王 靜 徐 萍# 楊志文 徐 凱 賴躍興
上海交通大學(xué)附屬第一人民醫(yī)院松江分院消化內(nèi)科1(201600) 藥劑科2
PI3K/AKT激動(dòng)劑和抑制劑對巨噬細(xì)胞炎癥反應(yīng)的影響*
王 靜1徐 萍1#楊志文2徐 凱1賴躍興1
上海交通大學(xué)附屬第一人民醫(yī)院松江分院消化內(nèi)科1(201600) 藥劑科2
背景:近年發(fā)現(xiàn)磷脂酰肌醇3激酶/絲氨酸-蘇氨酸激酶(PI3K/AKT)在重度急性胰腺炎(SAP)的發(fā)病中發(fā)揮重要作用,但機(jī)制尚未明確。目的:探討PI3K/AKT激動(dòng)劑胰島素樣生長因子-Ⅰ(IGF-Ⅰ)和抑制劑wortmannin對巨噬細(xì)胞株RAW264.7 Toll樣受體4(TLR4)信號(hào)通路的影響,闡明PI3K/AKT參與調(diào)節(jié)SAP炎癥反應(yīng)的作用機(jī)制。方法:分別以不同濃度脂多糖(LPS)、IGF-Ⅰ、wortmannin處理RAW264.7細(xì)胞,采用CCK-8實(shí)驗(yàn)檢測細(xì)胞活性。RAW264.7細(xì)胞分為空白對照組(不予處理)、LPS組(LPS 1 μg/mL)、IGF-Ⅰ組(IGF-Ⅰ 100 ng/mL+LPS 1 μg/mL)、wortmannin組(wortmannin 100 nmol/L+LPS 1 μg/mL)和IGF-Ⅰ+wortmannin組(wortmannin 100 nmol/L+IGF-Ⅰ 100 ng/mL+LPS 1 μg/mL),采用ELISA法檢測腫瘤壞死因子-α(TNF-α)、白細(xì)胞介素-6(IL-6)蛋白表達(dá),采用real-time PCR檢測TLR4、髓樣分化因子88(MyD88)、AKT、PI3K、p38絲裂原活化蛋白激酶(p38MAPK)、核因子-κB(NF-κB)mRNA表達(dá)。結(jié)果:RAW264.7細(xì)胞經(jīng)不同濃度LPS、IGF-Ⅰ、wortmannin處理后,各濃度組間細(xì)胞活性無明顯差異(P>0.05)。LPS組、IGF-Ⅰ組、wortmannin組、IGF-Ⅰ+wortmannin組TNF-α、IL-6表達(dá)水平均較空白對照組顯著升高(P<0.05);wortmannin組TNF-α、IL-6表達(dá)水平較LPS組和IGF-Ⅰ組顯著降低(P<0.05);IGF-Ⅰ+wortmannin組 TNF-α、IL-6表達(dá)水平較IGF-Ⅰ組顯著降低(P<0.05)。LPS組AKT、PI3K、TLR4及其下游分子MyD88、p38MAPK、NF-κB mRNA表達(dá)均顯著高于空白對照組(P<0.05);IGF-Ⅰ組上述指標(biāo)較LPS組進(jìn)一步升高,差異有統(tǒng)計(jì)學(xué)意義(P<0.05);wortmannin組上述指標(biāo)較LPS組和IGF-Ⅰ組顯著降低(P<0.05);IGF-Ⅰ+wortmannin組上述指標(biāo)顯著高于wortmannin組(P<0.05),但較IGF-Ⅰ組顯著降低(P<0.05)。結(jié)論:PI3K/AKT可能通過調(diào)節(jié)巨噬細(xì)胞中的TLR4及其下游分子影響促炎細(xì)胞因子表達(dá),從而參與SAP炎癥反應(yīng)的發(fā)生。
胰腺炎; 磷酸肌醇3-激酶類; 蛋白質(zhì)絲氨酸蘇氨酸激酶; Toll樣受體4; 胰島素樣生長因子 Ⅰ; Wortmannin; 腫瘤壞死因子α; 白細(xì)胞介素6
重度急性胰腺炎(severe acute pancreatitis, SAP)是病死率較高的消化系統(tǒng)疾病,其發(fā)病機(jī)制尚未完全闡明。本課題組前期研究[1]發(fā)現(xiàn)磷脂酰肌醇3激酶/絲氨酸-蘇氨酸激酶(PI3K/AKT)參與調(diào)控SAP 大鼠胰腺組織促炎細(xì)胞因子的釋放,可加重胰腺組織損傷;而PI3K/AKT抑制劑wortmannin可減輕胰腺組織損傷,提高SAP大鼠生存率。然而,PI3K/AKT參與SAP發(fā)病的具體機(jī)制尚未明確。已有研究[2]證實(shí)Toll樣受體4(Toll-like receptor 4, TLR4)信號(hào)通路是促炎細(xì)胞因子釋放的主要通路,刺激TLR4可激活核因子-κB(NF-κB)、p38絲裂原活化蛋白激酶(p38MAPK)信號(hào)通路,導(dǎo)致炎性因子釋放。故本研究通過探討PI3K/AKT激動(dòng)劑胰島素樣生長因子-Ⅰ (insulin-like growth factor-Ⅰ, IGF-Ⅰ)和抑制劑wortmannin對小鼠巨噬細(xì)胞TLR4信號(hào)通路的影響,旨在闡明PI3K/AKT參與調(diào)節(jié)SAP炎癥反應(yīng)的作用機(jī)制。
一、細(xì)胞株、主要試劑和儀器
小鼠巨噬細(xì)胞株RAW264.7購自中國科學(xué)院上海細(xì)胞庫。CCK-8試劑盒(日本同仁公司);脂多糖(LPS)、wortmannin(美國Sigma公司);IGF-Ⅰ、腫瘤壞死因子-α(TNF-α) ELISA試劑盒(美國Abcam公司);白細(xì)胞介素-6(IL-6) ELISA試劑盒(南京建成生物工程研究所);TRIzol試劑(美國Invitrogen公司);cDNA第一鏈合成試劑盒(美國Promega公司); PCR擴(kuò)增試劑盒[生工生物工程(上海)股份有限公司];SYBR?PrimeScriptTMreal-time RT-PCR試劑盒(日本TaKaRa公司)。
二、方法
1. 細(xì)胞培養(yǎng):RAW264.7細(xì)胞在37 ℃、5% CO2條件下,以含10%胎牛血清的RPMI1640培養(yǎng)基培養(yǎng)。
2. CCK-8實(shí)驗(yàn)檢測LPS、IGF-Ⅰ和wortmannin對RAW264.7細(xì)胞活性的影響:取對數(shù)生長期RAW264.7細(xì)胞,以1×103~5×103/孔接種于96孔板培養(yǎng)過夜,分別以LPS、IGF-Ⅰ、wortmannin處理細(xì)胞,每組設(shè)6個(gè)濃度組,LPS、IGF-Ⅰ、wortmannin濃度分別為0、0.1、0.3、1、3、10 μg/mL;0、1、10、30、100、300 ng/mL;0、3、10、20、100、300 nmol/L。加入100 μL無血清DMEM培養(yǎng)基和10 μL CCK-8試劑,37 ℃培養(yǎng)1 h,于酶標(biāo)儀450 nm波長處測定吸光度(A)值。
3. RAW264.7細(xì)胞分組處理:取對數(shù)生長期RAW264.7細(xì)胞,以5×103/mL接種于6孔板,設(shè)置空白對照組、LPS組、IGF-Ⅰ組、wortmannin組和IGF-Ⅰ+wortmannin組。空白對照組不予處理;LPS組以LPS(1 μg/mL)處理細(xì)胞;IGF-Ⅰ組以IGF-Ⅰ(100 ng/mL)預(yù)處理1 h后加入LPS(1 μg/mL)處理細(xì)胞;wortmannin組以wortmannin(100 nmol/L)預(yù)處理30 min后加入LPS(1 μg/mL)處理細(xì)胞;IGF-Ⅰ+wortmannin組以wortmannin(100 nmol/L)預(yù)處理30 min,以IGF-Ⅰ(100 ng/mL)預(yù)處理1 h,再以LPS(1 μg/mL)處理細(xì)胞。每孔細(xì)胞懸液終體積為1 mL,培養(yǎng)6 h后收集細(xì)胞。
4. ELISA法檢測促炎細(xì)胞因子TNF-α、IL-6表達(dá):取空白對照組、LPS組、IGF-Ⅰ組、wortmannin組和IGF-Ⅰ+wortmannin組細(xì)胞,檢測TNF-α、IL-6表達(dá),具體步驟參照相應(yīng)ELISA試劑盒說明書進(jìn)行。
5. Real-time PCR檢測TLR4、髓樣分化因子88(MyD88)、AKT、PI3K、p38MAPK、NF-κB mRNA表達(dá):取空白對照組、LPS組、IGF-Ⅰ組、wortmannin組和IGF-Ⅰ+wortmannin組細(xì)胞,棄上清液,PBS漂洗,加入1 mL TRIzol試劑抽提細(xì)胞總RNA。采用cDNA第一鏈合成試劑盒合成cDNA,以之為模板,采用ABI 7300型定量PCR儀行real-time PCR擴(kuò)增,檢測TLR4、MyD88、AKT、PI3K、p38MAPK、NF-κB mRNA表達(dá)。引物由生工生物工程(上海)股份有限公司合成,以GAPDH作為內(nèi)參照。TLR4引物上游:5’-CTA TGA ACA AAG GGT CTA TCA G-3’,下游:5’-AAG AAC AGC AAC CAC TAA AG-3’;MyD88引物上游:5’-CAC TCG CAG TTT GTT GGA TG-3’,下游:5’-TGT AAA GGC TTC TCG GAC TC-3’;AKT引物上游:5’-GGG CAC ATC AAG ATA ACG-3’,下游:5’-TGG TCC TGG TTG TAG AAG-3’;PI3K引物上游:5’-ATG CCA GAA AGG AGA ATG-3’,下游:5’-TGT TGG ACT CAG CAA TAC-3’;p38MAPK引物上游:5’-GTG TTC ACA CCC GCA AGG TC-3’,下游:5’-CGG TCA GCT TCT GGC ACT TC-3’;NF-κB引物上游:5’-CCC GAA ACT CAA CTT CTG-3’,下游:5’-ATC TGC CCT GAT GGT AAC-3’;GAPDH引物上游:5’-ATC ACT GCC ACC CAG AAG-3’,下游:5’-TCC ACG ACG GAC ACA TTG-3’。PCR反應(yīng)條件:95 ℃ 10 min;95 ℃ 15 s,60 ℃ 45 s,40個(gè)循環(huán)。以2-△△Ct法分析目的基因相對表達(dá)量。
三、統(tǒng)計(jì)學(xué)分析
一、不同濃度LPS、IGF-Ⅰ、wortmannin對細(xì)胞活性的影響
LPS、IGF-Ⅰ、wortmannin各濃度組間RAW264.7細(xì)胞活性無明顯差異(P>0.05)(圖1)。最終選擇以 1 μg/mL LPS、100 ng/mL IGF-Ⅰ和100 nmol/L wortmannin進(jìn)行后續(xù)實(shí)驗(yàn)。
A-F:LPS濃度分別為0、0.1、0.3、1、3、10 μg/mL;IGF-Ⅰ濃度分別為0、1、10、30、100、300 ng/mL;wortmannin濃度分別為0、3、10、20、100、300 nmol/L
圖1 不同濃度LPS、IGF-Ⅰ 和wortmannin對RAW264.7細(xì)胞 活性的影響
二、促炎細(xì)胞因子TNF-α、IL-6表達(dá)變化
LPS組RAW264.7細(xì)胞TNF-α、IL-6表達(dá)水平較空白對照組顯著升高(P<0.05);IGF-Ⅰ組TNF-α、IL-6表達(dá)水平與空白對照組和LPS組相比均升高,與空白對照組間差異顯著(P<0.05),與LPS組間差異則無統(tǒng)計(jì)學(xué)意義(P>0.05);Wortmannin組TNF-α、IL-6表達(dá)水平與空白對照組相比顯著升高(P<0.05),與LPS組和IGF-Ⅰ組相比顯著降低(P<0.05);IGF-Ⅰ+wortmannin組 TNF-α、IL-6表達(dá)水平與空白對照組相比顯著升高(P<0.05),與LPS組相比有所降低,但差異無統(tǒng)計(jì)學(xué)意義(P>0.05),與IGF-Ⅰ組相比顯著降低(P<0.05),與wortmannin組相比有所升高,但差異無統(tǒng)計(jì)學(xué)意義(P<0.05)(表1、圖2)。
三、TLR4、MyD88、AKT、PI3K、p38MAPK、NF-κB mRNA表達(dá)
LPS組TLR4、MyD88、AKT、PI3K、p38MAPK、NF-κB mRNA表達(dá)水平均顯著高于空白對照組(P<0.05)。IGF-Ⅰ 組上述指標(biāo)均顯著高于空白對照組和LPS組(P<0.05)。Wortmannin組上述指標(biāo)顯著高于空白對照組(P<0.05),與LPS組、IGF-Ⅰ組相比則顯著降低(P<0.05)。IGF-Ⅰ+wortmannin組上述指標(biāo)顯著高于wortmannin組(P<0.05),但較IGF-Ⅰ組顯著降低(P<0.05)(表2)。
組 別TNF?αIL?6空白對照組325.45±15.4653.64±3.06LPS組545.53±59.35137.80±12.30IGF?Ⅰ組570.29±51.24148.72±16.11wortmannin組490.20±25.97120.47±6.34IGF?Ⅰ+wortmannin組519.51±32.30131.92±9.58
PI3K是生長因子超家族信號(hào)轉(zhuǎn)導(dǎo)過程中的重要分子,可被多種細(xì)胞因子和理化因素激活。AKT主要負(fù)責(zé)由PI3K始動(dòng)的生物信息傳遞。PI3K/AKT作為細(xì)胞內(nèi)主要信號(hào)通路,在細(xì)胞代謝、細(xì)胞周期調(diào)控、細(xì)胞增殖、凋亡等多種生物學(xué)過程中發(fā)揮重要作用[3]。研究[4]表明PI3K/AKT通路可引起促炎細(xì)胞因子釋放,參與SAP發(fā)病。本課題組前期研究[1]結(jié)果顯示,SAP大鼠胰腺組織中磷酸化AKT表達(dá)增高,促炎細(xì)胞因子表達(dá)增加,予PI3K抑制劑wortmannin預(yù)處理后,AKT活性受抑,促炎細(xì)胞因子表達(dá)降低,胰腺組織病理學(xué)改變明顯緩解,SAP大鼠生存率升高。本研究結(jié)果顯示PI3K/AKT激動(dòng)劑IGF-Ⅰ可促進(jìn)LPS誘導(dǎo)巨噬細(xì)胞釋放促炎細(xì)胞因子TNF-α、IL-6,而wortmannin作用于巨噬細(xì)胞后可抑制LPS引起的促炎細(xì)胞因子分泌,并可拮抗IGF-Ⅰ對促炎細(xì)胞因子的上調(diào)作用,與前期動(dòng)物實(shí)驗(yàn)研究結(jié)果一致。
PI3K/AKT活化可導(dǎo)致細(xì)胞產(chǎn)生大量促炎細(xì)胞因子,此過程在炎癥反應(yīng)中發(fā)揮重要作用[5]。目前尚不明確PI3K/AKT促進(jìn)促炎細(xì)胞因子產(chǎn)生的具體機(jī)制。TLR4信號(hào)通路是促炎細(xì)胞因子釋放的主要通路, 活化的TLR4可通過MyD88等接頭蛋白激活其下游NF-κB、 p38MAPK,產(chǎn)生大量炎性因子。研究[6-8]證實(shí),SAP動(dòng)物模型的胰腺、腸道以及肺炎癥損傷均涉及TLR4信號(hào)通路激活。TLR4信號(hào)通路激活是SAP引發(fā)全身性炎癥反應(yīng)和臟器功能衰竭的重要病理生理學(xué)機(jī)制。本研究應(yīng)用LPS刺激巨噬細(xì)胞激活TLR4信號(hào)通路,并分別以PI3K/AKT激動(dòng)劑、抑制劑以及兩者同時(shí)應(yīng)用干預(yù)LPS引起的炎癥反應(yīng),結(jié)果顯示TLR4、 MyD88、p38MAPK、NF-κB表達(dá)隨PI3K/AKT激動(dòng)劑和抑制劑的干預(yù)而發(fā)生變化,提示PI3K/AKT與TLR4信號(hào)通路存在關(guān)聯(lián)。國外一項(xiàng)研究[9]發(fā)現(xiàn),尼古丁可減輕膿毒血癥小鼠的炎癥反應(yīng),此作用可能是通過影響PI3K/AKT信號(hào)通路、進(jìn)而調(diào)節(jié)TLR4表達(dá)實(shí)現(xiàn)的,進(jìn)一步提示PI3K/AKT與TLR4炎癥信號(hào)通路密切相關(guān)。本研究結(jié)果顯示IGF-Ⅰ可進(jìn)一步激活LPS引起的炎癥反應(yīng),活化TLR4信號(hào)通路,使TLR4、MyD88、p38MAPK、NF-κB表達(dá)上調(diào),促炎細(xì)胞因子TNF-α、IL-6表達(dá)升高,而wortmannin可拮抗IGF-Ⅰ的作用;單獨(dú)應(yīng)用wortmannin作用于LPS刺激的巨噬細(xì)胞則可抑制LPS引起的TLR4信號(hào)通路活化,下調(diào)TLR4、MyD88、p38MAPK、NF-κB表達(dá),并使促炎細(xì)胞因子表達(dá)降低。上述研究結(jié)果提示PI3K/AKT可能通過調(diào)節(jié)TLR4及其下游分子影響促炎細(xì)胞因子表達(dá),從而參與SAP炎癥反應(yīng)的發(fā)生。
圖2 各組RAW264.7細(xì)胞TNF-α、IL-6表達(dá)變化
組 別TLR4MyD88AKTPI3Kp38MAPKNF?κB空白對照組1.00±0.071.00±0.031.00±0.081.00±0.060.06±0.011.01±0.18LPS組7.06±0.793.26±0.084.05±0.314.89±0.150.25±0.033.92±0.27IGF?Ⅰ組9.11±0.365.97±0.565.13±0.346.04±0.590.35±0.015.28±0.31wortmannin組1.77±0.161.74±0.411.27±0.231.32±0.200.08±0.011.52±0.09IGF?Ⅰ+wortmannin組7.91±0.663.80±0.344.71±0.344.94±0.210.25±0.083.98±0.62
綜上所述,本研究從細(xì)胞水平證實(shí)PI3K/AKT可通過影響TLR4信號(hào)通路調(diào)控p38MAPK、NF-κB活性,從而調(diào)節(jié)促炎細(xì)胞因子表達(dá),參與SAP炎癥反應(yīng)。后期研究還需完善相關(guān)體內(nèi)實(shí)驗(yàn),進(jìn)一步驗(yàn)證SAP中PI3K/AKT與TLR4信號(hào)通路的關(guān)系,為控制SAP炎癥反應(yīng)提供理論依據(jù)。
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(2016-07-01收稿;2016-07-20修回)
Effect of Agonist and Inhibitor of PI3K/AKT on Inflammatory Response in Macrophages
WANGJing1,XUPing1,YANGZhiwen2,XUKai1,LAIYuexing1.1
DepartmentofGastroenterology,2DepartmentofPharmacy,SongjiangHospitalAffiliatedtotheFirstPeople’sHospital,ShanghaiJiaotongUniversity,Shanghai(201600)
XU Ping, Email: sjzxxp@yeah.net
Pancreatitis; Phosphatidylinositol 3-Kinases; Protein-Serine-Threonine Kinases; Toll-Like Receptor 4; Insulin-Like Growth Factor Ⅰ; Wortmannin; Tumor Necrosis Factor-alpha; Interleukin-6
10.3969/j.issn.1008-7125.2017.02.004
上海市松江區(qū)衛(wèi)計(jì)委醫(yī)學(xué)領(lǐng)先專業(yè)項(xiàng)目(201358)
#本文通信作者,Email: sjzxxp@yeah.net
Background: Phosphoinositide 3-kinase/serine-threonine kinase (PI3K/AKT) has been found playing an important role in the pathogenesis of severe acute pancreatitis (SAP) in recent years, but the underlying mechanism has not been clarified. Aims: To investigate the role of PI3K/AKT in regulating the inflammatory response in SAP by evaluating the effect of insulin-like growth factor-Ⅰ (IGF-Ⅰ) and wortmannin, the agonist and inhibitor of PI3K/AKT on Toll-like receptor 4 (TLR4) signaling pathway in macrophage cell line RAW264.7. Methods: RAW264.7 cells were treated with different concentrations of lipopolysaccharide (LPS), IGF-Ⅰ and wortmannin, respectively, and cell viability was determined by CCK-8 assay. RAW264.7 cells were divided into blank control group (no treatment), LPS group (LPS 1 μg/mL), IGF-Ⅰ group (IGF-Ⅰ 100 ng/mL+LPS 1 μg/mL), wortmannin group (wortmannin 100 nmol/L+LPS 1 μg/mL) and IGF-Ⅰ+wortmannin group (wortmannin 100 nmol/L+IGF-Ⅰ 100 ng/mL+LPS 1 μg/mL). Protein expressions of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were detected by ELISA; mRNA expressions of TLR4, myeloid differentiation factor 88 (MyD88), AKT, PI3K, p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor-κB (NF-κB) were determined by real-time PCR. Results: After treated with LPS, IGF-Ⅰ and wortmannin, respectively, no differences in cell viability of RAW264.7 cells were found between different concentrations groups (P>0.05). Protein expressions of TNF-α and IL-6 in LPS, IGF-Ⅰ, wortmannin and IGF-Ⅰ+wortmannin groups were significantly higher than those in blank control group (P<0.05). Protein expressions of TNF-α and IL-6 in wortmannin group were significantly lower than those in LPS and IGF-Ⅰ groups (P<0.05), and those in IGF-Ⅰ+wortmannin group were significantly lower than those in IGF-Ⅰ group (P<0.05). In LPS group, mRNA expressions of AKT and PI3K as well as TLR4 and its downstream molecules MyD88, p38MAPK and NF-κB were significantly higher than those in blank control group (P<0.05). Expressions of all above-mentioned mRNAs in IGF-Ⅰ group were further increased and significantly higher than those in LPS group (P<0.05). Expressions of all above-mentioned mRNAs in wortmannin group were significantly lower than those in LPS and IGF-Ⅰ groups (P<0.05), and those in IGF-Ⅰ+wortmannin group were significantly higher than those in wortmannin group (P<0.05), but significantly lower than those in IGF-Ⅰ group (P<0.05). Conclusions: PI3K/AKT might regulate TLR4 signaling pathway and its downstream molecules in macrophages, thereby affects the expressions of inflammatory cytokines and being involved in the pathogenesis of inflammatory response in SAP.