An independent positive relationship between the serum total osteocalcin level and fat-free mass in healthy premenopausal women

Effect of adipokine and ghrelin levels on BMD and fracture risk: an updated systematic review and meta-analysis

Context

Circulating adipokines and ghrelin affect bone remodeling by regulating the activation and differentiation of osteoblasts and osteoclasts. Although the correlation between adipokines, ghrelin, and bone mineral density (BMD) has been studied over the decades, its correlations are still controversial. Accordingly, an updated meta-analysis with new findings is needed.

Objective

This study aimed to explore the impact of serum adipokine and ghrelin levels on BMD and osteoporotic fractures through a meta-analysis.

Data sources

Studies published till October 2020 in Medline, Embase, and the Cochrane Library were reviewed.

Study selection

We included studies that measured at least one serum adipokine level and BMD or fracture risk in healthy individuals. We excluded studies with one or more of the following: patients less than 18 years old, patients with comorbidities, who had undergone metabolic treatment, obese patients, patients with high physical activities, and a study that did not distinguish sex or menopausal status.

Data extraction

We extracted the data that include the correlation coefficient between adipokines (leptin, adiponectin, and resistin) and ghrelin and BMD, fracture risk by osteoporotic status from eligible studies.

Data synthesis

A meta-analysis of the pooled correlations between adipokines and BMD was performed, demonstrating that the correlation between leptin and BMD was prominent in postmenopausal women. In most cases, adiponectin levels were inversely correlated with BMD. A meta-analysis was conducted by pooling the mean differences in adipokine levels according to the osteoporotic status. In postmenopausal women, significantly lower leptin (SMD = -0.88) and higher adiponectin (SMD = 0.94) levels were seen in the osteoporosis group than in the control group. By predicting fracture risk, higher leptin levels were associated with lower fracture risk (HR = 0.68), whereas higher adiponectin levels were associated with an increased fracture risk in men (HR = 1.94) and incident vertebral fracture in postmenopausal women (HR = 1.18).

Conclusions

Serum adipokines levels can utilize to predict osteoporotic status and fracture risk of patients.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021224855, identifier CRD42021224855.

Effect of cachexia on bone turnover in cancer patients: a case-control study

Background

Increased bone turnover is frequently observed in advanced cancer and predominantly related to bone metastases or therapy. Cachexia represents an important cause of morbidity and mortality in cancer patients. Key features are weight loss, muscle wasting and chronic inflammation, which induce profound metabolic changes in several organs, including the bone. However, whether cachexia contributes to abnormal bone metabolism in cancer patients is unknown. Aim of the present study was to determine the potential correlation of bone turnover markers with body composition and laboratory parameters in treatment-naïve cancer patients.

Methods

In this cross-sectional study we measured the levels of carboxy terminal telopeptide of collagen (CTX), an indicator of bone resorption, as well as osteocalcin (Ocn) and procollagen type I N-terminal propeptide (PINP), indicators of bone formation, in 52 cancer patients and correlated with body composition and laboratory parameters. Univariate and multivariate logistic analysis were performed to identify determinants of negative bone remodeling balance, estimated by CTX/Ocn and CTX/PINP ratio.

Results

Based on weight loss, body mass index and muscle mass, patients were divided into a cachectic (59.6%) and a control (40.4%) group. After correcting for the presence of bone metastases, our results showed a significant upregulation of CTX in cachectic patients compared to non-cachectic cancer patients (median 0.38 vs 0.27 ng/mL, p < 0.05), with no difference in Ocn and PINP levels (mean 14 vs. 16 ng/ml, p = 0.2 and median 32 vs. 26 μg/L, p = 0.5, respectively). In addition, the CTX/Ocn and the CTX/PINP ratio were indicative of bone resorption in 68% and 60% of cachexia patients, respectively (vs. 20% and 31% in the control group, p = 0.002 and p = 0.06). The main determinants of the unbalanced bone turnover were hypoalbuminemia for the CTX/Ocn ratio (OR 19.8, p < 0.01) and high CRP for the CTX/PINP ratio (OR 5.3, p < 0.01) in the multivariate regression analysis.

Conclusions

CTX is substantially higher in cachectic patients compared to non-cachectic oncological patients and hypoalbuminemia as well as elevated CRP concentrations are independent predictors of a negative bone remodeling balance in cancer patients. These results strongly indicate that cachexia correlates with exacerbated bone turnover in cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08518-9.

Circulating osteocalcin: A potential predictor of ketosis in type 2 diabetes

AIMS

Osteocalcin contributes to the regulation of endocrine system. However, the association between osteocalcin and ketosis has not been evaluated. We thus aimed to explore the relationship between total osteocalcin and risk of ketosis in type 2 diabetes (T2DM).

MATERIALS AND METHODS

We identified 6157 diabetes patients from Shanghai Tenth People's Hospital between 1 January 2011 and 1 March 2017. Six hundred eight subjects were enrolled in the retrospective cross-sectional study: 304 T2DM patients with ketosis whose age, gender, and body mass index were matched with 304 T2DM patients without ketosis. A further retrospective nested case-control study was conducted in 252 T2DM patients without ketosis for a mean duration of 21.58 ± 12.43 months to investigate the occurrence of ketosis.

RESULTS

Osteocalcin levels were negatively correlated with blood ketones (adjusted r = -0.263) and urine ketones (adjusted r = -0.183). The inverse dose-dependent relationship of osteocalcin and risk of ketosis was present across osteocalcin level quintiles (top quintile as the reference, adjusted odds ratio [95% CI] = 2.56 [0.80-8.17], 3.71 [0.90-15.29], 10.77 [2.63-44.15], 23.81 [4.32-131.17] per osteocalcin quintile, respectively). Ketosis occurred in 17 of the 252 T2DM patients during follow-up. The Cox regression analysis indicated that osteocalcin was an independent protective factor against development of ketosis (adjusted hazard ratio [95% CI]: 0.668 [0.460-0.971]).

CONCLUSIONS

Total osteocalcin can be used as a predictor of ketosis in T2DM.

Chronic Stress Contributes to Osteosarcopenic Adiposity via Inflammation and Immune Modulation: The Case for More Precise Nutritional Investigation

Chronic stress and low-grade chronic inflammation (LGCI) are key underlying factors formany diseases, including bone and body composition impairments. Objectives of this narrativereview were to examine the mechanisms by which chronic stress and LGCI may influenceosteosarcopenic adiposity (OSA) syndrome, originally named as ostoesarcopenic obesity (OSO).We also examined the crucial nutrients presumed to be affected by or cause of stress andinflammation and compared/contrasted them to those of our prehistoric ancestors. The evidenceshows that stress (particularly chronic) and its related inflammatory processes, contribute toosteoporosis, sarcopenia, and adiposity ultimately leading to OSA as a final and most derangedstate of body composition, commencing at the mesenchymal cell lineage disturbance. Thefoods/nutrients consumed by modern humans, as well as their altered lifestyle, also contribute tostress, LGCI and subsequently to OSA. The processes can also go in opposite direction when stressand inflammation impact nutritional status, particularly some micronutrients' levels. Whilenutritional management of body composition and LGCI have been studied, the nutrients (and theirquantities) most affected by stressors and those which may act toward the alleviation of stressfulstate, ultimately leading to better body composition outcomes, need to be elucidated.

The role of osteoblasts in energy homeostasis

Osteoblasts are specialized mesenchymal cells that synthesize bone matrix and coordinate the mineralization of the skeleton. These cells work in harmony with osteoclasts, which resorb bone, in a continuous cycle that occurs throughout life. The unique function of osteoblasts requires substantial amounts of energy production, particularly during states of new bone formation and remodelling. Over the last 15 years, studies have shown that osteoblasts secrete endocrine factors that integrate the metabolic requirements of bone formation with global energy balance through the regulation of insulin production, feeding behaviour and adipose tissue metabolism. In this article, we summarize the current understanding of three osteoblast-derived metabolic hormones (osteocalcin, lipocalin and sclerostin) and the clinical evidence that suggests the relevance of these pathways in humans, while also discussing the necessity of specific energy substrates (glucose, fatty acids and amino acids) to fuel bone formation and promote osteoblast differentiation.

Roles for osteocalcin in brain signalling: implications in cognition- and motor-related disorders

It is now generally accepted that the extra-skeleton functionalities of bone are multifaceted. Its endocrine functions came first to light when it was realized that osteoblasts, the bone forming cells, maintain energy homeostasis by improving glucose metabolism, insulin sensitivity and energy expenditure through osteocalcin, a multipurpose osteokine secreted by osteoblasts. Recently, the emerging knowledge on the functional aspects of this osteokine expanded to properties including adult and maternal regulation of cognitive functions. Therapeutic potential of this osteokine has also been recently reported in experimental Parkinson’s disease models. This review highlights such findings on the functions of osteocalcin in the brain and emphasizes on exploring and analyzing much more in-depth basic and clinical studies.

Osteocalcin Levels in Male Idiopathic Hypogonadotropic Hypogonadism: Relationship With the Testosterone Secretion and Metabolic Profiles

Idiopathic hypogonadotropic hypogonadism (IHH) patients are characterized by the absence of puberty and varying degrees of deteriorated metabolic conditions. Osteocalcin (OC) could regulate testosterone secretion and energy metabolism, but it remains unknown whether such an effect exists in IHH patients. Our study is aimed to examine the relationship between serum OC levels with testosterone and its responsiveness to gonadotropin stimulation and metabolic profiles in male IHH patients. A total of 99 male patients aged 18-37 years and diagnosed with IHH were enrolled in the current study, and the relationships between OC and testicular volume, baseline total testosterone (TT), free testosterone (FT), and peak TT (Tmax) levels after human chorionic gonadotropin (hCG) stimulation, gonadotropin responsiveness index (GRI), which is calculated by dividing Tmax by testicular volume, as well as metabolic profiles, such as 2-h post-challenge glucose (2hPG) and fat percentage (fat%), were analyzed. The results showed that OC had an independent negative relationship with testicular volume (r = -0.253, P = 0.012) and a positive association with Tmax (r = 0.262, P = 0.014) after adjusting for confounders. In addition, OC was a major determinant of GRI (adjusted R ² for the model = 0.164, P = 0.012), fat% (adjusted R ² for the model = 0.100, P = 0.004), and 2hPG (adjusted R ² for the model = 0.054, P = 0.013) in IHH patients. In conclusion, OC is associated with testosterone secretion upon gonadotropin stimulation, glucose metabolism, and fat mass variations in IHH. This study was registered at clinicaltrials.gov (NCT02310074).

Role of hyperglycaemia in the relationship between serum osteocalcin levels and relative skeletal muscle index

BACKGROUND & AIMS

Studies have shown that osteocalcin is involved in energy metabolism and is sufficient to prevent age-related muscle loss. The present study investigated the association of serum osteocalcin levels with muscle mass and the influence of metabolic factors on this association in humans.

METHODS

A total of 1742 middle-aged and elderly subjects (median age: 61.2 years; interquartile range: 56.9-65.3 years) were enrolled from Shanghai communities, including 775 men and 967 postmenopausal women. Serum osteocalcin levels were measured by an electrochemical immunoluminescence assay. An automatic bioelectric impedance analyser (BIA) was used to measure body compositions. Relative skeletal muscle index (SMI) was calculated using the BIA equation from Janssen et al.

RESULTS

SMI was significantly higher in men than in postmenopausal women (37.30% [35.14%-39.63%] versus 27.72% [25.99%-29.66%], p < 0.001). Increasing SMI was associated with decreases in the frequency of overweight/obesity, central obesity, dyslipidaemia, elevated blood pressure, and hyperglycaemia (all p < 0.001). Serum osteocalcin levels were positively correlated with SMI in both men and women, regardless of treatment as a categorical or continuous variable (all p < 0.001). However, after accounting for confounding variables, the relationship remained only in men with hyperglycaemia (standardized β = 0.068, p = 0.024). Among men with isolated impaired glucose tolerance, the odds ratio of increased SMI was 2.861 in the fourth osteocalcin quartile compared with the lowest (p = 0.046). Multiple stepwise regression revealed that each standard deviation (SD) increase of serum osteocalcin levels resulted in an increase of 0.131 SD in SMI (p = 0.024).

CONCLUSION

Serum osteocalcin levels were positively related to SMI in men with hyperglycaemia, especially in those with isolated impaired glucose tolerance. No association was detected between serum osteocalcin levels and SMI in postmenopausal women.

Association between osteocalcin and glucose metabolism: a meta-analysis

This meta-analysis aimed to investigate the associations between osteocalcin (Ocn) and fasting plasma glucose (FPG) and glycated hemoglobin A1c (HbA1c). It was revealed that both total Ocn and undercarboxylated Ocn (unOcn) were negatively related with FPG and HbA1c, and the association of unOcn with FPG was more pronounced in men.

INTRODUCTION

The aim of this study was to investigate the strength of associations between Ocn and FPG and HbA1c using a meta-analysis approach.

METHODS

A search was carried out using the databases of PubMed, ISI Web of Science, and the Cochrane library from 2007 to 2014 to identify related studies. A pooled effect size with 95 % confidence intervals (CI) was derived.

RESULTS

The meta-analysis included 39 studies involving 23,381 participants. The overall correlation was -0.16 (95 % CI, -0.19 to -0.14) between total Ocn (tOcn) and FPG and -0.15 (95 % CI, -0.20 to -0.11) between undercarboxylated Ocn (unOcn) and FPG. In the analysis of the association between Ocn and HbA1c, the pooled correlation was -0.16 (95 % CI, -0.18 to -0.14) for tOcn and -0.16 (95 % CI, -0.23 to -0.08) for unOcn. The magnitude of the correlation between unOcn and FPG is significantly higher in men than in women (r = -0.18, 95 % CI, -0.21 to -0.14; r = -0.09, 95 % CI, -0. 13 to -0.05, respectively; P for interaction < 0.05). Similar trend was also found between unOcn and HbA1c but without significance (for men, r = -0.19, 95 % CI, -0.24 to -0.14; for women, r = -0.09, 95 % CI, -0.22 to 0.04, respectively; P for interaction > 0.05). No indication of significant publication bias was found in any method.

CONCLUSIONS

This meta-analysis demonstrated that both unOcn and tOcn were similarly and negatively correlated with FPG and HbA1c in humans. The negative correlations between unOcn and glucose metabolism appear to be more pronounced in men than in women.

Association between serum osteocalcin level and visceral obesity in Chinese postmenopausal women

BACKGROUND

A low serum osteocalcin level, visceral obesity and postmenopausal status are recognized risk factors for cardiovascular disease.

OBJECTIVE

We investigated the relationship between the serum osteocalcin level and visceral fat content in a population of Chinese postmenopausal women.

DESIGN AND PATIENTS

In total, 1481 postmenopausal women (mean age ± standard deviation, 57·1 ± 4·8 years) were selected from the Shanghai Obesity Study.

MEASUREMENTS

Abdominal fat accumulation was quantified using magnetic resonance imaging. Subjects with a visceral fat area (VFA) of ≥80 cm(2) were classified as abdominally obese. The total serum osteocalcin level was measured by electrochemiluminescence immunoassay.

RESULTS

The median serum osteocalcin level was 20·66 μg/l (interquartile range, 16·88-25·42 μg/l). The overall prevalence of abdominal obesity was 49·1% (n = 727). Abdominally obese subjects had lower serum osteocalcin levels than did nonabdominally obese subjects [19·14 (16·02-23·82) vs 21·97 (18·14-26·77) μg/l, respectively; P < 0·001]. Partial correlation analysis showed that the serum osteocalcin level was still negatively correlated with VFA after adjusting for age, years since menopause and body mass index (P < 0·01). Moreover, VFA was independently associated with the serum osteocalcin level after adjustment for confounding factors (P < 0·05). A low serum osteocalcin level was an independent risk factor for abdominal obesity (odds ratio, 0·972; 95% confidence interval, 0·953-0·991; P = 0·004).

CONCLUSION

The serum osteocalcin level was inversely correlated with the visceral fat content in these Chinese postmenopausal women.

Interrelationship among muscle, fat, and bone: connecting the dots on cellular, hormonal, and whole body levels

While sarcopenia and sarcopenic obesity have been recognized in the last decade, a combined concept to include decreased muscle mass and strength, as well as decreased bone mass with coexistence of adiposity is discussed here. We introduce a new term, osteopenic obesity, and operationalize its meaning within the context of osteopenia and obesity. Next, we consolidate osteopenic obesity with the already existing and more familiar term, sarcopenic obesity, and delineate the resulting combined condition assigning it the term osteosarcopenic obesity. Identification and possible diagnosis of each condition are discussed, as well as the interactions of muscle, fat and bone tissues on cellular level, considering their endocrine features. Special emphasis is placed on the mesenchymal stem cell commitment into osteoblastogenic, adipogenic and myogenic lineages and causes of its deregulation. Based on the presented evidence and as expounded within the text, it is reasonable to say that under certain conditions, osteoporosis and sarcopenia could be the obesity of bone and muscle, respectively, with the term osteosarcopenic obesity as an encompassment for all.