过氧化物酶体增殖物激活受体γ在脓毒症中的研究进展

背景 现已证实脓毒症是由感染因素诱发的全身性炎症反应综合征,在病程中表现为机体和病原体相互作用导致的促炎和抗炎反应不平衡. 目的 过氧化物酶体增殖物激活受体-γ(peroxisome proliferator activated receptor-γ,PPAR-γ)作为一种配体激活的核受体转录因子,与配体结合后作用于炎性信号转录途径的多个环节,抑制炎症反应,进而对脓毒症有一定的保护作用.因此,了解PPAR-γ在脓毒症中的研究现状以及未来发展趋势是十分必要的. 内容 PPAR-γ在缓和自身免疫性疾病、抗炎、抑制超敏反应、抗肿瘤及移植排斥中发挥重要的作用.针对PPAR-γ在脓毒症发病机制及治疗的研究作一综述. 趋向 PPAR-γ已成为炎症研究的方向,由于PPAR-γ结构与功能的复杂性,其作用机制尚未完全清楚,但随着对PPAR-γ研究的深入,有望为临床提供新的治疗方案.     

过氧化物酶体增殖物激活受体-γ配体抗肿瘤机制的研究进展

过氧化物酶体增殖物激活受体(PPAR-γ)及其配体已成为肿瘤基础研究的热点之一,文中从细胞分化、细胞增殖、细胞凋亡、血管形成及肿瘤侵袭性等方面综述了PPAR-γ配体抗肿瘤机制的研究进展。     

PTEN基因在过氧化物酶体增殖物激活受体γ调节肝癌细胞生长中的作用

目的探讨过氧化物酶体增殖物激活受体γ（PPARγ）在肝癌细胞生长中的调节作用,以及PTEN和磷酸化蛋白激酶B（pAkt）在该过程中的变化,进一步揭示PPARγ调节肝癌细胞生长的机理。方法培养SMMC-7721肝癌细胞,经不同浓度的PPARγ配体15-脱氧-前列腺素J2（15-d-PGJ2）或匹格列酮（pioglitazone）作用不同时间后,用MTT法测定细胞活力,用流式细胞仪进行细胞周期分析,用RT-PCR检测细胞PTEN mRNA的表达,用Western blot检测细胞PTEN和pAkt蛋白的表达。结果15-d-PGJ2和pioglitazone对肝癌细胞的增殖均具有抑制作用,且呈时间和剂量依赖性,均能增加G0/G1期细胞的比例,减少S期细胞的比例,增加SMMC-7721细胞PTEN mRNA和蛋白的表达,减少pAkt蛋白的表达。结论PPARγ的配体能够呈时间和剂量依赖性地抑制肝癌细胞的增殖,其机理可能是部分通过上调PTEN的表达而实现的。     

过氧化物酶体增殖物激活受体γ配体抑制大鼠肝纤维化的实验研究

目的 研究过氧化物酶体增殖物激活受体γ(peroxisome proliferator activated receptorgamma,PPARγ)配体对大鼠肝纤维化的作用.方法 将Wistar大鼠40只随机分为两组,对照组(20只)和罗格列酮组(20只).所有动物使用饮水中加人质量比0.3‰硫代乙酰胺的方法 制作肝纤维化模型.对照组喂饲普通颗粒饲料.罗格列酮组喂饲含200 ppm罗格列酮的颗粒饲料.喂饲6个月后,用RT-PCR方法 检测肝纤维化大鼠肝脏PPARγ、TGF-β 1 及Ⅰ型前胶原mRNA表达,用Westernblot法检测PPARγ、TGF-β 1 、Ⅰ型胶原及α平滑肌肌动蛋白(α-SMA)表达,用Van Gieson(VG)染色的方法 检测肝组织切片的胶原表达情况.结果 罗格列酮组与对照组相比,PPARγmRNA表达显著增强(t=6.93,P<0.01),TGF-β 1 mRNA(t=3.89,P<0.01)和Ⅰ型前胶原mRNA表达显著降低(t=5.67,P<0.01).PPARγ、TGF-β 1 及Ⅰ型胶原蛋白表达所得结果 与RT-PCR结果 相一致.罗格列酮组与对照组相比,α-SMA表达显著降低(t=3.12,P<0.01).罗格列酮组肝组织切片的胶原染色低于对照组(t=3.47,P<0.01).结论 PPARγ配体能够抑制大鼠纤维化肝脏的胶原产生,在体内具有一定的抗肝纤维化作用.     

过氧化物酶体增殖物激活受体-γ及其共激活蛋白1的单核苷酸多态性与多囊卵巢综合征表型的关系

目的研究过氧化物酶体增殖物激活受体-γ2(PPAR-γ2)和过氧化物酶体增殖物激活受体-γ共激活蛋白1(PGC-1)α的单核苷酸多态性与多囊卵巢综合征(PCOS)发病及生殖激素的关系。方法收集PCOS患者和非PCOS妇女正常对照的血液标本。记录两组的初潮年龄,身高、体重,分离血清测定生殖激素,分离血液中的淋巴细胞提取总DNA,特异引物扩增后限制性酶切(PCR-RFLP),电泳分离,溴化乙锭(EB)染色。结果PCOS患者的PPAR-γ2(Pro12Pro,Pro12Ala和Ala12Ala)基因型分布(分别为0.910,0.090,0)与正常人的分布(分别为0.925,0.068,0.007)无显著差异。PCOS患者的PGC-1α(Gly482Gly,Gly482Ser和Ser482Ser)基因型分布(分别为0.328,0.402,0.269)与正常人的分布(分别为0.333,0.374,0.293)无显著差异。体重指数(BMI)、血清总睾酮(T)和卵泡刺激素(FSH)、黄体生成素(LH)、LH/FSH、孕酮(P)和雌二醇(E2)在PPAR-γ2和PGC-1α各基因型之间无显著差异。与其他人种比较,中国人PPAR-γ2中Ala等位基因频率较低(4.4%),但PGC-1α的频率较高(48%)。结论结果提示PPARγ2 Pro12Ala和PGC-1αGly482Ser这两种单核苷酸多态性与PCOS的发病无相关性。     

急性肺损伤中过氧化物酶体增殖物激活受体γ通路参与保护作用的阶段性研究

背景 急性肺损伤(acute lung injury,ALI)在临床上主要表现为严重的低氧血症、弥漫性肺浸润和肺微血管通透性增高所致的肺水肿.目前认为,ALI的主要发病机制为炎症反应失衡,促炎因子大量释放.过氧化物酶体增殖物激活受体γ(peroxisome proliferator-activated receptorγ,PPARγ)是调节目的基因表达的核内受体转录因子超家族成员,主要表达于脂肪组织以及巨噬细胞和其他脂肪贮存细胞. 目的 介绍PPARγ在ALI中的保护作用. 内容 PPARγ具有广泛的抗炎作用,近年来的研究发现其在ALI的保护方面具有重要作用. 趋向 为预防和治疗ALI提供新思路.     

过氧化物酶体增殖物激活受体γ对人肝癌细胞生长和凋亡的影响及其机制

目的 检测过氧化物酶体增殖物激活受体γ(PPARγ)在人肝癌、癌旁和正常肝组织的表达,探讨激活或抑制PPARγ在肝癌细胞株生长和凋亡中的作用及其机制.方法 应用免疫组织化学方法检测20例肝癌、癌旁和正常肝组织中PPARγ的表达,Western blot检测2种肝癌和1种正常肝细胞株中PPARγ表达;PPARγ激动剂15dPGJ2和拮抗剂T0070907分别干预培养的2种肝癌细胞株,噻唑蓝(MTT)检测细胞生存率,流式细胞术(FCM)检测细胞周期及凋亡,试剂盒检测Caspase-3活性变化.结果 肝癌组织中PPARγ表达高于癌旁和正常肝组织(P＜0.05),PPARγ主要在肝癌细胞质中表达;肝癌细胞株PPARγ表达比正常肝细胞株高(P＜0.05);15dPG-J2抑制肝细胞增殖而T0070907则促进肝癌细胞增殖(P＜0.05).15dPG-J2可使肝癌HepG2和SMMC7721细胞G0/G1期细胞比例由(42.5±0.9)%和(49.0±3.8)%增高至(61.0±2.0)%和(67.5±2.2)%,(P＜0.05),S期由(30.5±0.3)%和(43.0±2.5)%降低至(6.6±1.1)%和(25.1±2.0)%(P＜0.05).而且,15dPG-J2可明显促进两种肝癌细胞凋亡,凋亡率分别增加约24.4%和22.4%,并可增强细胞Caspase-3活性(P＜0.05);Caspase抑制剂Z-VAD-FMK则可逆转15dPG-J2对肝癌细胞的促凋亡作用.结论 PPARγ在肝癌细胞中表达升高,其表达主要位于细胞质中,为无活性状态.PPARγ激动剂可活化PPARγ和Caspase通路,抑制肝癌细胞生长,促进细胞凋亡.

Abstract：

Objective To investigate the expression of peroxisome proliferator-activated receptor γ (PPARγ) in human liver cancer tissue and cells, and to explore the effects and mechanisms of PPARγ on growth and apoptosis in human hepatocellular carcinoma cells. Methods The expression of PPARγ in 20 cases of liver cancer, tumor adjacent tissue, normal liver, one liver cell line and two liver cancer cell lines were detected by immunohistochemistry or Western blotting. Two incubated malignant cell lines were exposed to PPARγ agonist 15dPGJ2 or antagonist T0070907, cell viability was determined by methyl thiazol tetrazolium (MTT) assay and cell cycle distribution and apoptosis were examined by flow cytometry (FCM). Consequently, the activity of caspase-3 following treatments of 15dPGJ2 or T0070907 was observed by the commercial Caspase-3 Activity Kit. Results The expression of PPARγin liver cancer was higher than that in adjacent and normal liver tissue ( P ＜ 0. 05) and PPART was predominantly expressed in the cytoplasm. Further,the expression of PPARγwas higher in hepatoma cell line than that in normal liver cell line (P＜ 0.05 ). PPARγ agonist 15dPG-J2 inhibited the proliferation while the antagonist T0070907 induced the growth of hepatoma cells (P ＜ 0. 05). G0/G1 phase of HepG2 and SMMC772 cells was blocked by 15dPG-J2, and the ratio were raised from (42.5 ±0.9)% and (49.0 ±3.8)% to (61.0 ±2. 0)% and (67.5 ±2. 2)% ,respectively. Meantime,S phase ratio were decreased from (30. 5 ± 0. 3 ) % and (43.0 ± 2. 5 ) % to ( 6. 6 ± 1. 1 ) % and ( 25. 1 ± 2. 0 ) %. Further, 15 dPG-J2 facilitated significant apoptosis in those cell lines and the increased apoptosis ratio were 24. 4% and 22. 4% respectively.Accordingly,the activity of Caspase-3 induced by 15dPGJ2 were 21-and 23-fold higher than those in control groups (P ＜ 0. 05 ). The Caspase inhibitor Z-VAD-fmk expectedly reversed the apoptosis induced by 15dPGJ2 in HepG2 and SMMC772 cells. Conclusion The expression of PPARγ increases in human hepatoma predominantly in cytoplasm with its inactivated form. 15dPG-J2 ,an agonist of PPART inhibits growth and induces apoptotic in hepatoma cells through activation of PPARγ pathway and the consequent Caspase3 signal.     

过氧化物酶体增殖物激活受体与肾脏病研究新进展

过氧化物酶体增殖物激活受体(PPARs)是一类配体激活的核转录因子超家族成员之一.近年来由于PPARs参与调节许多细胞功能,如脂肪细胞分化、炎症反应、脂肪酸及脂类代谢、细胞周期调控等,因而成为研究的热点之一,并且在大量的PPARs与很多全身性疾病的关系研究中取得了很大成就,如2型糖尿病、肥胖、动脉粥样硬化、高血压、肿瘤和炎症等.已经证实肾脏组织和细胞中表达PPARs,有关其在肾脏领域里的研究逐年增多.研究最为广泛的是其表型之一PPAR-γ.本文就近年来有关PPAR-γ及其激动剂与肾脏病的研究新进展做一简要综述.     

过氧化物酶体增殖物激活受体γ激动剂对肝星状细胞增殖的影响

目的 观察过氧化物酶体增殖物激活受体γ（PPARγ）激动剂对肝星状细胞增殖的影响，探讨其抗肝纤维化的可能作用机制。方法 利用胶原酶原位灌注梯密度离心方法分离大鼠肝星状细胞（HSC），利用噻唑蓝（MTT）比色法、流式细胞技术检测曲格列酮、15-脱氧-前列腺素J2（15-d-PGJ2）对HSC增殖及细胞周期的作用。结果 MTT检测表明曲格列酮、15-d—PGJ2在5～100μmoL／L浓度范围内可显著抑制HSC的增殖，与对照组比较P〈0．01；流式细胞检测表明25、50μmoL／L的曲格列酮可显著降低HSCS期细胞数量，降低细胞增殖指数，与对照组比较，差异有统计学意义（P〈0．05）。结论 PPARy激动剂通过影响HSC的增殖而发挥其抗肝纤维化作用。     

过氧化物酶体增殖物激活受体-γ在神经病理性疼痛中作用的研究进展

神经病理性疼痛（NP）由躯体感觉神经系统的损伤或疾病引起，其病理机制复杂，主要与神经结构及功能异常有关，现有治疗手段难以取得满意效果。随着对过氧化物酶体增殖物激活受体-γ（PPAR-γ）的深入研究，其在神经炎症、氧化应激、离子通道、线粒体功能、神经保护等方面的作用陆续被发现，并有望成为疼痛预防与治疗新靶点。本文就PPAR-γ在NP中的作用及机制作一综述，以期为NP的临床治疗提供新思路。     

Expression of peroxisome proliferator-activated receptor-gamma in renal ischemia-reperfusion injury

The pathogenesis of ischemia-reperfusion injury is known to involve cytokines and particularly surface adhesion molecules, the expression of which initiates the attachment of inflammatory cells. Peroxisome proliferator-activated receptor (PPAR)-gamma is considered an important immunomodulatory factor as well as a fatty acid regulator. In this study, we researched the expression of PPAR-gamma in renal ischemia-reperfusion injury of the rat. The right kidney was harvested and left renal artery and vein were clamped under laparotomy. The kidney was reperfused after 90 minutes of ischemia, and rats were sacrificed at 0, 1.5, 3, 5, 12, and 24 hours after reperfusion. PPAR-gamma expression was analyzed by immunohistochemical staining using monoclonal antibody. In normal kidney, PPAR-gamma staining was weak on endothelial cells, including mesangial cells. On the other hand, PPAR-gamma staining was weak on interstitial cells and strong on collecting ducts of medulla. From 1.5 to 5 hours after reperfusion, PPAR-gamma staining was strong on endothelial cells, moderate on interstitial cells, and strong on collecting ducts. Twelve hours after reperfusion, PPAR-gamma staining was weak on endothelial cells, moderate on interstitial cells, and strong on collecting ducts. PPAR-gamma is induced on collecting ducts, interstitial cells, and endothelial cells in a rat model having renal ischemia-reperfusion injury.     

Expression of peroxisome proliferator-activated receptor-gamma1 and peroxisome proliferator-activated receptor-gamma2 in visceral and subcutaneous adipose tissue of obese women

Data regarding the expression of peroxisome proliferator-activated receptor (PPAR)-gamma(1) and PPAR-gamma(2) in human visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) are conflicting. To clarify this issue, we studied 50 women who had a BMI >35 kg/m(2) were undergoing gastric reduction surgery. Phenotyping included recording of anthropometric parameters and of a biological profile. Quantification of the expression of PPAR-gamma(1) and PPAR-gamma(2) in samples of VAT and SAT was performed by real-time RT-PCR. In both SAT and VAT, the level of expression of PPAR-gamma(2) were >20-fold that of PPAR-gamma(1) (P < 0.001 for both). However, only PPAR-gamma(1) was differentially expressed, its levels in SAT being 216 +/- 34% those in VAT (P < 0.001). In a stepwise, multivariate regression analysis, the levels of PPAR-gamma(1) in both SAT and VAT were the major determinants of waist circumference (R(2) = 21% for both; P < 0.01). Finally, leptin but not PPARs appeared as the single parameter explaining the largest part of the variability of BMI in our cohort of patients (R(2) = 22%, P < 0.001). These results are consistent with the putative roles of PPAR-gamma(1) and PPAR-gamma(2) in carbohydrate metabolism and energy homeostasis, respectively. As such, they constitute an important step toward the identification of potential targets for novel therapeutic strategies in the fields of obesity.     

Progression of renal failure in the Han: SPRD polycystic kidney rat

The Han: SPRD Pkd rat mutant is an autosomal dominant rat modelwith incomplete penetration of polycystic renal transformation.Progressive renal failure occurs in heterozygous male animals.The mechanisms of progression have not been elucidated. To identifysome pathogenetic factors involved we subjected male SPRD Pkdrats (and their non-affected littermates as controls) to uninephrectomy(UNX), castration or enalapril treatment. To assess progressionS-urea at age 150 days was chosen as endpoint. (i) In uninephrectomizedmale Han: SPRD Pkd (n=12 animals per group) S-urea at age 150days was consistently above 300 mg/dl, while it was 245 mg/dl(191–290) in control Han: SPRD Pkd. (ii) In castratedmale Han: SPRD median S urea at 150 days was 100 mg/dl (69–211)compared to sham-operated male Han: SPRD controls (245; 191–290).Castration did not, however, prevent accelerated progressionafter uninephrectomy. (iii) Enalapril (50 mg/l) in the drinkingfluid did not significantly lower median systolic blood pressure(by plethysmography) in animals on 0.2% sodium diet (at 185days 160 mmHg; 140–170 versus 170; 140–195 in non-enalaprilcontrols), although circulating ACE was significantly inhibited(17 U; 11–33 versus 89; 52–108 in controls). S-ureaat age 185 days was not significantly different in the 2 groups.In conclusion, the Han: SPRD Pkd model differs from human ADPKDto some extent. Uninephrectomy accelerates renal failure inthe rat, but not in humans. On the other hand, in contrast tohuman ADPKD the renin system is suppressed in the rat modeland ACE inhibition does not affect the course of renal failure.     

Potential for peroxisome proliferator-activated receptor-gamma agonists in progression: beyond metabolism

PURPOSE OF REVIEW: The thiazolidinediones are agonists for peroxisome proliferator-activated receptor-gamma, and promote insulin sensitization and improve dyslipidemia in patients with type II diabetes mellitus. Peroxisome proliferator-activated receptor-gamma transduces its actions by binding to common consensus response elements called peroxisome proliferator-activated receptor-response elements, thus modifying expression of numerous genes. Peroxisome proliferator-activated receptor-gamma is widely expressed, including in macrophages and vascular smooth muscle cells. I will review recent novel insights into peroxisome proliferator-activated receptor-gamma agonist actions. RECENT FINDINGS: The thiazolidinediones have beneficial effects in humans with type II diabetes related in part to improvement of dysmetabolic syndrome, and also have beneficial effects on progressive renal damage in animal models of diabetic nephropathy and in models with severe hyperlipidemia. Peroxisome proliferator-activated receptor-gamma agonists also have direct benefits on progressive renal injury independent of altering the dysmetabolic profile. SUMMARY: We will review selected evidence of actions of peroxisome proliferator-activated receptor-gamma agonists beyond metabolism, focusing on experimental work, and examine interactions with other key profibrotic mediators, including transforming growth factor-beta and the renin-angiotensin system.     

Activation of peroxisome proliferator-activated receptor-gamma during hepatic ischemia is age-dependent

Hepatic ischemia/reperfusion injury is a complication of liver surgery, transplantation, and shock and is known to be age-dependent. Our laboratory has recently shown that peroxisome proliferator-activated receptor-gamma (PPARgamma) is down-regulated during hepatic ischemia and that this exacerbates injury. Here we examined whether activation of PPARgamma during ischemia was age-dependent. Male mice of different ages (young: 4-5 weeks; adult: 10-12 weeks; old: 10-12 months) were subjected to up to 90 min of hepatic ischemia. PPARgamma activation occurred throughout ischemia in young mice, whereas activation in adult and old mice was lost after 30 min. No significant differences were noted in PPARgamma ligand expression among the age groups. However, in young mice we observed a predominance of PPARgamma1 in the nucleus, whereas in old mice this isoform remained largely in the cytoplasm. Finally, the degree of PPARgamma activation was associated with autophagy in the liver, a mechanism of self-preservation. PPARgamma activation is prolonged in young mice as compared to older mice. This appears to be mediated by a selective retention of PPARgamma1 in the nucleus and is associated with increased autophagy. The data suggest that PPARgamma activation is an important component of the age-dependent response to hepatic ischemia/reperfusion injury.     

Insulin acutely regulates the expression of the peroxisome proliferator-activated receptor-gamma in human adipocytes

Peroxisome proliferator-activated receptor (PPAR)-gamma is one of the key actors of adipocyte differentiation. This study demonstrates 1) that PPAR-gamma mRNA expression is not altered in subcutaneous adipose tissue (n = 44) or in skeletal muscle (n = 19) of subjects spanning a wide range of BMIs (20-53 kg/m2) and 2) that insulin acutely increases PPAR-gamma mRNA expression in human adipocytes both in vivo and in vitro. The effect of insulin was investigated in abdominal subcutaneous biopsies obtained before and at the end of a 3-h euglycemic-hyperinsulinemic clamp. Insulin significantly increased PPAR-gamma mRNA levels in lean subjects (88 +/- 17%, n = 6), in type 2 diabetic patients (100 +/- 19%, n = 6), and in nondiabetic obese patients (91 +/- 20%, n = 6). Both PPAR-gamma1 and PPAR-gamma2 mRNA variants were increased (P < 0.05) after insulin infusion. In isolated human adipocytes, insulin induced the two PPAR-gamma mRNAs in a dose-dependent manner, with half-maximal stimulation at a concentration of approximately 1-5 nmol/l. However, PPAR-gamma2 mRNA was rapidly (2 h) and transiently increased, whereas a slow and more progressive induction of PPAR-gamma1 was observed during the 6 h of incubation. In explants of human adipose tissue, PPAR-gamma protein levels were significantly increased (42 +/- 3%, P < 0.05) after 12 h of incubation with insulin. These data demonstrate that PPAR-gamma belongs to the list of the insulin-regulated genes and that obesity and type 2 diabetes are not associated with alteration in the expression of this nuclear receptor in adipose tissue.