1.
The ubiquitin-proteasome system and inflammatory activity in diabetic atherosclerotic plaques: effects of rosiglitazone treatment.
Marfella, R, D'Amico, M, Esposito, K, Baldi, A, Di Filippo, C, Siniscalchi, M, Sasso, FC, Portoghese, M, Cirillo, F, Cacciapuoti, F, et al
Diabetes. 2006;(3):622-32
Abstract
The role of ubiquitin-proteasome system in the accelerated atherosclerotic progression of diabetic patients is unclear. We evaluated ubiquitin-proteasome activity in carotid plaques of asymptomatic diabetic and nondiabetic patients, as well as the effect of rosiglitazone, a peroxisome proliferator-activated receptor (PPAR)-gamma activator, in diabetic plaques. Plaques were obtained from 46 type 2 diabetic and 30 nondiabetic patients undergoing carotid endarterectomy. Diabetic patients received 8 mg rosiglitazone (n = 23) or placebo (n = 23) for 4 months before scheduled endarterectomy. Plaques were analyzed for macrophages (CD68), T-cells (CD3), inflammatory cells (HLA-DR), ubiquitin, proteasome 20S activity, nuclear factor (NF)-kappaB, inhibitor of kappaB (IkappaB)-beta, tumor necrosis factor (TNF)-alpha, nitrotyrosine, matrix metalloproteinase (MMP)-9, and collagen content (immunohistochemistry and enzyme-linked immunosorbent assay). Compared with nondiabetic plaques, diabetic plaques had more macrophages, T-cells, and HLA-DR+ cells (P < 0.001); more ubiquitin, proteasome 20S activity (TNF-alpha), and NF-kappaB (P < 0.001); and more markers of oxidative stress (nitrotyrosine and O2(-) production) and MMP-9 (P < 0.01), along with a lesser collagen content and IkappaB-beta levels (P < 0.001). Compared with placebo-treated plaques, rosiglitazone-treated diabetic plaques presented less inflammatory cells (P < 0.01); less ubiquitin, proteasome 20S, TNF-alpha, and NF-kappaB (P < 0.01); less nitrotyrosine and superoxide anion production (P < 0.01); and greater collagen content (P < 0.01), indicating a more stable plaque phenotype. Similar findings were obtained in circulating monocytes obtained from the two groups of diabetic patients and cultured in the presence or absence of rosiglitazone (7.0 micromol/l). Ubiquitin-proteasome over-activity is associated with enhanced inflammatory reaction and NF-kappaB expression in diabetic plaques. The inhibition of ubiquitin-proteasome activity in atherosclerotic lesions of diabetic patients by rosiglitazone is associated with morphological and compositional characteristics of a potential stable plaque phenotype, possibly by downregulating NF-kappaB-mediated inflammatory pathways.
2.
Effect of rosiglitazone on endothelial function and inflammatory markers in patients with the metabolic syndrome.
Esposito, K, Ciotola, M, Carleo, D, Schisano, B, Saccomanno, F, Sasso, FC, Cozzolino, D, Assaloni, R, Merante, D, Ceriello, A, et al
Diabetes care. 2006;(5):1071-6
Abstract
OBJECTIVE The aim of this study was to assess the effect of rosiglitazone on endothelial function and inflammatory markers in patients with the metabolic syndrome. RESEARCH DESIGN AND METHODS This was a randomized, double-blind, controlled clinical trial. One hundred subjects (54 men and 46 women) with the metabolic syndrome, as defined by the Adult Treatment Panel III, were followed for 12 months after random assignment to rosiglitazone (4 mg/day) or placebo. Primary end points were flow-mediated dilation and high-sensitivity C-reactive protein (hs-CRP) levels; secondary end points were lipid and glucose parameters, homeostasis model assessment (HOMA) of insulin sensitivity, endothelial function score, and circulating levels of interleukin (IL)-6, IL-18, and adiponectin. RESULTS Compared with 60 control subjects matched for age and sex, patients with the metabolic syndrome had decreased endothelial function, raised concentrations of inflammatory markers, and reduced insulin sensitivity. After 12 months, subjects with the metabolic syndrome receiving rosiglitazone showed improved flow-mediated vasodilation (4.2%, P < 0.001) and reduced hs-CRP levels (-0.7 mg/dl, P = 0.04), compared with the placebo group. Moreover, HOMA (-0.8, P = 0.01) and serum concentrations of IL-6 (-0.5 pg/ml, P = 0.045) and IL-18 (-31 pg/ml, P = 0.036) were significantly reduced in subjects receiving rosiglitazone, whereas adiponectin levels showed a significant increment (2.3 microg/ml, P = 0.02). High-density lipoprotein-cholesterol levels increased more and triglyceride levels decreased more in the rosiglitazone group compared with the placebo group. At 1 year of follow-up, 30 subjects receiving rosiglitazone still had features of the metabolic syndrome, compared with 45 subjects receiving placebo (P < 0.001). CONCLUSIONS Rosiglitazone might be effective in reducing the prevalence of the metabolic syndrome.