孫倩+曾誠(chéng)++段薇娜++孟慶濤++夏中元
[摘要] 目的 探討血管緊張素-(1-7)/血管緊張素-Ⅱ[Ang-(1-7)/Ang-Ⅱ]調(diào)節(jié)NF-E2-related factor-2(Nrf2)/血紅素氧合酶1(HO-1)通路在糖尿病腎臟缺血再灌注損傷中的作用及機(jī)制。 方法 60只成年雄性SD大鼠隨機(jī)分為正常假手術(shù)組(Sham組)、正常缺血再灌注組(IR組)、糖尿病假手術(shù)組(DS組)、糖尿病缺血再灌注組(DIR組),每組各15只。檢測(cè)血尿素氮(BUN)、肌酐(Cr)和中性粒細(xì)胞明膠酶相關(guān)載脂蛋白(NGAL),觀察腎臟病理學(xué)改變,檢測(cè)腎組織超氧化物歧化酶(SOD)活性、丙二醛(MDA)含量,Western blot檢測(cè)Ang-(1-7)和Ang-Ⅱ蛋白以及Nrf2和HO-1蛋白表達(dá)。 結(jié)果 Ang-(1-7)蛋白在DS組中表達(dá)較Sham組增加(P < 0.05),在IR組中表達(dá)較Sham組減少(P < 0.05),而在DIR組中較IR組進(jìn)一步減少(P < 0.05)。IR組和DS組中Ang-Ⅱ蛋白表達(dá)顯著高于Sham組(P < 0.05),而DIR組中Ang-Ⅱ蛋白表達(dá)進(jìn)一步增高(P < 0.05)。IR組和DS組中Nrf2和HO-1蛋白表達(dá)顯著高于Sham組(P < 0.05),而DIR組中Nrf2和HO-1蛋白表達(dá)較IR組和DS組降低(P < 0.05)。與Sham組比較,IR組和DS組中腎臟損傷程度顯著增高(P < 0.05),血清BUN、Cr和NGAL水平、腎臟組織MDA含量明顯升高而SOD活性顯著降低(P < 0.05)。與IR組和DS組比較,DIR組中腎臟損傷程度進(jìn)一步增高(P < 0.05),血清BUN、Cr和NGAL水平、腎臟組織MDA含量明顯增高,而SOD活性明顯降低(P < 0.05)。 結(jié)論 缺血再灌注可能通過(guò)抑制Ang-(1-7),激活A(yù)ng-Ⅱ,下調(diào)Nrf2/HO-1通路的抗氧化應(yīng)激能力,加重了糖尿病腎臟的損傷。
[關(guān)鍵詞] 血管緊張素-(1-7);血管緊張素-Ⅱ;NF-E2-related factor-2;糖尿?。荒I臟缺血再灌注損傷
[中圖分類號(hào)] R692.9 [文獻(xiàn)標(biāo)識(shí)碼] A [文章編號(hào)] 1673-7210(2017)07(b)-0012-05
Role of angiotensin-(1-7)/angiotensin-Ⅱin kidney ischemia-reperfusion injury by regulating Nrf2/HO-1 pathway in diabetic rats
SUN Qian ZENG Cheng DUAN Weina MENG Qingtao XIA Zhongyuan
Department of Anesthesiology, Renmin Hospital of Wuhan University, Hubei Province, Wuhan 430061, China
[Abstract] Objective To investigate the role of angiotensin-(1-7)/angiotensin-Ⅱ[Ang-(1-7)/Ang-Ⅱ] in kidney ischemia-reperfusion injury by regulating NF-E2-related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) pathway in diabetic rats. Methods Sixty male SD rats were randomly divided into four groups: Sham group, kidney ischemia-reperfusion group (IR group), diabetic group (DS group), diabetic+KIR group (DIR group), with 15 rats in each group. Kidney ischemia reperfusion model of STZ-diabetic rat model was used. After 24h reperfusion, blood urea nitrogen (BUN), creatinine (Cr), and neutrophil gelatinase-associated lipocalin (NGAL) levels in serum were measured. Renal histology was observed and evaluated. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels in renal tissues were detected. Western blot were used to observe the expression levels of Ang-(1-7), Ang-Ⅱ and Nrf2, HO-1 in renal tissues. Results Expressions of Ang-(1-7) in DS group were higher than those in sham group (P < 0.05), the expressions of Ang-(1-7) in IR group were lower than those in sham group (P < 0.05), the expressions of Ang-(1-7) in DIR group were much lower than those in IR group (P < 0.05). The expressions of Ang-Ⅱ in IR and DS group were higher than those in Sham group (P < 0.05), the expressions of Ang-Ⅱ in DIR group were higher than those in IR and DS group (P < 0.05). The expressions of Nrf2 and HO-1 in IR and DS group were higher than those in sham group (P < 0.05), the expressions of Nrf2 and HO-1 in DIR group were lower than those in IR and DS group (P < 0.05). Compare with Sham group, BUN, Cr and NGAL in serum and MDA levels in the renal tissues were increased, and SOD levels were decreased in IR and DS group (P < 0.05). Compare with IR and DS group, BUN, Cr and NGAL in serum and MDA levels in the renal tissues were further increased (P < 0.05), and SOD levels were further decreased in DIR group (P < 0.05). Conclusion Ischemia reperfusion might inhibit the Ang-(1-7), activate the Ang-Ⅱ and down regulate the anti-oxidative stress of Nrf2/HO-1 pathway, resulting in the damage of diabetic kidney.
[Key words] Angiotensin-(1-7); Angiotensin-Ⅱ; NF-E2-related factor-2; Diabetic; Kidney ischemia-reperfusion injury
糖尿病腎?。―N)是威脅糖尿病患者生命的重要原因,腎臟缺血再灌注損傷可發(fā)生在腎移植、復(fù)雜腎臟手術(shù)和休克復(fù)蘇過(guò)程中[1]。然而,糖尿病腎臟缺血再灌注損傷的分子機(jī)制尚不明確。近年來(lái)研究表明NF-E2-related factor-2(Nrf2)/血紅素氧合酶1(HO-1)通路作為內(nèi)源性抗氧化應(yīng)激通路,在糖尿病及其腎臟損傷中起著重要的作用[2-3]。進(jìn)一步研究表明,低濃度血管緊張素-Ⅱ(Ang-Ⅱ)激活Nrf2/ARE通路,高濃度Ang-Ⅱ?qū)rf2/ARE通路起到抑制作用[4]。血管緊張素-(1-7)[Ang-(1-7)]對(duì)Ang-Ⅱ發(fā)揮負(fù)性調(diào)控作用,被認(rèn)為是內(nèi)源性的Ang-Ⅱ阻斷劑[5]。因此,本課題旨在研究Ang-(1-7)/Ang-Ⅱ通過(guò)調(diào)節(jié)Nrf2/ARE通路在糖尿病腎臟缺血再灌注損傷中的作用機(jī)制。
1 材料與方法
1.1 試劑和材料
成年雄性SD大鼠,SPF級(jí),9~12周(北京維通利華實(shí)驗(yàn)動(dòng)物技術(shù)有限公司,合格證號(hào):11400700202769),鏈脲佐菌素(STZ,sigma公司),Ang-(1-7)和Ang-Ⅱ蛋白以及Nrf2和HO-1蛋白抗體(Cell Signal公司),中性粒細(xì)胞明膠酶相關(guān)脂質(zhì)運(yùn)載蛋白(NGAL)酶聯(lián)免疫試劑盒(武漢博士德生物技術(shù)公司),丙二醛(MDA)及超氧化物歧化酶(SOD)試劑盒(南京建成生物技術(shù)公司),BX50及AU5400(Olympus Optica,日本)。
1.2 實(shí)驗(yàn)動(dòng)物及分組
SD大鼠,實(shí)驗(yàn)前禁食12 h,自由飲水。所有大鼠隨機(jī)分為4組,每組各15只:正常假手術(shù)組(Sham組),腎臟缺血再灌注組(IR組),糖尿病正常組(DS組),糖尿病腎臟缺血再灌注組(DIR組)。
1.3 動(dòng)物模型的建立
1.3.1 糖尿病模型的建立[6] 成年雄性9~12周SD大鼠,氟烷麻醉下尾靜脈注射STZ(40~60 mg/kg),72 h后當(dāng)血糖濃度>16.7 mmol/L時(shí)表示糖尿病鼠模型成功。所有實(shí)驗(yàn)在成模4周后開(kāi)始,實(shí)驗(yàn)期間每周監(jiān)測(cè)血糖水平1次。
1.3.2 腎臟缺血再灌注模型的建立[7] 術(shù)前禁食8~12 h,腹腔注射三溴乙醇(200 mg/kg)麻醉后,沿腹中線切口,逐層分離皮膚、腹膜,進(jìn)入腹腔,將腸道推向一側(cè),找到腎蒂后用無(wú)損傷微型動(dòng)脈夾迅速阻斷左右腎蒂,30 min后去除動(dòng)脈夾,分層縫合關(guān)閉腹腔。術(shù)后大鼠于24~29℃的環(huán)境保暖,補(bǔ)充水與飼料,再灌注24 h。Sham組:同法打開(kāi)腹腔并找到腎蒂,但不夾閉腎蒂。
1.3.3 模型成功與否判定 造模成功:術(shù)中夾閉雙側(cè)腎蒂后,可見(jiàn)腎臟由鮮紅變紫黑色,去除動(dòng)脈夾,恢復(fù)血流灌注,可見(jiàn)腎臟迅速由紫黑色變?yōu)轷r紅,恢復(fù)原來(lái)顏色;并且術(shù)后1~3 h,可見(jiàn)大鼠蘇醒,逐漸恢復(fù)正常活動(dòng)。造模不成功:腎臟恢復(fù)血流后5 min,腎臟未恢復(fù)正常顏色;或術(shù)中損傷周圍組織或器官;或術(shù)后1~3 h,大鼠未蘇醒或死亡。
1.4 取材及指標(biāo)測(cè)定
1.4.1 腎組織病理學(xué)檢測(cè) 左腎固定包埋后,用蘇木精伊紅染色。在BX50光學(xué)顯微鏡下觀察各組腎組織。利用McWhinnie 等[8]方法對(duì)腎小管壞死進(jìn)行半定量病理學(xué)評(píng)分。每個(gè)腎臟標(biāo)本累計(jì)100個(gè)交叉處的剖面腎小管損傷總分,最高為300分。
1.4.2 血清尿素氮(BUN)、肌酐(Cr)和NGAL檢測(cè) 左心采血1 mL,4℃ 3500 r/min離心15 min,取上清,運(yùn)用AU5400自動(dòng)分析儀檢測(cè)BUN和Cr水平。采用酶聯(lián)免疫吸附法(ELISA)測(cè)定血清NGAL濃度,具體操作步驟參照試劑盒說(shuō)明書(shū)。
1.4.3 腎臟組織SOD和MDA檢測(cè) 取50 mg腎臟組織,加入0.9 mL NS制成10%的組織勻漿。采用硫代巴比妥酸法測(cè)定MDA含量,鄰苯三酚法測(cè)定SOD活性。
1.4.4 腎臟Ang-(1-7)和Ang-Ⅱ蛋白以及Nrf2和HO-1蛋白 Western blot分析,組織樣品用BCA法測(cè)蛋白濃度。BandScan分析膠片灰度值進(jìn)行半定量分析。
1.5 統(tǒng)計(jì)學(xué)方法
采用統(tǒng)計(jì)軟件Graphpad Prism 5對(duì)數(shù)據(jù)進(jìn)行分析,正態(tài)分布計(jì)量資料以均數(shù)±標(biāo)準(zhǔn)差(x±s)表示多組間比較采用方差(ANOVA)分析,兩兩比較采用LSD-t檢驗(yàn)。計(jì)數(shù)資料以率表示,采用χ2檢驗(yàn)。以P < 0.05為差異有統(tǒng)計(jì)學(xué)意義。
2 結(jié)果
2.1 腎臟組織病理學(xué)變化
IR組與DS組的腎小管出現(xiàn)病理?yè)p傷,包括水腫、壞死和空泡化。而DIR組腎小管水腫、壞死和空泡化損傷現(xiàn)象進(jìn)一步加重。見(jiàn)圖1。與Sham組[(19.30±5.12)分]比較,IR組[(192.47±11.74)分]和DS組[(183.24±8.28)分]病理?yè)p傷評(píng)分顯著增高,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05);與IR組和DS組比較,DIR組[(242.77±6.35)分]病理學(xué)評(píng)分進(jìn)一步增高,差異有統(tǒng)計(jì)學(xué)意義(P < 0.05)。
2.2 各組血清BUN、Cr和NAGL含量的變化
與Sham組比較,IR組與DS組再灌注后血清BUN、Cr和NAGL含量顯著升高,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。與IR組和DS組比較,DIR組中血清BUN、Cr和NAGL進(jìn)一步升高,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。見(jiàn)表1。
表1 血清BUN、Cr和NAGL含量變化(n=15,x±s)
注:與Sham組比較,*P < 0.05;與DS組比較,#P < 0.05;BUN:尿素氮;Cr:肌酐;NGAL:中性粒細(xì)胞明膠酶相關(guān)載脂蛋白
2.3 各組腎臟組織SOD和MDA含量變化
與Sham組比較,IR組與DS組SOD活性顯著降低,而MDA含量明顯升高,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。較之于IR組,DIR組則進(jìn)一步降低SOD活性并升高M(jìn)DA的含量,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。見(jiàn)表2。
表2 腎臟組織SOD和MDA含量(n=15,x±s)
注:與Sham組比較,*P < 0.05;與DS組比較,#P < 0.05;SOD:超氧化物歧化酶;MDA:丙二醛
2.4 腎臟組織中Ang-(1-7)和Ang-Ⅱ蛋白以及Nrf2和HO-1蛋白表達(dá)
Ang-(1-7)蛋白在DS組中表達(dá)較Sham組增加,在IR組中表達(dá)較Sham組減少,而在DIR組中較IR組進(jìn)一步減少,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。IR組和DS組中Ang-Ⅱ蛋白表達(dá)顯著高于Sham組,而DIR組中Ang-Ⅱ蛋白表達(dá)進(jìn)一步增高,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。IR組和DS組中Nrf2和HO-1蛋白表達(dá)顯著高于Sham組,而DIR組中Nrf2和HO-1蛋白表達(dá)較IR組和DS組降低,差異均有統(tǒng)計(jì)學(xué)意義(P < 0.05)。見(jiàn)圖2、表3。
圖2 腎臟組織Ang-(1-7)和Ang-Ⅱ蛋白以及Nrf2和HO-1蛋白表達(dá)
表3 腎臟組織Ang-(1-7)和Ang-Ⅱ蛋白以及Nrf2和HO-1蛋白表達(dá)變化(n=8,x±s)
注:與Sham組比較,*P < 0.05;與DS組比較,#P < 0.05;Ang-(1-7):血管緊張素-(1-7);Ang-Ⅱ:血管緊張素-Ⅱ;Nrf2:NF-E2-related factor-2;HO-1:血紅素氧合酶1
3 討論
糖尿病機(jī)體組織存在活性氧負(fù)荷增加和腎素-血管緊張素-醛固酮系統(tǒng)(RAAS)激活等病理生理改變,加重腎臟缺血再灌注損傷[9-12]。Ang-Ⅱ是RAAS系統(tǒng)中具有代表性的活性肽,可導(dǎo)致氧化應(yīng)激損傷、血管重構(gòu)、炎性反應(yīng)和內(nèi)皮損傷[13-14]。近年來(lái)大量研究證實(shí)Ang-(1-7)在心血管血流動(dòng)力學(xué)、壓力反射調(diào)節(jié)和血管內(nèi)皮功能等生物學(xué)活性上與Ang-Ⅱ相拮抗,并通過(guò)其受體(Mas)發(fā)揮血管擴(kuò)張、抗氧化應(yīng)激、抗炎和抗增殖等作用,對(duì)心血管系統(tǒng)和腎臟功能都具有保護(hù)作用[15-17],并可減弱由高血糖所致的活性氧的升高[18]。
Nrf2/ARE通路在內(nèi)源性細(xì)胞抗氧化防御體系中起著非常重要的作用。當(dāng)機(jī)體受到外界氧化應(yīng)激刺激時(shí),Nrf2與Keap1解離,進(jìn)入細(xì)胞核與ARE結(jié)合,啟動(dòng)下游抗氧化基因的表達(dá),從而清除過(guò)多氧自由基[19]。本課題組前期研究表明Nrf2/ARE通路在糖尿病及腎臟損傷過(guò)程中起到重要的保護(hù)作用[20-21]。與此同時(shí),有研究證實(shí)Ang-Ⅱ和Ang-(1-7)誘導(dǎo)細(xì)胞氧化應(yīng)激后激活了Nrf2/ARE通路,但是它的激活作用有時(shí)間和刺激濃度限制[22]。
本研究發(fā)現(xiàn)Ang-(1-7),Ang-Ⅱ蛋白和Nrf2、HO-1蛋白在DS組中表達(dá)較Sham組均增加,而SOD酶活性降低,MDA含量增多。結(jié)果表明在糖尿病早期Ang-(1-7)蛋白被激活以控制過(guò)量的Ang-Ⅱ,體內(nèi)的Ang-(1-7)蛋白及少量的Ang-Ⅱ雖可激活Nrf2/ARE通路,發(fā)揮抗氧化應(yīng)激的作用,但是其激活的HO-1及SOD酶不足以對(duì)抗高糖產(chǎn)生的致?lián)p傷作用,故仍然表現(xiàn)為腎臟組織損傷程度顯著,BUN、Cr和NAGL含量以及MDA含量較Sham組顯著增高。在DIR組蛋白Ang-Ⅱ較DS組進(jìn)一步增高,而Ang-(1-7)、Nrf2和HO-1蛋白較DS組表達(dá)均明顯降低,同時(shí)SOD酶活性進(jìn)一步降低,MDA含量進(jìn)一步增多,表明缺血再灌注抑制了Ang-(1-7)蛋白,導(dǎo)致高濃度的Ang-Ⅱ下調(diào)了Nrf2的表達(dá),從而加重了糖尿病腎臟的損傷,其損傷可能與缺血再灌注產(chǎn)生大量氧自由基,遠(yuǎn)遠(yuǎn)超出了抗氧化防御體系的清除能力相關(guān)。
綜上所述,本研究證實(shí)在糖尿病中早期Ang-(1-7)蛋白被激活以控制過(guò)量的Ang-Ⅱ,體內(nèi)的Ang-(1-7)蛋白及少量的Ang-Ⅱ可激活Nrf2/ARE通路發(fā)揮抗氧化應(yīng)激的作用;而缺血再灌注抑制了Ang-(1-7) 蛋白,導(dǎo)致高濃度的Ang-Ⅱ下調(diào)了Nrf2 的表達(dá),從而加重了糖尿病腎臟的損傷。本研究提示Ang-(1-7)可能成為為今后治療糖尿病腎臟缺血再灌注損傷的作用靶點(diǎn)。
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(收稿日期:2017-4-12 本文編輯:蘇 暢)