丁智勇， 卜 樂， 魯鴻燕， 饒正軒

(1 上海市第十人民醫(yī)院崇明分院 內(nèi)分泌科， 上海 202157； 2 上海市第十人民醫(yī)院 內(nèi)分泌科 200072)

非酒精性脂肪性肝病患者血清維生素A水平、肝臟脂肪含量與胰島素抵抗的相關(guān)性分析

丁智勇1， 卜 樂2， 魯鴻燕1， 饒正軒1

(1 上海市第十人民醫(yī)院崇明分院 內(nèi)分泌科， 上海 202157； 2 上海市第十人民醫(yī)院 內(nèi)分泌科 200072)

目的觀察和分析非酒精性脂肪性肝病(NAFLD)患者肝臟脂肪含量(LFC)與血清維生素A (VA)水平及胰島素抵抗(IR)之間的關(guān)系。方法征集2016年2月-2017年1月上海市崇明地區(qū)初診NAFLD患者200例和健康志愿者98例。根據(jù)口服75 g葡萄糖耐量試驗和胰島素釋放試驗，將NAFLD患者分為單純NAFLD組(n=91)、NAFLD合并糖調(diào)節(jié)受損(IGR)組(n=69)，NAFLD合并2型糖尿病(T2DM)組(n=40)，另將98例健康志愿者作為健康對照組。用穩(wěn)態(tài)模型評估IR，用高效液相色譜法檢測血清VA水平，采用3.0 T質(zhì)子磁共振波譜進(jìn)行LFC檢測。符合正態(tài)分布的計量資料多組間比較采用單因素方差分析，進(jìn)一步兩兩比較采用LSD-t檢驗；不符合正態(tài)分布的計量資料組間比較采用Kruskal-WallisH檢驗，進(jìn)一步兩兩比較采用Mann-WhitmeyU檢驗。計數(shù)資料組間比較采用Pearsonχ2檢驗。相關(guān)性分析采用Spearman相關(guān)性分析法。結(jié)果健康對照組、單純NAFLD組、NAFLD合并IGR組和NAFLD合并T2DM組4組間FPG、葡萄糖耐量試驗負(fù)荷后2 h血糖(2hPG)、糖化血紅蛋白(HbA1c)比較差異均有統(tǒng)計學(xué)意義(F值分別為303.8、133.1和249.3，P值均<0.01)。FPG、2hPG和HbA1c在單純NAFLD組、NAFLD合并IGR組、NAFLD合并T2DM組依次上升(P值均<0.01)，與單純NAFLD組、NAFLD合并IGR組、NAFLD合并T2DM組比較，健康對照組BMI、ALT、TG、低密度脂蛋白均明顯降低(P值均<0.01)。單純NAFLD組、NAFLD合并IGR組和NAFLD合并T2DM組患者血清VA、LFC和HOMA2-IR均明顯高于健康對照組(F=9.22、H=216.1、H=151.0，P值均<0.01)。在單純NAFLD組、NAFLD合并IGR組和NAFLD合并T2DM組中，HOMA2-IR、LFC逐步增高(H值分別為26.7、38.6，P值均<0.01)。NAFLD合并IGR組與NAFLD合并T2DM組HOMA2-IR、LFC比較差異均有統(tǒng)計學(xué)意義(U值分別為995、800，P值均<0.01)；NAFLD合并IGR組和NAFLD合并T2DM組分別與單純NAFLD組比較，HOMA2-IR、LFC、VA差異均有統(tǒng)計學(xué)意義(P值均<0.05)。LFC與VA(R2=0.103,P<0.001) 和HOMA2-IR(R2=0.531,P<0.001)呈正相關(guān)關(guān)系。結(jié)論NAFLD患者LFC增加與高血清VA水平及糖代謝紊亂有關(guān)。

非酒精性脂肪性肝病； 維生素A； 肝臟脂肪含量； 胰島素抵抗

非酒精性脂肪性肝病(NAFLD)目前已成為肝功能異常的最主要病因，其發(fā)病率呈增長趨勢。上海地區(qū)的研究[1]顯示在成年人群中NAFLD 患病率已達(dá)到了13%，在糖尿病患者中達(dá)50%之多。脂肪代謝紊亂和胰島素抵抗(insulin resistance, IR)是NAFLD的主要危險因素，且在NAFLD患者中，代謝綜合征或2型糖尿病(type 2 diabetes mellitus, T2DM)的發(fā)病風(fēng)險明顯增加[2-4]。維生素A(vitamin A, VA)是重要的脂源性微量營養(yǎng)素，在肝臟中含量豐富。有研究[5]表明，VA可調(diào)節(jié)肝臟葡萄糖和脂肪代謝，并與胰島素分泌有關(guān)。但是，在NAFLD患者中，血清VA與肝臟脂肪含量(liver fat content, LFC)及IR的關(guān)系還不明確。

1 資料與方法

1.1 研究對象 隨機征集2016年2月-2017年1月上海市崇明地區(qū)NAFLD患者200例，分為單純NAFLD組(n=91)、NAFLD合并糖調(diào)節(jié)受損(Impaired glucose regulation, IGR)組(n=69例)，NAFLD合并T2DM組(n=40)，另收集健康志愿者98例為健康對照組。

1.2 診斷標(biāo)準(zhǔn)和排除標(biāo)準(zhǔn) NAFLD診斷標(biāo)準(zhǔn)[6]：(1) 無飲酒史或飲酒折合乙醇量<140 g/周(女性<70 g/周)；(2)除外病毒性肝炎、全胃腸外營養(yǎng)等可導(dǎo)致脂肪肝的特定疾?。?3)除原發(fā)病臨床表現(xiàn)外，可出現(xiàn)乏力、腹脹、肝區(qū)隱痛等癥狀，可伴肝脾腫大；(4)血清轉(zhuǎn)氨酶可升高，并以ALT增加為主，常伴有GGT、TG等水平增高；(5)磁共振及質(zhì)子磁共振波譜(1H MRS)測定LFC>5%。以上5項標(biāo)準(zhǔn)全部滿足即診斷為NAFLD。T2DM和IGR診斷標(biāo)準(zhǔn)參考《中國2型糖尿病防治指南(2013年版)》[7]。T2DM：典型糖尿病癥狀(多飲、多尿、多食、體質(zhì)量下降)加上隨機血糖檢測≥11.1 mmol/L，或加上空腹葡萄糖(fasting plasma glucose，F(xiàn)PG)≥7.0 mmol/L，或加上75 g口服葡萄糖耐量試驗負(fù)荷后2 h血糖(2hPG)≥11.1 mmol/L。IGR：空腹血糖受損(FPG:6.1～<7.0)和(或)糖耐量減低(2hPG: 7.8～<11.1)。排除標(biāo)準(zhǔn): (1) 嚴(yán)重心、腎疾病，其他原因引起的肝臟疾病；(2) 既往或正在服用有改變糖類代謝功效的藥物(如類固醇激素、β 受體阻滯劑、噻嗪類利尿劑); (3)1型糖尿病、感染、妊娠及哺乳期等；(4) 毒品攝入史，合并精神疾病。檢查前告知受試者研究目的并簽署知情同意書。

1.3 研究方法 所有受試者詳細(xì)詢問個人史、既往史及家族史。空腹隔夜禁食水12 h，于次日清晨測量身高、體質(zhì)量，檢測肝功能和血脂全套。受試者接受1H MRS檢查。肝臟1H MRS診斷脂肪肝分割點為LFC>5%[8]。進(jìn)行口服葡萄糖耐量試驗和胰島素釋放實驗，分別測定0、30、60、120 min 血糖(葡萄糖氧化酶法)及胰島素(放射免疫法)。依據(jù)FPG和空腹胰島素水平計算 HOMA2-IR。采用高效液相色譜法(HPLC)測定各組VA水平。

2 結(jié)果

2.1 一般資料及生化指標(biāo)比較 在NAFLD患者中，單純NAFLD占42.5%，NAFLD合并IGR占37.5%，NAFLD合并T2DM占20.0%。健康對照組、單純NAFLD組、NAFLD合并IGR組和NAFLD合并T2DM組4組間FPG、2hPG、糖化血紅蛋白(HbA1c)比較差異均有統(tǒng)計學(xué)意義(F值分別為303.8、133.1和249.3，P值均<0.01)。FPG、2hPG和HbA1c在單純NAFLD組、NAFLD合并IGR組、NAFLD合并T2DM組依次上升(P值均<0.01)。與單純NAFLD組、NAFLD合并IGR組、NAFLD合并T2DM組比較，健康對照組BMI、ALT、TG、低密度脂蛋白(LDL)均明顯降低(P值均<0.01)(表1)。

單純NAFLD組、NAFLD合并IGR組和NAFLD合并T2DM組患者血清VA、LFC和HOMA2-IR均明顯高于健康對照組(P值均<0.01)。在單純NAFLD組、NAFLD合并IGR組和NAFLD合并T2DM組中，HOMA2-IR、LFC逐步增高(H值分別為26.7、38.6，P值均<0.01)，其中NAFLD合并IGR組與NAFLD合并T2DM組HOMA2-IR、LFC比較差異有統(tǒng)計學(xué)意義(U值分別為995、800，P值均<0.01)；NAFLD合并IGR組和NAFLD合并T2DM組分別與單純NAFLD組比較，HOMA2-IR、LFC、VA差異均有統(tǒng)計學(xué)意義(P值均<0.05)(表1)。

2.2 血清VA與LFC、IR與LFC、VA與IR間的相關(guān)性分析 VA和HOMA2-IR均與LFC呈正相關(guān)關(guān)系(P值均<0.001)，但VA與HOMA2-IR無相關(guān)性(P>0.05) (圖1) 。

圖1 NAFLD患者血清VA、LFC、HOMA2-IR之間的相關(guān)性分析a：VA與LFC的相關(guān)性； b：HOMA2-IR與LFC的相關(guān)性； c：VA與HOMA2-IR的

相關(guān)性

注：1)與單純NAFLD組比較，P<0.05;2)與NAFLD合并IGR組比較，P<0.05

3 討論

本研究發(fā)現(xiàn)，NAFLD患者BMI、VA、TG、LDL、FPG、2hPG、HbA1c、LFC、HOMA2-IR均明顯高于健康對照組，表明NAFLD患者存在明顯的葡萄糖、脂肪和VA代謝異常；NAFLD患者LFC與血清VA、HOMA2-IR呈線性正相關(guān)，而VA與HOMA2-IR無線性相關(guān)性，表明VA可促進(jìn)肝臟脂肪合成，并進(jìn)一步導(dǎo)致胰島素抵抗，但VA并不直接導(dǎo)致胰島素抵抗；通過比較單純NAFLD組、NAFLD合并IGR組、NAFLD合并T2DM組檢測指標(biāo)，發(fā)現(xiàn)NAFLD患者血清VA水平、LFC和HOMA2-IR均與葡萄糖代謝紊亂有關(guān)。

NAFLD如不早期預(yù)防和治療，發(fā)展為糖尿病、代謝紊亂及心血管并發(fā)癥的風(fēng)險則明顯增加[3]。筆者團(tuán)隊在前期臨床研究[9]中發(fā)現(xiàn)，NAFLD是選擇性IR(即糖代謝抵抗和脂代謝敏感)在肝臟的表現(xiàn)，NAFLD對糖尿病的發(fā)生具有良好的預(yù)測作用，及時干預(yù)可起到預(yù)防糖代謝紊亂的作用。本研究中NAFLD患者T2DM患病率為20.0%，IGR患病率為34.5%。T2DM、肥胖及高脂血癥常常被認(rèn)為與NAFLD有關(guān)[10]。人體內(nèi)游離脂肪酸過多時會在肝臟、骨骼肌、胰腺、心臟等非脂肪組織的器官中異位沉積，其脂毒性會影響這些組織器官的功能[11]。脂肪異位沉積于非脂肪組織的器官被認(rèn)為是T2DM和IR的主要因素[12-13]。1H-MRS是一種無創(chuàng)、快速、安全、有效的 LFC 定量方法[14]，LFC 真實反映了肝臟脂肪異位沉積的程度，而HOMA2-IR主要反映肝臟IR程度和空腹?fàn)顟B(tài)下的胰島素敏感性[15]。脂肪組織IR亦會促進(jìn)游離脂肪酸在肝細(xì)胞中沉積，對肝臟IR一定程度上起正協(xié)同作用。

VA是第一個被發(fā)現(xiàn)的脂源性維生素，其可調(diào)節(jié)肝臟糖脂代謝相關(guān)基因的表達(dá)，并與胰島素協(xié)同促進(jìn)肝臟脂肪沉積[16]。急性早幼粒細(xì)胞白血病患者使用VA類似物全反式維甲酸治療后體質(zhì)量增加，血漿TG和膽固醇水平升高[17]。大鼠喂VA缺乏飼料3個月后，血漿TG、膽固醇水平以及肝臟脂肪含量均明顯低于VA飼料喂養(yǎng)大鼠[18]。還有研究[19]表明，高濃度VA培養(yǎng)大鼠胰島細(xì)胞可抑制葡萄糖刺激的胰島素釋放。肥胖小鼠，ob/ob和db/db小鼠胰腺B細(xì)胞VA水平明顯高于正常小鼠[20]。這些研究結(jié)果表明VA在糖脂代謝平衡中具有調(diào)節(jié)作用。

綜上所述，LFC與VA和IR密切相關(guān)，LFC增加及血清VA過量是NAFLD患者糖代謝紊亂的危險因素。進(jìn)一步研究VA代謝途徑與NAFLD發(fā)病的關(guān)系可能有助于發(fā)現(xiàn)NAFLD治療新靶點。

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CorrelationofliverfatcontentwithserumvitaminAlevelandinsulinresistanceinpatientswithnonalcoholicfattyliverdisease

DINGZhiyong,BULe,LUHongyan,etal.

(DepartmentofEndocrinology,ShanghaiTenthPeople'sHospitalChongmingBranch,Shanghai202157,China)

ObjectiveTo investigate the correlation of liver fat content (LFC) with serum vitamin A (VA) level and insulin resistance (IR) in patients with nonalcoholic fatty liver disease (NAFLD).MethodsA total of 200 patients with an initial diagnosis of NAFLD in Shanghai Chongming from February 2016 to January 2017 were enrolled. According to the results of oral glucose tolerance test with 75 g glucose and insulin releasing test, NAFLD patients were divided into simple NAFLD group with 91 patients, NAFLD-impaired glucose regulation (IGR) group with 69 patients, and NAFLD-type 2 diabetes mellitus (T2DM) group with 40 patients. A total of 98 healthy volunteers were enrolled as healthy control group. The homeostasis model was used to evaluate IR, high-performance liquid chromatography was used to measure serum VA level, and 3.0 T1H-magnetic resonance spectroscopy was used to measure LFC. A one-way analysis of variance was used for comparison of normally distributed continuous data between multiple groups, and the LSD-t-test was used for further comparison between two groups; the Kruskal-WallisHtest was used for comparison of non-normally distributed continuous data between multiple groups, and the Mann-WhitmeyUtest was used for further comparison between two groups. The Pearson′s chi-squared test was used for comparison of categorical data between groups. A Spearman correlation analysis was also performed.ResultsThere were significant differences in fasting plasma glucose (FPG), 2-hour postprandial glucose (2hPG), and HbAlc between the healthy control group, simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group (F=303.8，133.1, and 249.3, allP<0.01). The simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group had significant increases in FPG, 2hPG, and HbAlc (allP<0.01), and compared with the simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group, the healthy control group had significant reductions in body mass index, alanine aminotransferase, triglyceride, and low-density lipoprotein (allP<0.01). The simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group had significantly higher serum VA level, LFC, and HOMA2-IR than the healthy control group (F=9.2,H=216.1, andH=151.0, allP<0.01). HOMA2-IR and LFC gradually increased in the simple NAFLD group, NAFLD-IGR group, and NAFLD-T2DM group (H=26.7 and 38.6, bothP<0.01). There were significant differences in HOMA2-IR and LFC between the NAFLD-IGR group and the NAFLD-T2DM group (U=995 and 800, bothP<0.01); there were also significant differences in HOMA2-IR, LFC, and VA between the NAFLD-IGR group and the simple NAFLD group, as well as between the NAFLD-T2DM group and the simple NAFLD group (allP<0.05). LFC was positively correlated with VA (R2=0.103,P<0.001) and HOMA2-IR (R2=0.531,P<0.001).ConclusionThe increase in LFC is closely associated with high serum VA level and disorder of glucose metabolism in patients with NAFLD.

nonalcoholic fatty liver disease; vitamin A; liver fat content; insulin resistance

575.5

A

1001-5256(2017)12-2361-05

10.3969/j.issn.1001-5256.2017.12.021

2017-07-07；修回日期：2017-07-24。 基金項目：崇明縣科學(xué)技術(shù)委員會科技項目(cky2017-21) 作者簡介：丁智勇(1974-)，男，主治醫(yī)師，主要從事糖脂代謝疾病的相關(guān)研究。

引證本文：DING ZY, BU L, LU HY, et al. Correlation of liver fat content with serum vitamin A level and insulin resistance in patients with nonalcoholic fatty liver disease[J]. J Clin Hepatol, 2017, 33(12): 2361-2365. (in Chinese)

丁智勇, 卜樂, 魯鴻燕, 等. 非酒精性脂肪性肝病患者血清維生素A水平、肝臟脂肪含量與胰島素抵抗的相關(guān)性分析[J]. 臨床肝膽病雜志, 2017, 33(12): 2361-2365.

(本文編輯：林 姣)