缺氧诱导因子1α调控wnt/β-catenin信号通路对常氧条件下大鼠髓核细胞衰老的作用及机制

【摘要】 目的：探究缺氧诱导因子1α（HIF-1α）调控wnt/β-catenin信号通路对常氧培养下大鼠髓核细胞衰老的影响及作用机制。方法：取5只4周龄雌性SD大鼠，提取鼠尾髓核原代细胞进行研究。（1）将髓核细胞分为5组：转染对照组[用磷酸盐缓冲盐水（PBS）处理髓核细胞]、空载腺病毒组（用空载腺病毒处理髓核细胞）、过表达HIF-1α组（用载过表达HIF-1α质粒的腺病毒处理髓核细胞）、空载siRNA组（用空载siRNA处理髓核细胞）、敲减HIF-1α组（用siRNA敲减HIF-1α处理髓核细胞），在常氧下培养48h后，免疫蛋白印迹（western blot，WB）检测HIF-1α和衰老相关基因p53、p21、p16，β-gal染色检测细胞衰老，评估常氧条件下HIF-1α对于髓核细胞衰老的影响。（2）取髓核细胞，分为空载腺病毒组、过表达HIF-1α组、空载siRNA组、敲减HIF-1α组，处理方式同前，在常氧下培养48h后，WB检测HIF-1α、GSK-3β和β-catenin通路的表达。取髓核细胞，分为对照组（用PBS处理髓核细胞）、过表达HIF-1α组（用载过表达HIF-1α质粒的腺病毒处理髓核细胞）、XAV-939组（用XAV-939处理髓核细胞）、XAV-939+过表达HIF-1α组（用XAV-939+载过表达HIF-1α质粒的腺病毒处理髓核细胞），WB检测HIF-1α、p53、p21、p16和wnt/β-catenin的表达，β-gal染色检测细胞衰老，以检测HIF-1α与wnt/β-catenin信号通路的关系以及对髓核细胞衰老的影响。结果：（1）腺病毒转染HIF-1α后，与转染对照组和空载腺病毒组相比，过表达HIF-1α组HIF-1α表达增加（P<0.05）。小干扰RNA转染HIF-1α后，与转染对照组和空载siRNA组相比敲减HIF-1α组HIF-1α表达降低（P<0.05）。WB结果显示，与空载腺病毒组相比过表达HIF-1α组HIF-1α表达增加（P<0.05），而p53、p21和p16表达降低（P<0.05），与空载siRNA组相比敲减HIF-1α组HIF-1α表达降低（P<0.05），而p53和p16表达增加（P<0.05）。β-gal染色显示，在常氧条件下培养48h，与空载腺病毒组相比，过表达HIF-1α组衰老细胞降低（P<0.05），与空载siRNA组相比，敲减HIF-1α组衰老细胞数量则增加（P<0.001）。（2）与空载腺病毒组相比，过表达HIF-1α组β-catenin表达升高（P＜0.01），同时GSK-3β表达降低（P＜0.05）。与空载siRNA组相比敲减HIF-1α组β-catenin表达降低（P＜0.0001），同时GSK-3β表达升高（P＜0.05）。与对照组相比，XAV-939组β-catenin表达降低（P<0.001），p53、p21和p16的表达升高，XAV-939+过表达HIF-1α组β-catenin表达降低（P<0.05），p21表达升高（P<0.05）。与过表达HIF-1α组相比XAV-939+过表达HIF-1α组衰老细胞数增加（P<0.001），与对照组相比过表达HIF-1α组的细胞核内β-catenin表达更多，而XAV-939组和XAV-939+过表达HIF-1α组则相对较少（P<0.05）。结论：HIF-1α通过激活wnt/β-catenin信号通路抑制常氧条件培养下大鼠髓核细胞的衰老。     

p16INK4a与Fas对椎间盘细胞功能影响的比较

目的分析p16^INK4a及Fas在椎间盘细胞中的功能作用，探讨椎间盘退变的机制。方法利用p16^INK4a及Fas特异性短链干扰RNA（siRNA）转染体外培养的内破裂（IDD）及突出（LIDP）椎间盘细胞。观察p16^INK4a及Fas表达的沉默情况。分析视网膜母细胞瘤（Rb）蛋白磷酸化状态、β-半乳糖苷酶（β-gal）染色阳性率、细胞形态和增殖的变化；放射性同位素标记培养细胞，观察细胞合成氨基葡聚糖（GAG）及核心蛋白的变化。结果p16^INK4a。及Fas特异性siRNA分别有效地沉默了椎间盘细胞内p16^INK4a及Fas表达。p16^INK4a表达沉默使退变椎间盘细胞衰老表型及合成能力得以明显改善；Fas特异性siRNA转染的LIDP椎间盘细胞的生理功能有所恢复，但未及正常水平，而转染的IDD椎间盘细胞的功能无明显变化。结论p16^INK4a。基因介导的细胞衰老是椎间盘退变的一个关键启动因子。     

过表达NDRG2基因促进人髓核细胞衰老的体外实验研究

[目的]研究NDRG2(N-Myc downstream-regulated gene 2)对人髓核细胞衰老的影响,进而探讨NDRG2在椎间盘退变中的作用。[方法]通过慢病毒过表达NDRG2基因稳定感染髓核细胞。设立正常髓核细胞组(空白组)、红色荧光蛋白标记的慢病毒感染髓核细胞组(对照组)及过表达NDRG2慢病毒感染髓核细胞组(实验组)。Western blot检测NDRG2蛋白表达水平,细胞衰老相关β半乳糖苷酶(senescence associated-β-galactosidase,SA-β-ga1)染色检测髓核细胞衰老变化,流式细胞仪检测髓核细胞周期变化,MTT法绘制生长曲线,并分析髓核细胞的增殖情况。[结果]正常髓核细胞感染过表达NDRG2慢病毒48 h后荧光显微镜下观察基因感染效率在95%以上;感染72 h后Western blot检测示NDRG2表达明显升高(P0.01);实验组SA-β-gal染色阳性率明显高于对照组和空白组(P0.01);MTT生长曲线显示慢病毒感染后髓核细胞增殖速度较对照组和空白组均减慢,潜伏期延长,缓慢进入对数期;细胞周期结果示实验组G0/G1期百分比明显高于对照组和空白组,S期明显低于对照组和空白组,差异有统计学意义(P0.05)。[结论]NDRG2基因过表达的髓核细胞衰老速度明显加快,提示NDRG2可能通过调控髓核细胞的衰老参与椎间盘退变过程,为椎间盘的退变生物学治疗提供依据。     

退变腰椎间盘髓核组织中NDRG2表达的变化及其意义

[目的]研究退变的腰椎间盘髓核组织中NDRG2表达的变化及其在椎间盘退变中的作用。[方法]收集腰椎间盘标本47例,根据Pfirrmann分级分为Ⅰ~Ⅴ级。采用免疫组织化学染色、实时-定量PCR(RT-PCR)和Western-Blotting技术从细胞、蛋白和基因水平分别检测腰椎间盘髓核组织中NDRG2的表达,并与Pfirrmann分级进行相关性分析;通过RT-PCR分析P53 mRNA的表达;采用衰老相关的β-半乳糖苷酶(SA-β-gal)实验检测腰椎间盘髓核组织中衰老髓核细胞比例,并与NDRG2表达量进行相关性分析。[结果]免疫组织化学染色、RT-PCR及Western-Blotting检测示NDRG2表达随椎间盘退变程度加重而增加,且与Pfirrmann分级呈正相关;P53 mRNA在腰椎间盘髓核组织中的相对表达随着椎间盘退变程度加重而增加,且与NDRG2的表达量呈正相关。SA-β-gal阳性细胞比例在椎间盘髓核组织中随退变程度加重而增加,并且与NDRG2阳性细胞比例呈正相关。[结论]NDRG2参与了腰椎间盘退变的病理过程,并且可能通过介导腰椎间盘髓核细胞衰老对椎间盘退变起促进作用。     

TGF-β3修饰退变髓核细胞移植修复兔退变椎间盘的效果观察

目的探讨TGF-β3基因修饰后退变髓核细胞生物学效应以及植入兔退变椎间盘后对退变椎间盘的影响。方法将重组腺病毒载体Ad-TGF-β3与第2代退变髓核细胞按10∶1比例混合培养转染(Ad-TGF-β3组),待细胞融合后传代,MTT检测转染细胞增殖活性,Western blot检测TGF-β3蛋白含量,免疫细胞化学染色观察对数生长期转染细胞Ⅱ型胶原染色阳性率;采用病毒空载体转染髓核细胞(Adv组)和未经转染髓核细胞(空白组)作为对照。取30只新西兰兔,体重3.2～3.5 kg,雌雄不限,通过针刺L3、4、L4、5和L5、6椎间盘制备椎间盘退变模型。将实验动物按照随机数字法分为3组,转染细胞组(A组,n=12)、退变细胞组(B组,n=12)和空白对照组(C组,n=6)。A、B组将100μL浓度为1×105个/mL对应细胞悬液注射入退变椎间盘,C组同法注入等量PBS。注射后6、10、14周取A、B组各4只、C组2只实验动物处死,取L3、4、L4、5和L5、6椎间盘行组织学观察,RT-PCR检测Ⅱ型胶原和蛋白多糖mRNA表达。结果 Ad-TGF-β3转染后髓核细胞活性明显改善;转染后3、7、14 d,TGF-β3在髓核细胞内表达逐渐升高;Ad-TGF-β3组髓核细胞细胞质内见棕黄色Ⅱ型胶原阳性染色,阳性率显著高于Adv组及空白组(P<0.05)。组织学观察示,A组椎间盘退变程度较B、C组明显减轻。6、10、14周A组Ⅱ型胶原和蛋白多糖mRNA表达显著高于B、C组,差异均有统计学意义(P<0.05)。结论 TGF-β3基因修饰退变髓核细胞后可明显改善细胞生物活性,转染后髓核细胞植入兔体内可明显增加退变椎间盘的基质分泌。     

siRNA转染对大鼠髓核细胞TRAIL表达和细胞行为的影响

[目的]探讨siRNA转染对大鼠髓核细胞TRAIL表达和细胞行为的影响。[方法]采用弯曲鼠尾法建立椎间盘退变模型。处死动物。取退变椎间盘组织分离培养髓核细胞。P1髓核细胞分为4组,分别为空白对照组、TRAIL-siRNA转染组(siTRAIL组)、TNF-α处理组(TNF-α组)和TNF-α处理+TRAIL-siRNA转染组(TNF-α+siTRAIL组)。采用MTT法检测P1髓核细胞增殖,流式细胞仪检测细胞凋亡,Western blot法检测髓核细胞Caspase-3的活性和表达。[结果]相较于空白对照细胞,TRAIL siRNA转染对细胞增殖、凋亡、Caspase-3的表达无明显影响(P0.05);TNF-α处理引发髓核细胞增殖显著下降(P0.05),而凋亡率显著升高(P0.05),Caspase-3的表达显著升高(P0.05)。TNF-α处理后再用TRAIL-siRNA转染可显著逆转TNF-α对细胞增殖、凋亡和Caspase-3表达的影响(P0.05)。[结论] TRAIL siRNA转染可沉默TRAIL表达,从而逆转TNF-α诱导大鼠髓核细胞增殖抑制、细胞凋亡和Caspase-3表达。     

重组腺相关病毒2介导hTGF-β_1基因体内转染兔退变髓核细胞对蛋白多糖含量的影响

目的应用重组腺相关病毒2(recombinant adeno-associated virus2,rAAV2)介导hTGF-β1基因体内转染兔退变椎间盘髓核细胞,观察基因产物的表达及其对退变髓核细胞蛋白多糖合成的生物调节作用。方法于24只成年新西兰大白兔,雌雄不限,体重1.7～2.2kg,L1、2、L2、3、L3、4、L4、5椎间盘注射25μL浓度为1mmol/L的纤维结合素片段(fi bronectin fragment,Fn-f)制备椎间盘退变模型,注射Fn-f4周时的造模椎间盘模拟早期退变的椎间盘。将24只兔随机分为3组(n=8),A、B、C组分别于造模椎间盘髓核内注射25μL rAAV2-hTGF-β1(1×1012vg/mL)、rAAV2-增强绿色荧光蛋白(enhanced green?uorescent protein,EGFP,rAAV2-EGFP)、PBS。术后1周A、C组各处死2只兔,取髓核组织采用免疫组织化学染色观察hTGF-β1的表达;术后4、8、12周每组取2只兔髓核组织,35S整合分析法检测新合成蛋白多糖的含量;术后12周处死B组2只兔,荧光显微镜观察髓核组织中EGFP的表达。结果术后1周,免疫组织化学染色示A组髓核细胞及基质中广泛存在强阳性染色颗粒,C组仅存在少量阳性颗粒。35S整合法检测示,各时间点A组35S蛋白多糖合成率均高于B、C组,比较差异有统计学意义(P0.05);B、C组间比较差异无统计学意义(P0.05)。术后12周,荧光显微镜下观察B组盘髓核组织可见大量绿色荧光表达。结论新型基因转导载体rAAV2可有效介导hTGF-β1基因体内转染兔退变髓核细胞,基因产物可持续表达超过12周,hTGF-β1可有效促进退变髓核细胞蛋白多糖的合成。     

慢病毒载体GV115介导Caspase-3 siRNA转染人椎间盘髓核细胞的生物学效应

目的 :研究慢病毒载体GV115介导Caspase-3 si RNA转染人椎间盘髓核细胞的生物学效应。方法 :采集12例外伤致脊柱爆裂性骨折患者(22~36岁)术中切除的椎间盘髓核组织,采用组织块法分离培养髓核细胞并传代。取第2代髓核细胞,分为GV115-Caspase3 si RNA组、GV115组和对照组,各组12个细胞培养孔。在荧光显微镜下观察计数阳性髓核细胞,计算GV115-Caspase3 siRNA对人椎间盘髓核细胞的转染效率;采用免疫荧光法检测三组髓核细胞中Caspase-3表达;采用MTT法检测三组髓核细胞活性;采用Western-Blot法和Antonopulos法分别检测三组髓核细胞的Ⅱ型胶原和蛋白多糖含量。结果 :椎间盘髓核细胞被成功分离培养,培养1周后细胞达到80%融合,进行传代培养。转染后1周(85.6±1.3)%的髓核细胞可被GV115-Caspase3 si RNA转染而表达绿色荧光素。GV115-Caspase3 siRNA组Caspase-3免疫荧光阳性细胞率[(19.4±3.2)%]较GV115组[(84.3±9.2)%]和对照组[(83.9±8.7)%]明显减少(P0.05),OD值(1.56±0.21)较GV115组(0.91±0.15)和对照组(0.92±0.17)高(P0.05),Ⅱ型胶原免疫印迹染色强度(1.32±0.09)较GV115组(0.81±0.05)和对照组(0.79±0.04)高(P0.05),蛋白多糖含量(0.56±0.09)较GV115组(0.35±0.06)和对照组(0.34±0.05)高(P0.05)。结论:GV115-Caspase3 siRNA可高效转染人椎间盘髓核细胞,增强髓核细胞的生物活性,并促进细胞外基质的合成。     

腺相关病毒载体介导的TIMP1对人退变腰椎间盘髓核细胞蛋白多糖的影响

目的:探讨腺相关病毒(Adeno-associated virus;AAV)载体介导的基质金属蛋白酶组织抑制剂1(tissue inhibitor of metalloproteinases 1;TIMP1)对人退变腰椎间盘髓核细胞的生物学效应.方法:单层培养并鉴定人退变腰椎间盘髓核细胞.采用绿色荧光蛋白标记的腺相关病毒(rAAV2-EGFP)检测其对髓核细胞的转染效率.应用构建的rAAV2-TIMP1转染髓核细胞;通过细胞形态学观察、35S标记氨基酸整合法检测rAAV2-TIMP1对人退变腰椎问盘髓核细胞基质合成的影响.在35S检测中;以未转染的退变髓核细胞做为正常对照组.结果:光镜下观察所培养的细胞类型以成纤维样细胞为主;Ⅱ型胶原免疫组化和番红O染色鉴定培养细胞为髓核细胞.AAV转染人退变腰椎间盘髓核细胞的转染效率为12%.35S标记整合法检测rAAV2-TIMP1转染组每分钟计数值为341.43±42.85;正常对照组为224.20±29.26;两组间比较差异有统计学意义(P＜0.05).结论:TIMP1能够促进退变椎间盘髓核细胞蛋白多糖的合成.     

内质网应激在酸诱导的人椎间盘髓核细胞损伤中的作用机制研究

目的 :模拟人椎间盘髓核(nucleus pulposus,NP)酸性环境,研究酸诱导的内质网应激活化以及内质网应激在酸诱导的髓核细胞损伤中的作用机制。方法:体外单层培养人正常髓核细胞(nucleus pulposus cells,NPCs)系,以p H值7.4为对照,p H值7.0和6.5分别模拟正常和退变椎间盘酸性环境,培养12~72h,建立酸诱导的髓核细胞损伤模型。采用CCK8法检测髓核细胞增殖情况,透射电镜检测髓核细胞中内质网应激活化情况,免疫荧光检测内质网应激特异性标志物糖调节蛋白78(78 k Da glucose-regulated protein,GRP78)和C/EBP同源蛋白(C/EBP homologous protein,CHOP)表达。应用4-PBA(内质网应激阻断剂)阻断内质网应激后,流式细胞术检测细胞凋亡和细胞周期;β半乳糖苷酶染色检测细胞老化。Western blot检测LC3、GATA4、p53、p21、p16、Bax、Bcl-2和Caspase3蛋白变化情况。结果 :与对照组相比,酸刺激下(p H6.5组)髓核细胞整体增殖力较对照组明显下降;透射电镜下可见内质网扩张明显,膜表面积增加,内质网线粒体膜结构形成,伴线粒体肿胀;细胞免疫荧光检测提示GRP78和CHOP表达明显增加(P0.05)。应用4-PBA后,细胞凋亡率增加,且能够显著增加酸诱导的G1期停滞及β半乳糖苷酶阳性染色率(P0.05)。Western blot检测发现,酸刺激下,髓核细胞LC3、GATA4、p53、p21、p16、Bax和Caspase3表达增高(P0.05),Bcl-2表达降低(P0.05);应用4-PBA后可降低LC3比值和Bcl-2表达水平,并显著升高GATA4、p53、p21、p16、Bax和Caspase3(P0.05)。结论:酸性微环境能够活化内质网应激,在酸诱导的人髓核细胞急性损伤中起保护作用。     

Senescence mechanisms of nucleus pulposus chondrocytes in human intervertebral discs

Background contextThe population of senescent disc cells has been shown to increase in degenerated or herniated discs. However, the mechanism and signaling pathway involved in the senescence of nucleus pulposus (NP) chondrocytes are unknown.PurposeTo demonstrate the mechanisms involved in the senescence of NP chondrocytes.Study design/settingSenescence-related markers were assessed in the surgically obtained human NP specimens.Patient sampleNP specimens remaining in the central region of the intervertebral disc were obtained from 25 patients (mean: 49 years, range: 20–75 years) undergoing discectomy. Based on the preoperative magnetic resonance images, there were 3 patients with Grade II degeneration, 17 patients with Grade III degeneration, and 5 patients with Grade IV degeneration.Outcome measuresWe examined cell senescence markers (senescence-associated β-galactosidase [SA-β-gal], telomere length, telomerase activity, p53, p21, pRB, and p16) and the hydrogen peroxide (H₂O₂) content as a marker for an oxidative stress in the human NP specimens.MethodsSA-β-gal expression, telomere length, telomerase activity, and H₂O₂ content as well as their relationships with age and degeneration grades were analyzed. For the mechanism involved in the senescence of NP chondrocytes, expressions of p53, p21, pRB, and p16 in these cells were assessed with immunohistochemistry and Western blotting.ResultsThe percentages of SA-β-gal-positive NP chondrocytes increased with age (r=.82, p<.001), whereas the telomere length and telomerase activity declined (r=?.41, p=.045; r=?.52, p=.008, respectively) However, there was no significant correlation between age and H₂O₂ contents (p=.18). The NP specimens with Grade III or Grade IV degeneration showed significantly higher percentages of SA-β-gal-positive NP chondrocytes than those with Grade II degeneration (p=.01 and p=.025, respectively). Immunohistochemistry showed that the senescent NP chondrocytes in all the specimens expressed p53, p21, and pRB, but a few NP chondrocytes in only two specimens expressed p16. Western blotting showed that the expressions of p53, p21, and pRB displayed a corresponding pattern, that is, a strong p53 expression led to strong p21 and pRB expressions and vice versa.ConclusionsOur in vivo study demonstrated that senescent NP chondrocytes increased or accumulated in the NP with increasing age and advancing disc degeneration. The NP chondrocytes in the aging discs exhibited characteristic senescent features such as an increased SA-β-gal expression, shortened telomeres, and decreased telomerase activity. We further demonstrated that the telomere-based p53-p21-pRB pathway, rather than the stress-based p16-pRB pathway, plays a more important role in the senescence of NP chondrocytes in an in vivo condition. Our results suggest that prevention or reversal of the senescence of NP chondrocytes can be a novel therapeutic target for human disc degeneration.     

pH对衰老相关β-半乳糖苷酶染色的影响

目的观察正常老化及应激诱导老化（stress—inducedprematuresenescence,SIPS）的小鼠成纤维细胞在不同pH值条件下,衰老相关β-半乳糖苷酶（senescence—associatedp—galactosidase,SA—β-Gal）染色效果的变化规律。方法取新生1～3dC57BL／6小鼠背部皮肤成纤维细胞进行传代培养,UVB照射应激诱导老化细胞,以不同代次的细胞和应激诱导老化细胞为实验对象,进行衰老相关蛋白检测,并在不同pH条件下进行衰老相关β-半乳糖苷酶染色,对其着色情况进行观察和分析。结果在P1代细胞、P6代细胞、应激诱导老化细胞和P12代细胞中,p53／p21蛋白表达依次增多;正常P1代细胞衰老相关β-半乳糖苷酶染色阴性,其余细胞组随着pH值的由低到高（6．0～8．0）,着色情况均呈现由强到弱的变化趋势,P6细胞、SIPS细胞、P12细胞分别在pH7．0、7．5和8．0时阳性染色消失。结论随着细胞衰老程度的增加,衰老相关p一半乳糖苷酶染色将在较高pH时才会呈现假阴性,提示染色时安全pH范围应根据细胞代次而定。     

BMP-2联合低氧环境诱导BMSCs向软骨表型分化的研究

目的探讨BMP-2联合低氧环境诱导BMSCs向软骨表型分化的可行性,并进一步研究其生物学机制。方法取4周龄健康清洁级雌性SD大鼠骨髓采用贴壁法体外培养BMSCs,取第2代细胞根据培养条件不同分为4组:常氧对照组(A组)、常氧加BMP-2诱导液组(B组)、低氧(O2浓度3%)对照组(C组)和低氧加BMP-2诱导液组(D组)。倒置相差显微镜下观察细胞形态变化,培养7、14、21 d阿利新蓝染色检测各组软骨基质糖胺聚糖(glycosaminoglycans,GAG)分泌水平,21 d时Western blot检测细胞内Ⅱ型胶原和低氧诱导因子1α(hypoxia-inducible factor 1α,HIF-1α)蛋白表达水平,RT-PCR检测成软骨、成骨以及低氧相关基因表达水平。结果诱导培养21 d,D组细胞变为类圆形,细胞密度降低,细胞周边呈陷窝样,基质包裹细胞;A、B、C组均未见上述典型变化。D组阿利新蓝染色明显较其他组深,并随诱导时间延长蓝染加深,21 d时出现成片深染蓝色,其他组各时间点仅见散在少量的淡染蓝色。Western blot检测D组细胞内Ⅱ型胶原蛋白表达水平较其他组显著增高,C、D组HIF-1α蛋白表达水平较A、B组显著增高,差异均有统计学意义(P<0.05)。RT-PCR检测D组成软骨分化相关指标Ⅱ型胶原α1(collagenⅡα1,COL2α1)、聚集蛋白聚糖表达最高,而B组成骨分化相关指标COL1α1、ALP、Runt相关转录因子2表达水平最高,C、D组低氧相关指标HIF-1α较A、B组显著增强,差异均有统计学意义(P<0.05)。结论 BMP-2联合低氧(O2浓度3%)环境可以诱导大鼠BMSCs向软骨分化,并抑制其成骨分化,HIF-1α可能是参与促软骨生成过程中的一个重要信号分子。     

小分子RNA干扰沉默缺氧诱导因子1α加重缺氧状态肾小管上皮细胞的生长抑制和坏死

目的 探讨沉默缺氧诱导因子1α （HIF-1α）对缺氧状态肾小管上皮细胞增殖、凋亡和坏死的影响。 方法 利用氯化钴模拟缺氧状态,并应用小分子RNA干扰（siRNA）技术沉默HIF-1α基因表达。将细胞分成5组,分别是正常培养组、缺氧培养组、转染试剂组、阴性对照组和HIF-1α siRNA组。用MTT试验检测细胞的生长抑制率;用TUNEL法、半胱氨酸天冬氨酸蛋白酶（aspase）-3蛋白定量法检测细胞的凋亡率;检测细胞上清液中乳酸脱氢酶（LDH）活力来测定细胞的坏死情况;用实时定量PCR法和Western印迹法检测细胞HIF-1α、HIF-2α、葡萄糖转运蛋白1（Glut-1）、血管内皮生长因子（VEGF） mRNA和蛋白表达水平。 结果 （1）siRNA的细胞转染效率为95%～100%。在常氧条件下,终浓度100 nmol/L 的HIF-1α siRNA沉默HIF-1α基因的效率为70%;在缺氧条件下,HIF-1α siRNA沉默HIF-1α基因的效率达到97%。（2）HIF-1α siRNA组细胞的生长抑制率显著高于其它组（P < 0.05）;细胞凋亡率在缺氧培养组、转染试剂组、阴性对照组和HIF-1α siRNA组4组间的差异无统计学意义（P > 0.05）;HIF-1α siRNA组细胞培养液中LDH水平显著高于缺氧培养组、转染试剂组和阴性对照组（P < 0.05）。（3）HIF-1α siRNA组细胞的HIF-1α、Glut-1、VEGF mRNA和蛋白表达量显著低于缺氧培养组、转染试剂组、阴性对照组（P < 0.05）;而HIF-2α mRNA和蛋白表达在缺氧培养组、转染试剂组、阴性对照组和HIF-1α siRNA组4组间的差异无统计学意义（P > 0.05）。 结论 siRNA沉默HIF-1α能显著抑制缺氧状态下肾小管上皮细胞Glut-1和VEGF表达,加重缺氧状态下肾小管上皮细胞的生长抑制和坏死。     

Effect and mechanism of cysteine-rich protein 61 on transforming growth factor -β1-activated renal fibroblasts

Objective To observe the expression of cysteine-rich protein 61 (Cyr61) in transforming growth factor -β1 (TGF-β1)-activated renal fibroblasts (NRK-49F), and to explore its effect and mechanism. Methods (1) NRK-49F cells were activated by TGF-β1 with different concentrations (0.0, 0.5, 1.0, 2.0, 5.0 μg/L). Western blotting was used to detect the expression of Cyr61 protein, and CCK-8 assay was used to test the proliferative activity of NRK-49F cells. (2) NRK-49F cells with low expression and over expression of Cyr61 were established by plasmid transfection. The cells were divided into control group (null vector transfection), over-expression group and low-expression group. The proliferation was discovered by CCK-8 assay after 24, 48 and 72 h. Further, 5.0 μg/L TGF-β1 activated these three groups. The proliferation was also discovered by CCK-8 assay and the cell cycle was analyzed by flow cytometry. The mRNA expressions of fibrosis markers (Col1α1, Col3α1, MMP9, MMP13) and factors of cell senescence signal pathway (p53, p21, Rb, p16) were ascertained by real time PCR, and the protein expressions of Col3 and MMP9 were detected by Western blotting. Results (1) Compared with 0.0 μg/L TGF-β1 group, the proliferation of NRK-49F cells was enhanced in 0.5, 1.0, 2.0 and 5.0 μg/L TGF-β1 groups (all P＜0.05), while the expression of Cyr61 protein was decreased in 1.0 μg/L group and increased in 5.0 μg/L group (all P＜0.05). (2) The proliferation of over-expression group was lower than that of control group after 24, 48 and 72 h (all P＜0.05), which was in a time-dependent manner. (3) Compared with control group activated by TGF-β1, the over-expression group expressed less fibrosis factors (Col1α1 and Col3α1) and more anti-fibrosis factors (MMP9 and MMP13) with decreased proliferation (all P＜0.05). Simultaneously, the proportion of cells bogged down in G1 phases, as well as the expressions of p53, p21 and Rb mRNA increased (all P＜0.05). The above effects of low-expression group were just opposite to over-expression group. Moreover, there was no significant difference in the expression of p16 gene among the three groups (P＞0.05). Conclusions Cyr61 can curb the proliferation and fibrotic phenotypes of fibroblasts, thereafter slowing down the process of renal fibrosis. The p53/p21/Rb interrelated cell senescence signal pathway may be involved in the anti-fibrosis process.     

Differential phenotypic behaviors of human degenerative nucleus pulposus cells under normoxic and hypoxic conditions: influence of oxygen concentration during isolation,expansion, and cultivation

Background contextIntervertebral discs (IVDs) are the largest avascular structures in the body; therefore, cells within these discs might be adapted to low-oxygen conditions. Although it has been demonstrated that a low oxygen concentration could promote synthesis of the extracellular matrix by IVD cells in the in vitro culture, isolation, expansion, and cultivation of IVD cells under classical tissue culture O₂ saturation could still be detrimental.PurposeTo investigate the phenotypic differences between human degenerative nucleus pulposus (NP) cells during isolation and expansion under normoxic (Nx: 21% O₂) or hypoxic (Hx: 3.5% O₂) conditions.Study designWe investigated in vitro isolation, expansion, and cultivation of human NP cells.MethodsHuman NP tissue samples were obtained from patients who underwent lumbar disc surgeries. Nucleus pulposus cells were then isolated, expanded, and cultivated under normoxic or hypoxic conditions. To determine whether the effects of normoxic expansion are reversible, another group of cells was isolated and expanded in normoxic conditions and then cultivated under hypoxic conditions (Nx→Hx group). Cellular proliferation, RNA expression of selected genes, and immunohistochemical staining were performed to evaluate the phenotypic behaviors of human NP cells under different conditions.ResultsExpressions of Type II collagen and aggrecan in the Nx→Hx group were significantly higher than those in the normoxic group but were significantly lower than those in the hypoxic group. The normoxic group showed higher expression of matrix metalloproteinase (MMP)-2 and MMP-13 than did the other groups. Expression levels of hypoxia-inducible factors (HIFs) were significantly higher in the normoxic groups; however, a greater degree of HIF-1α staining was found in the hypoxic group, whereas a greater degree of HIF-2α staining was found in the normoxic group.ConclusionsHuman degenerative NP cells isolated, expanded, and cultivated in hypoxic conditions could better preserve the cells' regenerative potential. Compromised properties that were observed during isolation and expansion under normoxic conditions could only be partially rescued by later hypoxic cultivation. The superior phenotypic behaviors of human NP cells under hypoxia may be related to higher HIF-1α production and lower HIF-2α production. Cells that are isolated, expanded, and cultivated under hypoxic conditions may show better regenerative results when transplanted; therefore, the isolation and expansion processes of human degenerative NP cells should be managed in a hypoxic environment.     

缺氧诱导因子在大鼠肾缺血再灌注损伤中的表达和意义

目的：探讨缺氧诱导因子-1α（HIF-1α）和氧自由基在肾脏缺血再灌注损伤中的表达情况。方法：SD大鼠随机分为假手术组、缺血组、缺血再灌注组、RNAi阴性对照缺血组及HIF-1αRNAi预处理后的缺血组和预处理后缺血再灌注组，利用RT—PCR和western blot技术检测各组大鼠肾脏中HIF-1α和bcl-2的表达情况。检测细胞超氧化物歧化酶（SOD）的活性和丙二醛（MDA）的含量，间接反应氧自由基的生成量。测定各组大鼠肾功能。取各组大鼠肾组织切片并做HE染色。结果：缺血组HIF-1α的表达在5组中最高（P〈0．05）。与缺血组对比，缺血再灌注后HIF-1α和bcl-2的表达降低，同时氧自由基的生成增加（P〈0．05），肾功能明显降低，但经HIF-1αRNAi预处理后上述指标与假手术组相比改变甚微，肾功能得到明显改善。HE染色可见缺血及再灌注组排列紊乱，胞浆萎缩，纹状缘消失，细胞间质增宽，经HIF-1αsiRNA预处理后，接近假手术组水平。结论：HIF-1α的过度表达可能导致氧自由基生成增加，肾功能受损，从而加重缺血再灌注肾脏的损伤，而HIF-1αRNAi可以减轻并改善这一状况，其机制可能与上调凋亡抑制基因有关。     

缺血再灌注损伤后肾小管上皮细胞的衰老演变及其意义

目的观察肾脏缺血再灌注损伤（IRI）后正常和衰老肾小管上皮细胞的演变，探讨细胞衰老在衰老相关性肾脏病理变化中的作用。方法以低龄（2月龄）和高龄（12月龄）野生鼠为研究对象。建立左肾IRI模型。于IRI后0d、1d、3d、7d、1月、3月、6月取肾组织，用HE染色观察肾小管组织学变化；免疫组织化学检测肾小管上皮细胞增殖细胞核抗原（PCNA）的表达；组织化学染色观察肾小管上皮细胞衰老相关β-半乳糖苷酶（SA-β-gal）的活性；TUNEL法检测凋亡肾小管上皮细胞。结果肾脏IRI后0d，肾小管以坏死为主，高龄鼠比低龄鼠更为明显（P〈0．05）。IRI1d后出现肾小管上皮细胞凋亡，7d凋亡达到高峰（P〈0．05），且在同一时间点，高龄鼠比低龄鼠严重（P〈0．05）。低龄鼠IRI肾1月时出现肾小管上皮细胞衰老，而对侧肾没有出现，3月、6月点衰老细胞显著增多（P〈0．05）；高龄鼠IRI后0d双肾均可见大量衰老的肾小管上皮细胞，但IRI肾的衰老细胞在IRIld后明显减少（P〈0．05），1月后又逐渐增多。6月后高龄鼠双肾衰老的肾小管上皮细胞几乎又达到同一水平。PCNA阳性染色细胞出现的几率两组相比差异无统计学意义（P〉0．05），但低龄组细胞增殖能力要强于高龄组。对高龄鼠IRI后1d点肾小管上皮细胞凋亡与衰老之间的相关分析显示，二者存在显著负相关（r=-0．82,P〈0．001）。结论IRI可促进正常肾小管上皮细胞衰老的进程。已经进入衰老状态的肾小管上皮细胞在遭受IRI刺激后，更易走向死亡[坏死和（或）凋亡]。肾小管上皮细胞的这种演变，在老化相关性肾脏病理变化发生和进展中可能发挥着重要作用。     

High glucose promotes human glomerulus mesangial cells senescence through activating p53/p21 pathways and suppressing autophagy

Objective To observe the changes of senescence and autophagy in human glomerulus mesangial cells (HGMCs) induced by high glucose at different times, and to investigate the effects of rapamycin and 3-methyladenine (3-MA) on these changes. Methods HGMCs were cultured in vitro, exposed to high glucose (30.0 mmol/L glucose) for 12, 24, 48 and 72 h, and stimulated by high glucose with 500 nmol/L rapamycin or 2 mmol/L 3-MA for 72 h. Normal control group (5.5 mmol/L glucose) and hypertonic group (5.5 mmol/L glucose + 24.5 mmol/L mannitol) were set up. Cytomorphology changes were examined by light microscope to test whether cells were in senescent stage. The quantity of autophagosome was observed by electron microscope. The cell senescence was evaluated by β-galactosidase (SA β-gal) staining. The protein expressions of p53, p21, LC3 and p62 were determined by Western blotting. Results High glucose group gradually had larger size and more flat cytoplasm, polymorphonuclear cells and binucleate cells than control group as the stimulation times was prolonged. Compared with those in control group, SA β-gal positive cells in high glucose group after incubation for 72 h statistically were increased (P＜0.05); the protein expressions of p62, p53 and p21 in high glucose group after incubation for 48 h and 72 h were increased (all P＜0.05), while the autophagosome and the expression of LC3 decreased (P＜0.05). Compared with those in high glucose group, the expression of LC3 was increased dramatically in high glucose with rapamycin group (P＜0.05), while the protein expressions of p62, p53 and p21 decreased (all P＜0.05), and SA β-gal positive cells decreased (P＜0.05). However, there was no statistical difference between high glucose group and high glucose with 3-MA group in terms of above effects. Conclusions High glucose may induce HGMCs senescence through activating p53/p21 pathways and suppressing the activity of autophagy. Through enhanced autophagy activity with rapamycin, the expression of p53/p21 pathway was suppressed and senescence was relieved.