@article {3579, title = {Osteoprotegerin increases in metabolic syndrome and promotes adipose tissue proinflammatory changes.}, journal = {Mol Cell Endocrinol}, volume = {394}, year = {2014}, month = {2014 Aug 25}, pages = {13-20}, abstract = {

BACKGROUND: Inflammation is believed to link obesity to insulin resistance, as in the setting of metabolic syndrome (MetS). Osteoprotegerin (OPG) is a soluble protein that seems to exert proatherogenic and prodiabetogenic effects. This study aims at determining OPG levels in MetS and whether OPG might contribute to MetS development and progression.

METHODOLOGY/PRINCIPAL FINDINGS: Circulating OPG was measured in 46 patients with MetS and 63 controls, and was found significantly elevated in those with MetS. In addition, circulating and tissue OPG was significantly increased in high-fat diet (HFD) fed C57BL6 mice, which is one of the animal models for the study of MetS. To evaluate the consequences of OPG elevation, we delivered this protein to C57BL6 mice, finding that it promoted systemic and adipose tissue proinflammatory changes in association with metabolic abnormalities.

CONCLUSIONS/SIGNIFICANCE: These data suggest that OPG may trigger adipose tissue proinflammatory changes in MetS/HFD-induced obesity.

}, keywords = {Adipose Tissue, Adult, Animals, Blood Glucose, Body Mass Index, C-Reactive Protein, Case-Control Studies, Cholesterol, HDL, Cholesterol, LDL, Diet, High-Fat, Female, Humans, Inflammation, Insulin, Insulin Resistance, Male, Metabolic Syndrome X, Mice, Mice, Inbred C57BL, Middle Aged, Obesity, Osteoprotegerin, Triglycerides}, issn = {1872-8057}, doi = {10.1016/j.mce.2014.06.004}, author = {Bernardi, Stella and Fabris, Bruno and Thomas, Merlin and Toffoli, Barbara and Tikellis, Christos and Candido, Riccardo and Catena, Cristiana and Mulatero, Paolo and Barbone, Fabio and Radillo, Oriano and Zauli, Giorgio and Secchiero, Paola} } @article {1710, title = {Osteoprotegerin induces morphological and functional alterations in mouse pancreatic islets.}, journal = {Mol Cell Endocrinol}, volume = {331}, year = {2011}, month = {2011 Jan 1}, pages = {136-42}, abstract = {

Although serum osteoprotegerin (OPG) is significantly increased in diabetic subjects, its potential role in beta cell dysfunction has not been investigated. This study aimed to assess the effect of full-length OPG administered in vivo in mice on pancreatic islet structure and function and its interaction with the renin-angiotensin system (RAS). OPG-treated mice showed increased islet monocyte/macrophage infiltration, fibrosis and apoptosis with reduction of islet function. The remodeling of islet architecture was associated with increased pancreatic expression of components of the RAS, growth factor genes (transforming growth factor β and connective tissue growth factor) and inflammatory molecules (monocyte chemotactic protein-1 and vascular adhesion molecule type 1). Prevention of these changes with improvement of insulin secretion was observed in ramipril treated animals. Our data suggest that OPG might play an important role in promoting beta cell dysfunction and that the upregulation of the local RAS represents one possible mechanism responsible for the OPG-induced beta cell dysfunction.

}, keywords = {Animals, Apoptosis, Blood Glucose, Blood Pressure, Body Weight, Cell Lineage, Cell Movement, Chemokine CCL2, Connective Tissue Growth Factor, Fibrosis, Gene Expression Regulation, Humans, Insulin, Islets of Langerhans, Macrophages, Mice, Monocytes, Organ Size, Osteoprotegerin, Peptidyl-Dipeptidase A, Receptor, Angiotensin, Type 1, Systole, Transforming Growth Factor beta, Vascular Cell Adhesion Molecule-1}, issn = {1872-8057}, doi = {10.1016/j.mce.2010.08.019}, author = {Toffoli, Barbara and Bernardi, Stella and Candido, Riccardo and Sabato, Nicoletta and Carretta, Renzo and Corallini, Federica and Secchiero, Paola and Zauli, Giorgio and Fabris, Bruno} } @article {1784, title = {Osteoprotegerin promotes vascular fibrosis via a TGF-β1 autocrine loop.}, journal = {Atherosclerosis}, volume = {218}, year = {2011}, month = {2011 Sep}, pages = {61-8}, abstract = {

BACKGROUND: This study was designed to evaluate the potential role of osteoprotegerin (OPG) in arterial fibrosis.

METHODS: Aortic samples were analyzed after in vivo treatment of ApoE(-/-) mice with recombinant human OPG. Mouse vascular smooth muscle cells (VSMC) were exposed in vitro to recombinant OPG and analyzed for markers of inflammation and fibrosis, such as fibronectin, collagen I, III, IV and transforming growth factor-β1 (TGF-β1). Conversely, the potential modulation of endogenous OPG expression and release by VSMC was analyzed in response to different pro-atherosclerotic cytokines, TGF-β1, platelet derived growth factor (PDGF) and angiogensin II (Ang II).

RESULTS: In vivo treatment with human OPG induced signs of fibrosis and up-regulated the arterial expression of TGF-β1. Consistently, in vitro treatment of VSMC with human OPG induced the expression of fibronectin, collagen type I, III, IV, metalloprotein-2 (MMP-2) and MMP-9, as well as of TGF-β1. On the other hand, exposure to recombinant TGF-β1 promoted the expression/release of endogenous OPG and mediated the increase of OPG release induced by PDGF and Ang II in VSMC.

CONCLUSIONS: Taken together, these data support a pathogenic role for OPG in the development and progression of atherosclerotic lesions and suggest the existence of a vicious circle between TGF-β1 and OPG.

}, keywords = {Animals, Apolipoproteins E, Cell Proliferation, Collagen, Fibronectins, Fibrosis, Gene Expression Regulation, Humans, Mice, Mice, Inbred C57BL, Mice, Transgenic, Muscle, Smooth, Vascular, Myocytes, Smooth Muscle, Osteoprotegerin, Platelet-Derived Growth Factor, Transforming Growth Factor beta1}, issn = {1879-1484}, doi = {10.1016/j.atherosclerosis.2011.05.019}, author = {Toffoli, Barbara and Pickering, Raelene J and Tsorotes, Despina and Wang, Bo and Bernardi, Stella and Kantharidis, Phillip and Fabris, Bruno and Zauli, Giorgio and Secchiero, Paola and Thomas, Merlin C} }