Yuko Jinnouchi

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 p22phox and gp91phox, 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 p22PHOX and gp91PHOX. This led to blockade of the AGE-elicited Ras activation and NF-κB-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.

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

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.

Atorvastatin decreases serum levels of advanced glycation end products (AGEs) in patients with type 2 diabetes

Lipid-lowering agents, statins and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors have recently been shown to reduce the risk for cardiovascular events in diabetic patients [1]. Indeed, the Collaborative Atorvastatin Diabetes Study (CARDS), a multicentre randomised placebo-controlled trial, revealed that atorvastatin prevented first cardiovascular events including stroke in patients with type 2 diabetes without high low-density lipoprotein (LDL)-cholesterol levels [1]. Intensive therapy with atorvastatin is associated with an early clinical benefit in patients with acute coronary syndrome [2]. In addition, statin treatment is also associated with a lower risk of cardiovascular events than placebo treatment, even in overlap groups where patients exhibited equivalent LDL-cholesterol levels [3]. These observations support the concept that beyond the lipid-lowering effects of statin, that is, pleiotropic effects, it could contribute at least in part to cardiovascular event reduction. Reducing sugars can react non-enzymatically with amino groups of protein to form Amadori products. These early glycation products undergo further complex reaction such as rearrangement, dehydration and condensation to become irreversibly cross-linked, heterogeneous fluorescent derivatives, termed advanced glycation end products (AGEs) [4]. The formation and accumulation of AGEs have been known to progress at an accelerated rate in diabetes. Recent understanding of this process has revealed the putative involvement of AGEs in accelerated atherosclerosis in diabetes, thus suggesting that the inhibition of AGE formation may be a promising target for therapeutic intervention in atherosclerotic cardiovascular disease in these patients [4, 5]. However, the effect of statin on serum AGE levels remains to be elucidated. In this study, we investigated whether atorvastatin could decrease serum levels of AGEs in patients with type 2 diabetes. The study protocol was approved by our institutional ethics committee and written informed consent was obtained from all patients. Sixteen hypercholesterolaemic type 2 diabetic patients (mean age of 63.6±2.1 years, 8 males and 8 females) without any cardiovascular disease who were previously untreated with statins were enrolled for the present study. The patients were treated with 10 mg atorvastatin once daily for 4 weeks. Nine ageand sexmatched hypercholesterolaemic diabetic patients (4 males and 5 females, mean age of 62.4±3.4 years) who were treated with diet therapy only for 4 weeks served as control subjects. Blood pressure, serum AGE levels, serum 8hydroxydeoxyguanosine (8-OHdG), an oxidative stress marker, and other biochemistries were measured before and after the treatment of atorvastatin. Blood samples were obtained after a 12-h overnight fasting. Serum levels of AGEs were measured with ELISA as described previously Clin Exp Med (2006) 6:191–193 DOI 10.1007/s10238-006-0115-6

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.

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-β 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.

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.

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.

Pigment epithelium-derived factor inhibits vascular endothelial growth factor-induced vascular hyperpermeability both in vitro and in vivo.

Administration of pigment epithelium-derived factor (PEDF) inhibits advanced glycation end products-elicited retinal vascular hyperpermeability, as well as cold injury-induced brain oedema in rats. However, the underlying molecular mechanism by which PEDF blocks the hyperpermeability in vivo is not fully understood. This study investigated whether PEDF could inhibit vascular endothelial growth factor (VEGF)-induced vascular hyperpermeability both in vitro and in vivo. The Miles assay revealed that, after intradermal injection of VEGF in nude mice, simultaneous administration of PEDF inhibited vascular hyperpermeability in a dose-dependent manner. The in vitro permeability assay also showed that PEDF blocked the VEGF-induced barrier dysfunction in endothelial cells. These results demonstrated that PEDF could inhibit the VEGF-induced vascular hyperpermeability both in vitro and in vivo, and suggest that PEGF may be suitable to be considered as a novel therapeutic agent for various vasopermeable disorders in which VEGF is involved.

The p66shc Gene Expression in Peripheral Blood Monocytes Is Increased in Patients With Coronary Artery Disease

The p66shc protein has been shown to control cellular responses to oxidative stress, being involved in atherosclerosis in animal models. However, the relationship between the p66shc gene expression levels and coronary artery disease (CAD) in humans remains unknown. In this study, we examined whether the p66shc gene expression in peripheral blood monocytes (PBMs) was increased in patients with CAD, compared with age‐ and sex‐matched subjects without CAD.

Signal Transduction Therapy of Diabetic Vascular Complication

Diabetic vascular complication is a leading cause of end-stage renal failure, acquired blindness, a variety of neuropathies and accelerated atherosclerosis, which could account for disabilities and high mortality rates in patients with diabetes. There is a growing body of evidence to conclude that intensive control of plasma glucose and blood pressure is crucial for effectively reducing diabetic vascular complication. So far, various molecular mechanisms have been proposed to play a role in the development and progression of diabetic vascular complication. In this paper, we review potential therapeutic strategies for the prevention of diabetic vascular complication, especially focusing on the signal transduction pathways activated under diabetes.