超重肥胖孕妇皮下脂肪组织维生素D受体及血清维生素D水平与妊娠期糖尿病的相关性

Vitamin D receptor in subcutaneous adipose tissue and serum vitamin D levels relate to gestational diabetes mellitus in overweight/obese pregnant women

目的探讨皮下脂肪组织维生素D受体(vitamin D receptor, VDR)及血清维生素D水平在超重肥胖和正常体重孕妇中的表达差异,及其与妊娠期糖尿病(gestational diabetes mellitus, GDM)的相关性。 方法选择2015年1月至2017年4月在南京医科大学附属常州妇幼保健院住院行择期剖宫产的单胎足月孕妇为研究对象。其中确诊GDM的孕妇70例为GDM组,包括正常体重者(GDM正常体重组)和超重肥胖者(GDM超重肥胖组)各35例。另选择本院同期行剖宫产,且口服葡萄糖耐量试验结果未见异常的孕妇70例作为对照组,其中正常体重对照组35例,超重肥胖对照组35例。术前空腹抽血检测维生素D水平、血脂、空腹血糖、空腹胰岛素和脂联素,计算稳态模型胰岛素抵抗指数(homeostasis model assessment-insulin resistance, HOMA-IR)。剖宫产术中取腹壁切口皮下脂肪组织2块,运用免疫组织化学链霉菌抗生物素蛋白-过氧化物酶连结法检测脂肪组织中VDR蛋白定位,并半定量其表达强度。同时运用实时荧光定量聚合酶链反应法定量分析每组孕妇皮下脂肪组织VDR mRNA转录水平。采用单因素方差分析、LSD分析、Kruskal-Wallis检验、Mann-Whitney U检验、χ^2检验及logistic回归分析等方法进行统计学分析。 结果(1)超重肥胖对照组和GDM超重肥胖组的孕前和分娩前体重指数分别高于正常体重对照组和GDM正常体重组[孕前分别为(29.2±2.9)、(29.4±3.8)、(21.1±2.3)和(21.9±2.0) kg/m^2,F=87.766,P<0.001;分娩前分别为(35.2±3.4)、(35.1±4.3)、(27.9±2.8)和(28.8±3.3) kg/m^2,F=44.827,P<0.001]。GDM超重肥胖组新生儿出生体重和有糖尿病家庭史的比例分别高于正常体重和超重肥胖对照组[(3 893±498)、(3 501±402)与(3 625±332)g,F=4.751;22.9%(8/35)、5.7%(2/35)与5.7%(2/35),χ^2=7.869;P值均<0.05]。(2)超重肥胖对照组空腹胰岛素和HOMA-IR均高于正常体重对照组,而脂联素和维生素D水平低于正常体重对照组[13.3(12.3~14.5)与12.0(10.4~13.3) mmol/L,2.7(2.4~3.0)与2.2(2.0~2.7),(61.8±20.4)与(74.9±29.3) ng/ml,(21.6±7.2)与(25.9±7.3) ng/ml,P值均<0.05]。GDM超重肥胖组空腹胰岛素和HOMA-IR均高于GDM正常体重组,脂联素和维生素D水平低于GDM正常体重组[15.3(12.3~19.5)与12.0(10.1~15.8) mmol/L,3.4(2.6~4.1)与2.6(2.1~3.2),(50.3±22.3)与(62.1±23.2) ng/ml,(17.1±6.7)与(20.6±7.9)ng/ml,P值均<0.05]。GDM正常体重组空腹血糖高于正常体重对照组,而高密度脂蛋白胆固醇(high density lipoprotein-cholesterol, HDL-C)、脂联素和维生素D水平低于正常体重对照组[4.6(4.3~5.1)与4.3(4.0~4.5) mmol/L,1.7(1.6~1.9)与2.1(1.6~2.4) mmol/L,(62.1±23.2)与(74.9±29.3) ng/ml,(20.6±7.9)与(25.9±7.3) ng/ml,P值均<0.05]。GDM超重肥胖组空腹血糖、空腹胰岛素和HOMA-IR高于超重肥胖对照组,HDL-C、脂联素和维生素D水平低于超重肥胖对照组[4.7(4.4~5.4)与4.5(4.2~4.7) mmol/L,15.3(12.3~19.5)与13.3(12.3~14.5) mmol/L,3.4(2.6~4.1)与2.7(2.4~3.0),1.6(1.4~1.8)与1.9(1.7~2.2) mmol/L,(50.3±22.3)与(61.8±20.4) ng/ml,(17.1±6.7)与(21.6±7.2) ng/ml,P值均<0.05]。(3)4组孕妇孕晚期总体维生素D缺乏率为78.6%(110/140),其中正常体重对照组、超重肥胖对照组、GDM正常体重组和GDM超重肥胖组维生素D缺乏率分别为62.8%(22/35)、82.8%(29/35)、77.1%(27/35)和91.4%(32/35)(χ^2=8.994,P=0.029)。GDM超重肥胖组维生素D缺乏率高于正常体重对照组(χ^2=8.102,P=0.004)。(4)免疫组织化学检测表明VDR定位于脂肪组织细胞核。4组VDR蛋白表达强度差异有统计学意义。GDM 2个亚组VDR mRNA表达明显高于相应的对照组亚组,超重肥胖2个亚组VDR mRNA表达明显高于相应的正常体重亚组。(5)维生素D水平受空腹血糖、孕前体重指数和脂联素影响。糖尿病家族史、VDR mRNA、总胆固醇、HDL-C和HOMA-IR与GDM相关(P值均<0.05)。 结论脂肪组织在GDM的发病中起重要作用。GDM和超重肥胖患者血清维生素D水平下降,皮下脂肪组织VDR上调。

ObjectiveTo investigate the differences in the expression of vitamin D receptor (VDR) and serum vitamin D levels in subcutaneous adipose tissue between overweight/obese and normal-weight gravidas, and the relationship between these two indicators and gestational diabetes mellitus (GDM). MethodsWomen with full-term singleton pregnancies who underwent elective cesarean section in Changzhou Maternal and Child Health Care Hospital Affiliated to Nanjing Medical University from January 2015 to April 2017 were enrolled. Among them, there were 70 cases GDM women, including 35 normal-weight (NW-GDM group) and 35 overweight/obese women (OW-GDM group). During the same period, another 70 pregnant women with normal glucose tolerance who underwent scheduled cesarean delivery were selected as the control group, including 35 normal weight women (NW-control group) and 35 obese/overweight women (OW-control group). Fasting blood samples were collected before operation to determine the levels of different biomarkers, including vitamin D, lipid, fasting blood glucose, fasting insulin and adiponectin, and to calculate the homeostasis model assessment-insulin resistance (HOMA-IR). Two subcutaneous adipose tissue samples of the abdominal wall were taken during the operation to detect the expression and distribution of VDR protein with immunohistochemistry. Meanwhile, VDR mRNA transcription level was quantitatively analyzed using real-time fluorescence quantitative polymerase chain reaction. One-way analysis of variance, LSD, Kruskal-Wallis test, Mann-Whitney U test, Chi-square test and logistic regression analysis were used for statistical analysis. Results(1) The body mass index (BMI) of the OW-control group and the OW-GDM group before pregnancy and delivery were all higher than that of the NW-control group and the NW-GDM group [BMI before pregnancy:(29.2±2.9),(29.4±3.8) vs (21.1±2.3) and (21.9±2.0) kg/m^2, F=87.766;BMI before delivery:(35.2±3.4),(35.1±4.3) vs (27.9±2.8) and (28.8±3.3) kg/m^2, F=44.827;all P<0.001]. Newborn birth weight and the proportion of diabetic family history in the OW-GDM group were higher comparing to the NW- and OW- control group [(3 893±498) vs (3 501±402) and (3 625±332) g, F=4.751;22.9%(8/35) vs 5.7%(2/35) and 5.7%(2/35),χ^2=7.869;all P<0.05].(2) In the OW-control group, the fasting insulin level and HOMA-IR were higher and the adiponectin and vitamin D concentration were lower than those in the NW-control group [13.3(12.3-14.5) vs 12.0(10.4-13.3) mmol/L, 2.7(2.4-3.0) vs 2.2(2.0-2.7),(61.8±20.4) vs (74.9±29.3) ng/ml,(21.6±7.2) vs (25.9±7.3) ng/ml;all P<0.05], and similar results were found between the OW-GDM group and the NW-GDM group [15.3(12.3-19.5) vs 12.0(10.1-15.8) mmol/L, 3.4(2.6-4.1) vs 2.6(2.1-3.2),(50.3±22.3) vs (62.1±23.2) ng/ml,(17.1±6.7) vs (20.6±7.9) ng/ml, all P<0.05]. Compared with the NW-control group, the NW-GDM group had higher fasting glucose and lower high density lipoprotein-cholesterol (HDL-C), adiponectin and vitamin D levels [4.6(4.3-5.1) vs 4.3(4.0-4.5) mmol/L, 1.7(1.6-1.9) vs 2.1(1.6~2.4) mmol/L,(62.1±23.2) vs (74.9±29.3) ng/ml,(20.6±7.9) vs (25.9±7.3) ng/ml;all P<0.05]. Compared with the OW-control group, fasting glucose, fasting insulin and HOMA-IR were higher and HDL-C, adiponectin and vitamin D levels were lower in the OW-GDM group [4.7(4.4-5.4) vs 4.5(4.2-4.7) mmol/L, 15.3(12.3-19.5) vs 13.3(12.3-14.5) mmol/L, 3.4(2.6-4.1) vs 2.7(2.4-3.0), 1.6(1.4-1.8) vs 1.9(1.7-2.2) mmol/L,(50.3±22.3) vs (61.8±20.4) ng/ml,(17.1±6.7) vs (21.6±7.2) ng/ml;all P<0.05].(3)The overall vitamin D deficiency rate during the third trimester of the four groups was 78.6%(110/140), and the figure was 62.8%(22/35), 82.8%(29/35), 77.1%(27/35) and 91.4%(32/35) in the NW-control group, OW-control group, NW-GDM group and OW-GDM group (χ^2=8.994, P=0.029), indicating a higher rate in the OW-GDM group than that in the NW-control group (χ^2=8.102, P=0.004).(4) VDR was expressed in the nucleus of adipose tissue in all samples and statistic difference in protein expression was found among the four groups. VDR mRNA expression was higher in both GDM subgroups than that in the two control subgroups, and also higher in the two overweight/obese subgroups than in the corresponding normal-weight subgroups.(5)Serum vitamin D level was negatively correlated with fasting blood glucose and pre-pregnancy BMI, and positively correlated with adiponectin (P<0.05). The incidence of GDM was related to family history of diabetes, VDR mRNA, total cholesterol, HDL-C and HOMA-IR. ConclusionsGDM and overweight/obese patients had decreased serum vitamin D level and increased VDR in subcutaneous adipose tissue. These two factors are closely related to GDM.