肥胖与KCNJ11基因多态性在中国汉族人群糖尿病视网膜病变发生中的作用

吴慧慧　刘乃嘉　李燕良 　杨　震　陶晓明　杜艳萍　王宣春　张朝云　胡仁明　鹿　斌 　闻　杰,2△

(1复旦大学附属华山医院内分泌科　上海　200040; 2上海市静安区中心医院内分泌科　上海　200040;3上海交通大学附属新华医院内分泌科　上海　200020; 4复旦大学附属华东医院内分泌科　上海　200040)



肥胖与KCNJ11基因多态性在中国汉族人群糖尿病视网膜病变发生中的作用

吴慧慧1▲刘乃嘉1▲李燕良1杨震3陶晓明4杜艳萍4王宣春1张朝云1胡仁明1鹿斌1闻杰1,2△

(1复旦大学附属华山医院内分泌科上海200040;2上海市静安区中心医院内分泌科上海200040;3上海交通大学附属新华医院内分泌科上海200020;4复旦大学附属华东医院内分泌科上海200040)

目的确认在中国汉族人群中KCNJ11基因多态性是否为糖尿病视网膜病变(diabetic retinopathy,DR)的独立危险因素,探讨其与肥胖的交互作用对DR的影响。 方法以580名2型糖尿病(type 2 diabetes mellitus,T2DM)患者为研究对象(475名非DR患者和105名DR患者),利用iPLEX技术进行KCNJ11 rs5219的基因型测定,DR的确诊由经验丰富的眼科医师根据非散瞳眼底数码成像的图像分析来判断。通过构建单因素、多因素回归模型来研究肥胖或KCNJ11基因多态性与DR的关系及两者间的交互作用。结果KCNJ11基因多态性是DR的独立危险因素。而KCNJ11 rs5219等位基因为G的肥胖患者(BMI≥28.0 kg/m2),发生DR的风险更高(等位基因分析:P<0.05,基因型分析:P<0.01)。结论在中国汉族糖尿病患者中,KCNJ11基因多态性与DR显著相关,并与肥胖有交互作用。

KCNJ11基因;肥胖;糖尿病视网膜病变;中国汉族人群

糖尿病视网膜病变(diabetic retinopathy,DR)是糖尿病最常见的微血管并发症之一,是一种具有特异性改变的眼底病变。其发生发展与多种因素有关,如高血压、血糖控制不良等[1]。该疾病的家族聚集性及不同种族间发病率的差异[2-5],提示遗传因素在其发生过程中起着关键作用。

钾离子内向整流通道蛋白J亚单位 11号成员(potassium inwardly-rectifying-channel,subfamily-J,member 11,KCNJ11)是ATP敏感性钾通道(KATP)的成员之一[6],它在胰腺组织中高表达,并与2型糖尿病(type 2 diabctes mellitus,T2DM)的易感性密切相关[7-9]。关于KCNJ11基因多态性在DR发生过程中的作用则研究甚少。已有数据证实,肥胖是DR的独立危险因素[10-11]。本研究旨在探讨KCNJ11基因多态性与DR发病风险之间的关系,及其与肥胖间是否存在交互作用。

资 料 和 方 法

研究对象选取就诊于复旦大学附属华山医院内分泌科门诊的580例T2DM患者(105例DR,475例非DR)。本研究经复旦大学附属华山医院伦理委员会批准,患者及家属签署知情同意书。入组患者均为居住在上海市区的汉族人群。

问卷调查内容包括一般情况、性别、年龄、饮酒史、病史及药物治疗史等。

检测方法所有受试者于清晨空腹、脱鞋后测定身高和体重,计算体质指数(body mass index,BMI)。血压为受试者休息5 min后,取坐位,右臂血压重复测3次的平均值。病程是初次诊断为糖尿病到患者入组之间的时间段。

所有受试者均空腹采血,采用日立7600全自动生化分析仪检测总胆固醇、血尿酸、尿素氮、肌酐、三酰甘油。空腹采血后行75g口服葡萄糖耐量试验(oral glucose tolerance test,OGTT),并于2 h后再次采血测血糖。空腹血糖及餐后血糖均采用葡萄糖氧化酶过氧化物酶法测定,糖化血红蛋白(hemoglobin A1C,HbA1C)采用高压液相离子交换层析法测定(美国伯乐公司全自动分析仪及试剂盒)。

免散瞳数码眼底成像受试者先于暗室内休息5 min以达到视觉适应,然后由同一眼科医师使用日本免散瞳眼底数码照相机,拍摄以黄斑为中心的45°眼底后极部彩色照片。照片以1 024×768的像素保存于电脑,之后由同一医师阅片诊断[12-13]。

诊断标准BMI≥28.0 kg/m2即视为肥胖[14]。所有受试者均符合1999年WHO糖尿病诊断标准:空腹血糖≥7.0 mmol/L, OGTT 2 h后血糖≥11.1 mmol/L,或自述有降糖药物治疗史。排除标准:1型糖尿病、妊娠期糖尿病及继发性糖尿病(胰腺炎、血色沉着病等)患者,或合并心、肝功能障碍者,急性感染者。存在至少一种以下损伤者即可确诊为DR:微动脉瘤、点状或火焰状出血、硬性渗出及DR的激光治疗。

SNP测定利用传统的苯酚-氯仿抽提法从580例受试者的外周血淋巴细胞中提取基因组DNA,并用基质辅助激光解吸/电离质谱检测其KCNJ11 rs5219的基因型。该人群的基因型分布符合Hardy-Weinberg平衡(P>0.05)。

结　　　果

本研究发现在580名受试者中,DR患者血尿素氮、肌酐、HbA1C、空腹及餐后血糖均高于非DR患者,差异有统计学意义(P均<0.05)。同时,DR患者的糖尿病病程明显长于非DR患者,前者患病年龄也大于后者(P均<0.05)。但两组患者的性别、年龄、身高、体重、收缩压、舒张压、C肽、总胆固醇、三酰甘油、血尿酸水平差异均无统计学意义(P均>0.05,表1)。

在校正以上因素后,Logistic回归分析提示KCNJ11rs5219的等位基因(A/G)及基因型(AA/AG/GG)在DR组和非DR组的分布情况差异有统计学意义(等位基因分析P=0.004,基因型分析P=0.001),即rs5219的基因分型与DR发生之间存在显著的相关性(表2、3)。但BMI与DR发生之间并无相关性(95%CI:0.942～1.030,P>0.05),这与以往的研究不符,可能与样本量太小有关。MLR回归模型分析提示,rs5219与DR的相关性仅存在于肥胖人群(BMI≥28.0kg/m2)中，等位基因分析、ORInt=2.463,95%CI为1.001～6.071,P<0.05;基因型分析：ORInt=2.555,95%CI为1.298～5.029,P<0.01,提示KCNJ11rs5219与肥胖在DR的发生过程中存在交互作用(表4)。

表1　受试者的基线特征

SBP:Systolic blood pressure;DBP:Diastolic blood pressure;FPG:Fasting plasma glucose;CP:C peptide;PPG:Postprandial plasma glucose;TC:Total cholesterol;TG:Triglyceride;HbA1C:Hemoglobin A1C;BUN:Blood urea nitrogen;CR:Serum creatinine;UA:Uric acid.1 mmHg=0.133 kPa.

讨　　　论

世界范围内约有30%的糖尿病患者会发生眼部血管闭塞、视网膜缺血或新生血管形成,严重影响视力甚至致盲[15]。DR作为糖尿病最常见的眼部并发症,主要表现为血管通透性增加、糖尿病性黄斑水肿和/或增值性病变[16],其发病与糖脂代谢及血压控制情况密切相关。

KCNJ11是ATP敏感性钾通道的重要组成蛋白,该通道是典型的代谢门控传感器,其功能障碍与葡萄糖刺激的胰岛素分泌有关[17]。有研究证实,KCNJ11基因缺失小鼠葡萄糖刺激的胰岛素分泌减少;而人类KCNJ11基因发生突变则可导致多种胰岛素相关性疾病,如新生儿糖尿病、先天性高胰岛素血症及移植后糖尿病[18-21]。机制可能是KCNJ11基因变异体可降低离子通道对ATP的敏感性,进而减少胰岛β细胞的活性,导致ATP消耗过多及胰岛素释放障碍[7,22-23]。大量研究证实,肥胖是DR发生的独立危险因素[10-11],而KCNJ11突变基因携带者的BMI显著高于野生基因携带者[24],但关于该基因变异体对DR发生的影响以及其是否与肥胖存在交互作用尚未见报道。

表2　rs5912的等位基因在DR和非DR组的分布情况

There were significantly differences in allele rate between the two groups (P=0.004).

表3　rs5912的基因型在DR和非DR组的分布情况

There were significantly differences in allele rate between the two groups (P=0.001).

表4　 KCNJ11 rs5219与BMI的交互作用

Adjusted for variables of age,sex,SBP,FPG,PPG,TC,TG,HbA1C,duration,age of onset,family history of DM and alcohol.

本研究对580名T2DM患者进行KCNJ11基因型的测定,首次发现KCNJ11 rs5219与DR显著相关(校正年龄、性别、BMI及血脂等)。同时,HbA1C、糖尿病病程与DR的相关性也得到证实 (P均< 0.05),这与以往的研究结果一致[25-26]。尽管肥胖早已被证实是DR的独立危险因素,但我们的实验却未观察到二者间的相关性,可能需要更大的样本量来进一步研究。MLR回归模型分析发现,在肥胖的T2DM患者(BMI≥28.0 kg/m2)中,野生型G-等位基因携带者 (AG和GG) 的DR发生率显著高于A-等位基因携带者 (AA和AG) (等位基因分析:P<0.05,基因型分析:P<0.01),提示KCNJ11基因突变可降低肥胖的T2DM病患者的DR发病风险,即该基因多态性与肥胖在DR的发生中存在交互作用。我们推测KCNJ11 rs5219可能与肥胖之间存在一定的相关性,进而通过肥胖来参与影响DR的发生。

KCNJ11基因多态性是DR的独立危险因素,并在其发生过程中与肥胖有交互作用。但本研究的受试者均来自上海地区,并不能代表整个中国汉族人群,因而需要更大的样本量以及更广泛的基础研究来阐明其机制。

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E-mail:wenjie@hotmail.com

The interaction analysis of KCNJ11 gene and obesity on diabetic retinopathy in Chinese Han population

WU Hui-hui1▲, LIU Nai-jia1▲, LI Yan-liang1, YANG Zhen3, TAO Xiao-ming4,DU Yan-ping4,WANG Xuan-chun1, ZHANG Zhao-yun1, HU Ren-ming1, LU Bin1, WEN Jie1,2△

(1DepartmentofEndocrinology,HuashanHospital,FudanUniversity,Shanghai200040,China;2DepartmentofEndocrinology,Jing′anDistrictCenterHospitalofShanghai,Shanghai200040,China;3DepartmentofEndocrinology,XinhuaHospital,ShanghaiJiaoTongUniversity,Shanghai200020,China;4DepartmentofEndocrinology,HuadongHospital,FudanUniversity,Shanghai200040,China)

ObjectiveTo clarify whetherKCNJ11 gene is an independent risk factor for diabetic retinopathy (DR) and its interaction with obesity to DR susceptibility in Chinese population.MethodsWe conducted a study in a cohort of 580 patients with type 2 diabetes mellitus (T2DM),including 475 non-DR and 105 DR subjects,for the genotype of a most common polymorphism-rs5219 ofKCNJ11.Genotyping was performed by iPLEX technology.DR was diagnosed by experienced ophthalmologists based on image analysis of the nonmydriatic digital fundus imaging.The association

KCNJ11 gene;obesity;diabetic retinopathy;Chinese Han population

R587.1

Adoi: 10.3969/j.issn.1672-8467.2016.04.005

2015-09-06;编辑:段佳)

国家自然科学基金(81270903,30900501,81370884),上海市自然科学基金(13140901600)

▲WU Hui-hui and LIU Nai-jia contributed equally to the article

betweenKCNJ11 rs5219 or obesity and DR,as well as the interaction effect ofKCNJ11 and obesity on DR susceptibility were assessed by univariate and multivariate Logistic regression analysis controlling confounders.ResultsThe possible association betweenKCNJ11 rs5219 and DR has been confirmed in this cohort.Interestingly,obese patiens (BMI≥28.0 kg/m2) with G-allele ofKCNJ11 rs5219 had higher risk of DR in Chinese Han population (for allele,P<0.05;for genotype,P<0.01).ConclusionsKCNJ11 gene polymorphism is an independent risk factor for DR,and it may interact with obesity to effect on the development of DR in diabetic patients of Chinese Han population.

*This work was supported by the National Natural Science Foundation of China (81270903,30900501,81370884) and the Natural Science Foundation of Shanghai (13140901600).