The bone-adipose axis in obesity and weight loss

Revisiting the beyond BMI paradigm in excess weight diagnosis and management: A call to action

Adolphe Quételet, a 19th-century Belgian sociologist and statistician, pioneered the incorporation of statistics into social sciences. He initiated the development of anthropometry since he was interested in identifying the proportions of the 'ideal man'. He devised a ratio between weight and height, originally termed the Quételet Index, and today widely known and used as the body mass index or BMI. In 1835, he demonstrated that a normal curve accommodates the distribution of human traits articulating his reasoning on human variance around the average. Quételet's long-lasting legacy of the establishment of a simple measure to classify people's weight relative to an ideal for their height endures today with minor variations having dramatically influenced public health agendas. While being very useful, the limitations of the BMI are well known. Thus, revisiting the beyond BMI paradigm is a necessity in the era of precision medicine with morphofunctional assessment representing the way forward via incorporation of body composition and functionality appraisal. While healthcare systems were originally designed to address acute illnesses, today's demands require a radical rethinking together with an original reappraisal of our diagnosis and treatment approaches from a multidimensional perspective. Embracing new methodologies is the way forward to advance the field, gain a closer look at the underlying pathophysiology of excess weight, keep the spotlight on improving diagnostic performance and demonstrate its clinical validity. In order to provide every patient with the most accurate diagnosis together with the most appropriate management, a high degree of standardization and personalization is needed.

Patients who received sleeve gastrectomy have lower plasma osteopontin levels than those who did not

BACKGROUND

The aim of this study was to compare metabolic parameters, plasma Osteopontin (OPN) and Hepatocyte Growth Factor (HGF) levels between Sleeve Gastrectomy (SG) patients in their 6th post-operation month and healthy control patients.

METHODS

Height, weight, Body Mass Index (BMI) and laboratory parameters of 58 SG patients aged 18‒65 years (Group 1) and 46 healthy control patients (Group 2) were compared. In addition, preoperative and postoperative sixth-month BMI and laboratory parameters of the patients in Group 1 were compared.

RESULTS

The mean age and gender distributions of the groups were similar (p > 0.05). Mean BMI was 28.9 kg/m2 in Group 1 and 27 kg/m2 in Group 2 (p < 0.01). While plasma HGF levels were similar between both groups, plasma OPN levels were higher in Group 2 (p < 0.001). Fasting plasma glucose, total cholesterol, triglyceride, fasting plasma insulin and insulin resistance values were higher in Group 1, while alanine aminotransferase and aspartate aminotransferase levels were higher in Group 2 (p < 0.05). There was a strong correlation between plasma HGF and OPN levels in Group 1, but not in Group 2 (Rho = 0.805, p < 0.001).

CONCLUSION

OPN and HGF are promising biomarkers that can be used to better understand and detect problems related to obesity. The fact that patients in the early post-SG period had lower plasma OPN and similar plasma HGF compared to non-surgical patients of similar age and gender with higher BMI may be another favorable and previously unknown metabolic effect of SG.

Short-term effects of Roux-en-Y gastric bypass or gastric sleeve on bone mineral density and calciotropic hormones: a systematic review and meta-analysis

Roux-en-Y gastric bypass (RYGB) and gastric sleeve (GS) have been associated with significant reductions in bone mineral density (BMD) and fluctuations in serum levels of calciotropic hormones. These changes pose a risk to bone health. The study assessed the short-term (12 and 24 months) effects of RYGB and GS on BMD and calciotropic hormones. PubMed, Embase, and Cochrane Library databases were searched. Analyses considered follow-up (12 and 24 months) with BMD as main outcome at three sites (femoral neck, total hip, and lumbar spine) and one for each calciotropic hormone (25 OH vitamin D and parathyroid hormone [PTH]). Estimated effect sizes were calculated as standardized mean differences (SMD), confidence interval of 95%, and P value. Nine studies totaling 473 participants (RYGB = 261 and GS = 212) were included. RYGB resulted in lower BMD than GS at 12 months for femoral neck (SMD = -0.485, 95% CI [-0.768, -0.202], P = .001), lumbar spine (SMD = -0.471, 95% CI [-0.851, -0.092], P = .015), and total hip (SMD = -0.616, 95% CI [-0.972, -0.259], P = .001), and at 24 months for total hip (SMD = -0.572, 95% CI [-0.907, -0.238], P = .001). At 24 months, 25 OH vitamin D was lower in RYGB than GS (SMD = -0.958 [-1.670, -0.245], P = .008) and PTH levels were higher in RYGB than in GS (SMD = 0.968 [0.132, 1.804, P = .023]). RYGB demonstrated significant reduction in regional BMD. It also induces lower serum 25 OH vitamin D and higher PTH levels than GS. The results support the need for preventive bone health measures in the short-term postoperative period, especially in the case of RYGB.

Association between triglyceride glucose index and total bone mineral density: a cross-sectional study from NHANES 2011-2018

The Homeostatic Model Assessment for Triglyceride Glucose Index (TyG) and its related indices, including triglyceride glucose-waist circumference (TyG-WC), triglyceride glucose-waist-to-height ratio (TyG-WHtR) and triglyceride glucose-body mass index (TyG-BMI), has emerged as a practical tool for assessing insulin resistance in metabolic disorders. However, limited studies have explored the connection between TyG, TyG-related indices and osteoporosis. This population-based study, utilizing data from the National Health and Nutrition Examination Survey 2011-2018, involved 5456 participants. Through weighted multivariate linear regression and smoothed curve fitting, a significant positive correlation was found between TyG, TyG-related indices and total bone mineral density (BMD) after adjusting for covariates [β = 0.0124, 95% CI (0.0006, 0.0242), P = 0.0390; β = 0.0004, 95% CI (0.0003, 0.0004), P < 0.0001; β = 0.0116, 95% CI (0.0076, 0.0156), P < 0.0001; β = 0.0001, 95% CI (0.0001, 0.0001), P < 0.0001]. In subgroup analysis, race stratification significantly affected the relationship between TyG and total BMD. Additionally, gender and race were both significant for TyG-related indices. Non-linear relationships and threshold effects with inflection points at 9.106, 193.9265, 4.065, and 667.5304 (TyG, TyG-BMI, TyG-WHtR, TyG-WC) were identified. Saturation phenomena were observed between TyG-BMI, TyG-WC and total BMD with saturation thresholds at 314.177 and 1022.0428. These findings contributed to understanding the association between TyG, TyG-related indices and total BMD, offering insights for osteoporosis prevention and treatment.

Novel PFOS alternative OBS inhibits body growth of developing zebrafish by triggering thyroid function disorder and osteoclast differentiation

The extensive use of the perfluorooctane sulfonate (PFOS) alternative sodium p-perfluorous nonenoxybenzene sulfonate (OBS) has resulted in its widespread detection in the environment and enrichment in wildlife and humans. However, little is known about its potential toxicity, particularly in terms of body development. In this study, zebrafish embryos were acutely exposed to PFOS and OBS for a comparative developmental toxicity assessment. Both PFOS and OBS led to lower body weight and shorter body length, and the damaging effects of PFOS were more severe than those of OBS at the same exposure concentration. Biochemical assays of THs and transcription profiles correlated to the HPT axis demonstrated that OBS-induced body development inhibition resulted mainly from interference in THs synthesis, transfer, coupling with receptors, and conversion from T4 to T3, which was similar to the case of PFOS, except that the disruptive effects of OBS on thyroid function were more intense. Further transcriptome analysis showed that PFOS and OBS also promoted osteoclast differentiation, aggravating the inhibitory effects on body growth, and that PFOS had more obvious inhibitory effects than OBS. This study systematically explored the inhibitory effects of PFOS and OBS exposure on body development and tightly linked the toxic effects to thyroid function disorder and osteoclast differentiation. Our findings highlight that the health risks associated with OBS, an emerging substitute for PFOS, should not be ignored.

Bone mineral density saturation as influenced by the visceral adiposity index in adults older than 20 years: a population-based study

OBJECTIVE

The goal of this research was to determine whether or not there is a saturation effect and whether or not the visceral adiposity index (VAI) correlates with bone mineral density (BMD) in adult Americans.

METHODS

This study used multivariate logistic regression models to examine the association between VAI and total femur BMD, drawing on the most up-to-date data from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2018. Saturation levels and non-linear connections were calculated using a smooth curve-fitting algorithm and an investigation of saturation effects. Subgroup analyses and interaction tests were also conducted.

RESULTS

This study ultimately recruited 6257 individuals aged 20 years or older. According to multivariate regression analysis, those with high VAI scores exhibited higher total femur BMD. Total femur BMD was greater in the highest VAI quartile (Q4: 0.060 g/cm2) after adjustment than in the lowest VAI quartile (Q1) (P < 0.05). After controlling for variables, subgroup analysis failed to reveal any significant interaction effects. Furthermore, the study determined that VAI and BMD exhibited a specific saturation effect through the investigation of the saturation effect and the fitting of smooth curves. Saturation effect investigation of total femur BMD using VAI revealed a saturation value of 3.3.

CONCLUSION

The present study uncovered a non-linear relationship between VAI and total femur BMD, which exhibited a saturation effect.

A cross-sectional study from NHANES found a positive association between obesity with bone mineral density among postmenopausal women

PURPOSE

Obesity has been demonstrated to improve bone mineral density (BMD), according to previous research. Nevertheless, there is a dearth of clarity regarding the optimal body mass index (BMI) and waist circumference (WC) for achieving the highest beneficial BMD in postmenopausal women. The objective of this study was to establish the correlation between obesity and BMD.

METHODS

The relationship between BMI, WC, and BMD was examined by using multivariate logistic regression models, fitting smoothing curves and utilizing the latest data from the National Health and Nutrition Examination Survey (NHANES) survey conducted between 2007 and 2018. Furthermore, the analysis of saturation effects was employed to examine the association of nonlinear connections among BMI, WC, and BMD.

RESULTS

The research examined information from a combination of 564 participants. A significant correlation between BMD and BMI as well as WC was observed in our findings. The enduring correlation between BMI and WC with BMD was demonstrated across subgroup analyses categorized by age and race, except among other Hispanic and other race. Furthermore, the smoothing curve fitting indicated that there existed not just a linear correlation among BMI, WC, and BMD, but also a saturation threshold in the association of these three factors.

CONCLUSIONS

Based on our study, we have found a strong and positive relationship between obesity and BMD. According to the results of this research, maintaining obesity at a moderate level in postmenopausal women would result in achieving an optimal equilibrium between obesity and BMD.

High-Dose Intravenous Steroid Treatment Seems to Have No Long-Term Negative Effect on Bone Mineral Density of Young and Newly Diagnosed Multiple Sclerosis Patients: A Pilot Study

High-dose intravenous steroid treatment (HDIST) represents the first choice of treatment for multiple sclerosis (MS) relapses. Chronic oral glucocorticoid (GC) administration correlates with bone loss whereas data regarding HDIST in MS are still conflicting. Twenty-five newly diagnosed MS patients (NDMSP) (median age: 37 years) were prospectively studied for the effects of HDIST on bone mineral density (BMD) and bone metabolism. Patients received 1000 mg methylprednisolone intravenously every day for 5 days followed by oral prednisolone tapering over 21 days. Bone metabolism indices were determined prior to GC, on days 2, 4, 6, and 90, and at months 6, 12, 18, and 24 post GC therapy. Femoral, lumbar-spine BMD, and whole-body measurement of adipose/lean tissue were assessed prior to GC-administration and then every six months. Ten patients completed the study. N-terminal-propeptide-procollagen-type-1 and bone-specific alkaline phosphatase showed a significant increase at day-90 (p < 0.05). A transient non-significant fall of BMD was observed at 6 months after GC-administration, which subsequently appeared to be restored. We conclude that HDIST seems not to have long-term negative effects on BMD, while the observed transient increase of bone formation markers probably indicates a high bone turnover phase to GC-administration. Additional prospective studies with larger sample size are needed.

Higher BMI and lower femoral neck strength in males with type 2 diabetes mellitus and normal bone mineral density

BACKGROUND

Type 2 diabetes mellitus (T2DM) and osteoporosis are two age-associated diseases. Body mass index (BMI) is positively associated with osteoporosis or osteopenia in T2DM population. Bone mineral density does not necessarily reflect the alterations in bone microarchitecture. Our aims were to investigate the relationship between BMI and femoral neck strength in males with T2DM and normal range of bone mineral density (BMD).

METHODS

This study enrolled 115 males (median age 53.3 years) with T2DM and normal BMD. Femoral neck strength indexes, including compression strength index (CSI), bending strength index (BSI), impact strength index (ISI), were calculated by parameters generated from Dual-energy X-ray absorptiometry software. Pearson correlation analysis was performed to evaluate the relationships between BMI and femoral neck strength variables.

RESULTS

Compared with T2DM-normal weight group, T2DM-overweight group and T2DM-obesity group had a higher femur neck and total femur BMDs. Cross sectional moment of inertia (CSMI), cross sectional area (CSA), section modulus (SM) were significantly higher (all p<0.05), and buckling ratio (BR) (6.35±2.08 vs 7.18±1.71) was lower in T2DM-obesity group than in T2DM-normal weight group. Compared with T2DM-normal weight group, CSI (all p<0.001), BSI (all p<0.001), ISI (all p<0.001) were significantly reduced in T2DM-obesity and T2DM-overweight groups. Pearson correlation analysis indicated that BMI was negatively correlated with CSI (r= - 0.457, p<0.001), BSI(r = -0.397, p<0.001), ISI (r = - 0.414, p<0.001).

CONCLUSIONS

Higher BMI is associated with lower femoral neck strength in males with T2DM and normal BMD. It implies that femoral neck fracture risk increases in obese and diabetic males, despite their high bone density.

Knockdown of CDC20 promotes adipogenesis of bone marrow-derived stem cells by modulating β-catenin

Background

Bone is a rigid organ that provides physical protection and support to vital organs of the body. Bone loss disorders are commonly associated with increased bone marrow adipose tissue. Bone marrow mesenchymal stromal/stem cells (BMSCs) are multipotent progenitors that can differentiate into osteoblasts, adipocytes, and chondrocytes. Cell division cycle 20 (CDC20) is a co-activator of anaphase promoting complex/cyclosome (APC/C), and is required for ubiquitin ligase activity. Our previous study showed that CDC20 promoted the osteogenic commitment of BMSCs and Cdc20 conditional knockout mice suggested a decline in bone mass. In this study, we found that knockdown of CDC20 promoted adipogenic differentiation of BMSCs by modulating β-catenin, which suggested a link between adipogenesis and osteogenesis.

Methods

Lentivirus containing a CDC20 shRNA was used for CDC20 knockdown in human BMSCs (hBMSCs). Primary mouse BMSCs (mBMSCs) were isolated from Cdc20^f/f and Sp7-Cre;Cdc20^f/f mice. Adipogenesis was examined using quantitative real-time reverse transcription PCR (qRT-PCR) and western blotting analysis of adipogenic regulators, Oil Red O staining, and transplantation into nude mice. CDC20 knockout efficiency was determined through immunochemistry, qRT-PCR, and western blotting of bone marrow. Accumulation of adiposity was measured through histology and staining of bone sections. Exploration of the molecular mechanism was determined through western blotting, Oil Red O staining, and qRT-PCR.

Results

CDC20 expression in hBMSCs was significantly decreased during adipogenic differentiation. CDC20 knockdown enhanced hBMSC adipogenic differentiation in vitro. CDC20-knockdown hBMSCs showed more adipose tissue-like constructs upon hematoxylin and eosin (H&E) and Oil Red O staining. Sp7-Cre;Cdc20^f/f mice presented increased adipocytes in their bone marrow compared with the control mice. mBMSCs from Sp7-Cre;Cdc20^f/f mice showed upregulated adipogenic differentiation. Knockdown of CDC20 led to decreased β-catenin levels, and a β-catenin pathway activator (lithium chloride) abolished the role of CDC20 in BMSC adipogenic differentiation.

Conclusions

Our findings showed that CDC20 knockdown enhanced adipogenesis of hBMSC and mBMSCs adipogenesis in vitro and in vivo. CDC20 regulates both adipogenesis and osteogenesis of BMSCs, and might lead to the development of new therapeutic targets for “fatty bone” and osteoporosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-03062-0.

Effects of Extracellular Vesicles from Osteogenic Differentiated Human BMSCs on Osteogenic and Adipogenic Differentiation Capacity of Naïve Human BMSCs

Osteoporosis, or steroid-induced osteonecrosis of the hip, is accompanied by increased bone marrow adipogenesis. Such a disorder of adipogenic/osteogenic differentiation, affecting bone-marrow-derived mesenchymal stem cells (BMSCs), contributes to bone loss during aging. Here, we investigated the effects of extracellular vesicles (EVs) isolated from human (h)BMSCs during different stages of osteogenic differentiation on the osteogenic and adipogenic differentiation capacity of naïve (undifferentiated) hBMSCs. We observed that all EV groups increased viability and proliferation capacity and suppressed the apoptosis of naïve hBMSCs. In particular, EVs derived from hBMSCs at late-stage osteogenic differentiation promoted the osteogenic potential of naïve hBMSCs more effectively than EVs derived from naïve hBMSCs (naïve EVs), as indicated by the increased gene expression of COL1A1 and OPN. In contrast, the adipogenic differentiation capacity of naïve hBMSCs was inhibited by treatment with EVs from osteogenic differentiated hBMSCs. Proteomic analysis revealed that osteogenic EVs and naïve EVs contained distinct protein profiles, with pro-osteogenic and anti-adipogenic proteins encapsulated in osteogenic EVs. We speculate that osteogenic EVs could serve as an intercellular communication system between bone- and bone-marrow adipose tissue, for transporting osteogenic factors and thus favoring pro-osteogenic processes. Our data may support the theory of an endocrine circuit with the skeleton functioning as a ductless gland.

The Predictive Role of Parathyroid Hormone for Nonalcoholic Fatty Liver Disease following Bariatric Surgery

Background

Morbid obesity is frequently complicated by chronic liver diseases, including nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), and fibrosis. Parathyroid hormone (PTH) is found to be elevated in morbid obesity due to the defective hepatic metabolism of vitamin D. Bariatric surgery is performed to help patients with BMI>40 kg/m² to effectively lose weight, particularly in patients with obesity who are afflicted with complications such as NAFLD/NASH.

Objective

This study aimed to evaluate the PTH level as a predictor of hepatic function in individuals with morbid obesity who have undergone bariatric surgery.

Methods

Ninety subjects with morbid obesity referred for Roux en-Y gastric bypass surgery were recruited. After IRB approval, demographic profiles, anthropometric factors, liver biopsy, and laboratory tests were obtained. The two-dimensional shear wave elastography (2D-SWE) technique was applied to assess hepatic stiffness.

Results

A significant reduction occurred six months after bariatric surgery in the anthropometric indices (p < 0.001), hepatic elasticity (p=0.002), alanine aminotransferase (p < 0.001), serum alkaline phosphatase (p < 0.001), gamma-glutamyl transpeptidase (GGT) (p < 0.001), and nonalcoholic fatty liver disease fibrosis score (NFS) (p < 0.001). Serum PTH concentration was not predictive of postsurgical liver fibrosis and steatosis at six months but could predict weight loss success rate. No significant alteration in serum PTH levels was observed between presurgical vs. postsurgical time points.

Conclusion

A significant reduction was observed in the anthropometric parameters, liver enzymes, and hepatic elasticity after bariatric surgery. No significant effect was found on PTH levels.

Saturation Effect of Body Mass Index on Bone Mineral Density in Adolescents of Different Ages: A Population-Based Study

BACKGROUND

Adolescence is a critical period for bone development, and peak bone mass may be reached in late adolescence. Boosting bone accumulation at this time can help preserve adult bone health and avoid osteoporosis later in life. Body mass index (BMI) has been found to have a favorable impact on bone mineral density (BMD) in previous research. However, excessive obesity is harmful to health and may lead to various systemic diseases. Therefore, finding an appropriate BMI to maintain a balance between obesity and BMD is critical for adolescents.

METHODS

The datasets from the National Health and Nutrition Examination Survey (NHANES) 2011-2020 were used in a cross-sectional investigation. Multivariate linear regression models were used to examine the linear connection between BMI and BMD. Fitted smoothing curves and threshold effect analysis were used to describe the nonlinear relationship. Subgroup analyses were then conducted based on gender and age.

RESULTS

This population-based study included a total of 6,143 adolescents aged 8-19 years. In a multivariate linear regression analysis, a good association between BMI and total BMD was shown [0.014 (0.013, 0.014)]. This positive association was maintained in all subgroup analyses grouped by sex and age. Furthermore, the association between BMI and BMD was nonlinear with a saturation point present, as evidenced by smoothed curve fitting. According to the threshold effect study, with an age group of two years, adolescents of different ages had different BMI saturation values with respect to BMD.

CONCLUSIONS

Our study showed a significant positive and saturated association between BMI and BMD in adolescents aged 8-19 years. Maintaining BMI at saturation values may reduce other adverse effects while achieving optimal BMD.

The Saturation Effect of Obesity on Bone Mineral Density for Older People: The NHANES 2017-2020

INTRODUCTION

Previous studies have shown that obesity has a positive effect on bone mineral density (BMD). However, excessive obesity is harmful to health, especially in older adults. In addition, it is unclear what body mass index (BMI) and waist circumference (WC) to maintain for the most beneficial BMD in older adults.

METHODS

Multivariate logistic regression models were used to investigate the association between BMI, WC, and femoral neck BMD using the most recent data from the 2017-2020 National Health and Nutrition Examination Survey (NHANES). Fitting smoothing curves and saturation effects analysis were also used to determine the association of nonlinear relationships between BMI, WC, and femoral neck BMD.

RESULTS

The analysis included a total of 2,903 adults. We discovered that BMD and WC were positively linked to femoral neck BMD. The favorable associations of BMI and WC with femoral neck BMD were maintained in all subgroup analyses stratified by sex and race, except among Mexican Americans. Furthermore, smoothing curve fitting revealed that the link between BMI and BMD was not only a linear connection, and that there was a saturation point. The BMI saturation value in the femoral neck BMD was 24.3 (kg/m²), according to the saturation effect analysis.

CONCLUSIONS

In persons over the age of 50, our research found a positive relationship between obesity and BMD, and we also found a saturation value between BMI and BMD. According to this study, maintaining BMI at a moderate level (about 24.3 kg/m²) would result in an optimal balance between BMI and BMD in adults over 50 years of age.

OUP accepted manuscript

Cells of the stromal vascular fraction (SVF) of human adipose tissue have the capacity to generate osteogenic grafts with intrinsic vasculogenic properties. However, cultured adipose-derived stromal cells (ASCs), even after minimal monolayer expansion, lose osteogenic capacity in vivo. Communication between endothelial and stromal/mesenchymal cell lineages has been suggested to improve bone formation and vascularization by engineered tissues. Here, we investigated the specific role of a subpopulation of SVF cells positive for T-cadherin (T-cad), a putative endothelial marker. We found that maintenance during monolayer expansion of a T-cad-positive cell population, composed of endothelial lineage cells (ECs), is mandatory to preserve the osteogenic capacity of SVF cells in vivo and strongly supports their vasculogenic properties. Depletion of T-cad-positive cells from the SVF totally impaired bone formation in vivo and strongly reduced vascularization by SVF cells in association with decreased VEGF and Adiponectin expression. The osteogenic potential of T-cad-depleted SVF cells was fully rescued by co-culture with ECs from a human umbilical vein (HUVECs), constitutively expressing T-cad. Ectopic expression of T-cad in ASCs stimulated mineralization in vitro but failed to rescue osteogenic potential in vivo, indicating that the endothelial nature of the T-cad-positive cells is the key factor for induction of osteogenesis in engineered grafts based on SVF cells. This study demonstrates that crosstalk between stromal and T-cad expressing endothelial cells within adipose tissue critically regulates osteogenesis, with VEGF and adiponectin as associated molecular mediators.

Association between Sensitivity to Thyroid Hormone Indices and Bone Mineral Density in US Males

OBJECTIVES

Thyroid hormone is acknowledged as a pivotal factor in skeletal development and adult bone maintenance. However, available data about the relationship between sensitivity to thyroid hormone and bone mineral density (BMD) remain limited and conflicting. The purpose of the study was to explore the complex relationship between sensitivity to thyroid hormone indices and BMD using cross-sectional analysis.

METHODS

An overall sample of 3,107 males from the National Health and Nutrition Examination Survey (NHANES) was studied in the study. The thyroid hormone sensitivity indices included free triiodothyronine/tree thyroxine (FT3/FT4), thyroid-stimulating hormone index (TSHI), thyrotroph thyroxine resistance index (TT4RI), and thyroid feedback quantile-based index (TFQI). Given the complex study design and sample weights, the correlation between sensitivity to thyroid hormone indices and BMD was evaluated through multivariate linear regression models, and extra subgroup analyses were performed to examine the robustness of the results.

RESULTS

Among the 3,107 participants, we demonstrated that FT3/FT4 was negatively correlated with lumbar BMD (β = -0.0.35, 95% CI: -0.084-0.013, P < 0.05). In the terms of central sensitivity to thyroid hormone, TFQI showed a significant negative relationship with the BMD of the lumbar (β = -0.018, 95% CI: -0.033 to -0.003, P < 0.05), total femur (β = -0.020, 95% CI: -0.035 to -0.006, P < 0.01), and femur neck (β = -0.018, 95% CI: -0.031 to -0.005, P < 0.01). In the subgroup analyses stratified by body mass index (BMI), the significant negative correlation between TFQI and lumbar BMD remained in the male participants with BMI between 18.5 and 24.9 kg/m².

CONCLUSIONS

Decreased indices of sensitivity to thyroid hormones are strongly associated with increased lumbar BMD, suggesting that the dysfunction of peripheral and central response to thyroid hormone might contribute to bone loss. In addition, FT3/FT4 and TFQI were considered to be the preferable indicators to guide the prevention and clinical treatment of osteoporosis.

Bone Response to High-Intensity Interval Training versus Moderate-Intensity Continuous Training in Adolescents with Obesity

INTRODUCTION

Since adolescents with obesity are prone to bone fragility during weight loss, the aim was to compare the impact of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on bone density, geometry, and strength.

METHODS

Sixty-one adolescents were randomly assigned to 2 cycling trainings (HIIT and MICT) and a control (CTR, without training) group. Anthropometry, dual-energy X-ray absorptiometry with hip structural analysis and the trabecular bone score (TBS) were assessed before and after the 16-week intervention.

RESULTS

Body mass index (BMI) and fat mass (FM) percentage decreased at T1 versus T0 in both training groups (p < 0.001 for HIIT, p = 0.01 for MICT), though to a larger extent in HIIT (p < 0.05). Total body bone mineral density (BMD) and bone mineral content (BMC) increased in both training groups (p < 0.001), but to a greater extent in HIIT for BMC (p < 0.05). Lumbar spine BMD and BMC increased in both training groups (p < 0.001 for HIIT, p < 0.01 for MICT), with a time × group interaction between HIIT and CTR (p < 0.05) only. TBS increased in both training groups (p < 0.01 for HIIT, p < 0.05 for MICT). Hip BMD and BMC increased in both HIIT (p < 0.001 and p < 0.01) and MICT (p < 0.01 and p < 0.05). At the narrow neck (NN), endocortical diameter, width (p < 0.01), cross-sectional moment of inertia, and section modulus (Z) (p < 0.05) increased only in the HIIT group, such as BMD and Z (p < 0.05) at the intertrochanteric region (IT) and average cortical thickness (p < 0.001) and width (p < 0.05) at the femoral shaft. At the NN and IT, the buckling ratio decreased only in the HIIT group (p < 0.05), predicting higher resistance to fracture.

CONCLUSIONS

In addition to inducing greater BMI and FM percentage decreases in comparison to MICT, HIIT improves multisite bone density, geometry, and strength, which heighten the justification for HIIT as part of weight loss interventions in adolescents with obesity.

Does the severity of obesity influence bone density, geometry and strength in adolescents?

BACKGROUND

Relationships between the severity of obesity and bone health remain underexplored.

OBJECTIVES

To compare whole-body and localized bone mineral content (BMC) and density (BMD), trabecular bone score (TBS) and hip geometry and strength between adolescents with obesity versus extreme obesity.

METHODS

This cross-sectional study included 154 adolescents (12-15 years, 62% females) who were classified as having obesity (OG, [95th-99th] percentile) or extreme obesity (EOG, >99th percentile). Fat mass (FM), lean mass (LM), BMC, BMD for total-body-less-head (TBLH), lumbar spine (LS), hip, TBS and geometric and strength indices at the narrow-neck (NN), femoral shaft (FS) and intertrochanteric regions (IT) were assessed by Dual-X-ray Absorptiometry (DXA).

RESULTS

There was no significant sex-interaction. For both sexes, TBLH BMC and BMD were not different between groups. TBS was lower in EOG compared with OG in both sexes in univariate analysis and after adjustment with maturation and body weight (p < 0.05). Hip BMD was significantly higher in the EOG compared to OG only after adjustment with maturation and fat mass percentage (p < 0.05 for men, p < 0.01 for women). For both sexes, TBLH, LS and hip BMC and BMD positively correlated with weight, BMI, LM and FM. TBS negatively correlated with BMI-percentile in both sexes, with a negative correlation with FM for males alone. Hip BMC and BMD, BMD, ACT and CSA at the three hip sites positively correlated with BMI-percentile in males.

CONCLUSIONS

Extreme obesity impacts bone health depending on anatomical sites, altering lumbar trabecular bone in both males and females adolescents.

The Saturation Effect of Body Mass Index on Bone Mineral Density for People Over 50 Years Old: A Cross-Sectional Study of the US Population

Background: Previous studies had revealed that Body Mass Index (BMI) positively affected Bone Mineral Density (BMD). However, an excessively high BMI was detrimental to health, especially for the elderly. Moreover, it was elusive how much BMI was most beneficial for BMD in older adults to maintain.

Objective: To investigate whether there was a BMI saturation effect value that existed to maintain optimal BMD.

Methods: A cross-sectional study was conducted using the datasets of the National Health and Nutrition Examination Survey (NHANES) 2005–2006, 2007–2008, 2009–2010, 2013–2014, and 2017–2018. After adjusting for covariates, an analysis of the association between BMI and BMD in different femoral regions (Total femur, Femoral neck, Trochanter, Intertrochanter, and Ward's triangle) and lumbar spine regions (Total spine, L1, L2, L3, and L4) in the whole population was performed using the multivariate linear regression models, smoothing curve fitting, and saturation effects analysis models. Then, subgroup analyses were performed according to gender, age, and race.

Results: A total of 10,910 participants (5,654 males and 5,256 females) over 50 years were enrolled in this population-based study. Multivariate linear regression analyses in the population older than 50 years showed that BMI was positively associated with femoral BMD and lumbar spine BMD (P < 0.001, respectively). Smoothing curve fitting showed that the relationship between BMI and BMD was not simply linear and that a saturation value existed. The saturation effect analysis showed that the BMI saturation value was 26.13 (kg/m²) in the total femur, 26.82 (kg/m²) in the total spine, and showed site-specificity in L1 (31.90 kg/m²) and L2 (30.89 kg/m²). The saturation values were consistent with the whole participants in males, while there was high variability in the females. BMI saturation values remained present in subgroup analyses by age and race, showing specificity in some age (60–70 years old) groups and in some races.

Conclusions: Our study showed a saturation value association between BMI and BMD for people over 50 years old. Keeping the BMI in the slightly overweight value (around 26 kg/m²) might reduce other adverse effects while obtaining optimal BMD.

Effect of body mass index on bone mineral density is age-specific

BACKGROUND AND AIMS

Obesity and osteoporosis are two important and growing public health problems worldwide. Body mass index (BMI) has been found to be inversely related to the risk of osteoporotic fracture. We aimed to assess the association of BMI with thoracic vertebral bone mineral density (BMD) measured from a quantitative computed tomography (QCT).

METHODS AND RESULTS

We retrospectively evaluated the data from 15,758 consecutive patients (5675 females and 10,083 males) between age 20-90 years, who underwent Coronary Artery Calcium (CAC) scoring. Quantitative data analyses of thoracic trabecular BMD (mg/cm³) was performed with a phantom system or phantomless using validated software. The gender-specific subgroup was divided based on age (<45, 45-55, 55-65, >65 yrs in females; <40,40-60,>60 yrs in Males) and weight by BMI (kg/m²) as < 25 (normal or low weight), >25 - <30 (overweight) and >30 (obesity). Analysis of variance (ANOVA) and Scheffe's post hoc procedure tested the association of body weight/BMI on BMD. A significant positive association between the body weight and BMD existed in obese population in elder groups in both genders (p < 0.05). There was no significant difference in BMD in 40-60 years in men and <55 years in women with normal or low weight compared to overweight or obese cohorts.

CONCLUSIONS

We concluded that the effect of weight on BMD is age-specific and the BMD should be monitored routinely with a cardiac CT scan in the senile population.

Adiposity and bone microarchitecture in the GLOW study

Low body mass index (BMI) is an established risk factor for fractures in postmenopausal women but the interaction of obesity with bone microarchitecture is not fully understood. In this study, obesity was associated with more favourable bone microarchitecture parameters but not after parameters were normalised for body weight.

INTRODUCTION

To examine bone microarchitecture in relation to fat mass and examine both areal bone mineral density (aBMD) and microarchitecture in relation to BMI categories in the UK arm of the Global Longitudinal Study of Osteoporosis in Women.

METHODS

Four hundred and ninety-one women completed questionnaires detailing medical history; underwent anthropometric assessment; high-resolution peripheral quantitative computed tomography (HRpQCT) scans of the radius and tibia and DXA scans of whole body, proximal femur and lumbar spine. Fat mass index (FMI) residuals (independent of lean mass index) were derived. Linear regression was used to examine HRpQCT and DXA aBMD parameters according to BMI category (unadjusted) and HRpQCT parameters in relation to FMI residuals (with and without adjustment for anthropometric, demographic and lifestyle covariates).

RESULTS

Mean (SD) age was 70.9 (5.4) years; 35.0% were overweight, 14.5% class 1 obese and 7.7% class 2/3 obese. There were significant increasing trends according to BMI category in aBMD of whole body, hip, femoral neck and lumbar spine (p ≤ 0.001); cortical area (p < 0.001), thickness (p < 0.001) and volumetric density (p < 0.03), and trabecular number (p < 0.001), volumetric density (p < 0.04) and separation (p < 0.001 for decreasing trend) at the radius and tibia. When normalised for body weight, all HRpQCT and DXA aBMD parameters decreased as BMI increased (p < 0.001). FMI residuals were associated with bone size and trabecular architecture at the radius and tibia, and tibial cortical microarchitecture.

CONCLUSION

Significant trends in HRpQCT parameters suggested favourable bone microarchitecture at the radius and tibia with increasing BMI but these were not proportionate to increased weight.

Novel regulatory roles of UCP1 in osteoblasts

AIMS

The bone-adipose axis requires complex homeostasis in energy and global metabolism. The bioenergetics of bone establishes the necessary energy balance to coordinate endocrine functions that are affected by various factors and is not limited to matrix proteins only. UCP1 is an uncoupling protein of adipocytes, commonly known for its unique feature of promoting thermogenesis, mainly in brown fat; however, the effects of UCP1 in other cell types remain unreported.

MAIN METHODS

In the current study, we determined the roles of UCP1 in osteoblasts by silencing the Ucp1 gene in MC-3T3-E1 cells, as well as C3H10T1/2 mesenchymal stem cells, and explored its functional activities.

KEY FINDINGS

Our results demonstrate for the first time the presence of UCP1 in osteoblast cells. We identified that UCP1 regulates ATP and oxidative phosphorylation in MC-3T3-E1 cells. In addition, our data reveal that the lack of Ucp1 results in reduced expressions of regulatory proteins involved in scavenging of ROS by enhancing an autophagic event to balance osteogenic differentiation.

SIGNIFICANCE

In conclusion, this study highlights a novel perspective on the importance of UCP1 in bone cells.

LGR4 Gene Polymorphisms Are Associated With Bone and Obesity Phenotypes in Chinese Female Nuclear Families

OBJECTIVE

The current study was conducted to determine whether peak bone mineral density (BMD) and obesity phenotypes are associated with certain LGR4 gene polymorphisms found in Chinese nuclear families with female children.

METHODS

A total of 22 single nucleotide polymorphisms (SNPs) located in and around the LGR4 gene were identified in 1,300 subjects who were members of 390 Chinese nuclear families with female children. Then, BMD readings of the femoral neck, total hip, and lumbar spine as well as measurements of the total lean mass (TLM), total fat mass (TFM), and trunk fat mass were obtained via dual-energy X-ray absorptiometry. The quantitative transmission disequilibrium test was used to analyze the associations between specific SNPs and LGR4 haplotypes and peak BMD as well as between LGR4 haplotypes and TLM, percent lean mass, TFM, percent fat mass, trunk fat mass, and body mass index (BMI).

RESULTS

Here, rs7936621 was significantly associated with the BMD values for the total hip and lumbar spine, while rs10835171 and rs6484295 were associated with the trunk fat mass and BMI, respectively. Regarding the haplotypes, we found significant associations between GAA in block 2 and trunk fat mass and BMI, between AGCGT in block 3 and total hip BMD, between TGCTCC in block 5 and femoral neck BMD, and between TACTTC in block 5 and both lumbar spine and femoral neck BMD (all P-values < 0.05).

CONCLUSION

Genetic variations of the LGR4 gene are related to peak BMD, BMI, and trunk fat mass.

Barocrinology: The Endocrinology of Obesity from Bench to Bedside

Obesity has reached pandemic proportions. Hormonal and metabolic imbalances are the key factors that lead to obesity. South Asian populations have a unique phenotype, peculiar dietary practices, and a high prevalence of consanguinity. Moreover, many lower middle-income countries lack appropriate resources, super-specialists, and affordability to manage this complex disorder. Of late, there has been a substantial increase in both obesity and diabesity in India. Thus, many more patients are being managed by different types of bariatric procedures today than ever before. These patients have many types of endocrine and metabolic disturbances before and after bariatric surgery. Therefore, these patients should be managed by experts who have knowledge of both bariatric surgery and endocrinology. The authors propose “Barocrinology”, a novel terminology in medical literature, to comprehensively describe the field of obesity medicine highlighting the role of knowing endocrine physiology for understating its evolution, insights into its complications and appreciating the changes in the hormonal milieu following weight loss therapies including bariatric surgery. Barocrinology, coined as a portmanteau of “baro” (weight) and endocrinology, focuses upon the endocrine and metabolic domains of weight physiology and pathology. This review summarizes the key pointers of bariatric management from an endocrine perspective.

Bone response to eccentric versus concentric cycling in adolescents with obesity

OBJECTIVES

Because adolescents with obesity are susceptible to bone fragility during weight loss (WL), we evaluated the impact of eccentric (ECC) versus classical concentric (CON) training at the same oxygen consumption (V˙O₂) on bone density, geometry and strength.

METHODS

Thirty five adolescents were included into 2 training (CON and ECC cycling) and a control (CTR, without training) groups. Anthropometry, dual-energy X-ray absorptiometry, hip structural analysis and quantitative bone ultrasound were assessed before and after the 12-week intervention.

RESULTS

The trainings promoted significant improvements in body mass index, total fat (FM) and lean mass (LM), with better improvements for FM and LM in the ECC group (p < 0.05). Leg LM percentage increased only in the ECC group (p < 0.05). Total body bone mineral content and density increased in both training groups (p < 0.001) with significant time x group interactions only between ECC and CTR (p < 0.05). Buckling ratio at the intertrochanteric region and femoral shaft increased only in CTR and CON groups (p < 0.05). Speeds of sounds at the calcaneum increased only in ECC group (p < 0.01).

CONCLUSIONS

Bone fragility, from a compromised relationship between density, geometry and strength, might be prevented with the ECC modality.

The impact of genetic polymorphisms on weight regain after successful weight loss

Obesity is associated with an increased risk of various diseases and mortality. Although nearly 50 % of adults have been reported trying to lose weight, the prevalence of obesity has increased. One factor that hinders weight loss-induced decrease in obesity prevalence is weight regain. Although behavioural, psychological and physiological factors associated with weight regain have been reviewed, the information regarding the relationship between weight regain and genetics has not been previously summarised. In this paper, we comprehensively review the association between genetic polymorphisms and weight regain in adults and children with obesity after weight loss. Based on this information, identification of genetic polymorphism in patients who undergo weight loss intervention might be used to estimate their risks of weight regain. Additionally, the genetic-based risk estimation may be used as a guide for physicians and dietitians to provide each of their patients with the most appropriate strategies for weight loss and weight maintenance.

Two novel pleiotropic loci associated with osteoporosis and abdominal obesity

Aiming to uncover a shared genetic basis of abdominal obesity and osteoporosis, we performed a bivariate GWAS meta-analysis of femoral neck BMD (FNK-BMD) and trunk fat mass adjusted by trunk lean mass (TFMadj) in 11,496 subjects from 6 samples, followed by in silico replication in the large-scale UK Biobank (UKB) cohort. A series of functional investigations were conducted on the identified variants. Bivariate GWAS meta-analysis identified two novel pleiotropic loci 12q15 (lead SNP rs73134637, p = 3.45 × 10-7) and 10p14 (lead SNP rs2892347, p = 2.63 × 10-7) that were suggestively associated and that were replicated in the analyses of related traits in the UKB sample (osteoporosis p = 0.06 and 0.02, BMI p = 0.03 and 4.61 × 10-3, N up to 499,520). Cis-eQTL analysis demonstrated that allele C at rs73134637 was positively associated with IFNG expression in whole blood (N = 369, p = 0.04), and allele A at rs11254759 (10p14, p = 9.49 × 10-7) was negatively associated with PRKCQ expression in visceral adipose tissue (N = 313, p = 0.04) and in lymphocytes (N = 117, p = 0.03). As a proof-of-principle experiment, the function of rs11254759, which is 235 kb 5'-upstream from PRKCQ gene, was investigated by the dual-luciferase reporter assay, which clearly showed that the haplotype carrying rs11254759 regulated PRKCQ expression by upregulating PRKCQ promoter activity (p = 4.60 × 10-7) in an allelic specific manner. Mouse model analysis showed that heterozygous PRKCQ deficient mice presented decreased fat mass compared to wild-type control mice (p = 3.30 × 10-3). Mendelian randomization analysis demonstrated that both FNK-BMD and TFMadj were causally associated with fracture risk (p = 1.26 × 10-23 and 1.18 × 10-11). Our findings may provide useful insights into the genetic association between osteoporosis and abdominal obesity.

The Important Role of Adiponectin and Orexin-A, Two Key Proteins Improving Healthy Status: Focus on Physical Activity

Exercise represents the most important integrative therapy in metabolic, immunologic and chronic diseases; it represents a valid strategy in the non-pharmacological intervention of lifestyle linked diseases. A large body of evidence indicates physical exercise as an effective measure against chronic non-communicable diseases. The worldwide general evidence for health benefits are both for all ages and skill levels. In a dysregulated lifestyle such as in the obesity, there is an imbalance in the production of different cytokines. In particular, we focused on Adiponectin, an adipokine producted by adipose tissue, and on Orexin-A, a neuropeptide synthesized in the lateral hypothalamus. The production of both Adiponectin and Orexin-A increases following regular and structured physical activity and both these hormones have similar actions. Indeed, they improve energy and glucose metabolism, and also modulate energy expenditure and thermogenesis. In addition, a relevant biological role of Adiponectin and Orexin A has been recently highlighted in the immune system, where they function as immune-suppressor factors. The strong connection between these two cytokines and healthy status is mediated by physical activity and candidates these hormones as potential biomarkers of the beneficial effects induced by physical activity. For these reasons, this review aims to underly the interconnections among Adiponectin, Orexin-A, physical activity and healthy status. Furthermore, it is analyzed the involvement of Adiponectin and Orexin-A in physical activity as physiological factors improving healthy status through physical exercise.

Geometric and Mechanical Bone Response to a Multidisciplinary Weight Loss Intervention in Adolescents With Obesity: The ADIBOX Study

The effectiveness of structured multidisciplinary weight loss (WL) programs combining nutrition and physical activity on bone geometry and strength remains uncertain in adolescents with obesity. The study investigated the impact of a structured WL intervention on bone geometry and strength in adolescents with obesity. Thirty-one adolescents with obesity (mean [standard deviation] 13.61 [1.27] yr, body mass index Z-score 2.26 [0.30]) experienced an 8-mo WL program. A group of 23 maturation-matched controls (mean [standard deviation] 15.90 [0.43] yr, body mass index Z-score -0.12 [0.48]) were recruited for calculating Z-scores. Body composition, bone density, geometry, and mechanical properties were assessed using dual-energy X-ray absorptiometry and dual-energy X-ray absorptiometry-derived hip structural analysis. Plasma concentration of leptin, estradiol, collagen type 1 cross-linked C-telopeptide (CTx), and procollagen type 1 N-terminal propeptide were measured. Longitudinal analysis showed that adolescents with obesity reduced body weight and fat mass (total [g, %; p < 0.007]). After 8 mo, body mineral density at total body less head (Δ 3.22 [3.58] % p < 0.001) and lumbar spine (Δ 3.67 [4.04] % p < 0.001) increased. At the narrow neck (NN) of the femur, lower body mineral density (Δ -7.19 [8.79] % p < 0.001) and higher endocortical diameter and width were observed (NN endocortical diameter Δ 2.85 [0.26] %, NN width Δ 5.48 [10.84] %, respectively). An increased buckling ratio (Δ 8.24 [2.00] % p = 0.005) was also evident. Similar concentration of procollagen type 1 N-terminal propeptide and CTx was seen from baseline to 8 mo. However, at 4 mo, lower CTx levels were observed. The 8-mo WL program was associated with some positive adaptations among bone density parameters for the whole body and spine. However, bone geometry and strength estimates appeared to weaken at the NN. Clinically, the buckling ratio score at the NN was close to the fracture threshold. An "androgynous-like" adaptation was observed with bone geometry changes demonstrating periosteal expansion and endocortical resorption.

Association between Hypertension, Antihypertensive Drugs, and Osteoporosis in Postmenopausal Syrian Women: A Cross-Sectional Study

BACKGROUND

Osteoporosis and hypertension are frequent and often coexisting diseases among the elderly. Recent studies suggested that both diseases may share the same etiopathology. Moreover, the treatment of hypertension can affect the bone mineral density and worsen osteoporosis. The aim of this cross-sectional study was to assess the prevalence of low bone mass and osteoporosis in postmenopausal Syrian women and investigate their relationship with hypertension and antihypertensive drugs.

METHODS

813 postmenopausal women were involved in this cross-sectional study, aged between 40 and 96 yrs. Their menopause duration ranged between 1 and 43 yrs. Bone mineral density was measured using a dual-energy X-ray absorptiometry at the total lumbar spine (L1-L4) and left hip. T-score values were used to determine the diagnosis of osteoporosis. The existence of HTN was defined as blood pressure ≥130/85 mmHg or a history of hypertension medication.

RESULTS

Using the world health organization criteria, 24% had osteoporosis and 45.2% had low bone mass. The incidence of osteoporosis and low bone mass significantly increased with age and menopause duration and decreased with BMI. Prevalence of hypertension was almost equal among the women who had or did not have osteoporosis. However, hypertensive women who used thiazides or beta blockers had higher values of total lumbar BMD compared with the women who did not.

CONCLUSION

Hypertension in postmenopausal Syrian women aged over 40 was not found to be associated with osteoporosis. However, the mean total lumbar BMD of the hypertensive women who took thiazide diuretics or beta blocker was found to be increased significantly comparing to the women who did not take either.

Analysis of the Relationship between the Levels of Androgens and Biochemical Bone Markers in Men Aged 60-75 Years

Introduction: The purpose of this study was to analyze the relationship between the parameters of bone turnover and the levels of hormonal parameters, such as total testosterone (TT), bioavailable and free testosterone (FT), and estradiol (E2) in men. Material and methods: The study group included 63 men with testosterone deficiency syndrome (TDS). The control group consisted of 112 patients without TDS. Enzyme-linked immunosorbent assay (ELISA) was used to determine the levels of osteocalcin (OC), parathyroid hormone (PTH), E2, sex hormone binding globulin (SHBG), dehydroepiandrosterone sulphate (DHEAS), insulin (I), Serum CrossLaps (CtX-I), human procollagen I N-terminal peptide (PINP), and TT. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. Results: The groups with TSD and without TDS differed in terms of the following parameters: body weight (p = 0.001), BMI (p = 0.003), TT (p = 0.001), FT (p = 0.004), bioavailable testosterone (p = 0.001), E2 (p = 0.003), SHBG (p = 0.003), and PINP (p = 0.004). In the group without TDS, higher PINP levels were accompanied by higher levels of E2 (beta = 0.360, p = 0.002) and TT (beta = 0.389, p = 0.001). In the group without TDS, PINP was positively correlated with E2 (beta = 0.726, p <0.001). Patients with TDS had significantly lower PINP levels (p < 0.004). Conclusions: Analysis of sex hormones and biochemical bone markers in reflecting the quality of the bone tissue in men may suggest a relationship between these parameters. Nevertheless, further research based on a larger sample size is necessary to better describe this relationship.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

The effect of weight loss on body composition, serum bone markers, and adipokines in prepubertal obese children after 1-year intervention

Purpose/Aim: The influence of weight loss on bone turnover and bone quality in childhood remains controversial, but it may implicate interactions between adiposity and bone metabolism. Therefore, we studied the relationships between bone markers and adipokines during weight loss in obese children.

MATERIALS AND METHODS

We determined serum leptin, soluble leptin receptor, adiponectin, bone alkaline phosphatase (BALP), C-terminal telopeptide of type I collagen (CTX-I), osteocalcin (OC), carboxylated-OC (Gla-OC), undercarboxylated-OC (Glu-OC), sclerostin, body composition, and bone mineral density (BMD) in 40 obese prepubertal children before and after therapy. The control group, matched for sex and age, consisted of 40 non-obese children.

RESULTS

We found that values of the total body less head-bone mineral content (TBLH-BMC) and TBLH-BMD were significantly increased, but TBLH-BMD Z-score was decreased by 25% (p = 0.002) in obese children with weight loss after therapy. We observed increases of CTX-I to OC ratio (p = 0.009), and Gla-OC concentrations (p = 0.049). Changes in TBLH-BMD Z-score in patients were positively correlated with changes in BMI Z-score (p = 0.001), percentage of fat mass (p = 0.004), and BALP activity (p = 0.01). Changes in BALP activity were negatively correlated (p < 0.001) with changes in adiponectin concentrations, while changes in sclerostin levels were positively correlated (p = 0.001) with leptin changes.

CONCLUSIONS

We suggest that alterations in adipokines metabolism were associated with a lower rate of bone mineral accrual as a result of decreased bone formation rather than increased bone resorption. The lower rate of bone mass accrual in weight losing children may be an effect of reduced BALP levels related to increase in adiponectin levels.

Influence of adipose tissue mass on bone mass in an overweight or obese population: systematic review and meta-analysis

Context

The scientific literature shows conflicting evidence about the relationship between adiposity and bone mass in overweight and obese populations. The aim of this review was to quantify the correlation between adipose mass (absolute and relative) and bone mineral density (BMD) in overweight and obese populations. Three databases were searched electronically. In addition, reference lists of relevant articles were screened. A total of 16 studies, comprising 2587 participants and 75 correlation coefficients were selected for inclusion in the review. Data were extracted from each study using a standardized form. Multilevel modeling indicated opposing relationships between BMD and adiposity: absolute adiposity correlated positively, and relative adiposity negatively, with BMD. Sex and age were the primary moderators of these relationships. Strong evidence supported a negative relationship between relative adipose mass and BMD in men (R = -0.37; 95%CI, -0.57 to -0.12) and in those aged less than 25 years (R = -0.28; 95%CI, -0.45 to -0.08). To prevent bone loss in overweight and obese populations, nutrition- and exercise-based interventions that focus on a controlled reduction of adipose mass with concomitant preservation of lean mass are recommended. : PROSPERO no. CRD42015024313.

Molecular Mechanisms of Vaspin Action - From Adipose Tissue to Skin and Bone, from Blood Vessels to the Brain

Visceral adipose tissue-derived serine protease inhibitor (vaspin) or SERPINA12 according to the serpin nomenclature was identified together with other genes and gene products that were specifically expressed or overexpressed in the intra-abdominal or visceral adipose tissue (AT) of the Otsuka Long-Evans Tokushima fatty rat. These rats spontaneously develop visceral obesity, insulin resistance, hyperinsulinemia and -glycemia, as well as hypertension and thus represent a well suited animal model of obesity and related metabolic disorders such as type 2 diabetes.The follow-up study reporting the cloning, expression and functional characterization of vaspin suggested the great and promising potential of this molecule to counteract obesity induced insulin resistance and inflammation and has since initiated over 300 publications, clinical and experimental, that have contributed to uncover the multifaceted functions and molecular mechanisms of vaspin action not only in the adipose, but in many different cells, tissues and organs. This review will give an update on mechanistic and structural aspects of vaspin with a focus on its serpin function, the physiology and regulation of vaspin expression, and will summarize the latest on vaspin function in various tissues such as the different adipose tissue depots as well as the vasculature, skin, bone and the brain.

Identification of Novel Potentially Pleiotropic Variants Associated With Osteoporosis and Obesity Using the cFDR Method

CONTEXT

Genome-wide association studies (GWASs) have been successful in identifying loci associated with osteoporosis and obesity. However, the findings explain only a small fraction of the total genetic variance.

OBJECTIVE

The aim of this study was to identify novel pleiotropic genes important in osteoporosis and obesity.

DESIGN AND SETTING

A pleiotropic conditional false discovery rate method was applied to three independent GWAS summary statistics of femoral neck bone mineral density, body mass index, and waist-to-hip ratio. Next, differential expression analysis was performed for the potentially pleiotropic genes, and weighted genes coexpression network analysis (WGCNA) was conducted to identify functional connections between the suggested pleiotropic genes and known osteoporosis/obesity genes using transcriptomic expression data sets in osteoporosis/obesity-related cells.

RESULTS

We identified seven potentially pleiotropic loci-rs3759579 (MARK3), rs2178950 (TRPS1), rs1473 (PUM1), rs9825174 (XXYLT1), rs2047937 (ZNF423), rs17277372 (DNM3), and rs335170 (PRDM6)-associated with osteoporosis and obesity. Of these loci, the PUM1 gene was differentially expressed in osteoporosis-related cells (B lymphocytes) and obesity-related cells (adipocytes). WGCNA showed that PUM1 positively interacted with several known osteoporosis genes (AKAP11, JAG1, and SPTBN1). ZNF423 was the highly connected intramodular hub gene and interconnected with 21 known osteoporosis-related genes, including JAG1, EN1, and FAM3C.

CONCLUSIONS

Our study identified seven potentially pleiotropic genes associated with osteoporosis and obesity. The findings may provide new insights into a potential genetic determination and codetermination mechanism of osteoporosis and obesity.

Physical activity and hypocaloric diet recovers osteoblasts homeostasis in women affected by abdominal obesity

Obesity is a multifactorial disease linked to metabolic chronic disorders such as diabetes, and hypertension. Also, it has recently been associated with skeletal alterations and low bone mineral density. We previously demonstrated that exposure of osteoblasts to sera of sedentary subjects affected by obesity alters cell homeostasis in vitro, leading to disruption of intracellular differentiation pathways and cellular activity. Thus, the purpose of the present study has been to evaluate whether sera of sedentary obese women, subjected to physical activity and hypocaloric diet, could recover osteoblast homeostasis in vitro as compared to the sera of same patients before intervention protocol. To this aim, obese women were evaluated at time 0 and after 4, 6, and 12 months of individualized prescribed physical activity and hypocaloric diet. Dual-energy-X-ray absorptiometry measurements were performed at each time point, as well as blood was collected at the same points. Cells were incubated with sera of subjects before and after physical activity as described: obese at baseline and after for 4, 6, and 12 months of physical activity and nutritional protocol intervention. Osteoblasts exposed to sera of patients, who displayed increased lean and decreased fat mass (from 55.5 ± 6.5 to 57.1 ± 5.6% p ≤ 0.05; from 44.5 ± 1.1 to 40.9 ± 2.6% p ≤ 0.01 respectively), showed a time-dependent increase of Wnt/β-catenin signaling, versus cells exposed to sera of obese patients before intervention protocol, suggesting recovery of osteoblast homeostasis upon improvement of body composition. An increase in β-catenin nuclear accumulation and nuclear translocation was also observed, accompanied by an increase in Adiponectin receptor 1 protein expression, suggesting positive effect on cell differentiation program. Furthermore, a decrease in sclerostin amount and an increase of type 1 procollagen amino-terminal-propeptide were depicted as compared to baseline, proportionally to the time of physical activity, suggesting a recovery of bone remodeling modulation and an increase of osteoblast activity induced by improvement of body composition. In conclusion, our results show for the first time that sera of obese sedentary women who increased lean mass and decreased fat mass, by physical activity and hypocaloric diet, rescue osteoblasts differentiation and activity likely due to a reactivation of Wnt/β-catenin-pathway, suggesting that a correct life style can improve skeletal metabolic alteration induced by obesity.

Muscle strength rather than muscle mass is associated with osteoporosis in older Chinese adults

BACKGROUND

Assessment of the association of muscle strength and muscle mass with osteoporosis (OP) is of special interest as muscles are a potential target for interventions (i.e., strength training).

METHODS

A cross-sectional descriptive study encompassing people aged ≥ 60 years (average age: 66.9 ± 6.2 years; men, n = 516; women, n = 652) in the Hangu area of Tianjin, China. The study populations were invited to participate in a comprehensive geriatric assessment. OS was identified by measuring the calcaneal using a quantitative ultrasound and a T score of less than -2.5. Muscle characteristics included grip strength and appendicular skeletal muscle mass (ASM).

RESULTS

The prevalence of OS in this study was 61.6% (male 52.1%, female 69.1%). Grip strength was negatively related to OS and after adjusting for all other variables, higher grip strength was found to be associated with a lower OS risk (p = 0.023). ASM/height² was not associated with OS (p = 0.205).

CONCLUSION

Based on our study, muscle strength rather than muscle mass is negatively associated with OS in older people; thus, we should pay more attention to muscle strength training in the early stage of the OS.

Crosstalk between adipokines and myokines in fat browning

Skeletal muscle is the largest organ determining whole-body insulin sensitivity and metabolic homoeostasis. Adaptive changes of skeletal muscle in response to physical activity include adjustments in the production and secretion of muscle-derived bioactive factors, known as myokines, such as myostatin, IL-4, IL-6, IL-7 and IL-15, myonectin, follistatin-like 1 or leukaemia inhibitory factor. These myokines not only act locally in the muscle in an autocrine/paracrine manner, but also are released to the bloodstream as endocrine factors to regulate physiological processes in other tissues. Irisin, derived from the cleavage of FNDC5 protein, constitutes a myokine that induces myogenesis and fat browning (switch of white adipocytes to brown fat-like cells) together with a concomitant increase in energy expenditure. Besides being a target for irisin actions, the adipose tissue also constitutes a production site of FNDC5. Interestingly, irisin secretion from subcutaneous and visceral fat depots is decreased by long-term exercise training and fasting, suggesting a discordant regulation of FNDC5/irisin in skeletal muscle and adipose tissue. Accordingly, our group has recently reported that the adipokine leptin differentially regulates FNDC5/irisin expression in skeletal muscle and fat, confirming the crosstalk between both tissues. Moreover, irisin secretion and function are regulated by other myokines, such as follistatin or myostatin, as well as by other adipokines, including fibroblast growth factor 21 and leptin. Taken together, myokines have emerged as novel molecular mediators of fat browning and their activity can be modulated by adipokines, confirming the crosstalk between skeletal muscle and adipose tissue to regulate thermogenesis and energy expenditure.

The effect of mesoporous bioglass on osteogenesis and adipogenesis of osteoporotic BMSCs

This study evaluated the effect of mesoporous bioglass (MBG) dissolution on the differentiation of bone marrow mesenchymal stem cells (BMSCs) derived from either sham control or ovariectomized (OVX) rats. MBG was fabricated by evaporation-induced self-assembly method. Cell proliferation was tested by Cell Counting Kit-8 assay, and cytoskeletal morphology was observed by fluorescence microscopy. Osteogenic differentiation was evaluated by alkaline phosphatase (ALP) staining and activity, Alizarin Red staining, while adipogenic differentiation was assessed by Oil Red-O staining. Quantitative real-time PCR and Western blot analysis were taken to evaluate the expression of runt-related transcription factor 2 (Runx2) and proliferator-activated receptor-γ (PPARγ). We found that MBG dissolution (0, 25, 50, 100, 200 µg/mL) was nontoxic to BMSCs growth. Sham and OVX BMSCs exhibited the highest ALP activity in 50 µg/mL of MBG osteogenic dissolution, except that sham BMSCs in 100 µg/mL showed the highest ALP activity on day 14. Runx2 was significantly upregulated after 100 µg/mL of MBG stimulation in sham and OVX BMSCs for 7 and 14 days, except that 25 µg/mL showed highest upregulation effect on OVX BMSCs at day 7. PPARγ was downregulated after MBG stimulation. The protein level of Runx2 from the sham BMSCs group was significantly upregulated after lower doses (25 and 50 µg/mL) of MBG stimulation, whereas PPARγ was downregulated in the sham and OVX BMSCs group. Thus, both the osteogenic and adipogenic abilities of BMSCs were damaged under OVX condition. Moreover, lower concentration of MBG dissolution can promote osteogenesis but inhibit adipogenesis of the sham and OVX BMSCs. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 3004-3014, 2016.

The effects of weight loss approaches on bone mineral density in adults: a systematic review and meta-analysis of randomized controlled trials

We assessed the impact of weight loss strategies including calorie restriction and exercise training on BMD in adults using a systematic review of randomized controlled trials. Weight reduction results in reduced BMD at the hip, but has less effect on the spine. Both calorie restriction and a combination of calorie restriction and exercise result in a decrease in hip bone density, whereas weight loss response to exercise training without dietary restriction leads to increased hip BMD.

INTRODUCTION

Findings are not consistent on the effect of weight loss on bone mineral density (BMD). We conducted a systematic review on the randomized controlled trials to assess the effect of weight loss strategies, including calorie restriction and exercise programs on BMD in adults.

METHODS

A structured and comprehensive search of MEDLINE and EMBASE databases was undertaken up to March 2016. Study-specific mean differences (MD) were pooled using a random-effects model. Subgroup analysis and meta-regression were used to find possible sources of between-study heterogeneity.

RESULTS

Thirty-two randomized controlled trials met predetermined inclusion criteria. The meta-analysis revealed no significant difference on total BMD (MD 0.007, 95 % CI -0.020-0.034, p = 0.608). In contrast, the pooled data of studies showed a significant effect of weight loss on hip BMD (MD -0.008, 95 % CI -0.09 to -0.006 g/cm(2), p < 0.001) and also lumbar spine BMD (MD -0.018 g/cm(2), 95 % CI -0.019 to -0.017, p < 0.001). BMD in the hip site decreased after more than 4 months, especially in those who were obese. Moreover, calorie restriction interventions longer than 13 months showed a significant decreased in lumbar spine BMD.

CONCLUSION

Weight loss led to significant decreases at the hip and lumbar spine BMD but not at the total. Weight loss response following calorie restriction resulted in a decrease in hip and lumbar spine bone density especially more than 1 year; whereas an exercise-induced weight loss did not.

Mechanisms underlying the association between obesity and Hodgkin lymphoma

A solid body of knowledge indicates that overweight and obese subjects are prone to develop cancer, aggressive disease, and death more than their lean counterparts. While obesity has been causally associated with various cancers, only a limited number of studies beheld the link with classical Hodgkin lymphoma (HL). Contemporary meta-analysis and prospective studies confirmed the association of body mass index with HL. Besides epidemiological evidence, excess adiposity is known to influence tumor behavior through adipokines, adipose-derived stem cell migration, and metabolism regulation, and by modulating immunoinflammatory response. Nevertheless, the obesity paradox has been described in few cancers. Considering that adipose tissue is an immunomodulatory organ, and that inflammation is the cornerstone of HL pathophysiology, the rationale for being causally related due to endocrine/paracrine interactions cannot be negligible. In this hypothesis-generating review, we explore the biologically plausible links between excess adiposity and HL in light of recent basic and clinical data, in order to create a basis for understanding the underlying mechanisms and foster applied research. The establishment of an association of excess adiposity with HL will determine public health preventive measures to fight obesity and eventually novel therapeutic approaches in HL patients.

Inverse relationship of bone mineral density and serum level of N-terminal pro-B-type natriuretic peptide in peritoneal dialysis patients

Objective:

Chronic kidney disease is associated with decreased bone mineral density (BMD). In this study, the relationship between BMD and the fasting serum concentration of N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) was evaluated in peritoneal dialysis (PD) patients.

Material and Methods:

Fasting blood samples were obtained from 52 PD patients. BMD was measured by dual energy X-ray absorptiometry of the lumbar vertebrae (L2–L4). The serum NT-pro-BNP level was measured by an electrochemiluminescence immunoassay.

Results:

Ten patients (19.2%) had osteoporosis, 23 patients (44.2%) had osteopenia, and 19 patients had normal BMD. Increased serum NT-pro-BNP (p < 0.001), advanced age (p = 0.012), decreased body mass index (p = 0.006), body height (p = 0.018), and body weight (p = 0.004) were associated with lower lumbar T-scores, but sex, menopausal status, PD modality, diabetes mellitus, and hypertension were not. Multivariate forward stepwise linear regression analysis with adjustment for age, body height, body weight, body mass index, and log-NT-pro-BNP indicated that a high serum level of log-NT-pro-BNP (R² change = 0.346; p < 0.001) and low body weight (R² change = 0.208; p < 0.001) were significantly and independently associated with poor lumbar BMD.

Conclusion:

A high serum level of NT-pro-BNP and low body weight were associated with poor BMD in PD patients.

Fate decision of mesenchymal stem cells: adipocytes or osteoblasts?

Mesenchymal stem cells (MSCs), a non-hematopoietic stem cell population first discovered in bone marrow, are multipotent cells capable of differentiating into mature cells of several mesenchymal tissues, such as fat and bone. As common progenitor cells of adipocytes and osteoblasts, MSCs are delicately balanced for their differentiation commitment. Numerous in vitro investigations have demonstrated that fat-induction factors inhibit osteogenesis, and, conversely, bone-induction factors hinder adipogenesis. In fact, a variety of external cues contribute to the delicate balance of adipo-osteogenic differentiation of MSCs, including chemical, physical, and biological factors. These factors trigger different signaling pathways and activate various transcription factors that guide MSCs to commit to either lineage. The dysregulation of the adipo-osteogenic balance has been linked to several pathophysiologic processes, such as aging, obesity, osteopenia, osteopetrosis, and osteoporosis. Thus, the regulation of MSC differentiation has increasingly attracted great attention in recent years. Here, we review external factors and their signaling processes dictating the reciprocal regulation between adipocytes and osteoblasts during MSC differentiation and the ultimate control of the adipo-osteogenic balance.

The pathophysiological basis of bone tissue alterations associated with eating disorders

Anorexia nervosa (AN) and obesity are two major eating disorders present nowadays in Western countries. They are both characterized by striking body composition variations and hormonal alterations, which impact on skeletal metabolism, inducing bone tissue modifications and, thus, often cause an increased risk for fractures. AN and obesity are characterized by a severe reduction in fat mass and a high expression of it, respectively, and in both conditions hormones secreted or modulated by body fat content are important determinants of low bone density, impaired bone structure and reduced bone strength. In addition, in both AN and obesity, increased marrow adiposity, which correlates with low bone density, has been observed. This review will discuss the pathophysiological basis of bone alterations associated with AN and obesity, conditions of extreme energy deficiency and excess, respectively.

The obesity of bone

During the last decades, obesity and osteoporosis have become important global health problems, and the belief that obesity is protective against osteoporosis has recently come into question. In fact, some recent epidemiologic and clinical studies have shown that a high level of fat mass might be a risk factor for osteoporosis and fragility fractures. Several potential mechanisms have been proposed to explain the complex relationship between adipose tissue and bone. Indeed, adipose tissue secretes various molecules, named adipokines, which are thought to have effects on metabolic, skeletal and cardiovascular systems. Moreover, fat tissue is one of the major sources of aromatase, an enzyme that synthesizes estrogens from androgen precursors, hormones that play a pivotal role in the maintenance of skeletal homeostasis, protecting against osteoporosis. Moreover, bone cells express several specific hormone receptors and recent observations have shown that bone-derived factors, such as osteocalcin and osteopontin, affect body weight control and glucose homeostasis. Thus, the skeleton is considered an endocrine target organ and an endocrine organ itself, likely influencing other organs as well. Finally, adipocytes and osteoblasts originate from a common progenitor, a pluripotential mesenchymal stem cell, which has an equal propensity for differentiation into adipocytes or osteoblasts (or other lines) under the influence of several cell-derived transcription factors. This review will highlight recent insights into the relationship between fat and bone, evaluating both potential positive and negative influences between adipose and bone tissue. It will also focus on the hypothesis that osteoporosis might be considered the obesity of bone.