色素上皮细胞衍生因子在代谢综合征中的研究进展

代谢综合征（MS）是代谢层面的心血管危险因子的聚集现象,主要包括高血压、血脂异常、糖尿病、胰岛素抵抗及腹部肥胖等。近年来MS发病率明显上升并严重危害居民的身体健康。色素上皮细胞衍生因子(PEDF)属丝氨酸蛋白酶抑制基因家族,是由多种细胞表达,具有多种生物学活性的分泌性糖蛋白。近年来多项临床试验提示PEDF参与了MS的发生发展,是一个有希望的疾病治疗靶点。本文就PEDF在MS中的作用综述。     

色素上皮衍生因子与糖尿病视网膜病变

色素上皮衍生因子(PEDF)来源于人视网膜色素上皮细胞,是眼内有效的血管生成抑制剂,对保持正常眼组织透明无血管的状态有重要作用。PEDF能对抗多种促血管生成因子,有针对性地抑制病理性血管生成,延缓糖尿病视网膜病变的进展,发挥保护作用。同时,PEDF在眼部浓度降低可增加糖尿病视网膜病变的危险。其作用机制仍在探索中。外源性应用PEDF及进行基因治疗对眼部血管增生性疾病具有显著疗效。因此,深入研究可能会发现PEDF治疗临床血管增生性疾病更广泛的作用。     

锤头状核酶抑制色素衍生上皮因子对A549细胞活性影响的实验研究

色素衍生上皮因子（PEDF）是体内一种重要的血管抑制因子。在急性或慢性损伤下，PEDF也可以保护和营养多种神经元与雪旺细胞。体外实验也证实PEDF可以通过诱导子宫内膜癌细胞的凋亡而抑制其生长，其抑制作用呈时间与剂量依赖性。     

色素上皮衍生因子在2型糖尿病合并非酒精性脂肪肝病中的作用

<正>伴有非酒精性脂肪肝病(NAFLD)可导致2型糖尿病患者血糖更难控制,并可加速如冠心病和慢性肾脏疾病等糖尿病重要慢性并发症的发展和恶化[1]。色素上皮衍生因子(PEDF)具有抗新生血管形成、抗慢性炎症、抗氧化和营养神经等多种保护性效应[2]。本文就PEDF在2型糖尿病合并非酒精性脂肪肝病中的作用进行综述。     

肝癌组织中PEDF、VEGF的表达及意义

目的探讨色素衍生上皮因子（PEDF）、血管内皮生长因子（VEGF）在肝癌发生、发展中的作用。方法采用免疫组化法检测72份肝癌组织标本中PEDF、VEGF的表达,用CD31标记免疫组化法检测微血管密度（MVD）。结果PEDF、VEGF在肝癌组织中的阳性率分别为41．67％（30／72）、83．33％（60／72）;MVD值PEDF阴性者高于阳性者、VEGF阳性者高于阴性者;PEDF、VEGF表达均与术后复发、肝外转移、临床分期、门静脉癌栓有关;两者表达呈负相关。结论PEDF、VEGF在血管生成过程中具有拮抗作用;PEDF可能通过抑制MVD生成起抑癌作用。     

人色素上皮源性因子基因真核表达载体的构建及在大鼠眼内的表达

目的构建人色素上皮源性因子(PEDF)基因真核表达载体,并观察其在大鼠眼内的表达。方法将PEDF基因克隆到真核表达载体PcDNA3.0中,采用阳离子脂质体包裹pcPEDF,注射到SD大鼠玻璃体腔内。结果测序鉴定、酶切及琼脂糖电泳分析pcPEDF中含有PEDF基因,用免疫组化方法检测证实PEDF在大鼠视网膜神经细胞中表达。结论成功的构建了含有人PEDF基因的真核表达载体,并能持续、稳定地在大鼠视网膜神经细胞中表达。     

色素上皮衍生因子在心血管疾病中的作用

色素上皮衍生因子(PEDF)生物学功能复杂,既往研究证明其在眼部与神经系统的生理稳态和病理过程中扮演重要角色。近年发现PEDF在心血管系统与脂肪组织表达量高,PEDF与代谢综合征、动脉粥样硬化、高血压、心衰与心肌梗死等心血管疾病关系密切但机制尚未完全阐明,它可能在这些疾病的病理过程中发挥重要作用。PEDF有望成为一个新的有效的治疗心血管疾病的靶点和疾病预测分子。     

色素上皮细胞衍生因子原核表达重组体的构建

目的 构建色素上皮细胞衍生因子(PEDF)原核表达重组体。方法 从胚胎绒毛中提取总RNA，经RT-PCR扩增，获得编码人PEDF的全基因序列，采用T-A克隆法，将PEDF基因克隆人pMD18-T载体中并转化人E．coli JM 109，经DNA测序正确后构建原核表达重组体pET28a-PEDF。转化E．coli DH5a。结果 经酶切及DNA测序鉴定，获得了PEDF原核表达重组体pET28a-PEDF。结论 构建了PEDF原核表达重组体pET28a-PEDF，为获得重组PEDF奠定了基础。     

色素上皮衍生因子抑制糖基化终产物介导人肾小球系膜细胞糖基化终产物受体表达的研究

目的 观察色素上皮衍生因子（PEDF）、晚期糖基化终产物受体（RAGE）的表达及重组PEDF对RAGE表达的抑制作用,探讨PEDF与DN的关系及对DN的保护作用. 方法 采用糖化小牛血清白蛋白（AGE-BSA）体外诱导人肾小球系膜细胞（HRMCs）,Western blot及RT-PCR法分别检测RAGE、PEDF蛋白和mRNA表达. 结果 （1） AGE-BSA（100～400 mg/L）呈浓度梯度减少HRMCsPEDF表达（P＜0.01）,升高RAGE表达（P＜0.01）;（2）重组PEDF蛋白（5～40 nmol/L）呈浓度依赖性抑制AGE-BSA介导RAGE蛋白在HRMCs的表达（P＜0.05）. 结论 AGEs通过降低PEDF表达,增加RAGE表达参与DN的发生,PEDF可能通过抑制AGE-RAGE轴对DN发挥保护作用.     

非小细胞肺癌组织中VEGF、PEDF的表达变化及意义

目的 观察非小细胞肺癌组织中血管内皮生长因子（VEGF）与色素上皮衍生因子（PEDF）的表达变化,并探讨其意义.方法 采用免疫组化法对50例非小细胞肺癌组织中的VEGF、PEDF进行检测,以CD31标记免疫组化法检测微血管密度（MVD）.结果 VEGF、PEDF在肺癌组织中的阳性表达率分别为64%、44%,二者的表达呈负相关（r=-0.599,P＜0.01）.MVD值在PEDF阴性组高于阳性组（P＜0.05）,在VEGF阳性组则高于阴性组（P＜0.05）.VEGF和PEDF的表达与肺癌远处转移、分化程度、临床分期有关（P均＜0.05）.结论 在非小细胞肺癌组织中VEGF、PEDF的表达有相关性,且与MVD关系密切,PEDF可能通过抑制MVD生成而起抑癌作用;检测VEGF和PEDF有助于肺癌远处转移、分化程度、临床分期的判断.     

Antiangiogenic property of pigment epithelium-derived factor in hepatocellular carcinoma

Pigment epithelium-derived factor (PEDF) is one of the most powerful endogenous antiangiogenic reagents discovered to date. Its antiangiogenic potential in neoplastic disease remains unclear. In this study, we investigated antiangiogenic property of PEDF in hepatocellular carcinoma (HCC), a typical hypervascular tumor. In HCC cell lines, constitutive messenger RNA and protein expression of PEDF varied. Genomic DNA encoding the PEDF gene was the same in the cell lines examined by Southern blotting. In chemically induced hypoxic conditions, secreted PEDF protein was suppressed in contrast to elevation of vascular endothelial growth factor protein. When PEDF was overexpressed by gene transfer, proliferation and migration of endothelial cells were inhibited in conditioned media derived from all HCC cell lines. However, the serum concentration of PEDF, as measured by enzyme-linked immunosorbent assay, was decreased in patients with cirrhosis or HCC complicated by cirrhosis compared to healthy volunteers and patients with chronic hepatitis. According to the endothelial cell proliferation assay, the serum PEDF of patients with HCC had antiangiogenic activity. Moreover, intratumoral injection of a PEDF-expressing plasmid in athymic mouse models caused significant inhibition of preestablished tumor growth. In conclusion, PEDF plays a role in the angiogenic properties of HCC. Reduction of serum PEDF concentration associated with the development of chronic liver diseases may contribute to the progression of HCC. In addition, gene therapy using PEDF may provide an efficient treatment for HCC.     

Variable phosphorylation states of pigment-epithelium-derived factor differentially regulate its function

The pigment epithelium-derived factor (PEDF) belongs to the family of noninhibitory serpins. Although originally identified in the eye, PEDF is widely expressed in other body regions including the plasma. This factor can act either as a neurotrophic or as an antiangiogenic factor, and we previously showed that the 2 effects of PEDF are regulated through phosphorylation by PKA and CK2. Here, we studied the interplay between the PKA and CK2 phosphorylation of PEDF, and found that a PEDF mutant mimicking the CK2-phosphorylated PEDF cannot be phosphorylated by PKA, while the mutant mimicking the PKA-phosphorylated PEDF is a good CK2 substrate. Using triple mutants that mimic the PKA- and CK2-phosphorylated and nonphosphorylated PEDF, we found that PEDF can induce several distinct cellular activities dependent on its phosphorylation. The mutant mimicking the accumulative PKA plus CK2 phosphorylation exhibited the strongest antiangiogenic and neurotrophic activities, while the mutants mimicking the individual phosphorylation site mutants had either a reduced activity or only one of these activities. Thus, differential phosphorylation induces variable effects of PEDF, and therefore contributes to the complexity of PEDF action. It is likely that the triple phosphomimetic mutant can be used to generate effective antiangiogenic or neurotrophic drugs.     

Plasma concentration of pigment epithelium-derived factor in patients with diabetic retinopathy

CONTEXT: Pigment epithelium-derived factor (PEDF) is a strong inhibitor of angiogenesis. Eyes with diabetic retinopathy have low levels of ocular PEDF; however, the PEDF levels in the blood of diabetics have still not been determined. OBJECTIVES: Our objective was to determine the plasma levels of PEDF in diabetic patients and to determine the relationship with the stage of the diabetic retinopathy. DESIGN AND SETTING: This study was designed as a cross-sectional, institutional study. PATIENTS OR OTHER PARTICIPANTS: A total of 145 Japanese were studied; 112 had type 2 diabetes mellitus, and 33 were healthy controls. INTERVENTION: There was no intervention. MAIN OUTCOME MEASURES: The plasma level of PEDF was measured by ELISA, and the stage of diabetic retinopathy was determined by ophthalmic examinations. Clinical systemic status of diabetic patients was also examined. RESULTS: The plasma PEDF level in diabetic patients (6.68 +/- 0.54 microg/ml; mean +/- sem) was significantly higher than that in controls (4.38 +/- 0.59 microg/ml, P = 0.03), and the level was especially high in patients with proliferative diabetic retinopathy (7.78 +/- 0.98 microg/ml; n = 45; P = 0.005). The gender (P = 0.03), blood urea nitrogen (P = 0.005), and triglycerides (P = 0.04) were significant and independent determinants of plasma PEDF levels in diabetic patients. CONCLUSIONS: The PEDF level in the plasma was significantly elevated in diabetic patients, especially those with proliferative diabetic retinopathy. High levels of PEDF in the plasma may be related to the progression of diabetic retinopathy.     

Anti-angiogenic pigment epithelium-derived factor regulates hepatocyte triglyceride content through adipose triglyceride lipase (ATGL)

BACKGROUND/AIMS: Anti-angiogenic pigment epithelium-derived factor (PEDF) is a 50 kDa secreted glycoprotein that is highly expressed in hepatocytes. Adipose triglyceride lipase (ATGL), a novel lipase critical for triglyceride metabolism, is a receptor for PEDF. We postulated that hepatocyte triglyceride metabolism was dependent on interactions between PEDF and ATGL, and loss of PEDF would impair mobilization of triglycerides in the liver. METHODS: Immunoprecipitation studies were performed in PEDF null and control hepatocytes with recombinant PEDF (rPEDF) as bait. Immunofluorescent microscopy was used to localize ATGL. Triglyceride content was analyzed in hepatocytes and in whole liver with and without rPEDF. ATGL was blocked using an inhibitor, (R)-bromoenol lactone. RESULTS: PEDF co-immunoprecipitated with ATGL in hepatic and HCC lysates. All PEDF deficient livers demonstrated steatosis. Triglyceride content was significantly increased in PEDF null livers compared to wildtype (p<0.05) and in isolated hepatocytes (p<0.01). Treatment of PEDF null hepatocytes with rPEDF decreased TG content (p<0.05) and this activity was dependent on ATGL. CONCLUSIONS: Our results identify a novel role for PEDF in hepatic triglyceride homeostasis through binding to ATGL and demonstrate that rPEDF and ATGL localize to adiposomes in hepatocytes. Dysregulation of this pathway may be one mechanism underlying fatty liver disease.     

Pigment epithelium-derived factor inhibits oxidative stress-induced apoptosis and dysfunction of cultured retinal pericytes

Pigment epithelium-derived factor (PEDF) is a potent inhibitor of angiogenesis in the mammalian eye, suggesting that loss of PEDF is implicated in the pathogenesis of proliferative diabetic retinopathy. However, a role for PEDF in early diabetic retinopathy remains to be elucidated. Since oxidative stress is thought to be involved in pericyte loss and dysfunction, one of the changes characteristic of early diabetic retinopathy, we investigated whether and how PEDF could protect cultured retinal pericyte against oxidative stress injury. High glucose (30 mM) increased intracellular reactive oxygen species (ROS) generation in pericytes, which was completely blocked by PEDF. High glucose or H2O2 was found to induce growth retardation and apoptotic cell death of pericytes. PEDF completely restored these cytopathic effects on pericytes. An increased ratio of bax to bcl-2 mRNA level with subsequent activation of caspase-3 was observed in high-glucose- or H2O2-exposed pericytes, which was also completely prevented by PEDF. PEDF significantly increased glutathione peroxidase (GPx) mRNA levels and activity in pericytes. Further, PEDF was found to completely inhibit high-glucose- or H2O2-induced increase in a mRNA ratio of angiopoietin-2 to angiopoietin-1 and up-regulation of VEGF mRNA levels in pericytes. PEDF mRNA levels themselves were down-regulated in high-glucose- or H2O2-exposed pericytes. These results demonstrate that PEDF protects against high-glucose- or H2O2-induced pericyte apoptosis and dysfunction through its anti-oxidative properties via GPx induction. Our present study suggests that substitution of PEDF proteins might be a promising therapeutic strategy for treatment of patients with early diabetic retinopathy.     

Pigment epithelium-derived factor in idiopathic pulmonary fibrosis: a role in aberrant angiogenesis

Pigment epithelium-derived factor (PEDF) is a 50-kD protein with angiostatic and neurotrophic activities that regulates vascular development within the eye. PEDF expression was increased in the lungs of patients with idiopathic pulmonary fibrosis (IPF) based on microarray analyses. Angiogenesis has been implicated in the pathogenesis of fibrotic lung diseases, we therefore hypothesized that regional abnormalities in vascularization occur in IPF as a result of an imbalance between PEDF and vascular endothelial growth factor. We demonstrated that vascular density is regionally decreased in IPF within the fibroblastic foci, and that within these areas PEDF was increased, whereas vascular endothelial growth factor was decreased. PEDF colocalized with the fibrogenic cytokine, transforming growth factor (TGF)-beta 1, particularly within the fibrotic interstitium and the fibroblastic focus, and prominently within the epithelium directly overlying the fibroblastic focus. This suggested that TGF-beta 1 might regulate PEDF expression. Using 3T3-L1 fibroblasts and human lung fibroblasts, we showed that PEDF was indeed a TGF-beta 1 target gene. Collectively, our findings implicate PEDF as a regulator of pulmonary angiogenesis and an important mediator in IPF.     

Lack of Circulating Pigment Epithelium-Derived Factor Is a Marker of Osteogenesis Imperfecta Type VI

Background: Osteogenesis imperfecta (OI) type VI is a rare autosomal recessive bone fragility disorder that is caused by inactivating mutations in SERPINF1, the gene that encodes pigment-epithelium derived factor (PEDF). Determining PEDF serum levels might facilitate the diagnosis of OI type VI. Objective: The objective of the study was to assess whether lack of circulating PEDF is a specific marker of OI type VI and to evaluate whether PEDF serum levels are influenced by other metabolic bone diseases. Materials and Methods: Serum PEDF concentrations were measured in 12 patients with OI type VI (aged 2.7-31 yr) as well as in 96 children and adolescents with OI types I, III, and IV; in 26 young patients with hypophosphatemic rickets; and in 19 healthy controls. Results: Circulating PEDF was undetectable in all 12 patients with OI type VI but was measurable for the other 141 study participants. No significant differences in serum PEDF concentrations were found between the diagnostic groups other than OI type VI. Treatment with bisphosphonates (in OI types I, III, and IV) and with phosphate and calcitriol (in hypophosphatemic rickets) did not have a detectable influence on serum PEDF. In patients with OI types I, III, and IV, serum creatinine, body mass index z-score, and OI severity were significant predictors of PEDF serum levels. Conclusion: Determining PEDF serum concentration helps to diagnose OI type VI but does not seem to provide information on the activity of bone turnover or mineralization.