭示这种相关性依赖于维生素D水平。
[Abstract]:[background] obesity has become a global crisis induced by obesity, metabolic syndrome, type 2 diabetes, cardiovascular disease and cancer and other serious diseases and severe forms. In recent years, child and adolescent obesity is also increasing trend year by year, the track phenomenon, childhood obesity will continue into adulthood, become chronic adult in the reserve army. Obesity caused by genetic and environmental factors. At present, the genome-wide association analysis (Genome-wide Association, Study, GWAS) and so on, have been found FTO nearly 100 obesity susceptible genes or related sites, however, most of the GWAS studies in Europe in the adult, the relative lack of relevant research on Asian children adolescents. Recent studies found that not all obese people have metabolic abnormalities, which makes the normal metabolism of obesity (Metabolically healthy, obesity, MHO) the subtypes of obesity Of concern, MHO is the abnormal metabolism of obesity (Metabolically unhealthy obesity, MUO) with metabolic index more healthy, but still can not effectively distinguish between these two subtypes of obesity. To distinguish normal and abnormal metabolism metabolism found obesity biomarkers play an important role in the occurrence of early intervention of metabolic abnormalities in children and adolescents adipose tissue is not only the energy storage. But powerful endocrine organs, by secreting dozens of fat factor involved in lipid metabolism, energy balance, immune regulation, inflammation and vascular homeostasis and many other physiological functions. While leptin, adiponectin, resistin, fibroblast growth factor 21 (Fibroblast growth 21 factor, FGF21) and retinol binding protein 4 (Retinol binding 4 protein, RBP4) and the regulation of body weight through the central nervous system in the metabolism of fat factor, more played Can be ignored. In recent years, a new fat factor betatrophin, also known as lipoprotein lipase inhibitory factor (Lipasin), is a rich expression in liver and fat by nutritional factor regulation. Recent studies have found that obese people in the occurrence of metabolic abnormalities usually occur before adipokines spectrum disorder, so to explore early predictors of fat metabolic abnormalities spectrum is of great significance for obese people for the intervention. The syndrome of children and adolescents in Beijing (BCAMS) to explore the metabolism of childhood obesity related gene based baseline population cohort and 10 year follow-up groups, adipokines and metabolic phenotypes. The relationship between the spectrum of purpose] (1) effects of adult obesity related gene loci related indicators in Beijing area 6-18 year old children and adolescents obesity and metabolism. (2) the fat factor spectrum in children and teenagers of two kinds of fertilizer The difference and warning function fat subtypes. (3) to investigate the relationship between] betatrophin and cardiovascular risk factors. Methods this study included syndrome study of children and adolescents in Beijing in 2004 (Beijing children and adolescents metabolic metabolism of syndrome study, BCAMS) in the total sample 3506 6-18 year old children and adolescents, and after 10 years of follow-up, the BCAMS queue 559 people. Obesity and metabolic syndrome (Metabolic Syndrom, MS) were used to define Chinese children BMI classification standard and the revised National Cholesterol Education Program Adult Treatment Panel third report standards (Adult Treatment Panel guidelines ATP III, III). The insulin resistance index (Homeostasis model of assessment-insulin resistance, HOMA-IR insulin resistance (Insulin) of Resistance, IR.MHO) were evaluated by cardiometabolic risk factors (Cardio-metabolic ris K factors, CR) two definitions and HOMA-IR combination of exercise and diet were evaluated. Data were collected by questionnaire survey. The SNPs using mass spectrometry (Single nucleotide polymorphism, SNP). Sites were detected by enzyme-linked immunosorbent assay (Enzyme-linked immunosorbent, assay, ELISA) for determination of serum adipocytokines and insulin levels using chemiluminescence immunoassay of serum 25 hydroxy vitamin D (25-hydroxy-vitamin-D, 25 (OH) D). Compared between groups using t- test, variance analysis and chi square test, multivariate analysis using Logistic regression and multiple linear regression. Results (1) relationship between obesity and adult obesity related metabolism loci with children and adolescents: the relationship between adult obesity related gene in children with obesity and adipokines: multivariate correction after repeated in children 6 Asian adult obesity associated gene loci significantly associated with childhood obesity, are: MC4R-rs2331841 (2.8 x 10-7 P=), FTO-rs1558902 (5.6 P= * 10-5 GNPDA2-rs16858082 (P=), 3.4 x 10-1), PCSK1-rs261967 (P = 0.001), SEC16B-rs516636 (P = 0.004) and MAP2K5-rs4776970 (P=0.004), odds ratio (odds ratio OR), ranging from 1.211 to 1.421; another 2 loci in children with obesity related critical: ITIH4-rs2535633 and BDNF-rs2030323 and (F0.05). Similarly, the 8 loci associated with other indicators of obesity, such as body mass index (body mass, index, BMI, waist circumference, FAT% and UAC) also showed significant or critical relationship. And we found that the 6 SNP risk loci FTO-rs1558902 (P= 0.002), MC4R-rs2331841 (P=0.003), MAP2K5-rs4776970 (P= 0.003), GNPDA2-rs16858082 (P= 0.007), PCSK1-rs261967 (P=0.009) and BDNF-rs2030323 (P=0.027) and leptin levels are And the related, 6 genes of the risk score (genetic predisposition score, GPS2) and leptin levels significantly (P=6.2 * 10-11). It is also found that MC4R-rs2331841 and BDNF-rs2030323 and adiponectin (P0.05). The relationship between the critical correlation of adult obesity related gene loci related to metabolism: validation in children children in the 8 adult obesity related gene loci associated with childhood metabolic indexes have certain correlation. After adjustment for BMI, most of the correlations disappear, but KCNQ1-rs2237892 is negatively correlated with HDL-C (P = 3.7 * 10-4), MC4R-rs2331841 is positively correlated with fasting blood glucose (P = 0.012). (2) the fat factor of children the normal metabolism of obesity and metabolic abnormalities in obese adolescents: spectrum type combined with two kinds of the most commonly used MHO/MUO method to define the definition of MHO, and MUO groups: 1 MS group or HOMA-IR = 3 are more than MUO: but not MHO:; obesity The presence of MS component and HOMA-IR3.MHO accounts for the proportion of obese children have higher adiponectin 20.4%.MHO than those of the children with MUO (P=0.002) level, lower leptin (P0.001), RBP-4 (P= 0.001) and SPARC (P=0.011). The level of obesity, low levels of SPARC (OR = 0.821 per SD, 95 CI = 0.695-0.971, P=0.021), RBP-4 (OR=0.772,95%CI = 0.644-0.926, P=0.005), and leptin adiponectin ratio (OR = 0.576,95%CI = 0.433-0.765, P0.001) were independent predictors of MHO. With the above 3 kinds of adipokines (leptin / Adiponectin ratio, RBP-4 and SPARC) anomaly as the standard, there are 3 kinds of adipokines is abnormal the possibility of abnormal fat factor of obesity MHO decreased 80% (OR = 0.201,95%CI = 0.097-0.415), the risk of MS increased by nearly 3 fold (OR = 2.880,95%CI = 1.584-5.237). (3) the relationship between Betatrophin and cardiovascular risk factors: the level of Betatrophin and TC (P0.001), TG0.001) and LDL-C (P0.001) positive correlation, negative correlation and vitamin D levels (P = 0.003). Grouped according to levels of vitamin D, vitamin D15ng/ml group, betatrophin and cardiovascular risk factors, such as hypertension, hyperlipemia and hyperglycemia is related in vitamin D than 15ng/ml group in betatrophin, and 2 hours of fasting insulin, insulin and HOMA-IR negative correlation. Conclusion] (1) Asian adult obesity related loci associated with Chinese part GWAS childhood obesity and metabolic indicators, these children with obesity related gene expression mainly in central, and leptin levels increased, suggesting that these genes may influence the mechanism of childhood obesity and central leptin resistance, but also reflects the central regulation of the important role of obesity in children. (2) the strict CR and IR two ways combined with the definition of MHO, MHO accounted for about 1/5. of obese children In RBP-4, SPARC and adipokines leptin adiponectin ratio as the representative of the spectrum can be used as a novel biological distinction between MHO and MUO two kinds of obese phenotype markers, the existence of these 3 kinds of adipokines (leptin / Adiponectin ratio, RBP-4 and SPARC) than those without abnormal fat factor abnormalities in obese people group MHO decreased 80% possibility, risk while MS increased nearly 3 times. (3) in the high level of betatrophin and cardiovascular risk factors in young people, revealed for the first time this correlation depends on the level of vitamin D.

【学位授予单位】：北京协和医学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R723.14
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