osteoprotegerin and Weight-Gain

The receptor activator of nuclear factor-κB (NF-κB) (RANK), its ligand (RANKL), and the decoy receptor osteoprotegerin (OPG) are a triad of proteins that regulate bone metabolism, and serum OPG is considered a biomarker for cardiovascular diseases and Type 2 diabetes; however, the implications of OPG in adipose tissue metabolism remains elusive. In this study, we investigate RANK-RANKL-OPG signaling in white adipose tissue browning. Histological analysis of osteoprotegerin knockout (OPG-/-) mice showed subcutaneous white adipose tissue (sWAT) browning, resistance for high-fat diet-induced weight gain, and preserved glucose metabolism compared with wild-type (WT) mice. Stromal vascular fraction (SVF) cells from sWAT of OPG-/- mice showed multilocular morphology and higher expression of brown adipocyte marker genes compared with those from the WT group. Infusion of RANKL induced browning and elevated respiratory rates in sWAT, along with increased whole body oxygen consumption in mice measured by indirect calorimetry. Subcutaneous WAT-derived SVF and 3T3-L1 cells, but not mature white adipocytes, differentiated into beige adipose tissue in the presence of RANKL. Moreover, SVF cells, even under white adipocyte differentiation, showed multilocular lipid droplet, lower lipid content, and increased expression of beige adipocyte markers with RANKL stimulation. In this study, we show for the first time the contribution of RANKL to increase energy expenditure by inducing beige adipocyte differentiation in preadipocytes.

Topics: 3T3-L1 Cells; Adipocytes, Beige; Adipocytes, White; Adipogenesis; Adipose Tissue, Beige; Adipose Tissue, White; Animals; Calorimetry, Indirect; Diet, High-Fat; Energy Metabolism; Lipid Droplets; Mice; Mice, Knockout; Obesity; Osteoprotegerin; Oxygen Consumption; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Signal Transduction; Subcutaneous Fat; Weight Gain

Although drug therapies are available for postmenopausal osteoporosis, these drugs are not free of side effects and long-term adherence to them are low. A safe and effective nutritional approach to counter postmenopausal osteoporosis is an important research goal. We fed ovariectomized (OVX) Sprague-Dawley rats a diet supplemented with 1% or 2% green tomato extract (GTE). After 12 weeks, micro-computed tomography scans revealed that GTE supplementation effectively prevented distal femur bone loss. This prevention was due to improved bone formation and suppressed bone resorption as observed by the regulation of osteoblast and osteoclast activities. GTE supplementation also improved bone formation through Bmp2-Smad 1/5/8-Runx2 signaling, while bone resorption was regulated by the receptor activator of nuclear factor kappa-B (RANKL)/osteoprogeterin (OPG) pathway. These results suggest that GTE supplementation prevents severe postmenopausal bone loss by maintaining the regulation of bone homeostasis in OVX rats. GTE as a diet supplement might be a potential novel alternative for the prevention of postmenopausal osteoporosis.

Topics: Animals; Bone Density; Bone Morphogenetic Protein 2; Bone Resorption; Core Binding Factor Alpha 1 Subunit; Disease Models, Animal; Female; Humans; Osteogenesis; Osteoporosis, Postmenopausal; Osteoprotegerin; Ovariectomy; Phytotherapy; Plant Extracts; RANK Ligand; Rats; Rats, Sprague-Dawley; Signal Transduction; Smad Proteins, Receptor-Regulated; Solanum lycopersicum; Tomatine; Weight Gain

To investigate the effect of chronic alcohol consumption on apical periodontitis in rats.. Thirty-two male Wistar rats were arranged into four groups: Control (C): without apical periodontitis and nonalcoholic diet; (AL): without apical periodontitis and alcoholic diet; (AP): with apical periodontitis and nonalcoholic diet; and (AP + AL): with apical periodontitis and alcoholic diet. The alcoholic solution at 20% was given to the AL and AP + AL groups as the sole source of hydration throughout the experiment. AP was induced in the mandibular left first molars at the end of the 4th week. Weight changes and the amount of solid and liquid foods were recorded for 8 weeks. At the end, the animals were euthanized and the jaws removed followed by histological processing for histopathological and RANKL, OPG, TRAP and HIF-1α analyses. The Mann-Whitney test was used for nonparametric data, and anova followed by the Tukey test was performed for parametric data, with P < 0.05.. Animals that received the alcoholic diet had a lower weight gain than the other groups (P < 0.05). Control and AL groups did not have an inflammatory response in the periapical tissues. The median score of inflammatory infiltrate was significantly higher in the AP + AL group (2.5) compared to the AP group (1.5; P < 0.05). In the same comparison, AP + AL was associated with score 3 for RANKL and HIF-1α versus score 2 for AP group (P < 0.05). Moreover, the values for TRAP were 3.88 ± 0.70 cells mm. In rats, an alcoholic diet had a significant effect on the severity of apical periodontitis, exacerbating the inflammatory response and osteoclastogenesis.

Topics: Animals; Ethanol; Hypoxia-Inducible Factor 1, alpha Subunit; Male; Osteoclasts; Osteogenesis; Osteoprotegerin; Periapical Periodontitis; RANK Ligand; Rats; Rats, Wistar; Tartrate-Resistant Acid Phosphatase; Weight Gain

Type 2 diabetes is an emerging global health epidemic. Foundations for new therapies are arising from understanding interactions between body systems. Bone-derived factors that reduce RANKL (receptor activator of NF-kappa B ligand) signaling in the liver may prevent insulin resistance and the onset of type 2 diabetes. Here we demonstrate that deletion of the epigenetic regulator, Hdac3, in Osx1-expressing osteoprogenitors prevents insulin resistance induced by high fat diet by increasing serum and skeletal gene expression levels of osteoprotegerin (Opg), a natural inhibitor of RANKL signaling. Removal of one Opg allele in mice lacking Hdac3 in Osx1+ osteoprogenitors increases the insulin resistance of the Hdac3-deficient mice on a high fat diet. Thus, Hdac3-depletion in osteoblasts increases expression of Opg, subsequently preserving insulin sensitivity. The Hdac inhibitor vorinostat also increased Opg transcription and histone acetylation of the Opg locus. These results define a new mechanism by which bone regulates systemic insulin sensitivity.

Topics: Alleles; Animals; Biomarkers; Bone and Bones; Diet, High-Fat; Gene Deletion; Histone Deacetylases; Insulin Resistance; Mice, Inbred C57BL; Mice, Knockout; Osteoblasts; Osteoprotegerin; RNA, Messenger; Stem Cells; Weight Gain

Ecliptae herba (EH) has long been used in China to strengthen bones. Accumulating evidence indicates that EH may have antiosteoporotic effects. The aim of this study was to evaluate the effects of aqueous EH extract (EHE) on rats that had osteoporosis-like features induced by ovariectomy, using aqueous Fructus Ligustri Lucidi extract as positive control agent.. Three-month-old female rats that underwent ovariectomy were treated with EHE (1.4 g/kg per day). After 12 weeks, bone mineral density and bone histomorphometric indices of tibiae were measured. Protein and messenger RNA expressions of osteoprotegerin and receptor activator of nuclear factor κ-B ligand (RANKL) in tibiae were evaluated by immunohistochemistry and in situ hybridization. In addition, serum concentrations of osteocalcin, interleukin-1β, interleukin-6 (IL-6), calcitonin (CT), and parathyroid hormone were determined by enzyme-linked immunosorbent assay.. EHE treatment prevented body weight gain and loss of uterine wet weight in ovariectomized rats. It remarkably increased bone mass in ovariectomized rats compared with ovariectomized controls. EHE treatment significantly down-regulated RANKL expression in tibiae from ovariectomized rats compared with controls; however, it had no significant effect on osteoprotegerin expression. In addition, EHE treatment significantly reduced serum IL-6 levels and remarkably increased CT levels but had no effect on parathyroid hormone.. EHE increases bone mass in ovariectomized rats by inhibiting bone loss: down-regulated RANKL expression in tibiae and IL-6 level in serum, and up-regulated CT level in serum. This suggests that EHE may be developed as an alternative therapeutic agent for osteoporosis induced by postmenopause.

Topics: Animals; Bone and Bones; Bone Density; Calcitonin; Eclipta; Female; Humans; Immunohistochemistry; Interleukin-1beta; Interleukin-6; Organ Size; Osteocalcin; Osteoprotegerin; Ovariectomy; Plant Extracts; RANK Ligand; Rats; Rats, Wistar; RNA, Messenger; Tibia; Uterus; Weight Gain

Receptor activator of nuclear factor-κB ligand (RANKL) inhibitors are being considered for use in children with osteogenesis imperfecta (OI). We sought to assess efficacy of two doses of a RANKL inhibitor, osteoprotegerin-immunoglobulin Fc segment complex (OPG-Fc), in a growing animal model of OI, the col1α2-deficient mouse (oim/oim) and its wild-type controls (+/+).. Treated mice showed runting and radiographic evidence of osteopetrosis with either high- (20 mg/kg twice weekly) or low-dose (1 mg/kg/week) OPG-Fc. Because of this adverse event, OPG-Fc treatment was halted, and the mice were killed or monitored for recovery with monthly radiographs and assessment of serum osteoclast activity (tartrate-resistant acid phosphatase 5b, TRACP-5b) until 25 wk of age.. Twelve weeks of OPG-Fc treatment resulted in radiographic and histologic osteopetrosis with no evidence of bone modeling and negative tartrate-resistant acid phosphatase staining, root dentin abnormalities, and TRACP-5b activity suppression. Signs of recovery appeared 4-8 wk post-treatment.. Both high- and low-dose OPG-Fc treatment resulted in osteopetrotic changes in infant mice, an outcome that was not seen in studies with the RANKL inhibitor RANK-immunoglobulin Fc segment complex (RANK-Fc) or in studies with older animals. Further investigations of RANKL inhibitors are necessary before their consideration for use in children.

Topics: Acid Phosphatase; Age Factors; Animals; Biomarkers; Bone Remodeling; Collagen Type I; Dentin; Disease Models, Animal; Female; Immunoconjugates; Immunoglobulin Fc Fragments; Isoenzymes; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Osteoclasts; Osteogenesis Imperfecta; Osteopetrosis; Osteoprotegerin; Radiography; RANK Ligand; Risk Assessment; Tartrate-Resistant Acid Phosphatase; Time Factors; Tooth Eruption; Weight Gain

Both ovariectomized animals and animals fed with Ca-depleted diets are commonly used in vivo models for the investigation of osteoporosis-related bone loss. The present study aimed to study the genomic responses of bone in aged female rats to ovariectomy and dietary Ca deficiency in these models. Aged (11 months old) Sprague-Dawley rats were subjected to bilateral ovariectomy or sham-operation and fed with diets containing different dietary Ca content (LCD, 0.1% Ca or HCD, 1.2% Ca) for 12 weeks. Serum and urine were collected for biochemical marker measurement, and tibias were collected for bone mineral density (BMD) analysis by pQCT as well as for gene expression analysis by real-time PCR. Ovariectomy increased serum N-telopeptides of bone type I collagen (NTx) levels in aged rats fed with HCD (P<0.05). In addition, ovariectomy reduced BMD and predicted bone strength of tibial proximal metaphysis in aged rats fed with either LCD or HCD. Dietary Ca deficiency did not alter serum bone-specific alkaline phosphatase (BAP) or NTx levels, but induced a loss of BMD at tibia proximal metaphysis in aged rats. Ovariectomy promoted the mRNA expression of alpha-1 type I collagen (COL), osteoprotegerin (OPG) and receptor activator of nuclear factor-kappa B ligand (RANKL); and inhibited the mRNA expression of cathepsin K and matrix metalloproteinase-9 (MMP-9) in the proximal tibia of aged rats. Low-Ca diet significantly up-regulated the mRNA expression of COL, core binding factor I (Cbfa1), OPG and carbonic anhydrase II (CAII) in proximal tibia of aged rats. Our study revealed that the genomic responses of bone in proximal tibia to ovariectomy and dietary Ca deficiency were different. The bone loss induced by ovariectomy appears to be mediated primarily by an increase in RANKL mRNA expression; whereas the induction by dietary Ca restriction might be mediated by the induction of carbonic anhydrase II expression.

Topics: Aging; Animals; Biomarkers; Calcium, Dietary; Diet; Female; Gene Expression Profiling; Gene Expression Regulation; Organ Specificity; Osteoblasts; Osteoclasts; Osteoprotegerin; Ovariectomy; RANK Ligand; Rats; Rats, Sprague-Dawley; RNA, Messenger; Tibia; Tomography, X-Ray Computed; Weight Gain

Bone mineral density increases with fat body mass, and obesity has a protective effect against osteoporosis. However, the relationship between fat body mass and bone mineral density is only partially explained by a combination of hormonal and mechanical factors. Serum leptin levels are strongly and directly related to fat body mass. We report here the effects of leptin administration compared with estrogen therapy on ovariectomy-induced bone loss in rats. Leptin was effective at reducing trabecular bone loss, trabecular architectural changes, and periosteal bone formation. Interestingly, the combination of estrogen and leptin further decreased bone turnover compared with that in estrogen-treated ovariectomized rats. Leptin also significantly increased osteoprotegerin mRNA steady state levels and protein secretion and decreased RANK ligand mRNA levels in human marrow stromal cells in vitro. Our findings suggest that leptin could modulate bone remodeling in favor of a better bone balance in rats. This study is the first evidence that leptin therapy has a significant effect in preventing ovariectomy-induced bone loss, and this effect may at least in part be mediated by the osteoprotegerin/RANK ligand pathway.

Topics: Animals; Bone and Bones; Bone Development; Bone Marrow Cells; Gene Expression; Glycoproteins; Leptin; Osteoporosis; Osteoprotegerin; Ovariectomy; Rats; Rats, Sprague-Dawley; Receptors, Cytoplasmic and Nuclear; Receptors, Leptin; Receptors, Tumor Necrosis Factor; Stromal Cells; Weight Gain