Administration of pigment epithelium-derived factor inhibits left ventricular remodeling and improves cardiac function in rats with acute myocardial infarction.

Oxidative stress and inflammation are involved in cardiac remodeling after acute myocardial infarction (AMI). We have found that pigment epithelium-derived factor (PEDF) inhibits vascular inflammation through its anti-oxidative properties. However, effects of PEDF on cardiac remodeling after AMI remain unknown. We investigated whether PEDF could inhibit left ventricular remodeling and improve cardiac function in rats with AMI. AMI was induced in 8-week-old Sprague-Dawley rats by ligation of the left ascending coronary artery. Rats were treated intravenously with vehicle or 10 µg PEDF/100 g b.wt. every day for up to 2 weeks after AMI. Each rat was followed until 16 weeks of age. PEDF levels in infarcted areas and serum were significantly decreased at 1 week after AMI and remained low during the observational periods. PEDF administration inhibited apoptotic cell death and oxidative stress generation around the infarcted areas at 2 and 8 weeks after AMI. Further, PEDF injection suppressed cardiac fibrosis by reducing transforming growth factor-ß and type III collagen expression, improved left ventricular ejection fraction, ameliorated diastolic dysfunction, and inhibited the increase in left ventricular mass index at 8 weeks after AMI. The present study demonstrated that PEDF could inhibit tissue remodeling and improve cardiac function in AMI rats. Substitution of PEDF may be a novel therapeutic strategy for cardiac remodeling after AMI.

Protective role of pigment epithelium-derived factor (PEDF) in early phase of experimental diabetic retinopathy.

BACKGROUND: Pigment epithelium-derived factor (PEDF) is the most potent inhibitor of angiogenesis in the mammalian eye, thus suggesting that PEDF may protect against proliferative diabetic retinopathy. However, a role for PEDF in early diabetic retinopathy remains to be elucidated. We investigated here whether and how PEDF could prevent the development of diabetic retinopathy. METHODS: Streptozotocin-induced diabetic rats were treated with or without intravenous injection of PEDF for 4 weeks. Early neuronal derangements were evaluated by electroretinogram (ERG) and immunofluorescent staining of glial fibrillary acidic protein (GFAP). Expression of PEDF and 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative stress, was localized by immunofluorescence. Vascular endothelial growth factor (VEGF) and p22phox expression were evaluated with western blots. Breakdown of blood retinal barrier (BRB) was quantified with fluorescein isothiocynate (FITC)-conjugated dextran. NADPH oxidase activity was measured with lucigenin luminescence. RESULTS: Retinal PEDF levels were reduced, and amplitudes of a- and b-wave in the ERG were decreased in diabetic rats, which were in parallel with GFAP overexpression in the Müller cells. Further, retinal 8-OHdG, p22phox and VEGF levels and NADPH oxidase activity were increased, and BRB was broken in diabetic rats. Administration of PEDF ameliorated all of the characteristic changes in early diabetic retinopathy. CONCLUSIONS: Results suggest that PEDF could prevent neuronal derangements and vascular hyperpermeability in early diabetic retinopathy via inhibition of NADPH oxidase-driven oxidative stress generation. Substitution of PEDF may offer a promising strategy for halting the development of diabetic retinopathy.

Administration of pigment epithelium-derived factor (PEDF) inhibits cold injury-induced brain edema in mice.

Brain edema is the most life-threatening complication that occurs as a result of a number of insults to the brain. However, its therapeutic options are insufficiently effective. We have recently found that administration of pigment epithelium-derived factor (PEDF) inhibits retinal hyperpermeability in rats by counteracting biological effects of vascular endothelial growth factor (VEGF). In this study, we investigated whether PEDF could inhibit cold injury-induced brain edema in mice. Cold injury was induced by applying a pre-cooled metal probe on the parietal skull. VEGF and its receptor Flk-1 gene and/or protein expressions were up-regulated in the cold-injured brain. Cold injury induced brain edema, which was reduced by intraperitoneal injection of VEGF antibodies (Abs) or apocynin, an inhibitor of NADPH oxidase. PEDF mRNA and protein levels were up-regulated in response to cold injury. PEDF dose-dependently inhibited the brain edema, whose effect was neutralized by simultaneous treatments with anti-PEDF Abs. Although VEGF and Flk-1 gene and/or protein expressions were not suppressed by PEDF, PEDF or anti-VEGF Abs inhibited the cold injury-induced NADPH oxidase activity in the brain. Further, PEDF treatment inhibited activation of Rac-1, an essential component of NADPH oxidase in the cold-injured brain, while it did not affect mRNA levels of gp91phox, p22phox, or Rac-1. These results demonstrate that PEDF could inhibit the cold injury-induced brain edema by blocking the VEGF signaling to hyperpermeability through the suppression of NADPH oxidase via inhibition of Rac-1 activation. Our present study suggests that PEDF may be a novel therapeutic agent for the treatment of brain edema.

Elevated serum levels of pigment epithelium-derived factor in the metabolic syndrome.

CONTEXT: Pigment epithelium-derived factor (PEDF), a potent inhibitor of angiogenesis with neuronal differentiating activity, inhibits endothelial cell injury in vitro, thus suggesting the involvement of PEDF in atherosclerosis. Therefore, elucidating the relationship between serum levels of PEDF and coronary risk factors could provide a clue to understanding the pathophysiological role of PEDF in vivo. OBJECTIVE: We examined whether serum levels of PEDF were associated with risk factors for coronary artery disease. DESIGN: The study was designed as a cross-sectional study. SETTING: The study was set within the general community. PATIENTS OR OTHER PARTICIPANTS: A total of 196 general Japanese residents (age 65.7 +/- 9.3 yr; 71 males and 125 females) without clinical evidence of coronary or peripheral arterial occlusive diseases were enrolled in this study. RESULTS: PEDF showed a normal distribution, ranging from 8-24 microg/ml, with a mean of 14.6 +/- 3.2 microg/ml. Multivariate analyses revealed that uric acid (P < 0.001), waist circumference (P = 0.009), insulin (P = 0.019), and triglycerides (P = 0.028) were significant independent determinants of serum PEDF levels. Age- and uric acid-adjusted PEDF levels were significantly higher (P = 0.048 for men and P = 0.007 for women) in proportion to the accumulation of the number of the components of the metabolic syndrome. CONCLUSIONS: The present study reveals that serum levels of PEDF are strongly associated with the metabolic syndrome. Our results suggest that serum PEDF levels may be elevated as a counter-system in the metabolic syndrome.

Cardiovascular disease in diabetes.

Diabetes is associated with a marked increase in the risk of atherosclerotic vascular disorders, including coronary, cerebrovascular, and peripheral artery disease. Cardiovascular disease (CVD) could account for disabilities and high mortality rates in patients with diabetes. In this paper, we review the molecular mechanisms for accelerated atherosclerosis in diabetes, especially focusing on postprandial hyperglycemia, advanced glycation end products (AGEs) and the renin-angiotensin system. We also discuss here the potential therapeutic strategy that specifically targets CVD in patients with diabetes.

Positive association between serum levels of advanced glycation end products and the soluble form of receptor for advanced glycation end products in nondiabetic subjects.

The advanced glycation end products (AGEs)-receptor for AGE (RAGE) axis is implicated in diabetic vascular complications. Administration of soluble form of RAGE (sRAGE) to mice has been shown to block the AGE-elicited tissue damage by acting as a decoy. These observations suggest that endogenous sRAGE may capture and eliminate circulating AGEs and decrease its serum levels. However, because AGEs up-regulate tissue RAGE expression and endogenous sRAGE could be generated from the cleavage of cell surface RAGE, sRAGE may be positively, rather than inversely, associated with circulating AGEs by reflecting tissue RAGE expression. In this study, we investigated the association of sRAGE with serum levels of AGEs in humans. Data for fasting serum sRAGE and AGE levels of 184 nondiabetic subjects were obtained from a general population in Japan. We also measured body mass index (BMI), waist circumference, blood pressure, and blood biochemistries in this population. Uni- and multivariate analyses were applied for the determinants of serum sRAGE levels. The average sRAGE levels were 0.40 +/- 0.17 ng/mL in males and 0.43 +/- 0.14 ng/mL in females, respectively. In the univariate analysis, BMI (P < .05, inversely), waist circumference (P < .05, inversely), AGEs (P < .05), and alcohol intake (P < .05, inversely) were significantly associated with sRAGE levels. After performing multivariate analyses, BMI (P < .05, inversely) and AGEs (P < .05) still remained significant independently. The present study is the first demonstration that serum sRAGE levels were positively associated with circulating AGEs in the nondiabetic general population. Endogenous sRAGE levels are elevated in parallel with serum AGE levels.

Pigment epithelium-derived factor (PEDF)-induced apoptosis and inhibition of vascular endothelial growth factor (VEGF) expression in MG63 human osteosarcoma cells.

Pigment epithelium-derived factor (PEDF) has been shown to be the most potent inhibitor of angiogenesis in the mammalian eye, thus suggesting that loss of PEDF is involved in angiogenic eye diseases such as proliferative diabetic retinopathy. Angiogenesis is required for tumor growth and progression as well. We, along with others, have recently found that PEDF could inhibit growth of melanoma and hepatocellular carcinoma in nude mice through its anti-angiogenic effects on tumor endothelial cells. However, the possibility of the direct effect of PEDF on tumor cells has remained. In this study, we investigated the effects of PEDF on growth and vascular endothelial growth factor (VEGF) expression in MG63 human cultured osteosarcoma cells. PEDF decreased viable cell number as well as DNA synthesis in MG63 cells in a dose-dependent manner. Furthermore, PEDF was found to increase caspase-3/7 activity and to subsequently induce apoptotic cell death in MG63 cells. PEDF also inhibited VEGF expression in MG63 cells at both mRNA and protein levels. Our present study provides novel beneficial aspects of PEDF on osteosarcoma cells; one is induction of apoptotic cell death of tumor cells, and the other is the suppression of VEGF expression, which would lead to inhibition of tumor angiogenesis. PEDF therefore might be a promising therapeutic agent for treatment of patients with osteosarcoma.

Serum levels of advanced glycation end products (AGEs) are inversely associated with the number and migratory activity of circulating endothelial progenitor cells in apparently healthy subjects.

OBJECTIVES: Endothelial progenitor cells (EPCs) have been shown to participate in the process of vascular repair, thus playing a protective role against cardiovascular disease (CVD). It is known that atherosclerotic risk factors could affect EPC number and function. Advanced glycation end products (AGEs) contribute to the pathogenesis of atherosclerosis as well. However, as far as we know, there is no report to show the relationship between serum AGE levels and circulating EPCs in humans. Therefore, in this study, we investigated whether serum level of AGEs was associated with EPC number and functions in apparently healthy subjects, independent of traditional cardiovascular risk factors. RESEARCH DESIGN AND METHODS: Apparently healthy volunteers (34.6 ± 6.9 years old, 40 males and 8 females) who were not on any medications underwent a complete history and physical examination, determination of blood chemistries, including AGEs, and number, differentiation and migratory activity of circulating EPCs. RESULTS: Serum AGEs levels were 9.20 ± 1.85 U/mL. Multiple stepwise regression analysis revealed that serum levels of AGEs and smoking were independently correlated with reduced number of EPCs. Further, female, AGEs, and reduced HDL-cholesterol levels were independently associated with impaired migratory activity of circulating EPCs. CONCLUSIONS: This study demonstrated for the first time that the serum level of AGEs was one of the independent correlates of decreased cell number and impaired migratory activity of circulating EPCs in apparently healthy subjects. Our present observations suggest that even in young healthy subjects, serum level of AGEs may be a biomarker that could predict the progression of atherosclerosis and future cardiovascular events.

The p66shc gene expression in peripheral blood monocytes is increased in patients with coronary artery disease.

BACKGROUND: The p66(shc) protein has been shown to control cellular responses to oxidative stress, being involved in atherosclerosis in animal models. However, the relationship between the p66(shc) gene expression levels and coronary artery disease (CAD) in humans remains unknown. In this study, we examined whether the p66(shc) gene expression in peripheral blood monocytes (PBMs) was increased in patients with CAD, compared with age- and sex-matched subjects without CAD. HYPOTHESIS: We hypothesize that the p66(shc) gene expression level in PBMs is increased in patients with CAD. METHODS: Forty consecutive Japanese subjects who underwent coronary angiography for suspected CAD were enrolled in this study. The p66(shc) gene expression levels in PBMs were quantitatively measured by real-time reverse transcription-polymerase chain reactions. Uni- and multivariate analyses were applied for the correlates of CAD. CAD was diagnosed if there was > 75% obstruction of at least 1 major coronary artery or a history of percutaneous coronary intervention. RESULTS: There were no significant differences of blood chemistries and clinical characteristics between the patients with and without CAD, except the number of subjects who were on hypertension medication. The p66(shc) gene expression levels in PBMs were significantly higher in CAD patients compared with non-CAD subjects. Multiple stepwise regression analysis revealed that the p66(shc) gene expression levels and hypertension medication were independently related to CAD (R(2)=0.287). Further, the p66(shc) gene expres- sion levels were significantly increased (P < 0.05) in proportion to the number of diseased vessels. CONCLUSIONS: The present study is the first demonstration that increased the p66(shc) gene expression in PBMs is independently associated with CAD in Japanese subjects. The p66(shc) gene expression level in PBMs may be a novel biomarker of CAD in humans.

Pigment epithelium-derived factor (PEDF) administration inhibits occlusive thrombus formation in rats: a possible participation of reduced intraplatelet PEDF in thrombosis of acute coronary syndromes.

OBJECTIVES: Although remarkable therapeutic advances in the treatment of acute coronary syndromes (ACS) have been made with anti-platelet therapy, the therapeutic options may be limited by considerable side effects. Pigment epithelium-derived factor (PEDF) has anti-oxidative properties and may play a protective role against atherosclerosis. In this study, we investigated whether PEDF prevented occlusive thrombus formation in rats. METHODS AND RESULTS: Occlusive thrombus formation was induced by treating rats with ligation and cuff placement at the left common carotid artery. Intravenous injection of PEDF dose-dependently inhibited thrombus formation and blocked the increase in immunoreactivity of P-selectin, a marker of platelet activation, NADPH oxidase activity and superoxide generation in thrombi. In vitro, PEDF significantly decreased collagen-induced reactive oxygen species generation in platelets and subsequently suppressed the platelet activation and aggregation. Plasma and intraplatelet levels of PEDF in the coronary circulation in patients with ACS were significantly lower than those in age- and gender-matched controls without coronary artery disease. CONCLUSIONS: These results demonstrated that PEDF administration could inhibit occlusive thrombus formation by blocking the platelet activation and aggregation through its anti-oxidative properties. Our present study suggests that pharmacological up-regulation or substitution of PEDF may offer a promising strategy for the treatment of arterial thrombosis.

Pigment epithelium-derived factor inhibits neointimal hyperplasia after vascular injury by blocking NADPH oxidase-mediated reactive oxygen species generation.

Pigment epithelium-derived factor (PEDF) inhibits cytokine-induced endothelial cell activation through its antioxidative properties. However, the effect of PEDF on restenosis remains to be elucidated. Because the pathophysiological feature of restenosis is characterized by increased superoxide formation and accumulation of smooth muscle cells (SMCs), PEDF may inhibit this process via suppression of reactive oxygen species generation. We investigated here whether PEDF could prevent neointimal formation after balloon injury. PEDF levels were decreased in balloon-injured arteries. Adenoviral vector encoding human PEDF (Ad-PEDF) prevented neointimal formation. Expression and superoxide generation of the membrane components of NADPH oxidase, p22(phox) and gp91(phox), in the neointima were also suppressed by Ad-PEDF. Ad-PEDF reduced G(1) cyclin (cyclin D1 and E) expression and increased p27, a cyclin-dependent kinase inhibitor. In vitro, PEDF inhibited platelet-derived growth factor-BB-induced SMC proliferation and migration by blocking reactive oxygen species generation through suppression of NADPH oxidase activity via down-regulation of p22(PHOX) and gp91(PHOX). PEDF down-regulated G(1) cyclins and up-regulated p27 levels in platelet-derived growth factor-BB-exposed SMCs as well. These results demonstrate that PEDF could inhibit neointimal formation via suppression of NADPH oxidase-mediated reactive oxygen species generation. Our present study suggests that substitution of PEDF may be a novel therapeutic strategy for restenosis after balloon angioplasty.

Elevated circulating oxidized LDL levels in Japanese subjects with the metabolic syndrome.

In the present study, we examined the relationship between circulating oxidized low-density lipoprotein (LDL) and the metabolic syndrome in Japanese patients. Subjects who had no histories of coronary or peripheral artery disease and were taking no medications (n=119; age 57+/-10 years; male/female, 90:29) underwent a complete history and physical examination, determination of blood chemistries and oxidized LDL levels. In stepwise regression analysis, triglycerides (p=0.0001) and HDL-cholesterol (p=0.0493, inversely) were independently correlated to oxidized LDL levels. Furthermore, a significant association (p<0.0001) was found between circulating oxidized LDL levels and the accumulation of the number of the components of the metabolic syndrome. Oxidized LDL levels were one of the independent determinants of intima-media thickness of the common carotid artery, a surrogate marker of atherosclerosis. The present study reveals that circulating oxidized LDL levels are strongly associated with the metabolic syndrome. Our results suggest that elevation of oxidized LDL may be a possible molecular link between accelerated atherosclerosis and the metabolic syndrome in Japanese subjects.

Pigment epithelium-derived factor inhibits advanced glycation end product-induced retinal vascular hyperpermeability by blocking reactive oxygen species-mediated vascular endothelial growth factor expression.

Pigment epithelium-derived factor (PEDF) is the most potent inhibitor of angiogenesis, suggesting that loss of PEDF contributes to proliferative diabetic retinopathy. However, the role of PEDF against retinal vascular hyperpermeability remains to be elucidated. We investigated here whether and how PEDF could inhibit the advanced glycation end product (AGE) signaling to vascular hyperpermeability. Intravenous administration of AGEs to normal rats not only increased retinal vascular permeability by stimulating vascular endothelial growth factor (VEGF) expression but also decreased retinal PEDF levels. Simultaneous treatments with PEDF inhibited the AGE-elicited VEGF-mediated permeability by down-regulating mRNA levels of p22(phox) and gp91(phox), membrane components of NADPH oxidase, and subsequently decreasing retinal levels of an oxidative stress marker, 8-hydroxydeoxyguanosine. PEDF also inhibited the AGE-induced vascular hyperpermeability evaluated by transendothelial electrical resistance by suppressing VEGF expression. Furthermore, PEDF decreased reactive oxygen species (ROS) generation in AGE-exposed endothelial cells by suppressing NADPH oxidase activity via down-regulation of mRNA levels of p22(PHOX) and gp91(PHOX). This led to blockade of the AGE-elicited Ras activation and NF-kappaB-dependent VEGF gene induction in endothelial cells. These results indicate that the central mechanism for PEDF inhibition of the AGE signaling to vascular permeability is by suppression of NADPH oxidase-mediated ROS generation and subsequent VEGF expression. Substitution of PEDF may offer a promising strategy for halting the development of diabetic retinopathy.

Telmisartan inhibits expression of a receptor for advanced glycation end products (RAGE) in angiotensin-II-exposed endothelial cells and decreases serum levels of soluble RAGE in patients with essential hypertension.

There is a growing body of evidence that the advanced glycation end product (AGE)-their receptor (RAGE) system plays a central role in the pathogenesis of diabetic vascular complication. The renin-angiotensin system (RAS) contributes to the development and progression of diabetic angiopathy as well. However, the cross-talk between the AGE-RAGE system and the RAS is not fully understood. In this study, we examined the role of angiotensin II (Ang II) type 1 receptor system for RAGE expression in cultured endothelial cells (ECs) and in patients with essential hypertension. Ang II up-regulated RAGE mRNA levels of microvascular ECs and subsequently increased the soluble form of RAGE (sRAGE) expression in the medium of ECs, both of which were completely blocked by telmisartan, a commercially available Ang II type 1 receptor antagonist. Furthermore, telmisartan was found to decrease serum levels of sRAGE in patients with essential hypertension. These results demonstrate that sRAGE is released from the cell surface of Ang-II-exposed ECs. Our present study indicates that a cross-talk exists between the AGE-RAGE system and the RAS and suggests that serum levels of sRAGE may reflect endothelial RAGE expression.

Pigment epithelium-derived factor (PEDF) promotes growth of pericytes through autocrine production of platelet-derived growth factor-B.

Microvessels are composed of two types of cells, endothelial cells and pericytes. Pericyte loss or dysfunction participates in various types of disorders, including diabetic retinopathy. Recently, decreased levels of pigment epithelium-derived factor (PEDF) in the eye have been found to predict progression of diabetic retinopathy. However, the effect of PEDF on pericyte growth remains to be unknown. In this study, we investigated whether or how PEDF could stimulate proliferation of cultured retinal pericytes. PEDF stimulated DNA synthesis in pericytes in a dose-dependent manner. PEDF up-regulated pericyte mRNA levels of platelet-derived growth factor-B (PDGF-B). Down-regulation of PDGF-B gene expression by small interfering RNAs completely inhibited the PEDF-induced DNA synthesis in pericytes. Furthermore, PEDF increased protein kinase C (PKC) activity in pericytes and staurosporine, a potent cell-permeable inhibitor of PKC, completely blocked the PDGF-B gene induction and subsequent increase in DNA synthesis in PEDF-exposed pericytes. These results demonstrate that PEDF promotes the growth of cultured pericytes possibly through autocrine production of PDGF-B via PKC activation. Our present study suggests that PEDF could act as a mitogen or survival factor for pericytes, thereby being involved in the maintenance of retinal microvascular homeostasis.