Adipocytes regulate the bone marrow microenvironment in a mouse model of obesity

Selective modulation of the bone remodeling regulatory system through orthodontic tooth movement-a review

Little is known about how tissues mediate the ability to selectively form or resorb bone, as required during orthodontic tooth movement (OTM), facial growth, continued tooth eruption and for healing after fractures, maxillofacial surgical repositioning or implant dentistry. OTM has the unique ability to selectively cause apposition, resorption or a combination of both at the alveolar periosteal surface and therefore, provides an optimal process to study the regulation of bone physiology at a tissue level. Our aim was to elucidate the mechanisms and signaling pathways of the bone remodeling regulatory system (BRRS) as well as to investigate its clinical applications in osteoporosis treatment, orthopedic surgery, fracture management and orthodontic treatment. OTM is restricted to a specific range in which the BRRS permits remodeling; however, surpassing this limit may lead to bone dehiscence. Low-intensity pulsed ultrasound, vibration or photobiomodulation with low-level laser therapy have the potential to modify BRRS with the aim of reducing bone dehiscence and apical root resorption or accelerating OTM. Unloading of bone and periodontal compression promotes resorption via receptor activator of nuclear factor κB-ligand, monocyte chemotactic protein-1, parathyroid hormone-related protein (PTHrP), and suppression of anti-resorptive mediators. Furthermore, proinflammatory cytokines, such as interleukin-1 (IL-1), IL-6, IL-8, tumor necrosis factor-α, and prostaglandins exert a synergistic effect on bone resorption. While proinflammatory cytokines are associated with periodontal sequelae such as bone dehiscence and gingival recessions, they are not essential for OTM. Integrins mediate mechanotransduction by converting extracellular biomechanical signals into cellular responses leading to bone apposition. Active Wnt signaling allows β-catenin to translocate into the nucleus and to stimulate bone formation, consequently converging with integrin-mediated mechanotransductive signals. During OTM, periodontal fibroblasts secrete PTHrP, which inhibits sclerostin secretion in neighboring osteocytes via the PTH/PTHrP type 1 receptor interaction. The ensuing sclerostin-depleted region may enhance stem cell differentiation into osteoblasts and subperiosteal osteoid formation. OTM-mediated BRRS modulation suggests that administering sclerostin-inhibiting antibodies in combination with PTHrP may have a synergistic bone-inductive effect. This approach holds promise for enhancing osseous wound healing, treating osteoporosis, bone grafting and addressing orthodontic treatments that are linked to periodontal complications.

Evaluation of the effects of obesity on orthodontic tooth movement

Objective

This study aimed to evaluate bone remodeling in gingival crevicular fluid (GCF) during canine distalization in obese individuals and compare it to that in normal-weight individuals. Additionally, the orthodontic tooth movement rates of obese individuals were measured and compared with those of normal-weight individuals.

Methods

Thirty-six patients (18 obese and 18 normal-weight) aged 12-18 years who were candidates for maxillary first premolar extraction for Angle Class II malocclusion were included in the study. The two groups were formed according to World Health Organization guidelines. A normal-weight group (body mass index [BMI] 16-85%) and an obese group (BMI ≥ 95%). Gingival crevicular fluid samples were collected before, 24 hours after, and on the 7th, 14th, and 21st days after the application of the distalization force. Enzyme-linked immunosorbent assay was used to measure leptin, receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG) and interleukin-6 (IL-6) levels in GCF samples. In addition to the recorded GCF sampling times, the amount of canine tooth movement was calculated using digital models obtained on the 28th day and 3rd month.

Results

Leptin, RANKL, OPG, and IL-6 levels were significantly higher in the obese group (P < 0.05). The digital model measurements displayed high rates of repeatability (ICC 0.990). The difference in the amount of tooth movement between groups was not statistically significant (P > 0.05).

Conclusions

Although obese and normal-weight individuals showed different biomarker levels during tooth movement, there were no significant differences in the amount of movement.

Adipocyte maturation impacts daunorubicin disposition and metabolism

INTRODUCTION

Acute lymphoblastic leukaemia (ALL) is the most common type of childhood leukaemia with effective chemotherapeutic treatment. However, obesity has been associated with higher ALL chemoresistance rates and lower event-free survival rates. The molecular mechanism of how obesity promotes chemotherapy resistance is not well delineated.

OBJECTIVES

This study evaluated the effect of adipocyte maturation on sequestration and metabolism of chemotherapeutic drug daunorubicin (DNR).

METHODS

Using targeted LC-MS/MS multi-analyte assay, DNR sequestration and metabolism were studied in human preadipocyte and adipocyte cell lines, where expressions of DNR-metabolizing enzymes aldo-keto reductases (AKR) and carbonyl reductases (CBR) were also evaluated. In addition, to identify the most DNR-metabolizing AKR/CBR isoforms, recombinant human AKR and CBR enzymes were subject to DNR metabolism. The results were further validated by AKR-, CBR-specific inhibitors.

RESULTS

This report shows that adipocyte maturation upregulates expressions of AKR and CBR enzymes (by 4- to 60- folds, p < .05), which is positively associated with enhanced sequestration and metabolism of DNR in adipocytes compared to preadipocytes (by ~30%, p < .05). In particular, adipocyte maturation upregulates AKR1C3 and CBR1, which are the predominate metabolic enzyme isoforms responsible for DNR biotransformation to its metabolites.

CONCLUSION

Fat is an expandable tissue that can sequester and detoxify DNR when stimulated by obesity, likely through the upregulation of DNR-metabolizing enzymes AKR1C3 and CBR1. Our data partially explains why obese ALL patients may be more likely to become chemoresistant towards DNR, and provides evidence for potential clinical investigation targeting obesity to reduce DNR chemoresistance.

The role of interleukin-20 on inflammatory stress and periodontal tissue destruction in patients with metabolic syndrome and periodontitis

BACKGROUND

There is an increasing occurrence of periodontitis and metabolic syndrome (MetS), which is resulting in a decline in the overall quality of life. Both disorders can occur together since they are both linked to insulin resistance and systemic inflammation. However, evidence for a role of interleukin (IL)-20 in this comorbidity is very limited. This cross-sectional study aimed to comprehensively investigate, for the first time, the levels of RANKL/OPG, MMP-8 and OSI as well as the role of IL-20 in patients with MetS and periodontitis.

METHODS

The study included a total of 80 individuals, divided into four groups: 20 individuals who were healthy both systemically and periodontally, 20 individuals who were systemically healthy but had periodontitis, 20 individuals who had MetS but were periodontally healthy, and 20 individuals who had both MetS and periodontitis. Periodontal clinical parameters (plaque index, gingival index, bleeding on probing, clinical attachment loss, probing pocket depth) were evaluated. Gingival crevicular fluid (GGF) and serum samples were collected and used for biochemical assays. Enzyme-linked immunosorbent assay was used to determine the levels of IL-20, receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG), matrix metalloproteinase-8 (MMP-8) and oxidative stress index (OSI).

RESULTS

IL-20 levels measured in serum and GCF were statistically significantly highest in patients with MetS and periodontitis (p = 0.001). Significant positive correlation was observed between serum and GCF IL-20 values and periodontal parameters (p < 0.05). There was a positive correlation between RANKL and RANKL/OPG levels and IL-20 and clinical parameters (p < 0.05). OSI values were found to be increased in the presence of both periodontitis and MetS (p = 0.001) and were positively correlated with serum and GCF IL-20 (p < 0.05).

CONCLUSIONS

These data from the study suggest a correlation between IL-20 and both MetS and periodontitis. IL-20 may potentially worsen the condition of periodontal tissue by increasing both the oxidative stress levels, periodontal collagen degredation and the ratio of RANKL to OPG.

TRIAL REGISTRATION

This study was registered on ClinicTrials.gov (NCT06092853), 2023-10-10, retrospectively registered.

Bone marrow adipocytes and lung cancer bone metastasis: unraveling the role of adipokines in the tumor microenvironment

Bone is a common site of metastasis for lung cancer. The "seed and soil" hypothesis suggests that the bone marrow microenvironment ("soil") may provide a conducive survival environment for metastasizing tumor cells ("seeds"). The bone marrow microenvironment, comprising a complex array of cells, includes bone marrow adipocytes (BMAs), which constitute about 70% of the adult bone marrow volume and may play a significant role in tumor bone metastasis. BMAs can directly provide energy for tumor cells, promoting their proliferation and migration. Furthermore, BMAs participate in the tumor microenvironment's osteogenesis regulation, osteoclast(OC) regulation, and immune response through the secretion of adipokines, cytokines, and inflammatory factors. However, the precise mechanisms of BMAs in lung cancer bone metastasis remain largely unclear. This review primarily explores the role of BMAs and their secreted adipokines (leptin, adiponectin, Nesfatin-1, Resistin, chemerin, visfatin) in lung cancer bone metastasis, aiming to provide new insights into the mechanisms and clinical treatment of lung cancer bone metastasis.

Obesity and Bone Health: A Complex Relationship

Recent scientific evidence has shown an increased risk of fractures in patients with obesity, especially in those with a higher visceral adipose tissue content. This contradicts the old paradigm that obese patients were more protected than those with normal weight. Specifically, in older subjects in whom there is a redistribution of fat from subcutaneous adipose tissue to visceral adipose tissue and an infiltration of other tissues such as muscle with the consequent sarcopenia, obesity can accentuate the changes characteristic of this age group that predisposes to a greater risk of falls and fractures. Other factors that determine a greater risk in older subjects with obesity are chronic proinflammatory status, altered adipokine secretion, vitamin D deficiency, insulin resistance and reduced mobility. On the other hand, diagnostic tests may be influenced by obesity and its comorbidities as well as by body composition, and risk scales may underestimate the risk of fractures in these patients. Weight loss with physical activity programs and cessation of high-fat diets may reduce the risk. Finally, more research is needed on the efficacy of anti-osteoporotic treatments in obese patients.

Novel associations between inflammation-related proteins and adiposity: A targeted proteomics approach across four population-based studies

Chronic low-grade inflammation has been proposed as a linking mechanism between obesity and the development of inflammation-related conditions such as insulin resistance and cardiovascular disease. Despite major advances in the last 2 decades, the complex relationship between inflammation and obesity remains poorly understood. Therefore, we aimed to identify novel inflammation-related proteins associated with adiposity. We investigated the association between BMI and waist circumference and 72 circulating inflammation-related proteins, measured using the Proximity Extension Assay (Olink Proteomics), in 3,308 participants of four independent European population-based studies (KORA-Fit, BVSII, ESTHER, and Bialystok PLUS). In addition, we used body fat mass measurements obtained by Dual-energy X-ray absorptiometry (DXA) in the Bialystok PLUS study to further validate our results and to explore the relationship between inflammation-related proteins and body fat distribution. We found 14 proteins associated with at least one measure of adiposity across all four studies, including four proteins for which the association is novel: DNER, SLAMF1, RANKL, and CSF-1. We confirmed previously reported associations with CCL19, CCL28, FGF-21, HGF, IL-10RB, IL-18, IL-18R1, IL-6, SCF, and VEGF-A. The majority of the identified inflammation-related proteins were associated with visceral fat as well as with the accumulation of adipose tissue in the abdomen and the trunk. In conclusion, our study provides new insights into the immune dysregulation observed in obesity that might help uncover pathophysiological mechanisms of disease development.

The Influence of Obesity, Ovariectomy, and Greenshell Mussel Supplementation on Bone Mineral Density in Rats

Obesity is considered to impair long-term health by disturbing multiple physiological functions. However, it remains a controversial issue as to whether obesity has beneficial or detrimental effects on bone health in postmenopausal women. The aims of this study were to investigate the relationships between obesity and bone mineral density (BMD) under conditions of ovarian hormone deficiency in an animal model and to evaluate the potential health benefits of Greenshell mussel (GSM) on bone health. A total of 144 adult female Sprague-Dawley rats were fed from age 12 weeks on one of four diets (normal [ND]; ND + GSM; high fat/high sugar [HF/HS]; HF/HS + GSM; n = 36 per diet). At age 20 weeks, after a dual-energy X-ray absorptiometry (DXA) scan, 12 of the rats on each diet underwent ovariectomy (OVX) and the remaining rats were left intact. Twelve of the intact rats in each diet group were culled at age 26 weeks (short-term cohort). The remaining rats were culled at age 48 weeks (long-term cohort). Rats were DXA scanned before cull, then various fat pads were dissected. The results revealed that HF/HS rats and OVX rats dramatically increased body weight and fat deposition in correlation with leptin. In the long-term cohort, vertebral spine BMD rapidly declined after OVX. At termination, the OVX rats had decreased plasma bone turnover markers of CTX-1 and TRAP when compared with sham rats. Significantly higher BMD was found in OVX rats fed the HF/HS diet compared with ND, but this difference was not recapitulated in intact rats. BMD of right femur was significantly increased 5% to 10% by GSM in the short-term cohort. The data demonstrated that obesity can be beneficial by increasing BMD in OVX rats, and this may extrapolate to postmenopausal women as adipocyte-produced estrogen may slightly compensate for the reduction in ovarian hormones. Finally, the data showed that GSM may be beneficial to bone health by increasing BMD accrual. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Metabolic syndrome and fragility fracture risk

INTRODUCTION

The prevalence of metabolic syndrome has been reported to extremely vary depending on the gender, age, and ethnicity studied. Approximately, 25% of the worldwide adult population is affected by metabolic syndrome, indicating it as a significantly important public health challenge. Likewise, fragility fracture represents an important public health issue too, and the lifetime residual risk of its occurrence has been established in 50% in women and 30% in men over 50 years of age, respectively. Dysmobility syndrome summarizes a cluster of co-existing conditions such as osteoporosis, sarcopenia, obesity. Currently, clinical research focuses essentially on the cardiovascular risks associated with metabolic syndrome. Today, it is conceivable to incorporate all these conditions under a generic "disorder of energy metabolism."

EVIDENCE ACQUISITION

Animal and human studies suggest metabolic and dysmobility syndromes negatively impact on the risk for fragility fracture, contributing to increase the associated mortality rate.

EVIDENCE SYNTHESIS

In recent years, strong correlation between type 2 diabetes, a frequent constitutive part of metabolic syndrome and fragility fracture risk has been reported, but the possible molecular mechanisms by which it can occur are still to be defined.

CONCLUSIONS

Only very few human clinical studies faced these aspects, but they lack adequate endpoints for a good clinical practice in these subjects. Much more still needs to be done before appropriate therapeutic diagnostic pathways will be available for these patients at risk of bone and even generalized fragility. Suggestions for a future overall approach by generating global risk score for these conditions are given.

Direct and Indirect Effect of Honey as a Functional Food Against Metabolic Syndrome and Its Skeletal Complications

Metabolic syndrome (MetS) refers to the simultaneous presence of hypertension, hyperglycemia, dyslipidemia and/or visceral obesity, which predisposes a person to cardiovascular diseases and diabetes. Evidence suggesting the presence of direct and indirect associations between MetS and osteoporosis is growing. Many studies have reported the beneficial effects of polyphenols in alleviating MetS in in vivo and in vitro models through their antioxidant and anti-inflammation actions. This review aims to summarize the effects of honey (based on unifloral and multi-floral nectar sources) on bone metabolism and each component of MetS. A literature search was performed using the PubMed and Scopus databases using specific search strings. Original studies related to components of MetS and bone, and the effects of honey on components of MetS and bone were included. Honey polyphenols could act synergistically in alleviating MetS by preventing oxidative damage and inflammation. Honey intake is shown to reduce blood glucose levels and prevent excessive weight gain. It also improves lipid metabolism by reducing total cholesterol, triglycerides and low-density lipoprotein, as well as increasing high-density lipoprotein. Honey can prevent bone loss by reducing the adverse effects of MetS on bone homeostasis, apart from its direct action on the skeletal system. In conclusion, honey supplementation could be integrated into the management of MetS and MetS-induced bone loss as a preventive and adjunct therapeutic agent.

A promising biomarker of elevated galanin level in hypothalamus for osteoporosis risk in type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) and osteoporosis are two major healthcare problems worldwide. T2DM is considered to be a risk factor for osteoporosis. Interestingly, several epidemiological studies suggest that bone abnormalities associated with diabetes may differ, at least in part, from those associated with senile or post-menopausal osteoporosis. The growing prevalence that patients with T2DM simultaneously suffer from osteoporosis, puts forward the importance to discuss the relationship between both diseases, as well as to investigate correlative agents to treat them. Emerging evidences demonstrate that neuropeptide galanin is involved in the pathogenesis of T2DM and osteoporosis. Galanin via activation of central GALR2 increases insulin sensitivity as well as bone density and mass in animal models. The disorder of galanin function plays major role in development of both diseases. Importantly, galanin signaling is indispensable for ΔFosB, an AP1 antagonist, to play the bone mass-accruing effects in the ventral hypothalamic neurons of diabetic models. This review summarizes our and other recent studies to provide a new insight into the multivariate relationship among galanin, T2DM and osteoporosis, highlighting the beneficial effect of galanin on the comorbid state of both diseases. These may help us better understanding the pathogenesis of osteoporosis and T2DM and provide useful clues for further inquiry if elevated galanin level may be taken as a biomarker for both conjoint diseases, and GALR2 agonist may be taken as a novel therapeutic strategy to treat both diseases concurrently.

Caloric Intake in Renal Patients: Repercussions on Mineral Metabolism

The aim of this paper is to review current knowledge about how calorie intake influences mineral metabolism focussing on four aspects of major interest for the renal patient: (a) phosphate (P) handling, (b) fibroblast growth factor 23 (FGF23) and calcitriol synthesis and secretion, (c) metabolic bone disease, and (d) vascular calcification (VC). Caloric intake has been shown to modulate P balance in experimental models: high caloric intake promotes P retention, while caloric restriction decreases plasma P concentrations. Synthesis and secretion of the phosphaturic hormone FGF23 is directly influenced by energy intake; a direct correlation between caloric intake and FGF23 plasma concentrations has been shown in animals and humans. Moreover, in vitro, energy availability has been demonstrated to regulate FGF23 synthesis through mechanisms in which the molecular target of rapamycin (mTOR) signalling pathway is involved. Plasma calcitriol concentrations are inversely proportional to caloric intake due to modulation by FGF23 of the enzymes implicated in vitamin D metabolism. The effect of caloric intake on bone is controversial. High caloric intake has been reported to increase bone mass, but the associated changes in adipokines and cytokines may as well be deleterious for bone. Low caloric intake tends to reduce bone mass but also may provide indirect (through modulation of inflammation and insulin regulation) beneficial effects on bone. Finally, while VC has been shown to be exacerbated by diets with high caloric content, the opposite has not been demonstrated with low calorie intake. In conclusion, although prospective studies in humans are needed, when planning caloric intake for a renal patient, it is important to take into consideration the associated changes in mineral metabolism.

A non-pharmacological therapeutic approach in the gut triggers distal metabolic rewiring capable of ameliorating diet-induced dysfunctions encompassed by metabolic syndrome

Metabolic syndrome has increased at a worrisome level. Lifestyle changes are not sufficient to prevent and improve the adverse effects of obesity, thus novel interventions are necessary. The aim of this study was to investigate the use and metabolic outcomes of a non-pharmacological intervention in a high-fat diet (HFD) fed mouse model, capable of recapitulating key aspects of metabolic syndrome. We show that Policaptil Gel Retard has remarkable, beneficial effects on metabolic dysfunction caused by consumption of HFD. We describe the mechanism by which such effects are obtained, highlighting the fact that the amelioration of metabolic function observed upon Policaptil Gel Retard administration is profound and of systemic nature, despite being originated by sequestering, therefore non-pharmacological events elicited in the gut lumen.

Obesity-Induced Changes in Bone Marrow Homeostasis

Obesity is characterized by low-grade inflammation, which is accompanied by increased accumulation of immune cells in peripheral tissues including adipose tissue (AT), skeletal muscle, liver and pancreas, thereby impairing their primary metabolic functions in the regulation of glucose homeostasis. Obesity has also shown to have a detrimental effect on bone homeostasis by altering bone marrow and hematopoietic stem cell differentiation and thus impairing bone integrity and immune cell properties. The origin of immune cells arises in the bone marrow, which has been shown to be affected with the obesogenic condition via increased cellularity and shifting differentiation and function of hematopoietic and bone marrow mesenchymal stem cells in favor of myeloid progenitors and increased bone marrow adiposity. These obesity-induced changes in the bone marrow microenvironment lead to dramatic bone marrow remodeling and compromising immune cell functions, which in turn affect systemic inflammatory conditions and regulation of whole-body metabolism. However, there is limited information on the inflammatory secretory factors creating the bone marrow microenvironment and how these factors changed during metabolic complications. This review summarizes recent findings on inflammatory and cellular changes in the bone marrow in relation to obesity and further discuss whether dietary intervention or physical activity may have beneficial effects on the bone marrow microenvironment and whole-body metabolism.

Low bone mass is associated with carotid calcification plaque in Chinese postmenopausal women: the Chongqing osteoporosis study

Background: The aim of this study was to examine the relationship between low bone mass and the risk of carotid calcification plaques in Chinese postmenopausal women.Methods: We conducted a 5 years prospective study. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) scanning. Carotid computed tomography angiography (CTA) was conducted using a 64-multidetector row scanner to assess carotid arterial plaque at baseline and during follow-up. Cox proportional hazards analysis was used to evaluate the association of BMD and risk of carotid calcification plaques.Results: Four hundred and eighty-eight women sustained prospective carotid plaques during the follow-up. Women with carotid calcification plaques had low BMD than those with carotid non-calcification plaques. After adjustment for potential confounders, BMD, age, years since menopause, levels of plasma osteoprotegerin and adiponectin, hypertension, diabetes mellitus and hyperlipidemia were independently associated with increased risk of carotid calcification plaques. For carotid calcification plaques, a significant inverse correlation was indicated between BMD and the plaques, and a significant positive correlation was indicated between bone loss and plaques.Conclusions: This study suggested that lower BMD and increased loss rate of BMD were associated with a higher risk of carotid calcification plaques in Chinese postmenopausal women.

Mechanisms Involved in Childhood Obesity-Related Bone Fragility

Childhood obesity is one of the major health problems in western countries. The excessive accumulation of adipose tissue causes inflammation, oxidative stress, apoptosis, and mitochondrial dysfunctions. Thus, obesity leads to the development of severe co-morbidities including type 2 diabetes mellitus, liver steatosis, cardiovascular, and neurodegenerative diseases which can develop early in life. Furthermore, obese children have low bone mineral density and a greater risk of osteoporosis and fractures. The knowledge about the interplay bone tissue and between adipose is still growing, although recent findings suggest that adipose tissue activity on bone can be fat-depot specific. Obesity is associated to a low-grade inflammation that alters the expression of adiponectin, leptin, IL-6, Monocyte Chemotactic Protein 1 (MCP1), TRAIL, LIGHT/TNFSF14, OPG, and TNFα. These molecules can affect bone metabolism, thus resulting in osteoporosis. The purpose of this review was to deepen the cellular mechanisms by which obesity may facilitate osteoporosis and bone fractures.

Exploring the potential of tocotrienol from Bixa orellana as a single agent targeting metabolic syndrome and bone loss

Metabolic syndrome (MetS) is associated with osteoporosis due to the underlying inflammatory and hormonal changes. Annatto tocotrienol has been shown to improve medical complications associated with MetS or bone loss in animal studies. This study aimed to investigate the effects of annatto tocotrienol as a single treatment for MetS and osteoporosis in high-carbohydrate high-fat (HCHF) diet-induced MetS animals. Three-month-old male Wistar rats were randomly divided into five groups. The baseline group was euthanized at the onset of the study. The normal group received standard rat chow and tap water. The remaining groups received HCHF diet and treated with three different regimens orally daily: (a) tocopherol-stripped corn oil (the vehicle of tocotrienol), (b) 60 mg/kg annatto tocotrienol, and (c) 100 mg/kg annatto tocotrienol. At the end of the study, measurements of MetS parameters, body compositions, and bone mineral density were performed in animals before sacrifice. Upon euthanasia, blood and femur of the rats were harvested for the evaluations of bone microstructure, biomechanical strength, remodelling activities, hormonal changes, and inflammatory response. Treatment with annatto tocotrienol improved all MetS parameters (except abdominal obesity), trabecular bone microstructure, bone strength, increased osteoclast number, normalized hormonal changes and inflammatory response in the HCHF animals. In conclusion, annatto tocotrienol is a potential agent for managing MetS and osteoporosis concurrently. The beneficial effects of annatto tocotrienol may be attributed to its ability to prevent the hormonal changes and pro-inflammatory state in animals with MetS.

Osteoporosis is associated with metabolic syndrome induced by high-carbohydrate high-fat diet in a rat model

This study aimed to investigate the bone quality in rats induced with metabolic syndrome (MetS) using high-carbohydrate high-fat (HCHF) diet. Male Wistar rats (n = 14) were randomized into two groups. The normal group was given standard rat chow. The MetS group was given HCHF diet. Diet regimen was assigned for a period of 20 weeks. Metabolic syndrome parameters were measured monthly until MetS was established. Left tibiae were scanned using micro-computed tomography at week 0, 8, 12, 16, and 20 to analyze the trabecular and cortical bone structure. At the end of the study, rats were euthanized and their bones were harvested for analysis. Metabolic syndrome was established at week 12 in the HCHF rats. Significant deterioration of trabecular bone was observed at week 20 in the HCHF group (p < 0.05). The HCHF diet also decreased cortical and tissue area significantly (p < 0.05), but did not affect cortical thickness and bone calcium content (p > 0.05). Femur length and width in the HCHF group were significantly shorter than the normal group (p < 0.05). The biomechanical strength test showed that the femur of the HCHF rats could endure significantly lower force, but significantly higher displacement and strain compared to the normal rats (p < 0.05). In conclusion, HCHF diet-induced MetS can cause adverse effects on the bone.

Animal models of metabolic syndrome: a review

Metabolic syndrome (MetS) consists of several medical conditions that collectively predict the risk for cardiovascular disease better than the sum of individual conditions. The risk of developing MetS in human depends on synergy of both genetic and environmental factors. Being a multifactorial condition with alarming rate of prevalence nowadays, establishment of appropriate experimental animal models mimicking the disease state in humans is crucial in order to solve the difficulties in evaluating the pathophysiology of MetS in human. This review aims to summarize the underlying mechanisms involved in the pathophysiology of dietary, genetic, and pharmacological models of MetS. Furthermore, we will discuss the usefulness, suitability, pros and cons of these animal models. Even though numerous animal models of MetS have been established, further investigations on the invention of new animal model and clarification of plausible mechanisms are still necessary to confer a better understanding to researchers on the selection of animal models for their studies.

Molecular Mechanisms of Obesity-Induced Osteoporosis and Muscle Atrophy

Obesity and osteoporosis are two alarming health disorders prominent among middle and old age populations, and the numbers of those affected by these two disorders are increasing. It is estimated that more than 600 million adults are obese and over 200 million people have osteoporosis worldwide. Interestingly, both of these abnormalities share some common features including a genetic predisposition, and a common origin: bone marrow mesenchymal stromal cells. Obesity is characterized by the expression of leptin, adiponectin, interleukin 6 (IL-6), interleukin 10 (IL-10), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-α), macrophage colony stimulating factor (M-CSF), growth hormone (GH), parathyroid hormone (PTH), angiotensin II (Ang II), 5-hydroxy-tryptamine (5-HT), Advance glycation end products (AGE), and myostatin, which exert their effects by modulating the signaling pathways within bone and muscle. Chemical messengers (e.g., TNF-α, IL-6, AGE, leptins) that are upregulated or downregulated as a result of obesity have been shown to act as negative regulators of osteoblasts, osteocytes and muscles, as well as positive regulators of osteoclasts. These additive effects of obesity ultimately increase the risk for osteoporosis and muscle atrophy. The aim of this review is to identify the potential cellular mechanisms through which obesity may facilitate osteoporosis, muscle atrophy and bone fractures.

The Relationship between Metabolic Syndrome and Osteoporosis: A Review

Metabolic syndrome (MetS) and osteoporosis are two major healthcare problems worldwide. Metabolic syndrome is a constellation of medical conditions consisting of central obesity, hyperglycemia, hypertension, and dyslipidemia, in which each acts on bone tissue in different ways. The growing prevalence of MetS and osteoporosis in the population along with the controversial findings on the relationship between both conditions suggest the importance for further investigation and discussion on this topic. This review aims to assess the available evidence on the effects of each component of MetS on bone metabolism from the conventional to the contemporary. Previous studies suggested that the two conditions shared some common underlying pathways, which include regulation of calcium homeostasis, receptor activator of NF-κB ligand (RANKL)/receptor activator of the NF-κB (RANK)/osteoprotegerin (OPG) and Wnt-β-catenin signaling pathways. In conclusion, we suggest that MetS may have a potential role in developing osteoporosis and more studies are necessary to further prove this hypothesis.

Changes in Skeletal Integrity and Marrow Adiposity during High-Fat Diet and after Weight Loss

The prevalence of obesity has continued to rise over the past three decades leading to significant increases in obesity-related medical care costs from metabolic and non-metabolic sequelae. It is now clear that expansion of body fat leads to an increase in inflammation with systemic effects on metabolism. In mouse models of diet-induced obesity, there is also an expansion of bone marrow adipocytes. However, the persistence of these changes after weight loss has not been well described. The objective of this study was to investigate the impact of high-fat diet (HFD) and subsequent weight loss on skeletal parameters in C57Bl6/J mice. Male mice were given a normal chow diet (ND) or 60% HFD at 6 weeks of age for 12, 16, or 20 weeks. A third group of mice was put on HFD for 12 weeks and then on ND for 8 weeks to mimic weight loss. After these dietary challenges, the tibia and femur were removed and analyzed by micro computed-tomography for bone morphology. Decalcification followed by osmium staining was used to assess bone marrow adiposity, and mechanical testing was performed to assess bone strength. After 12, 16, or 20 weeks of HFD, mice had significant weight gain relative to controls. Body mass returned to normal after weight loss. Marrow adipose tissue (MAT) volume in the tibia increased after 16 weeks of HFD and persisted in the 20-week HFD group. Weight loss prevented HFD-induced MAT expansion. Trabecular bone volume fraction, mineral content, and number were decreased after 12, 16, or 20 weeks of HFD, relative to ND controls, with only partial recovery after weight loss. Mechanical testing demonstrated decreased fracture resistance after 20 weeks of HFD. Loss of mechanical integrity did not recover after weight loss. Our study demonstrates that HFD causes long-term, persistent changes in bone quality, despite prevention of marrow adipose tissue accumulation, as demonstrated through changes in bone morphology and mechanical strength in a mouse model of diet-induced obesity and weight loss.