Prevention and Reversal of Premature Endothelial Cell Senescence and Vasculopathy in Obesity-Induced Diabetes by Ebselen

Abstract

Abstract-Although the accelerated atherosclerosis and premature aging of the cardiovascular system in patients with metabolic syndrome have been appreciated, the mechanisms of their development and potential therapeutic interventions remain unresolved. Our previous studies implicated advanced glycosylation end products in development of premature senescence preventable with a peroxynitrite scavenger, ebselen. Therefore, the effect of ebselen on endothelial senescence and vasculopathy in a model of metabolic syndrome-Zucker diabetic rats (ZDF)-was investigated.Ebselen decreased the abundance of 3-nitrotyrosine-modified proteins in ZDF rats. A 6-fold increase in the number of senescent endothelial cells in 22-week-old ZDF was prevented by ebselen. Development of vasculopathy, as collectively judged by the acetylcholine-induced vasorelaxation, NO production, angiogenic competence, and number of circulating microparticles, was almost completely prevented when ebselen was administered from 8 to 22 weeks and partially reversed when the treatment interval was 13 to 22 weeks. In conclusion, premature senescence of endothelial cells is progressively rampant in ZDF rats and is associated with the signs of severe vasculopathy. In addition, prevention of premature senescence of vascular endothelium through controlled decrease in nitrotyrosine formation was chronologically associated with the amelioration of vasculopathy, lending support to the idea of the pathogenetic role of premature senescence of endothelial cells in diabetic macrovasculopathy. Key Words: metabolic syndrome Ⅲ macrovasculopathy Ⅲ nitric oxide Ⅲ vasorelaxation Ⅲ peroxynitrite A therosclerosis is responsible for the death of 80% of patients with diabetes, compared with only 30% in the general population of North America. 1 Although the accelerated atherosclerosis and premature aging of the cardiovascular system in patients with diabetes mellitus and metabolic syndrome X have long been appreciated, the mechanisms of their development and potential therapeutic interventions remain not fully understood. Several main concepts attempt to explain the phenomenon of premature aging of the cardiovascular system by ascribing it to the oxidative stress and mitochondrial dysfunction, advanced glycosylation end products (AGE) activating a cognate receptor, RAGE, and activation of protein kinase C-␤. [2][3][4][5] These metabolic abnormalities lead to the increased incidence of apoptosis in endothelial cells, a possible contributor to the accelerated atherosclerosis. 6 And yet a mechanistic view on the progression from oxidative stress to overt vasculopathy is missing. This study seeks to provide experimental evidence in support of an idea that premature endothelial cell senescence may represent a critical intermediate step between oxidative stress and vasculopathy.Our previous studies of endothelial cells subjected to a microenvironment emulating diabetic milieu in that it contains AGE-modified long-lived extracellular matrix protein glycated collagen I (GC) revealed dec...

Oral adsorbent AST-120 ameliorates endothelial dysfunction independent of renal function in rats with subtotal nephrectomy

“…21,29 Enhanced O 2 À production in the vasculature reduces NO bioavailability through scavenging NO by O 2 À , followed by endothelial dysfunction. 31 Peroxynitrite is generated by the immediate reaction of NO and O 2 À and is considered cytotoxic as it modifies tyrosine residues in proteins to generate nitrotyrosine.…”

“…Immunohistochemical staining and evaluation for nitrotyrosine, a tracer of nitrative stress, was performed in aorta as reported earlier. 28,29 A rabbit anti-nitrotyrosine polyclonal antibody (5 mg ml À1 ) (Upstate Biotechnology, Table 1 Changes in various physiological and biochemical parameters in sham-operated (Sham), subtotally nephrectomized (Nx) and subtotally nephrectomized-AST-120-treated rats (Nx+AST)…”

Premature vascular senescence in metabolic syndrome: Could it be prevented and reversed by a selenorganic antioxidant and peroxynitrite scavenger ebselen?

“…The number of circulating microparticles was quantified using FACS analysis after staining with Ulex Europeus (25). The data demonstrated a significant increase in the number of circulating endothelial microparticles in ZDF rats at 22 weeks, compared to ZL rats of the same age (not shown).…”

“…Ebselen-treated ZDF rats showed the same degree of hyperglycemia and levels of blood pressure as the vehicle-treated age-matched counterparts, Zucker lean (ZL) rats throughout the observation period of 8-22 weeks of age (25).…”

Protein 3-Nitrotyrosine in Complex Biological Samples: Quantification by High-Pressure Liquid Chromatography/Electrochemical Detection and Emergence of Proteomic Approaches for Unbiased Identification of Modification Sites

“…While inflammation-associated protein-3-NT forms predominantly via the reaction of proteinaceous tyrosine residues with peroxynitrite (ONOO − ), the latter arising from the near diffusion-limited reaction of nitric oxide ( • NO) with superoxide (O 2 •− ) (Beckmann et al, 1994;Pacher et al, 2007), other nitration mechanisms have also been implicated (Eiserich et al, 1998). Regardless of the mechanism of formation in vivo, protein 3-NT levels provide a useful measure of the severity of tissue exposure to reactive nitrogen species and a telling indicator of inflammatory disease severity and progression Brodsky et al, 2004;HalejcioDelophont et al, 2001;Skinner et al, 1997;Upmacis et al, 2007). Semiquantitative immunological methods (Ischiropoulos, 1998), as well as quantitative high-pressure liquid chromatography (HPLC)-based methods that utilize ultraviolet-visible (UV/VIS) absorption, electrochemistry, and mass spectrometry (MS) for detection (Frost et al, 2000;Maruyama et al, 1996;Schwedhelm et al, 1999;Shigenaga et al, 1997;Yi et al, 2000), have all been employed for the quantification of protein 3-NT residues; each method offers its own particular strengths and limitations.…”