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通讯作者:

邱文,E-mail: qiuwen@njmu.edu.cn

中图分类号:R692.3

文献标识码:A

文章编号:1007-4368(2024)09-1198-09

DOI:10.7655/NYDXBNSN240571

参考文献 1
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参考文献 7
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参考文献 8
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参考文献 9
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参考文献 10
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参考文献 11
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参考文献 12
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参考文献 13
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参考文献 14
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参考文献 15
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参考文献 16
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参考文献 18
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参考文献 19
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参考文献 20
SCHINOCCA C,RIZZO C,FASANO S,et al.Role of the IL⁃23/IL⁃17 pathway in rheumatic diseases:an overview[J].Front Immunol,2021,12:637829
参考文献 21
ZHANG J,LI Y,SHAN K,et al.Sublytic C5b⁃9 induces IL ⁃ 6 and TGF ⁃ β1 production by glomerular mesangial cells in rat Thy ⁃ 1 nephritis through p300 ⁃ mediated C/EBPβ acetylation[J].FASEB J,2014,28(3):1511-1525
参考文献 22
YING S,LIU L F,LUO C,et al.Sublytic C5b ⁃9 induces TIMP3 expression by glomerular mesangial cells via TRAF6 ⁃ dependent KLF5 K63 ⁃ linked ubiquitination in rat Thy⁃1 nephritis[J].Int Immunopharmacol,2023,124(Pt B):110970
参考文献 23
ZHANG J,XIE M X,XIA L,et al.Sublytic C5b⁃9 induces IL ⁃ 23 and IL ⁃ 36a production by glomerular mesangial cells via PCAF ⁃mediated KLF4 acetylation in rat Thy ⁃1 nephritis[J].J Immunol,2018,201(11):3184-3198
目录contents

    摘要

    目的:研究亚溶解型C5b-9(sublytic C5b-9)上调转录因子Krüppel样因子5(Krüppel-like factor 5,KLF5)促进Thy-1肾炎 (Thy-1 nephritis,Thy-1N)大鼠肾小球系膜细胞(glomerular mesangial cell,GMC)产生炎症因子白细胞介素(interleukin,IL)-23的作用。方法:①建立大鼠Thy-1N模型和体外培养大鼠GMC,用Western blot(WB)检查Thy-1N大鼠肾组织和受sublytic C5b-9刺激的 GMC中KLF5和IL-23的表达。②分别将KLF5过表达质粒(pIRES2-KLF5)或KLF5小干扰质粒(shKLF5)转染GMC,通过实时荧光定量PCR和WB检测KLF5和IL-23的mRNA和蛋白水平。③将IL-23全长启动子荧光素酶报告基因质粒(pGL3-IL-23-FL)转染 GMC,再给予sublytic C5b-9刺激,或将pGL3-IL-23-FL与pIRES2-KLF5或shKLF5共转染GMC,用荧光素酶报告基因实验检测 IL-23启动子活性的变化。④将慢病毒(lentivirus,LV)包装的LV-shKLF5和LV-shCTR行肾动脉灌注术导入大鼠肾组织,经小动物脏器可见光三维成像和冰冻切片观察GFP表达,证实LV-shCTR在肾组织中富集效率。之后再复制大鼠Thy-1N,用WB检查肾组织中KLF5和IL-23的蛋白表达。结果:①Thy-1N大鼠的肾组织和sublytic C5b-9刺激的GMC中,KLF5和IL-23的表达均显著升高,且KLF5的表达高峰稍早于IL-23。②在GMC中过表达或敲低KLF5能分别引起IL-23表达的升高或降低。③Sublytic C5b-9刺激或KLF5过表达均可增加GMC中IL-23启动子的活性,但敲低KLF5后可明显下调由sublytic C5b-9刺激GMC诱导的 IL-23启动子活性。④敲低Thy-1N大鼠肾组织中KLF5的表达后,其肾组织中IL-23的表达水平明显降低。结论:大鼠Thy-1N 发病早期,sublytic C5b-9刺激GMC后可通过上调KLF5促进IL-23基因的转录与表达。

    Abstract

    Objective:To explore the role of sublytic C5b -9 upregulating the transcription factor Krüppel -like factor 5(KLF5)in promoting the production of the inflammatory cytokine interleukin-23(IL-23)in glomerular mesangial cells(GMCs)of rats with Thy-1 nephritis(Thy-1N). Methods:①A rat model of Thy-1N was established and rat GMCs were cultured in vitro. The expression levels of KLF5 and IL-23 in the renal tissues of Thy-1N rats and in GMCs stimulated by sublytic C5b-9 were detected by using Western blot (WB). ②The levels of mRNA and protein of KLF5 and IL -23 in the GMCs transfected with either a KLF5 overexpressing plasmid (pIRES2 - KLF5)or a KLF5 small interfering plasmid(shKLF5)were examined by RT-qPCR and WB. ③The full-length IL - 23 promoter luciferase reporter gene plasmid(pGL3-IL-23-FL)was transfected into GMCs,followed by stimulation with sublytic C5b-9.Alternatively,pGL3- IL -23-FL was co -transfected with either pIRES2-KLF5 or shKLF5 into GMCs,and changes in IL -23 promoter activity were measured using a luciferase reporter gene assay. ④The LV-shKLF5 and LV-shCTR lentivirus vectors were respectively perfused into rat renal tissues via the artery perfusion. After confirming that LV-shCTR could enrich in rat kidney through animal imaging system and frozen section,the Thy-1N was reproduced,and the KLF5 and IL-23 expression in the renal tissues were measured by WB. Results:①The expressions of KLF5 and IL -23 were significantly increased in the renal tissues of Thy -1N rats and in GMCs stimulated by sublytic C5b-9,with KLF5 expression peaking slightly earlier than IL-23. ②Overexpression or knockdown of KLF5 in GMCs led to an increase or decrease in IL - 23 expression,respectively. ③ Sublytic C5b - 9 stimulation or KLF5 overexpression upregulated the activity of IL-23 promoter,while KLF5 knockdown markedly reduced the IL-23 promoter activity induced by sublytic C5b-9. ④IL-23 expression in the renal tissues of the rats treated by knocking down of renal KLF5 gene was significantly downregulated. Conclusion:In the early stage of Thy-1N in rats,sublytic C5b-9 stimulates GMCs to promote the transcription and expression of the IL-23 gene by upregulating KLF5.

  • 系膜增生性肾小球肾炎(mesangial proliferative glomerulonephritis,MsPGN)是一种免疫相关的肾脏疾病(如IgA型肾病),其主要病理特征是:肾组织早期炎症以及病程中后期的肾小球系膜细胞(glomer⁃ ular mesangial cell,GMC)增生和细胞外基质(extra⁃ cellular matrix,ECM)积聚,最终可引起肾脏的纤维化,导致患者的肾功能衰竭[1-3]。大鼠 Thy⁃1 肾炎 (Thy⁃1 nephritis,Thy⁃1N)的病理改变与人MsPGN的病变十分相似,是目前公认的研究MsPGN的动物模型[4]。有文献报道,无论是MsPGN患者还是Thy⁃1N 大鼠,其肾组织中不仅可见补体C5b⁃9复合物沉积于 GMC表面,而且还可见促炎细胞因子的增多[5-8]。此外,研究证实,Thy⁃1N大鼠的GMC病变具有C5b⁃9依赖性[9-10]

  • 已知补体系统激活后产生的C5b⁃9攻击靶细胞的方式可分为全溶解型(lytic)和亚溶解型(sublytic) 两种,前者可直接引起细胞膜穿孔破坏,而后者虽不直接溶解靶细胞,但能激活胞内多种信号通路,促使细胞产生不同的生物学效应[7-811]。本课题组以往的研究发现,Thy⁃1N大鼠发病早期,其GMC表面沉积的C5b⁃9多为sublytic C5b⁃9。体外用sublytic C5b⁃9刺激大鼠GMC后也能活化或上调细胞内某些信号分子或转录因子,促进多种靶基因的转录和表达,最终引起GMC增生或某些促炎细胞因子的合成与释放[8-10]

  • Krüppel 样因子 5(Krüppel ⁃like factor 5,KLF5) 属于KLF家族成员,是一种含有锌指结构的转录因子[12],在机体多种细胞中表达,参与调控组织和细胞的炎症反应。有研究发现,当人子宫肌层细胞受到白介素(interleukin,IL)⁃1β刺激时,其 KLF5 的表达显著升高,而当沉默KLF5基因后,由IL⁃1β诱导的促炎因子IL⁃6和IL⁃8的生成水平则明显降低[13]。另有研究证实,在糖尿病小鼠的血管平滑肌细胞中, KLF5是诱导TNF⁃α和IL⁃1β表达所必需的因素[14]。此外,在大鼠GMC中,敲低KLF5表达可下调由sub⁃ lytic C5b⁃9 诱导的 IL⁃36α的表达水平[15]。由此可见,KLF5在某些促炎因子的生成过程中发挥了重要的促进效应,加剧了组织的炎症。

  • IL⁃23属于IL⁃12家族的一个成员,其主要功能是参与多种组织的炎症反应,诱导炎性肠病、强直性脊柱炎和狼疮性肾炎[16-18]。研究报道,伴有间质性肾炎的小鼠和人肾小管上皮细胞中IL⁃23表达显著升高,而IL⁃23高表达既可重塑肾脏固有细胞代谢,又能促进肾组织的炎症[18]。系统性红斑狼疮(sys⁃ temic lupus erythematosus,SLE)患者血清中IL⁃23的水平亦显著升高,且其升高程度与狼疮性肾炎的活动程度呈正相关[19]。此外,在一些自身免疫性疾病 (如类风湿关节炎、多发性硬化症和银屑病)中,IL⁃23 能明显加重慢性免疫性炎症,且IL⁃23/IL⁃17轴还可加速其炎性病变的进展[20]。以上研究提示,IL⁃23表达升高起到了重要的促炎作用。

  • 由于大鼠 Thy⁃1N 是研究 MsPGN 的动物模型,其病变具有sublytic C5b⁃9依赖性[48-9],且本课题组前期实验也证实,Thy⁃1N大鼠的肾组织和受sublytic C5b⁃9刺激的GMC中,KLF5和IL⁃23的表达显著上调,且 KLF5 的升高峰值还稍早于 IL⁃23 的表达高峰。此外,国内外学者发现,KLF5能调控多种促炎因子的表达[13-15],但其能否促进 IL⁃23的表达尚不清楚。因此,本研究利用Thy⁃1N大鼠模型和体外培养的大鼠 GMC,探讨 KLF5 上调对 sublytic C5b⁃9 刺激 GMC 诱导 IL⁃23 表达的影响,拟揭示 Thy⁃1N 大鼠肾组织早期炎症的参与因素,为MsPGN的深入研究提供必要的实验依据。

  • 1 材料和方法

  • 1.1 材料

  • 雄性SD大鼠(180~200 g)来源于南京医科大学实验动物中心,动物实验操作经南京医科大学实验动物伦理委员会批准(IACUC⁃2011007)。大鼠GMC 细胞株HBZY⁃1由武汉大学中国典型培养物保藏中心提供。多克隆兔抗大鼠胸腺细胞血清(anti⁃thy⁃ mocyte serum,ATS)由本实验室制备(用 56℃水浴 30 min灭活补体)。正常人血清(normal human serum, NHS)来源于30位健康志愿者。单克隆鼠源性KLF5 和IL⁃23抗体(Santa Cruz 公司,美国),RIPA 裂解液 (上海碧云天生物科技有限公司),Lipofectamine2000 (Thermo Fisher Scientific 公司,美国),Hieff qPCR SYBR Green Master Mix(上海翊圣生物科技有限公司),双荧光素酶报告基因检测试剂盒、pGL3⁃basic、 pRL⁃SV40质粒(Promega公司,美国),pIRES2⁃EGFP 质粒(Clontech公司,美国)。IL⁃23全长启动子荧光素酶报告基因质粒(pGL3⁃IL⁃23⁃FL)、KLF5 过表达质粒(pIRES2⁃KLF5)、KLF5 小干扰质粒(shKLF5)、 shRNA 对照质粒(shCTR)、慢病毒包装的 shKLF5 (LV⁃shKLF5)和shCTR(LV⁃shCTR)由本课题组前期分别委托通用生物(安徽)股份有限公司和上海吉玛制药技术有限公司构建。

  • 1.2 方法

  • 1.2.1 Thy⁃1N大鼠模型的复制

  • 取雄性 SD 大鼠(180~200 g),经尾静脉注射含 Thy⁃1 抗体(Thy⁃1 antibody,Thy⁃1 Ab)的 ATS(剂量为0.75 mL/100 g),在注射后1、2、3、6、12 h取大鼠的肾组织(n=5/时间点),实验以0 h无处理的肾组织作对照。之后,提取肾组织中的蛋白质以检测目的蛋白的表达。

  • 1.2.2 GMC的培养

  • 将大鼠 GMC 细胞株接种于含 10%胎牛血清的 MEM完全培养液中,37℃、5% CO2孵箱内培养48 h。当细胞密度达 80%时,PBS 洗涤后予 0.25%胰蛋白酶消化细胞。1 000 r/min 离心 5 min,弃去上清,再按1∶3比例稀释进行传代培养。

  • 1.2.3 Sublytic C5b⁃9刺激GMC的剂量

  • 采用棋盘滴定法[8-10],即先以不同浓度的 ATS 致敏 GMC 30 min,再添加不同浓度的 NHS 孵育30 min。行乳酸脱氢酶(lactate dehydrogenase,LDH) 法检查GMC溶解的百分率(GMC溶解率<5%时被视为形成了 sublytic C5b⁃9 复合物)。本实验确定以 5% ATS 与 4% NHS 作为形成 sublytic C5b⁃9 的最佳剂量。

  • 1.2.4 质粒转染与表达验证

  • 用Lipofectamine2000将shCTR质粒转染GMC, 48 h后观察绿色荧光蛋白(green fluorescent protein, GFP)的表达,以评估其转染效率。之后,同法给 GMC转染pIRES2⁃EGFP或pIRES2⁃KLF5质粒48 h,或转染 shCTR 或 shKLF5 质粒 48 h,再给予 sublytic C5b⁃9 刺激 6 h。提取细胞蛋白,Western blot(WB) 检测KLF5和IL⁃23的表达水平。

  • 1.2.5 WB实验

  • 大鼠肾组织或 GMC 中加 RIPA 裂解液,离心收集上清测定其蛋白浓度。然后,取 30 μg 蛋白上样于10%的SDS⁃PAGE中,先用50 V电泳30 min(浓缩蛋白),再用120 V电泳2 h。接着用0.3 A恒流湿转 2 h。PVDF膜用脱脂牛奶封闭2 h,加KLF5或IL⁃23 抗体,4℃孵育过夜。次日,用TBST洗涤3次,再用 HRP 标记的二抗室温孵育 1 h,最后加入 ECL 发光液并予曝光。

  • 1.2.6 实时荧光定量PCR(RT⁃qPCR)

  • 用 TRIzol 提取 GMC 的总 mRNA,逆转录为 cDNA。另用Primer Premier 5软件设计大鼠IL⁃23的 PCR引物,并委托南京金斯瑞生物技术有限公司合成。IL⁃23引物序列是:上游,5′⁃TGTGCCTAGGAG⁃ TAGCAGTC⁃3′,下游,5′⁃TCCATTTGTCCCACTGGT⁃ GT⁃3′。RT⁃qPCR反应体系为cDNA模板1 μL,Hieff qPCR SYBR Green Master Mix 10 μL,上下游引物各 0.4 μL,DEPC 水补足至 20 μL。在 ABI StepOne⁃ PlusTM PCR 仪上行扩增反应,程序为:保温阶段 (95℃ 5 min)、循环阶段(95℃ 10 s、60℃ 30 s,共 40 个循环)和溶解曲线阶段(95℃ 15 s、60℃ 60 s、 95℃ 15 s)。每样本设3复孔,β⁃actin做内参基因,采用2-ΔΔCt计算相对倍数。

  • 1.2.7 荧光素酶报告基因实验

  • 将 GMC 用 sublytic C5b ⁃ 9 刺激 6 h,或转染 pIRES2⁃EGFP或pIRES2⁃KLF5质粒及pGL3⁃IL⁃23⁃FL 联同 pRL ⁃ SV40 内参质粒 48 h。另将 shCTR 或 shKLF5 质粒与 pGL3⁃IL⁃23⁃FL 和 pRL⁃SV40 质粒共转染 GMC 48 h,再加 sublytic C5b⁃9 刺激 6 h(针对 shCTR或shKLF5转染组)。之后,用1×被动裂解缓冲液(passive lysis buffer,PLB)处理上述 GMC,行荧光素酶报告基因实验测定IL⁃23的启动子活性。即先在检测管中加入25 μL荧光素酶检测试剂Ⅱ,放入荧光检测仪中,接着转移5 μL 1×PLB裂解的细胞液到检测管中,检测萤火虫荧光素酶的活性,最后向检测管中加25 μL 1×Stop&Glo®试剂,混匀后再测定海肾荧光素酶的活性。萤火虫荧光值与海肾荧光值的比值即为最终结果。

  • 1.2.8 LV⁃shCTR感染GMC

  • 收集大鼠GMC悬液,接种于96孔板(5×103 个/孔),培养24 h。用MEM培养液将LV⁃shCTR稀释成3个浓度,即1×107、1×106、1×105 TU/mL。每个培养孔内加100 μL的LV⁃shCTR稀释液,12 h后换液,继续培养60 h,置荧光显微镜下观察GFP表达情况,以选取最佳滴度的LV⁃shRNA。

  • 1.2.9 肾动脉灌注术

  • 经腹腔注射3 mg/mL戊巴比妥钠(1 mg/100 g),麻醉大鼠后,在其剑突下约0.5 cm处切开腹部。在腹腔中部找到腹主动脉旁的肾动脉。先后在两侧肾动脉开口的上端和下端用动脉夹夹闭。行头皮针穿刺并迅速将生理盐水稀释的1 mL病毒悬液(含 1×107 TU/mL 的 LV⁃shCTR 或 LV⁃shKLF5)推注到肾动脉内。用纱布按压创口 5 min 使其感染肾脏细胞。5 min后松开腹主动脉上的动脉夹,用明胶海绵按压止血。最后分层缝合,用碘伏消毒创口[922]

  • 1.2.10 可见光三维成像及冰冻切片检查

  • 为了确认上述肾动脉灌注术的成功率,在肾动脉灌注的第72 h时取大鼠的心、肝、脾、肺和肾5种脏器,快速置于小动物活体成像系统(PerkinElmer 公司,美国),进行可见光三维成像检查,即通过5种脏器的荧光强度判定肾动脉灌注LV⁃shCTR后的器官分布。此外,取大鼠肾组织行冰冻切片,再用荧光显微镜观察肾组织中GFP的表达与分布。

  • 1.2.11 基因沉默的体内实验

  • 取 20只雄性SD大鼠(180~200 g),随机分为4组 (每组 n=5),即正常血清组(normal serum,NS)组、 Thy⁃1N 组、LV⁃shCTR+Thy⁃1N 组和 LV⁃shKLF5+ Thy⁃1N组。前两组的处理是:分别给大鼠尾静脉注射正常兔血清或 ATS(剂量均为 0.75 mL/100 g),后两组的处理是:大鼠行肾动脉灌注术分别导入 LV⁃shCTR 或 LV⁃shKLF5 72 h 后,再注射 ATS 诱导 Thy⁃1N。当Thy⁃1N大鼠发病6 h时,取其肾组织,用 WB检测KLF5和IL⁃23蛋白的表达。

  • 1.3 统计学方法

  • 所有实验均独立重复3次,所得定量数据以均数±标准误(x-±sx-)表示,两两比较采用配对t检验,组间比较则采用单因素方差分析。应用 GraphPad Prism软件(版本5.01)进行统计学分析,P <0.05为差异有统计学意义。

  • 2 结果

  • 2.1 Thy⁃1N大鼠发病不同时间的肾组织中KLF5和 IL⁃23蛋白的表达

  • SD 大鼠尾静脉注射含 Thy ⁃1Ab 的 ATS,复制 Thy⁃1N 大鼠模型,并分别于注射 ATS 后 1、2、3、6、 12 h 收取大鼠的肾组织,以 0 h 无处理的肾组织作对照,WB 实验检测 KLF5 和 IL⁃23蛋白的表达。结果发现,两种蛋白的表达在1 h开始上升,2 h时上升显著,3 h时KLF5的表达呈现高峰,而IL⁃23的表达则在 6 h 时升到峰值,但在 12 h 时两种蛋白的表达均已回落(图1)。

  • 图1 Thy⁃1N大鼠发病不同时间的肾组织中KLF5和IL⁃23 蛋白的表达

  • Figure1 The expression levels of KLF5 and IL⁃23 protein in the renal tissues of Thy ⁃ 1N rats at different time

  • 2.2 Sublytic C5b⁃9刺激GMC不同时间KLF5和IL⁃23 蛋白的表达

  • 予 sublytic C5b⁃9 刺激大鼠 GMC 0、1、2、3、6、 12 h,提取GMC蛋白质,WB检测KLF5和IL⁃23两种蛋白的表达。结果显示,sublytic C5b⁃9刺激GMC后 1 h,KLF5和IL⁃23蛋白的表达开始上调,2 h时上升明显,并分别在3 h和6 h达到峰值,12 h时两种蛋白的表达已见回落(图2)。

  • 图2 Sublytic C5b⁃9刺激GMC不同时间KLF5和IL⁃23蛋白的表达

  • Figure2 The expression levels of KLF5 and IL⁃23 protein in rat GMC stimulated by sublytic C5b⁃9 at dif⁃ ferent time

  • 2.3 KLF5过表达或小干扰质粒转染GMC后KLF5 的表达

  • 将 KLF5 过表达质粒(pIRES2⁃KLF5)和对照质粒(pIRES2⁃EGFP)转染大鼠 GMC 48 h,或将 KLF5 小干扰质粒(shKLF5)及对照质粒(shCTR)转染 GMC 48 h时再行sublytic C5b⁃9刺激6 h。以shCTR质粒为代表检查GFP表达情况,发现其转染效率可达 80%左右(图3A)。之后,分别提取前述 GMC 中的蛋白质,用WB检查KLF5的过表达和沉默水平。结果证实,与 pIRES2⁃EGFP 转染组相比,pIRES2⁃ KLF5转染细胞后能显著表达KLF5。shCTR+sublytic C5b⁃9 组的 KLF5 表达量显著高于 shCTR 组,而与 shCTR+sublytic C5b⁃9组相比,shKLF5+sublytic C5b⁃9 组的 KLF5 表达则未见显著升高(图3B~D),提示, sublytic C5b⁃9刺激GMC能显著升高KLF5蛋白的表达,而用shKLF5则可沉默KLF5基因的表达。

  • 2.4 过表达或敲低 KLF5 对 sublytic C5b ⁃ 9 刺激 GMC诱导的IL⁃23表达的影响

  • 将 pIRES2⁃EGFP 和 pIRES2⁃KLF5 质粒分别转染 GMC 48 h,或将 shCTR 和 shKLF5 质粒分别转染 GMC后48 h再给予sublytic C5b⁃9刺激6 h。提取细胞的mRNA和蛋白,行RT⁃qPCR和WB实验。结果表明,转染pIRES2⁃KLF5过表达质粒的GMC,IL⁃23 mRNA和KLF5及IL⁃23的蛋白水平均明显升高,而转染shKLF5质粒的GMC,其由sublytic C5b⁃9诱导的 IL⁃23 mRNA以及蛋白水平均显著低于shCTR+sublytic C5b⁃9组(图4)。

  • 2.5 Sublytic C5b⁃9 刺激和高低表达 KLF5 对 IL⁃23 启动子活性的影响

  • 将 IL⁃23 全长启动子荧光素酶报告基因质粒 (pGL3⁃IL⁃23⁃FL)转染GMC 48 h,再用sublytic C5b⁃9 刺激 GMC 6 h,或将 pGL3 ⁃ IL ⁃ 23 ⁃ FL 质粒分别与 pIRES2⁃KLF5 或 shKLF5 质粒(包括各自的对照质粒)共同转染GMC 48 h,其中转染shKLF5的GMC再加sublytic C5b⁃9刺激6 h。测定IL⁃23启动子的活性发现,sublytic C5b⁃9刺激的GMC(图5A)或在GMC中过表达KLF5(图5B)均可明显升高IL⁃23启动子的活性,但沉默KLF5基因后由sublytic C5b⁃9刺激诱导的 IL⁃23启动子活性则未见显著提高(图5B)。

  • 图3 GMC质粒转染效率以及KLF5过表达或小干扰质粒转染GMC后KLF5的表达

  • Figure3 The efficiency of plasmid transfection into GMC and the expression of KLF5 in the GMC transfected with pIRES2⁃KLF5 or shKLF5 plasmids

  • 图4 GMC中过表达或敲低KLF5后对IL⁃23表达的影响

  • Figure4 Effect of KLF5 overexpression or knockdown on IL⁃23 expression in the GMC

  • 2.6 LV⁃shRNA 感染 GMC 的剂量及大鼠肾脏导入 LV⁃shRNA的确定

  • 先将 LV ⁃shCTR 制备成 3 种滴度(即 1×107、1× 106、1×105 TU/mL),分别感染GMC 72 h,观察GFP表达发现,3种滴度的LV⁃shCTR均能感染大鼠GMC,但以1×107 TU/mL滴度感染后GFP表达最强,效率可达90%以上(图6A)。选用最佳滴度的LV⁃shCTR行大鼠动脉灌注术[22],将其导入肾组织,同时设生理盐水灌注对照组。实验72 h时,取出大鼠心、肝、脾、肺和肾,进行可见光三维成像。结果显示,LV⁃shCTR灌注大鼠的肾脏荧光强度显著高于生理盐水灌注大鼠的肾脏,而其他脏器的荧光强度未见明显增强(图6B)。另取大鼠肾脏进行冰冻切片,行荧光显微镜观察证实,大鼠肾小球和肾小管部位均见 GFP 荧光,其中肾小球更为显著(图6C)。以上结果表明, LV⁃shCTR 不仅能有效地感染GMC,而且经肾动脉灌注后能将其有效地导入大鼠肾组织。

  • 2.7 敲低KLF5表达对Thy⁃1N大鼠肾组织中IL⁃23 蛋白表达的影响

  • 将大鼠分为 NS、Thy⁃1N、LV⁃shCTR+Thy⁃1N 和 LV⁃shKLF5+Thy⁃1N 4组,后两组先经肾动脉灌注相应的 LV⁃shCTR 或 LV⁃shKLF5,于灌注后 72 h 注射ATS,复制大鼠Thy⁃1N。当Thy⁃1N诱导后6 h时,取各组大鼠的肾组织,提取蛋白质行WB检测。结果发现,Thy⁃1N组和LV⁃shCTR+Thy⁃1N组,其大鼠肾组织中的KLF5和IL⁃23的表达量显著高于NS组,但敲低 KLF5 表达的 LV⁃shKLF5+Thy⁃1N 组,其 KLF5 和IL⁃23的表达水平则明显低于LV⁃shCTR+Thy⁃1N 组(图7)。这一实验表明,敲低大鼠肾组织中KLF5 表达后,其肾内促炎因子 IL⁃23 的表达受到了明显抑制,提示Thy⁃1N大鼠肾组织中过表达KLF5上调了IL⁃23的表达。

  • 图5 Sublytic C5b⁃9刺激GMC和高低表达KLF5后IL⁃23 启动子活性的变化

  • Figure5 The change of IL ⁃ 23 promoter activity in the GMC after sublytic C5b⁃9 stimulation and KLF5 overexpression or knockdown

  • 图6 LV⁃shCTR感染GMC和大鼠组织的效率

  • Figure6 Efficiency of LV⁃shCTR infection in GMC and rat tissues

  • 3 讨论

  • Thy⁃1N大鼠是研究人MsPGN的动物模型,其本质上属于一种免疫性肾小球炎症[3-4]。该模型的制作原理是,给大鼠注射含Thy⁃1抗体的ATS,该抗体能随血循环进入肾小球内,与GMC表面的Thy⁃1抗原结合,形成免疫复合物,继而激活补体系统,产生 C5b⁃9复合物并引起病变。本课题组前期研究已证实,在Thy⁃1N大鼠发病的早期,不仅可测到GMC表面有sublytic C5b⁃9的形成以及某些促炎因子(如IL⁃ 6、IL⁃17)的表达增多,而且体外用sublytic C5b⁃9刺激大鼠GMC后还能上调促炎因子IL⁃6和IL⁃17的表达,其机制涉及转录因子(如KLF4或C/EBPβ)的正向调控[821]。提示,Thy⁃1N大鼠早期肾组织的炎症病变与sublytic C5b⁃9形成后诱导GMC上调某些转录因子和促炎因子的表达明显相关。

  • 基于课题组前期研究及国内外相关文献的报道[22-23],本研究先检测了Thy⁃1N大鼠发病早期的肾组织和受 sublytic C5b⁃9 刺激的 GMC 中,转录因子 KLF5和促炎因子IL⁃23的蛋白表达。结果表明,无论是体内还是体外,其KLF5和IL⁃23的表达水平均明显上升,且KLF5的表达时相还略早于IL⁃23。已知,KLF5是一种C端含有3个连续锌指结构DNA结合结构域的转录因子,其表达增加能调控下游靶基因的转录[12]。为进一步探讨Thy⁃1N大鼠发病早期由 sublytic C5b⁃9 刺激 GMC 后上调 KLF5 表达对 IL⁃23 生成的影响,本研究利用KLF5过表达质粒(pIRES2 ⁃KLF5)和发夹状小干扰RNA质粒(shKLF5)分别转染 GMC,检查 KLF5 和 IL⁃23 的表达。结果证实,过表达KLF5蛋白后,GMC中IL⁃23的mRNA和蛋白水平也明显升高。而 shKLF5 沉默 KLF5 基因后,由 sublytic C5b⁃9 刺激 GMC 诱导的 IL⁃23 合成显著减少。这一实验表明,KLF5的表达水平影响GMC 中 IL⁃23的合成。

  • 图7 敲低KLF5表达后Thy⁃1N大鼠肾组织中IL⁃23蛋白表达的变化

  • Figure7 The change of IL ⁃23 protein expression in the renal tissues of Thy ⁃1N rats after KLF5 knock⁃ down

  • 一般情况下,转录因子调控靶基因表达的关键在于其能与靶基因启动子结合,并提高靶基因的启动子活性[21-22]。为明确KLF5作为转录因子,其表达升高或降低能否影响 IL⁃23 的启动子活性,本研究将大鼠 IL⁃23 全长启动子荧光素酶报告基因质粒 (pGL3⁃IL⁃23⁃FL)转染GMC,一方面,行sublytic C5b⁃9 刺激,另一方面,将其与 KLF5 过表达质粒共转染 GMC。结果显示,无论是 sublytic C5b⁃9 刺激 GMC,还是在GMC中过表达KLF5,其IL⁃23的启动子活性均见显著增加。此外,将shKLF5质粒与IL⁃23启动子质粒共转染GMC,再行sublytic C5b⁃9刺激,其IL⁃23 的启动子活性则未见明显升高。以上实验表明,作为Thy⁃1N致病始动因素,sublytic C5b⁃9 刺激 GMC 后确能上调 IL⁃23基因的启动子活性,而KLF5过表达与 sublytic C5b ⁃9 刺激的效果基本一致。但当 KLF5基因被沉默后,由sublytic C5b⁃9诱导IL⁃23启动子的活性则明显受到了抑制,提示sublytic C5b⁃9 刺激GMC后上调的KLF5能促进IL⁃23基因的转录与表达。

  • 尽管体外细胞学实验的结果影响因素相对简单,且实验条件易于控制,但是体外实验的结果往往需要体内实验(如动物模型)加以验证[48-9]。本课题组应用慢病毒包装 shKLF5 和 shCTR,在体外选定 LV⁃shCTR转染GMC的最佳浓度后,行大鼠肾动脉灌注术,将上述LV⁃shRNA分别导入大鼠的肾组织[921]。结果证实,不仅相应的LV⁃shRNA 能有效地富集于大鼠的肾脏中,而且LV⁃shKLF5还能沉默肾组织中的 KLF5 基因表达。与此同时,Thy⁃1N 大鼠肾组织中促炎因子IL⁃23的表达水平也相应降低。这一体内实验再次确证,敲低大鼠肾组织中 KLF5 的表达能明显抑制Thy⁃1N大鼠肾组织中IL⁃23的生成。

  • 综上所述,本研究发现,在Thy⁃1N大鼠发病早期,由 sublytic C5b⁃9 刺激 GMC 后诱导上调的 KLF5 能促进 IL⁃23 基因的转录与表达。然而,Thy⁃1N 大鼠肾组织早期发生炎症的机制较为复杂[48-9],本研究仅初探了 KLF5 表达升高对 sublytic C5b ⁃9 刺激 GMC诱导促炎因子IL⁃23生成的影响,至于KLF5调控 IL⁃23 表达的具体机制以及其他影响因素等,仍需进一步探究。

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