Telmisartan but not Valsartan Inhibits TGF-β-mediated Accumulation of Extracelluar Matrix via Activation of PPARγ

Glomerulosclerosis, defined as phenotype transition of mesangial cell and deposition of extracelluar matrix, remains a chronic disease with excessive morbidity and mortality. The molecular mechanism underlying the suppression of mesangial cell activation is not fully understood. Since activation of peroxisome proliferators-activated receptor γ (PPARγ) has been proposed to decrease the effects of transforming growth factor-β (TGF-β) on glomerulosclerosis, we examined here whether and how telmisartan, an angiotensin Ⅱ type 1 receptor blocker with PPARγ-modulating activity, inhibited TGF-β-induced glomerulosclerosis in rat glomerular mesangial cells. Protein levels of PPARγ were detected by Western blot. Activation of PPARγ response element (PPRE) was analyzed by luciferase assays. Deposition of extracelluar matrix was tested by confocol laser scanning. The results showed that telmisartan, but not valsartan, another angiotensin Ⅱ type 1 receptor blocker, up-regulated PPARγ protein levels in a dose-dependent manner (P<0.05). Activation of PPRE, represented by luciferase activity, was also increased with higher concentration of telmisartan in a dose-dependent manner (P<0.05). Furthermore, telmisartan inhibited TGF-β-induced α-smooth muscle actin expression and collagen IV secretion in mesangial cells. GW9662, an inhibitor of PPAR-γ, blocked the inhibitory effects of telmisartan on TGF-β-induced glomerulosclerosis in mesangial cells. Our study indicates a benefit of telmisartan as a PPARγ agonist against TGF-β-induced mesangial cells activation in renal glomerulus. It may provide possibility that telmisartan works as a potential agent against diabetic nephropathy and hypertensive renal disease.     

Role of Connective Tissue Growth Factor in Extracellular Matrix Degradation in Renal Tubular Epithelial Cells

In order to investigate the effects of connective tissue growth factor (CTGF) antisense oligodeoxynucleotide (ODN) on plasminogen activator inhibitor-1 (PAI-1) expression in renal tubular cells induced by transforming growth factor β1 (TGF-β1) and to explore the role of CTGF in the degradation of renal extracellular matrix (ECM), a human proximal tubular epithelial cell line (HKC) was cultured in vitro. Cationic lipid-mediated CTGF antisense ODN was transfected into HKC. After HKC were stimulated with TGF-β1 (5 μg/L), the mRNA level of PAI-1 was detected by RT-PCR. In-tracellular PAI-1 protein synthesis was assessed by flow cytometry. The secreted PAI-1 in the media was determined by Western blot. The results showed that TGF-β1 could induce tubular CTGF and PAI-1 mRNA expression. The PAI-1 mRNA expression induced by TGF-β1 was significantly inhib-ited by CTGF antisense ODN. CTGF antisense ODN also inhibited intracellular PAI-1 protein syn-thesis and lowered the levels of PAI-1 protein secreted into the media. It was concluded that CTGF might play a crucial role in the degradation of excessive ECM during tubulointerstitial fibrosis, and blocking the biological effect of CTGF may be a novel way in preventing renal fibrosis.     

Effects of curcumin on peroxisome proliferator-activated receptor γ expression and nuclear translocation/redistribution in culture-activated rat hepatic stellate cells

Background The function of peroxisome proliferator-activated receptor γ （PPARγ） in hepatic fibrogenesis remains largely unknown. Curcumin is a natural substance extracted form Curcuma Longa Linn and has a variety of pharmacological effects. In this study, the effects of curcumin on the proliferation, activation and apoptosis of rat hepatic stellate cells （HSCs） through PPARγ signaling were investigated. Methods HSCs were isolated from the normal Sprague Dawley rats through in situ peffusion of the liver with Pronase E and density-gradient centrifugation with Nycodenz. Cells were treated with curcumin, troglitazone, salvianolic acid B or GW9662. The effect on HSCs proliferation was determined by MTT colorimetry. Total RNA was extracted by TRizol reagent and gene levels were determined by semi-quantitative RT-PCR. Total cellular and nuclear protein were isolated and separated by 10% sodium dodecy Isulfate polyacrylamide gel electrophoresis. Protein levels were determined by Western blot. Cell apoptosis was detected by Hoechst 33258 staining. PPARγ subcellular distribution was detected by immunofluorescent staining. The activities of MMP-2 and 9 were measured by Gelatin zymograph assay. Results Curcumin suppressed HSCs proliferation in a dose-dependent manner. As HSCs underwent gradual activation with culture prolongation the PPARγ nuclear expression level decreased. Curcumin up-regulated PPARγ expression and significantly inhibited the production of a-SMA and collagen Ⅰ. PPARγ is expressed in the cytoplasm and nucleus and is evenly distributed in HSCs, but accumulated in the nucleus of HSCs and disappeared from cytoplasm after curcumin treatment. Hoechst 33258 staining showed that curcumin induced the apoptosis of culture-activated HSCs and significantly increased pro-apoptotic Bax expression and reduced anti-apoptotic Bcl-2 expression. Cyclin D1 gene, activated NFKB p65 protein and TGFβR-Ⅰ protein expression were down-regulated significantly by curcumin. The activities of MMP-2 and MMP-9 were enhanced significantly by curcumin. Conclusions Curcumin can inhibit the proliferation and activation of HSCs, induce the apoptosis of activated HSCs and enhance the activities of MMP-2 and MMP-9. The effects of curcumin are mediated through activating the PPARγ sianal transduction pathway and associated with PPARγ nuclear translocation/redistribution.     

Inhibitory Effect of TanshinoneⅡA on TGF-β1-induced Cardiac Fibrosis

This study examined the effect of tanshinoneⅡA (TSNⅡA) on the cardiac fibrosis induced by transforming growth factor β1 (TGF-β1) and the possible mechanisms. Cardiac fibroblasts were isolated from cardiac tissues of neonatal Sprague-Dawley (SD) rats by the trypsin digestion and differential adhesion method. The cells were treated with 5 ng/mL TGF-β1 alone or pretreated with TSNⅡA at different concentrations (10–5 mol/L, 10–4 mol/L). Immunocytochemistry was used for cell identification, RT-PCR for detection of the mRNA expression of connective tissue growth factor (CTGF) and collagen type Ⅰ (COLⅠ), Western blotting for detection of the protein expression of Smad7 and Smad3, and immunohistochemistry and immunofluorescence staining for detection of the protein expression of phosphorylated Smad3 (p-Smad3), CTGF and COLⅠ. The results showed that TGF-β1 induced the expression of CTGF, COLⅠ, p-Smad3 and Smad7 in a time-dependent manner. The mRNA expression of CTGF and COLⅠ was significantly increased 24 h after TGF-β1 stimulation (P<0.01 for all). The protein expression of p-Smad3 and Smad7 reached a peak 1 h after TGF-β1 stimulation, much higher than the baseline level (P<0.01 for all). Pretreatment with high concentration of TSNⅡA resulted in a decrease in the expression of p-Smad3, CTGF and COLⅠ (P<0.01). The protein expression of Smad7 was substantially upregulated after pretreatment with two concentrations of TSNⅡA as compared with that at 2h post TGF-β1 stimulation (P<0.05 for low concentration of TSNⅡA; P<0.01 for high concentration of TSNⅡA). It was concluded that TSNⅡA may exert an inhibitory effect on cardiac fibrosis by upregulating the expression of Smad7, suppressing the TGF-β1-induced phosphorylation of Smad3 and partially blocking the TGF-β1-Smads signaling pathway.     

Effect of retinoid X receptor alpha (RXRα) transfection on the proliferation and phenotype of rat hepatic stellate cells in vitro

Objective To study the effect of retinoid X receptor alpha (RXRα) transfection plus treatment with the RXRα ligand, 9-cis-RA, on the proliferation and phenotype of platelet-derived growth factor (PDGF)-activated hepatic stellate cells (HSCs). Methods PDGF activated rat hepatic stellate cells were transfected with eukaryotic expression vector pcDNA3.1- human RXRα, and confirmed by Western blot. Proliferation of transfected HSC was assayed by bromodeoxyuridine (BrdU) incorporation as well as MTT, and the phenotype (α-smooth muscle actin, desmin) was observed by immunocytochemistry with image analysis. Results Transfection of the RXRα gene and treatment with ligand 9-cis-RA of PDGF-activated HSCs extended the increased expression of RXRα protein for at least 168 hours. Cell proliferation and expressions of alpha-smooth muscle actin (α-SMA) and desmin were blocked, compared with groups of sham-transfected, PDGF-activated, no transfection, no ligand treatment, and irrelevant ligand treated HSCs. Conclusion Transfection with the RXRα gene followed by 9-cis-RA ligand treatment will inhibit the proliferation and reverse the phenotype of activated HSC.     

TGF-β1-induced synthesis of collagen fibers in skeletal muscle-derived stem cells

The aim of this study was to investigate the mechanism of deposition of extracellular matrix induced by TGF-β1 in skeletal muscle-derived stem cells (MDSCs). Rat skeletal MDSCs were obtained by using preplate technique, and divided into four groups: group A (control group), group B (treated with TGF-β1, 10 ng/mL), group C (treated with TGF-β1 and anti-connective tissue growth factor (CTGF), both in 10 ng/mL), and group D (treated with anti-CTGF, 10 ng/mL). The expression of CTGF, collagen type-Ⅰ (COL-Ⅰ) and collagen type-Ⅲ (COL-Ⅲ) in MDSCs was examined by using RT-PCR, Western blot and immunofluorescent stain. It was found that one day after TGF-β1 treatment, the expression of CTGF, COL-Ⅰ and COL-Ⅲ was increased dramatically. CTGF expression reached the peak on the day 2, and then decreased rapidly to a level of control group on the day 5. COL-Ⅰ and COL-Ⅲ mRNA levels were overexpresed on the day 2 and 3 respectively, while their protein expression levels were up-regulated on the day 2 and reached the peak on the day 7. In group C, anti-CTGF could partly suppress the overexpression of COL-I and COL-Ⅲ induced by TGF-β1 one day after adding CTGF antibody. It was concluded that TGF-β1 could induce MDSCs to express CTGF, and promote the production of COL-Ⅰ and COL-Ⅲ. In contrast, CTGF antibody could partially inhibit the effect of TGF-β1 on the MDSCs by reducing the expression of COL-Ⅰ and COL-Ⅲ. Taken together, we demonstrated that TGF-β1-CTGF signaling played a crucial role in MDSCs synthesizing collagen proteins in vitro, which provided theoretical basis for exploring the methods postponing skeletal muscle fibrosis after nerve injury.     

Inhibition effect of small interfering RNA of connective tissue growth factor on the expression of vascular endothelial growth factor and connective tissue growth factor in cultured human peritoneal mesothelial cells

Background The peritoneum response to peritoneal dialysis can lead to fibrosis. The transforming growth factor β1 （TGF-β1 ） plays a key role in regulating tissue repair and remodelling after injury. Connective tissue growth factor （CTGF）, a downstream mediator of TGF-β1 inducing fibrosis, has been implicated in peritoneal fibrosis. Vascular endothelial growth factor （VEGF） plays a key role in angiogenesis that can hasten peritoneal fibrosis. In this study, we investigated the effect of small interfering RNA （siRNA） of CTGF by pRETRO-SUPER （PRS） retrovirus vector on the expression of CTGF and VEGF in human peritoneal mesothelial cells. Methods Retrovirus producing CTGF siRNA were constructed from the inverted oligonucleotides and transferred into packaging cell line PT67 with lipofectamine, and the virus supernatant was used to infect human peritoneal mesothelial cell （HPMC）. The cells were divided into seven groups： low glucose DMEM, low glucose DMEM ＋ TGF-β1 5 ng/ml, low glucose DMEM ＋ TGF-β1 5 ng/ml ＋ PRS-CTGF-siRNA1-4 and low glucose DMEM ＋ TGF-β1 5 ng/ml ＋ PRS. The expression of CTGF and VEGF were measured by semiquantitative RT-PCR and Western blot. Results Low levels of CTGF and VEGF were detected in confluent HPMCs. Following stimulation with TGF-β1 , the levels of CTGF and VEGF were significantly upregulated （P〈0.01）. Introduction of PRS-CTGF-siRNA1-4 resulted in the significant reduction of CTGF mRNA and protein, and VEGF mRNA （P〈0.01）, especially in groups PRS-CTGF-siRNA, and PRS-CTGF-siRNA4. The introduction of PRS void vector did not have these effects （P〉0.05）. Conclusions The expression of CTGF siRNA mediated by PRS retrovirus vector can effectively reduce the level of CTGF and VEGF induced by TGF-β1 in cultured HPMCs. This study may provide potential therapeutic strategies to prevent the peritoneal fibrosis.     

Role of connective growth factor in plasminogen activator inhibitor-1 and fibronectin expression induced by transforming growth factor β1 in renal tubular cells

Background Connective tissue growth factor (CTGF) contributes greatly to renal tubulointerstitial fibrosis, which is the final event leading to end-stage renal failure. This study was designed to investigate the effects of CTGF antisense oligodeoxynucleotides (ODNs) on the expressions of plasminogen activator inhibitor-1 (PAI-1) and fibronectin in renal tubular cells induced by transforming growth factor β1 (TGF-β) in addition to the role of CTGF in the accumulation and degradation of renal extracellular matrix (ECM). Methods A human proximal tubular epithelial cell line (HKC) was cultured in vitro. Cationic lipidmediated CTGF antisense ODNs were transfected into HKC cells. After HKC cells were stimulated with TGF-β1 (5 μg/L), the mRNA levels of PAI-1 and fibronectin were measured by RT-PCR. Intracellular PAI-1 protein synthesis was assessed by flow cytometry. The secreted PAI-1 and fibronectin in the medium were determined by Western blot and ELISA, respectively. Results TGF-β was found to induce tubular CTGF, PAI-1, and fibronectin mRNA expression. PAI-1 and fibronectin mRNA expression induced by TGF-β was significantly inhibited by CTGF antisenes. ODNs CTGF antisense ODNs also inhibited intracellular PAI-1 protein synthesis and lowered the levels of PAI-1 and fibronectin protein secreted into the medium. Conclusions CTGF may play a crucial role in the accumulation and degradation of excessive ECM during tubulointerstitial fibrosis, and transfecting CTGF antisense ODNs may be an effective way to prevent renal fibrosis.     

大鼠自体原位肝移植胆道缺血再灌注损伤胆道组织PPARγmRNA表达的意义

目的:探讨PPARγ在大鼠自体原位肝移植胆道缺血再灌注损伤胆道组织中的表达情况以及意义。方法:40只SD大鼠随机分成假手术组(SO组)、缺血-再灌注组(I/R组)、罗格列酮组(ROS组)和GW9662组,每组10只。通过制作大鼠自体原位肝移植胆道缺血再灌注模型,应用PPARγ的配体罗格列酮(ROS)和拮抗剂GW9662作为干预,采用RT-PCR方法检测各组胆道组织中PPARγmRNA表达情况,应用图像分析系统进行灰度扫描,以各组β-actin条带的扫描值为标准,计算PPARγmRNA/β-actin吸光度比值,记录PPARγmRNA的相对表达量。结果:PPARγmRNA在SO组胆道组织中呈低表达;I/R组PPARγmRNA表达稍有增高,较SO组无显著差异;ROS组PPARγmRNA表达显著增加,与I/R组比较有显著差异(P<0.05);在GW9662组PPARγmRNA表达显著降低,与ROS组比较有显著差异(P<0.05)。结论:SD大鼠自体原位肝移植胆道缺血再灌注损伤各实验组胆道组织中存在PPARγmRNA表达,但各组表达量不同。配体罗格列酮可以活化原位肝移植胆道缺血再灌注损伤中肝外胆道组织中的PPARγ,但这种活化是PPARγ依赖性的,可被PPARγ的拮抗剂GW9662逆转。     

过氧化物酶体增殖物激活型受体γ在心肌间质纤维化中的作用及机制研究

目的 研究过氧化物酶体增殖物激活型受体γ（peroxisome proliferator activated receptorγ,PPARγ）不同表达对与大鼠心肌间质纤维化之间的关系,探讨过氧化物酶体增殖物激活型受体γ心肌间质纤维化进程中的作用和机制。方法 雄性SD大鼠48只随机分成4组：① 对照组（C 组）16只,采用0.05 %ISO（5 mg•kg-1•d-1×10 d）皮下注射制作大鼠心肌纤维化模型;②早期干预组（Pa组）12只,造模同时给予PPARγ激动剂罗格列酮 100 mg•kg-1•d-1,腹腔注射56 d;③ 晚期干预组（Pp组）12只,造模10 d后给予PPARγ激动剂罗格列酮 100 mg•kg-1•d-1,腹腔注射46 d;④空白组（B组）12只。建模成功后计算各组左心室质量指数,RT-PCR检测心肌PPARγ mRNA水平;比色法检测左室心肌组织中羟脯氨酸浓度;进行VG染色,测算胶原容积积分（collagen volume fraction,CVF）;免疫组化染色半定量检测PPARγ、TGF-β、CTGF、MMP9表达。结果 Pa组、Pp组和C组的左心室质量指数、CVF、心肌组织羟脯氨酸浓度和PPARγ、TGF-β、CTGF、MMP9表达均较B组明显增加（P<0.05）;Pa组和Pp组的左心室质量指数、CVF、心肌组织羟脯氨酸浓度和PPARγ、TGF-β、CTGF、MMP9均较C组明显减少（P<0.05）,Pa组减少更明显。结论 过氧化物酶体增殖物激活型受体γ可能在心肌间质纤维化进程中发挥重要作用,它可能是促进心肌胶原合成的重要信号分子。PPARγ活化可减少TGF-β、CTGF、MMP9表达,减少胶原沉积,从而减轻和延缓ISO诱导的心肌纤维化,早期干预效果更明显,这种作用机制可能是通过抑制TGF-β和CTGF的过度表达来实现。     

过氧化物酶体增殖物激活受体γ激动剂对肝星状细胞转化生长因子β1/Smad信号途径的作用研究

目的 研究过氧化物酶体增殖物激活受体γ(PPARγ)激动剂阻断转化生长因子(TGF)β1致肝纤维化作用的机制,探讨其抗肝纤维化的潜在作用.方法 体外培养肝星状细胞株HSC-T6.观察PPARγ配体15 d-PGJ2及其激动剂曲格列酮和齐格列酮对TGFβ1诱导的纤维连接蛋白(FN)表达的影响.利用Western印迹技术观...     

吡格列酮通过调控TGF-β信号通路和T细胞调节性免疫机制缓解ApoE-/-小鼠动脉粥样硬化

目的 研究ApoE-/-小鼠体内吡格列酮(PIO)是否通过TGF-β信号通路和T细胞调节性免疫机制来发挥抗动脉粥样硬化的作用.方法 动脉粥样硬化ApoE-/-小鼠模型连续8周每日灌胃给予PIO(日剂量20 mg/kg).免疫组化对动脉病变组织中TGF-β信号通路相关因子、IFN-γ+细胞及Foxp3+细胞的表达水平进行检测.体外研究中,用特异性抗原氧化低密度脂蛋白(oxLDL)刺激原代培养的ApoE-/-小鼠脾脏细胞,并与PIO或PIO+PPARγ阻断剂GW9662共同孵育.流式细胞术检测CD4+IFN-γ+细胞和CD4+CD25+Foxp3+细胞的水平.结果 PIO可通过提高TGFβ1(P<0.01),TGFβRII(P<0.05)和p-Smad3(P<0.05)的表达量、抑制Smad7(P<0.05)的表达量来缓解ApoE-/-小鼠动脉粥样硬化的病变程度.体外实验表明,PIO处理后原代小鼠脾细胞中IFN-γ的mRNA水平显著下调(P<0.05),而Foxp3的mRNA水平显著上调(P<0.05).流式细胞术表明PIO处理后CD4+IFN-γ+细胞(P<0.05)和CD4+CD25+Foxp3+细胞(P<0.05)的表达量明显上升,而PPARγ阻断剂GW9662可阻断PIO对两种细胞的调控作用.结论 PIO可能通过调控TGF-β/Smad信号通路及PPARγ介导的Th1/Treg细胞水平抑制ApoE-/-小鼠的动脉粥样硬化病变.     

罗格列酮拮抗博莱霉素致大鼠肺纤维化的实验研究

目的探讨罗格列酮抑制肺纤维化的作用及其机制。方法将24只大鼠分为生理盐水对照组、罗格列酮对照组、博莱霉素组、罗格列酮干预组,予博莱霉素诱导大鼠肺纤维化。HE染色和Masson染色行病理学检查;试剂盒检测肺组织中羟脯氨酸含量;应用Westen blot及荧光定量实时逆转录聚合酶链反应(RT-PCR)检测过氧化物酶体增殖物激活受体γ(PPARγ)、基质金属蛋白酶9(MMP-9)和转化生长因子β1(TGF-β1)的表达;采用酶联免疫吸附法(ELISA)检测支气管肺泡灌洗液(BALF)中TGF-β1浓度。结果博莱霉素气管内注入后,Ashcroft评分,肺组织胶原沉积、羟脯氨酸含量,BALF中TGF-β1水平及肺组织中TGF-β1、PPARγ、MMP-9表达较生理盐水对照组增加;给予罗格列酮干预后,除PPARγ表达进一步增加外,上述指标均下降。博莱霉素组PPARγ蛋白表达水平与TGF-β1mRNA、MMP-9mRNA表达水平分别呈负相关。结论罗格列酮对博莱霉素诱导的肺纤维化进程有拮抗作用,其具体机制可能与上调PPARγ蛋白表达,抑制TGFβ1、MMP-9mRNA转录有关。     

PPARγ通路在舒林酸抑制胃癌细胞增殖中的作用及机制

目的了解舒林酸是否通过过氧化物酶增殖物激活受体γ（PPARγ）途径影响人胃癌SGC-7901细胞的增殖,初步探讨PPARγ途径在舒林酸抗肿瘤作用中的机制。方法培养人胃癌SGC-7901细胞,经特异的PPARγ抑制剂GW9662作用,采用四甲基偶氮唑蓝比色法（MTT法）检测舒林酸对细胞增殖的影响及用免疫细胞化学法检测PPARγ、Bcl-2、Bax蛋白表达。结果MTT法显示GW9662作用后,舒林酸对SGC-7901细胞增殖的抑制作用减弱,细胞增殖增多,而且这种作用在一定范围内呈剂量和浓度依赖性;免疫细胞化学法显示GW9662预先干预与舒林酸单独作用相比,SGC7901细胞的PPAR-γ蛋白表达明显减少,Bax的表达亦明显降低,而Bcl-2蛋白表达增强（P〈0.01）。结论PPARγ途径在舒林酸抗肿瘤作用中具有一定作用,其机制与激活PPARγ对Bcl-2、Bax蛋白的表达有关。     

大豆苷原（DA）对成骨细胞雌激素受体（ER）和过氧化物酶体增殖物激活受体γ（PPARγ）

 目的 研究大豆苷原(daidzein,DA)对成骨细胞雌激素受体(estrogen receptor,ER)和过氧化物酶体增殖物激活受体γ (peroxisome proliferator-activated receptor γ,PPARγ)表达的调节作用,并观察雌激素对这种调节的影响。方法 小鼠成骨细胞MC3T3-E1体外低血清(α-MEM,含2% FBS)培养,分别用0.1和10 μmol/L的DA处理,采用实时定量PCR或Western blot分析细胞ERα、ERβ和PPARγ的表达变化。加入浓度均为0.1 μmol/L的ER拮抗剂ICI182780或PPARγ拮抗剂GW9662,观察ER和PPARγ在DA调节中的作用。为观察雌激素的影响,采用无血清培养,在10 nmol/L 17β-雌二醇(E2)条件下研究DA对细胞受体表达的作用。结果 DA抑制体外培养成骨细胞ER表达,而刺激其PPARγ表达。0.1和10 μmol/L的DA分别下调ERα 蛋白水平44%和38% (P<0.05),下调ERβ蛋白水平50%(P<0.05)和31% (P<0.05),上调PPARγ 74%和78% (P<0.05)。 ICI182780可阻断DA对ERα转录水平的抑制作用,DA对成骨细胞ERβ mRNA水平的下调无统计学意义(P=0.087 4);GW9662可阻断DA对PPARγ表达的上调作用,提示成骨细胞ER和PPARγ参与自身表达调节。在10 nmol/L 17β-雌二醇条件下,DA对无血清培养的成骨细胞ERα转录水平的抑制作用由28.0%～29.6%(P<0.05)增强至74.0%～82.8%(P<0.01),其对ERβ表达的抑制作用也明显增强,而对PPARγ的上调作用几乎丧失。结论 DA可通过调节ERs和PPARγ等受体表达间接影响成骨细胞的药物反应,雌激素可明显影响DA的受体调节作用。DA对细胞受体表达的调节作用可能是其对成骨细胞时间相关双相调节的重要机制之一。     

肺纤维中过氧化物酶体增殖物激活受体γ的参与机制研究

[摘要] 目的 探讨过氧化物酶体增殖物激活受体γ（PPARγ）及其配体在博莱霉素诱导大鼠肺纤维化中的作用及参与机制。 方法 将24只雄性SD大鼠随机分为生理盐水对照组、罗格列酮对照组、博莱霉素组、罗格列酮干预组。经气管内注射博莱霉素建立肺纤维化模型。HE染色及Masson染色观察肺组织形态学变化;检测支气管肺泡灌洗液（BALF）中乳酸脱氢酶（LDH）及转化生长因子β1（TGF-β1）浓度;应用荧光定量RT-PCR及Western blot检测肺组织中TGF-β1和PPARγ表达。 结果 博莱霉素气管内注入后肺Ashcroft评分,胶原沉积、TGF-β1表达、PPARγ表达及BALF中LDH、TGF-β1水平增加;给予罗格列酮干预后,除PPARγ表达进一步增加外,上述指标均下降。博莱霉素组PPARγ蛋白水平与TGF-β1mRNA表达、BALF中LDH含量呈负相关。 结论 PPARγ参与了肺纤维化的发生;PPARγ及其配体罗格列酮可能通过调节炎症反应,抑制TGFβ1转录,从而减少胶原沉积,对肺纤维化进行负性调控。     

大豆苷原(DA)对成骨细胞雌激素受体(ER)和过氧化物酶体增殖物激活受体γ(PPARγ)表达的调节作用及其受雌激素的影响(英文)

目的研究大豆苷原(daidzein,DA)对成骨细胞雌激素受体(estrogen receptor,ER)和过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptorγ,PPARγ)表达的调节作用,并观察雌激素对这种调节的影响。方法小鼠成骨细胞MC3T3-E1体外低血清(α-MEM,含2%FBS)培养,分别用0.1和10μmol/L的DA处理,采用实时定量PCR或Western blot分析细胞ERα、ERβ和PPARγ的表达变化。加入浓度均为0.1μmol/L的ER拮抗剂ICI182780或PPARγ拮抗剂GW9662,观察ER和PPARγ在DA调节中的作用。为观察雌激素的影响,采用无血清培养,在10nmol/L 17β-雌二醇(E2)条件下研究DA对细胞受体表达的作用。结果 DA抑制体外培养成骨细胞ER表达,而刺激其PPARγ表达。0.1和10μmol/L的DA分别下调ERα蛋白水平44%和38%(P<0.05),下调ERβ蛋白水平50%(P<0.05)和31%(P<0.05),上调PPARγ74%和78%(P<0.05)。ICI182780可阻断DA对ERα转录水平的抑制作用,DA对成骨细胞ERβmRNA水平的下调无统计学意义(P=0.087 4);GW9662可阻断DA对PPARγ表达的上调作用,提示成骨细胞ER和PPARγ参与自身表达调节。在10nmol/L 17β-雌二醇条件下,DA对无血清培养的成骨细胞ERα转录水平的抑制作用由28.0%～29.6%(P<0.05)增强至74.0%～82.8%(P<0.01),其对ERβ表达的抑制作用也明显增强,而对PPARγ的上调作用几乎丧失。结论 DA可通过调节ERs和PPARγ等受体表达间接影响成骨细胞的药物反应,雌激素可明显影响DA的受体调节作用。DA对细胞受体表达的调节作用可能是其对成骨细胞时间相关双相调节的重要机制之一。