Osteocalcin, glucose metabolism, lipid profile and chronic low-grade inflammation in middle-aged and elderly Chinese

Causal effect of blood osteocalcin on the risk of Alzheimer's disease and the mediating role of energy metabolism

Growing evidence suggests an association between osteocalcin (OCN), a peptide derived from bone and involved in regulating glucose and lipid metabolism, and the risk of Alzheimer's disease (AD). However, the causality of these associations and the underlying mechanisms remain uncertain. We utilized a Mendelian randomization (MR) approach to investigate the causal effects of blood OCN levels on AD and to assess the potential involvement of glucose and lipid metabolism. Independent instrumental variables strongly associated (P < 5E-08) with blood OCN levels were obtained from three independent genome-wide association studies (GWAS) on the human blood proteome (N = 3301 to 35,892). Two distinct summary statistics datasets on AD from the International Genomics of Alzheimer's Project (IGAP, N = 63,926) and a recent study including familial-proxy AD patients (FPAD, N = 472,868) were used. Summary-level data for fasting glucose (FG), 2h-glucose post-challenge, fasting insulin, HbA1c, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, total cholesterol (TC), and triglycerides were incorporated to evaluate the potential role of glucose and lipid metabolism in mediating the impact of OCN on AD risk. Our findings consistently demonstrate a significantly negative correlation between genetically determined blood OCN levels and the risk of AD (IGAP: odds ratio [OR, 95%CI] = 0.83[0.72-0.96], P = 0.013; FPAD: OR = 0.81 [0.70-0.93], P = 0.002). Similar estimates with the same trend direction were obtained using other statistical approaches. Furthermore, employing multivariable MR analysis, we found that the causal relationship between OCN levels and AD was disappeared after adjustment of FG and TC (IGAP: OR = 0.97[0.80-1.17], P = 0.753; FPAD: OR = 0.98 [0.84-1.15], P = 0.831). There were no apparent instances of horizontal pleiotropy, and leave-one-out analysis showed good stability of the estimates. Our study provides evidence supporting a protective effect of blood OCN levels on AD, which is primarily mediated through regulating FG and TC levels. Further studies are warranted to elucidate the underlying physio-pathological mechanisms.

Cardiorespiratory Fitness and Bone Turnover Markers in Adults With Metabolic Syndrome: The Mediator Role of Inflammation

The relationship between inflammatory markers and bone turnover in adults is well known, and a negative association between cardiorespiratory fitness (CRF) and inflammatory markers has also been described. Hence, we tested whether the association between CRF and bone turnover markers is mediated by inflammatory markers in adults with metabolic syndrome. A total of 81 adults (58.5 ± 5.0 years, 62.7% women) were included in the analysis. CRF was measured by the 6-min walking test. Serum interleukin (IL)-1β, IL-6, IL-10, tumor necrosis factor alpha, high-sensitivity c-reactive protein (hsCRP) and vascular endothelial growth factor, collagen type I cross-linked C-telopeptide, procollagen type I N-terminal propeptide (P1NP), and total osteocalcin were assessed using a sensitive ELISA kit. Body composition was assessed by dual-energy X-ray absorptiometry. Partial correlation was used to test the relationship between CRF, inflammatory markers, and bone turnover markers, controlling for sex, lean mass, and fat mass. Boot-strapped mediation procedures were performed, and indirect effects with confidence intervals not including zero were interpreted as statistically significant. CRF was positively correlated with P1NP levels (r = .228, p = .044) and osteocalcin levels (r = .296, p = .009). Furthermore, CRF was positively correlated with IL-1β levels (r = .340, p = .002) and negatively correlated with hsCRP levels (r = -.335, p = .003), whereas IL-1β levels were positively correlated with P1NP levels (r = .245, p = .030), and hsCRP levels were negatively correlated with P1NP levels (r = -.319, p = .004). Finally, the association between CRF and P1NP levels was totally mediated by hsCRP (percentage of mediation = 39.9). Therefore, CRF benefits on bone formation could be dependent on hsCRP concentrations in this population.

Does Serum Osteocalcin Level Affect Carotid Atherosclerosis in Post-Menopausal Diabetic Females? A Case-Control Study

Purpose

To determine the association between serum osteocalcin and carotid intima media thickness (CIMT) in a group of post-menopausal females with type 2 diabetes (T2DM).

Patients and Methods

This cross-sectional study enrolled 75 postmenopausal women with T2DM and 40 age matched postmenopausal healthy females. Age, body mass index, blood pressure were recorded for all subjects. Laboratory tests including fasting blood glucose (FBG), glycated hemoglobin (HbA1c) and lipid profile were measured. Serum osteocalcin was measured using ELISA. Bone mineral density (BMD) was measured by DEXA scan. CIMT was assessed with B-mode ultrasonography.

Results

Patients with T2DM had significantly lower serum osteocalcin compared to control (63.73±27.20 vs 136.16±21.96 pg/mL, P<0.001). Patients with osteoporosis had significantly lower osteocalcin level compared to those with normal BMD. Patients with T2DM had a significant negative correlation between serum osteocalcin and CIMT (r= -0.332; P=0.003), FBG (r= -0.732; P< 0.001), HbA1c (r=-0.672; P< 0.001), and HOMA-IR (r= -0.672; P< 0.001). However, multiple linear regression analysis revealed that CIMT in patients with diabetes was only significantly associated with age (P= 0.001), duration of diabetes (P< 0.001), SBP (P< 0.001), HOMA-IR (P=0.033), LDL (P=0.005), and HDL (P< 0.001). Furthermore, serum insulin (β= -0.183, P=0.033), FBG (β= -0.604, P< 0.001) and LDL (β= -0.195, P= 0.02) were independently negatively correlated with serum osteocalcin.

Conclusion

In this study, Postmenopausal women with diabetes had significantly lower osteocalcin compared to non-diabetic women. Although serum osteocalcin was negatively correlated with CIMT, multivariate regression analysis revealed that osteocalcin level was only independently related to worse glycemic parameters in postmenopausal women with T2DM.

Osteocalcin Alleviates Lipopolysaccharide-Induced Acute Inflammation via Activation of GPR37 in Macrophages

The G protein-coupled receptor 37 (GPR37) has been reported to be expressed in macrophages and the activation of GPR37 by its ligand/agonist, and it can regulate macrophage-associated functions and inflammatory responses. Since our previous work identified that osteocalcin (OCN) acts as an endogenous ligand for GPR37 and can elicit various intracellular signals by interacting with GPR37, we thus hypothesized that OCN may also play a functional role in macrophage through the activation of GPR37. To verify the hypothesis, we conducted a series of in vivo and in vitro studies in lipopolysaccharide (LPS)-challenged mice and primary cultured macrophages. Our results reveal that the OCN gene deletion (OCN−/−) and wild type (WT) mice showed comparable death rates and inflammatory cytokines productions in response to a lethal dose of LPS exposure. However, the detrimental effects caused by LPS were significantly ameliorated by exogenous OCN treatments in both WT and OCN−/− mice. Notably, the protective effects of OCN were absent in GPR37−/− mice. In coordination with the in vivo results, our in vitro studies further illustrated that OCN triggered intracellular responses via GPR37 in peritoneal macrophages by regulating the release of inflammatory factors and macrophage phagocytic function. Finally, we exhibited that the adoptive transfer of OCN-treated macrophages from WT mice significantly inhibits the release of pro-inflammatory cytokines in GPR37−/− mice exposed to LPS. Taken together, these findings suggest a protective role of OCN against LPS-caused acute inflammation, by the activation of GPR37 in macrophages, and provide a potential application of the activation of the OCN/GPR37 regulatory axis as a therapeutic strategy for inflammatory diseases.

Association between Serum Osteocalcin Levels and Metabolic Syndrome according to the Menopausal Status of Korean Women

BACKGROUND

Osteocalcin is known to regulate energy metabolism. Recently, metabolic syndrome (MetS) has been found to be associated with reduced levels of osteocalcin in men, as well as in postmenopausal women. The aim of this study was to investigate the association between serum osteocalcin and MetS in premenopausal women, compared with that in postmenopausal women.

METHODS

This cross-sectional study was based on 5,896 participants who completed a health screening examination. They were classified according to their menopausal status. Each group was subdivided into non-MetS and MetS groups according to the modified National Cholesterol Education Program-Adult Treatment Panel III criteria. Serum osteocalcin levels were measured using the electrochemiluminescence immunoassay.

RESULTS

Serum osteocalcin level was significantly lower in women with MetS than in those without MetS, after adjusting for confounders (14.12 ± 0.04 vs. 13.17 ± 0.13 [P = 0.004] in premenopausal women, and 20.34 ± 0.09 vs. 19.62 ± 0.21 [P < 0.001] in postmenopausal women), regardless of their menopausal status. Serum osteocalcin levels decreased correspondingly with an increasing number of MetS elements (P for trend < 0.001). Multiple regression analysis demonstrated that waist circumference (β = -0.085 [P < 0.001] and β = -0.137 [P < 0.001]) and hemoglobin A1c (β = -0.09 [P < 0.001] and β = -0.145 [P < 0.001]) were independent predictors of osteocalcin in premenopausal and postmenopausal women. Triglyceride levels were also independently associated with osteocalcin levels in premenopausal women (β = -0.004 [P < 0.013]). The odds ratio (OR) for MetS was significantly higher in the lowest quartile than in the highest quartile of serum osteocalcin levels after adjusting for age, alkaline phosphatase, uric acid, high sensitivity C-reactive protein, and body mass index in all women (OR, 2.00; 95% confidence interval [CI], 1.49-2.68) as well as in premenopausal (OR, 2.23; 95% CI, 1.39-3.58) and postmenopausal (OR, 2.01; 95% CI, 1.26-3.23) subgroups.

CONCLUSION

Lower serum osteocalcin concentrations were significantly associated with MetS in both premenopausal and postmenopausal women and were therefore independent of menopausal status.

Spirulina Enhances Bone Modeling in Growing Male Rats by Regulating Growth-Related Hormones

In recent years, growth hormone deficiency in children has been treated with hormone therapy despite the possible significant side effects. Therefore, it was deemed beneficial to develop functional foods or dietary supplements for safely improving children's growth. Spirulina platensis is known for its high antioxidant, anti-aging, anti-cancer, and immunity-enhancing properties, as well as its high digestibility and high protein content, but little has been reported about its influence on bone development in children with a normal supply of protein. In this study, we evaluated the effects of spirulina on the bone metabolism and antioxidant profiles of three-week-old growing male rats. The animals were divided into four groups (n = 17 per group) and were fed AIN93G diets with 0% (control), 30% (SP30), 50% (SP50), and 70% (SP70) of casein protein replaced by spirulina, respectively, for seven weeks. We observed that spirulina enhanced bone growth and bone strength by stimulating parathyroid hormone and growth hormone activities, as well its increased antioxidant activity. These results indicate that spirulina provides a suitable dietary supplement and alternative protein source with antioxidant benefits for growth improvement in early developmental stages.

Osteocalcin does not influence acute or chronic inflammation in human vascular cells

Some human observational studies have suggested an anti‐inflammatory role of osteocalcin (OCN). An inflammatory protocol using interferon‐γ and tumor necrosis factor‐α (10 ng/ml) was employed to examine the acute (24 hr) and chronic (144 hr) effects of uncarboxylated OCN (ucOCN) in commercial, primary, subcultured human aortic endothelial cells (HAEC), and human smooth muscle cells (HASMCs). The inflammatory protocol increased phosphorylation of intracellular signaling proteins (CREB, JNK, p38, ERK, AKT, STAT3, STAT5) and increased secretion of adhesion markers (vascular cell adhesion molecule‐1, intracellular adhesion molecule‐1, monocyte chemoattractant protein‐1) and proinflammatory cytokines (interleukin‐6 [IL‐6], IL‐8). After acute inflammation, there were no additive or reductive effects of ucOCN in either cell type. Following chronic inflammation, ucOCN did not affect cell responses, nor did it appear to have any pro‐ or anti‐inflammatory effects when administered acutely or chronically on its own in either cell type. Additionally, ucOCN did not affect lipopolysaccharide (LPS)‐induced acute inflammation in HAECs or HASMCs. The findings of this study do not support a causal role for OCN within the models of vascular inflammation chosen. Further confirmatory studies are warranted.

Correlation Between Serum miR-154-5p and Osteocalcin in Males and Postmenopausal Females of Type 2 Diabetes With Different Urinary Albumin Creatinine Ratios

Purpose: To investigate the serum levels of miR-154-5p, osteocalcin (OC), and other clinical parameters in male and post-menopausal female type 2 diabetes mellitus (T2DM) patients with different urinary albumin creatinine ratio (UACR) levels and to discuss the relationship between miR-154-5p and glycolipid metabolism, bone metabolism, and different urinary albumin excretion rate in T2DM. Methods: Seven hundred thirty-eight T2DM patients were categorized into six groups, including 374 men and 364 post-menopausal women who were sub-divided into three groups based on albumin excretion that involved normal albuminuria, microalbuminuria, and large amount of albuminuria (138, 127, 109, 135, 125, and 104 cases, UACR<30, 30-300, and >300 mg/g, M1, M2, M3, F1, F2, and F3). Measurement of circulating miR-154-5p, OC, and other biochemical indicators were performed by real-time PCR, ELISA, and chemiluminescence assays in T2DM patients and in 141 M0 and 139 F0 control subjects. Results: There are few differences appeared between groups. Comparing with men, women had higher age, waist-to-hip ratio (WHR), adiponectin (ADPN), connective tissue growth factor (CTGF), UACR, procollagen type 1 N-terminal propeptide (P1NP), β-C-terminal telopeptide of type I collagen (β-CTx), OC, and miR-154-5p, but lower FPG, HOMA-IR, and HbA1c. T2DM patients with albuminuria (micro or macro) had lower bone turnover markers (P1NP, β-CTx, and OC) and adiponectin, but higher HbA1c, CTGF, and miR-154-5p. In addition, after regression analysis, UACR was positively correlated with CTGF, HbA1c, and miR-154-5p, and negatively correlated with ADPN and bone turnover markers (P1NP, β-CTx, and OC). However, OC showed a positive correlation with ADPN and other bone turnover markers (P1NP and β-CTx), but negative correlation with CTGF, UACR, and miR-154-5p in all three groups. Conclusion: These findings suggested that increased serum levels of miR-154-5p and decreased OC levels may influence osteogenesis and proteinuria in T2DM and may identify novel targets for diagnosis and treatment of diabetic kidney disease and osteoporosis.

Osteokines and the vasculature: a review of the in vitro effects of osteocalcin, fibroblast growth factor-23 and lipocalin-2

Bone-derived factors that demonstrate extra-skeletal functions, also termed osteokines, are fast becoming a highly interesting and focused area of cross-disciplinary endocrine research. Osteocalcin (OCN), fibroblast growth factor-23 (FGF23) and lipocalin-2 (LCN-2), produced in bone, comprise an important endocrine system that is finely tuned with other organs to ensure homeostatic balance and health. This review aims to evaluate in vitro evidence of the direct involvement of these proteins in vascular cells and whether any causal roles in cardiovascular disease or inflammation can be supported. PubMed, Medline, Embase and Google Scholar were searched for relevant research articles investigating the exogenous addition of OCN, FGF23 or LCN-2 to vascular smooth muscle or endothelial cells. Overall, these osteokines are directly vasoactive across a range of human and animal vascular cells. Both OCN and FGF23 have anti-apoptotic properties and increase eNOS phosphorylation and nitric oxide production through Akt signalling in human endothelial cells. OCN improves intracellular insulin signalling and demonstrates protective effects against endoplasmic reticulum stress in murine and human endothelial cells. OCN may be involved in calcification but further research is warranted, while there is no evidence for a pro-calcific effect of FGF23 in vitro. FGF23 and LCN-2 increase proliferation in some cell types and increase and decrease reactive oxygen species generation, respectively. LCN-2 also has anti-apoptotic effects but may increase endoplasmic reticulum stress as well as have pro-inflammatory and pro-angiogenic properties in human vascular endothelial and smooth muscle cells. There is no strong evidence to support a pathological role of OCN or FGF23 in the vasculature based on these findings. In contrast, they may in fact support normal endothelial functioning, vascular homeostasis and vasodilation. No studies examined whether OCN or FGF23 may have a role in vascular inflammation. Limited studies with LCN-2 indicate a pro-inflammatory and possible pathological role in the vasculature but further mechanistic data is required. Overall, these osteokines pose intriguing functions which should be investigated comprehensively to assess their relevance to cardiovascular disease and health in humans.

Modulation of Bone and Marrow Niche by Cholesterol

Bone is a complex tissue composing of mineralized bone, bone cells, hematopoietic cells, marrow adipocytes, and supportive stromal cells. The homeostasis of bone and marrow niche is dynamically regulated by nutrients. The positive correlation between cardiovascular disease and osteoporosis risk suggests a close relationship between hyperlipidemia and/or hypercholesterolemia and the bone metabolism. Cholesterol and its metabolites influence the bone homeostasis through modulating the differentiation and activation of osteoblasts and osteoclasts. The effects of cholesterol on hematopoietic stem cells, including proliferation, migration, and differentiation, are also well-documented and further relate to atherosclerotic lesions. Correlation between circulating cholesterol and bone marrow adipocytes remains elusive, which seems opposite to its effects on osteoblasts. Epidemiological evidence has demonstrated that cholesterol deteriorates or benefits bone metabolism depending on the types, such as low-density lipoprotein (LDL) or high-density lipoprotein (HDL) cholesterol. In this review, we will summarize the latest progress of how cholesterol regulates bone metabolism and bone marrow microenvironment, including the hematopoiesis and marrow adiposity. Elucidation of these association and factors is of great importance in developing therapeutic options for bone related diseases under hypercholesterolemic conditions.

Serum osteocalcin level as an indicator of low-grade albuminuria in Chinese men free of kidney disease

OBJECTIVE

The presence of low-grade albuminuria (LGA) suggested that the pathophysiology of vascular dysfunction has been initiated. Clear evidence supports a role for osteocalcin in energy metabolism and a great incidence of pathological cardiovascular changes. The observational community-based study aims to examine the association of osteocalcin with LGA, which may provide new insight into potential involvement of osteocalcin in cardiovascular diseases.

METHODS

A total of 1951 adults [58.37 (53.34-63.13) years, 41.3% men] from Shanghai were enrolled. LGA was defined as a urinary albumin-to-creatinine ratio (UACR) < 30 mg/g. Serum osteocalcin was measured using an electrochemiluminescence immunoassay.

RESULTS

Serum osteocalcin level in men decreased with increasing UACR after adjusting for potential covariates (p = 0.045); however, the adjusted association disappeared in women (p = 0.258). Linear regression analysis showed that osteocalcin was a negative variable of UACR in men (standardized β = -0.074, p = 0.030), particularly prominent in non-hyperglycemic, non-hypertensive men, even regardless of estimated glomerular filtration rate (eGFR) (60 ≤ eGFR <90 mL/min/1.73 m², standardized β =-0.422, p = 0.004; ≥ 90 mL/min/1.73 m², standardized β = -0.167, p = 0.037).

CONCLUSION

After controlling for confounders, serum osteocalcin level was independently associated with LGA in men, which suggested that osteocalcin was closely related with atherosclerosis and vascular dysfunction.

Cytokines and Abnormal Glucose and Lipid Metabolism

Clear evidence indicates that cytokines, for instance, adipokines, hepatokines, inflammatory cytokines, myokines, and osteokines, contribute substantially to the development of abnormal glucose and lipid metabolism. Some cytokines play a positive role in metabolism action, while others have a negative metabolic role linking to the induction of metabolic dysfunction. The mechanisms involved are not fully understood, but are associated with lipid accumulation in organs and tissues, especially in the adipose and liver tissue, changes in energy metabolism, and inflammatory signals derived from various cell types, including immune cells. In this review, we describe the roles of certain cytokines in the regulation of metabolism and inter-organ signaling in regard to the pathophysiological aspects. Given the disease-related changes in circulating levels of relevant cytokines, these factors may serve as biomarkers for the early detection of metabolic disorders. Moreover, based on preclinical studies, certain cytokines that can induce improvements in glucose and lipid metabolism and immune response may emerge as novel targets of broader and more efficacious treatments and prevention of metabolic disease.

Association of body mass index and waist circumference with osteocalcin and C-terminal telopeptide in Iranian elderly: results from a cross-sectional study

There is no agreement on the role of obesity as a protection or unfavorable factor on bone. In the present study, the association of body mass index (BMI) and waist circumference (WC) with osteocalcin, C-terminal telopeptide of type 1 collagen (CTX-I), highly sensitive C-reactive protein (hs-CRP), parathormon (PTH) and 25-hydroxyvitamin D (25(OH)D) in elderly people was investigated. This cross-sectional study was conducted on 178 elderly residents in Tehran, with a mean age of 67.04 (60-83). Serum osteocalcin, hs-CRP, 25(OH) D, PTH and urine CTX-I were measured for all participants. Waist circumference, weight and height were measured and BMI was calculated. Linear regression and Pearson correlation were performed to evaluate the relation of BMI and waist circumference with other variables. A significant inverse association was found between BMI with osteocalcin (β = - 0.171, p = 0.027) after control for covariates. In addition, there were a significant relation of BMI and WC with hs-CRP (β = 0.246, p = 0.002 and β = 0.219, p = 0.006, respectively) and PTH (β = 0.1169, p = 0.040 and β = 0.200, p = 0.018), respectively. The present study did not show a significant relation of BMI and WC with urine CTX-I even after adjustment for potential confounders (β = - 0.143, p = 0.065 and β = - 0.104, p = 0.183, respectively). The present study has concluded that obesity is an undesirable factor for bone metabolism by reducing serum osteocalcin and by increasing hs-CRP and PTH which contribute to bone resorption.

The Association Between Osteocalcin and Chronic Inflammation in Patients with Type 2 Diabetes Mellitus

Osteocalcin acts as an endocrine hormone to regulate energy homeostasis. Although several in vivo and in vitro studies suggest that osteocalcin is involved in chronic inflammation, the association between osteocalcin and chronic inflammation in humans is unknown. In this cross-sectional study, 246 patients with type 2 diabetes mellitus (T2DM) were recruited to investigate the association of bone turnover markers with chronic inflammation parameters such as high-sensitive C-reactive protein (hsCRP), ferritin, and leukocyte subtype counts. Bone-specific alkaline phosphatase (BAP), total osteocalcin (OC), undercarboxylated OC (ucOC), and urinary N-terminal cross-linked telopeptide of type-I collagen (uNTX) were measured. Multiple regression analysis adjusted for age, duration of diabetes, body mass index, estimated glomerular filtration rate, and hemoglobin A1c showed that serum OC levels were significantly and negatively associated with hsCRP, ferritin, basophil count, and monocyte count (β = - 0.18, p = 0.013; β = - 0.22, p = 0.031; β = - 0.14, p = 0.038; and β = - 0.17, p = 0.012, respectively). Moreover, serum ucOC levels were significantly and negatively associated with hsCRP, ferritin, total leukocyte count, neutrophil count, and monocyte count (β = - 0.24, p = 0.007; β =- 0.37, p = 0.003; β = - 0.21, p = 0.007; β = - 0.24, p = 0.002; and β = - 0.20, p = 0.011, respectively). The ratio of ucOC to OC was significantly and negatively associated with ferritin (β = - 0.31, p = 0.014). However, neither BAP nor uNTX was associated with any chronic inflammation parameters. This is the first study to show that serum OC and ucOC levels were negatively associated with chronic inflammation parameters such as hsCRP, ferritin, and leukocyte subtypes in patients with T2DM. Therefore, OC could be a therapeutic target for protecting against chronic inflammation.

Association Between Bone Mineral Density, Bone Turnover Markers, and Serum Cholesterol Levels in Type 2 Diabetes

Purpose: The association between bone mineral density (BMD), bone turnover markers, and serum cholesterol in healthy population has already been proved. However, in patients with type 2 diabetes mellitus (T2D), it has not been adequately analyzed. In this study, we investigated the correlation between BMD, bone turnover markers, and serum cholesterol levels in people with T2D. Methods: We enrolled 1,040 men and 735 women with T2D from Zhongshan Hospital between October 2009 and January 2013. Their general condition, history of diseases and medication, serum markers, and BMD data were collected. We used logistic regression analysis to identify the association between serum cholesterol levels and BMD as well as bone turnover markers. Results: In multivariate regression analysis, we observed that in men with T2D, high high-density lipoprotein-cholesterol and total cholesterol levels were significantly associated with low total lumbar, femur neck, and total hip BMD, while low-density lipoprotein-cholesterol level was only inversely associated with total lumbar and femur neck BMD. Total cholesterol and low-density lipoprotein-cholesterol levels were also negatively associated with osteocalcin, procollagen type I N-terminal propeptide, and β-crosslaps. In women with T2D, high-density lipoprotein-cholesterol level was observed to be negatively correlated with total lumbar, femur neck, and total hip BMD, while total cholesterol and low-density lipoprotein-cholesterol levels were only associated with BMD at the total lumbar. Furthermore, total cholesterol was also negatively associated with osteocalcin, procollagen type I N-terminal propeptide, and β-crosslaps; high-density lipoprotein-cholesterol was only related to osteocalcin and parathyroid hormone, while low-density lipoprotein-cholesterol was only related to β-crosslaps in women. Conclusion: Our study suggests a significantly negative correlation between serum cholesterol levels and BMD in both men and women with T2D. The associations between serum cholesterol levels and bone turnover markers were also observed in T2D patients.

Relationship between Serum Osteocalcin and Carotid Atherosclerosis in Middle-Aged Men in China: A Cross-Sectional Study

BACKGROUND AND PURPOSE

Numerous investigations found that there exists a close relationship between serum osteocalcin and incurrence of atherosclerosis, but studies investigating the effect of serum osteocalcin on carotid atherosclerosis are very limited. Our study is aimed at investigating the role of osteocalcin in carotid atherosclerosis in middle-aged men in China.

METHODS

A total of 335 male middle-aged participants (40-60, 52.4 ± 3.87 years averagely) were enrolled from the institute. The carotid intima-media thicknesses (CIMT) of each subject were measured. All subjects were included either in the carotid atherosclerosis (AS) group or the control group according to the CAS diagnosis criteria. Serum osteocalcin and other markers of each patient were assessed following standard laboratory tests protocol.

RESULTS

135 subjects were included in AS group, and 199 subjects were included in control group. The average osteocalcin level in AS group was 18.71 ± 6.20 ng/ml and was significantly different from that in control group, which was 20.38 ± 7.19 ng/ml (p=0.039). Logistic regression analysis revealed that OCN (standardized β=-0.024, p=0.013) and FINS (standardized β=-0.065, p=0.010) were independently and inversely associated with the carotid atherosclerosis, while FPG (standardized β=0.538, p=0.006) was independently and positively associated with the carotid atherosclerosis.

CONCLUSION

Our study suggests that OCN is independently related to carotid atherosclerosis in middle-aged male individuals.

Nutrition and Inflammatory Biomarkers in Chronic Pancreatitis Patients

BACKGROUND

Chronic pancreatitis (CP) patients frequently experience malabsorption and maldigestion, leading to micronutrient and macronutrient deficiencies. Comorbid diabetes and lifestyle habits, such as alcohol consumption, may impact nutrition status.

METHODS

We compared micronutrient antioxidant, bone metabolism, serum protein, and inflammatory marker levels in 301 CP patients and 266 controls with no known pancreatic disease. We analyzed serum prealbumin and retinol binding protein; vitamins A, D, E, and B12; osteocalcin; tumor necrosis factor-α; and C-reactive protein (CRP). We also evaluated biomarkers among subsets of patients, examining factors including time since diagnosis, body mass index, alcohol as primary etiology, diabetes mellitus, vitamin supplementation, and pancreatic enzyme replacement.

RESULTS

After correcting for multiple comparisons, CP patients had significantly lower levels than controls of the following: vitamin A (40.9 vs 45.4 μg/dL) and vitamin E (α-tocopherol [8.7 vs 10.3 mg/L] and γ-tocopherol [1.8 vs 2.2 mg/L]), as well as osteocalcin (7.9 vs 10 ng/mL) and serum prealbumin (23 vs 27 mg/dL). Both patients and controls who took vitamin supplements had higher serum levels of vitamins than those not taking supplements. Compared with controls, in controlled analyses, CP patients had significantly lower levels of vitamins A, D, and E (both α-tocopherol and γ-tocopherol). CP patients also had significantly lower levels of osteocalcin, serum prealbumin, and retinol binding protein, and higher CRP.

CONCLUSIONS

CP patients demonstrated lower levels of selected nutrition and bone metabolism biomarkers than controls. Diabetes and alcohol did not impact biomarkers. Vitamin supplements and pancreatic enzyme replacement therapy improved nutrition biomarkers in CP patients.

Low serum osteocalcin concentration is associated with incident type 2 diabetes mellitus in Japanese women

Increasing evidence suggests that osteocalcin is involved in the regulation of glucose homeostasis. However, the relationship between serum osteocalcin levels and risk of incident type 2 diabetes mellitus is not clear. The objective of this study is to investigate whether serum osteocalcin levels are associated with the risk of incident type 2 diabetes mellitus. This study included 1691 Japanese postmenopausal women, 61 incident diabetes cases, and 1630 non-diabetic control subjects in the observation period. Baseline concentrations of intact osteocalcin, HbA1c, bone-specific alkaline phosphatase, adiponectin, leptin, urinary N-telopeptides were assessed. Serum osteocalcin levels were significantly correlated with HbA1c levels among 1691 Japanese postmenopausal women (R = -0.12, P < 0.0001). In receiver operating characteristic curve analysis, the optimal cut-off levels for serum osteocalcin to predict the development of type 2 diabetes mellitus was 6.1 ng/mL. The group with baseline osteocalcin levels <6.1 ng/mL showed a significantly higher risk for developing diabetes than the group with baseline osteocalcin levels >6.1 ng/mL (log-rank test, P  <  0.0001) during the mean observation period (7.6 ± 6.1 years; mean ± SD). In multiple Cox proportional hazard analysis, osteocalcin levels were significantly associated with development of type 2 diabetes mellitus during the observation period. Our results indicate that a decrease in serum osteocalcin levels is associated with future development of type 2 diabetes mellitus independent of conventional risk factors in Japanese postmenopausal women.

Longitudinal changes in bone-testis axis and their associations with insulin resistance in 11- to 12-year-old boys

PURPOSE

Associations between osteocalcin (OCN), an osteoblast-specific hormone, and different markers of energy metabolism and insulin resistance have been reported in adults, but few studies have investigated this in children. The aim of the current study was to investigate serum OCN levels during pubertal development in normal weight (NW) and overweight (OW) boys, and to evaluate possible associations of OCN with body composition, testosterone, insulin resistance and adipocytokine values during puberty.

METHODS

Ninety 11- to 12-year-old boys were investigated at 12-month intervals over the next 2years. Boys were divided by their BMI into NW (n=60) and OW (n=30) groups. Serum OCN, testosterone, leptin, adiponectin, insulin, HOMA-IR score, and body composition were measured.

RESULTS

Pubertal development over the 2-year period was similar in both groups. Serum OCN was not different at the beginning of the study and increased similarly in both groups. However, at the end of the study, NW had higher OCN than OW (142.9±5.2 vs. 124.0±7.4ng/ml; p<0.05). OW had higher leptin, insulin and HOMA-IR compared to NW, and these differences remained significant through the 2-year period. Testosterone, insulin and HOMA-IR increased through the study period in both groups. In multiple regression analyses increment in OCN was associated with the increase in testosterone in NW (p<0.001) and OW (p=0.049) boys. Increment in OCN was also associated with the increase in insulin (p=0.019) and HOMA-IR (p=0.012) over the 2-year period in NW boys.

CONCLUSION

Serum OCN concentration increases in puberty and the increment is positively associated with the rise in testosterone level in both NW and OW boys. The positive association between the rise in OCN and insulin in NW boys would suggest that OCN may have a role in the development of insulin resistance.

Serum Osteocalcin Levels in Children With Nonalcoholic Fatty Liver Disease

OBJECTIVES

The aim of the study was to investigate the relationship between osteocalcin and nonalcoholic fatty liver disease (NAFLD) in children with obesity.

METHOD

60 obese children with NAFLD were taken as a patient group and 60 obese children and normal liver with matching age, sex, and body mass index were taken as a control group. Anthropometric measurements, abdominal ultrasonography for diagnosis and grading of NAFLD, and laboratory investigations in the form of liver function tests, lipid profile, fasting serum glucose and insulin, and serum osteocalcin levels were done for all children. Patients with NAFLD were further divided into patients with metabolic syndrome (MS) and patients without MS.

RESULTS

Age of NAFLD children was (10.55 ± 2.71), 20 boys and 40 girls, whereas age of children in control group was (10.05 ± 3.51), 24 boys and 36 girls (P > 0.05). Patients with NAFLD showed significant increase in waist and hip circumference, alanine aminotransferase, alkaline phosphatase, total cholesterol, triglycerides, insulin resistance (IR), fasting serum glucose, and insulin, but lower serum osteocalcin level than control group. Serum osteocalcin level is inversely correlated with waist circumference, triglyceride, liver enzymes, fasting serum insulin, fasting serum glucose, IR, and grades of fatty liver. Increase in alanine aminotransferase, total cholesterol, triglycerides, fasting insulin, and IR went with increase in degree of hepatic steatosis. Serum osteocalcin level <44.5 ng/mL is a good predictor for severity of hepatic steatosis with sensitivity and specificity of 80%.

CONCLUSIONS

Osteocalcin plays an important role in glucose and lipid metabolism for protection against NAFLD occurrence and progression. Moreover, it could be a useful marker for progression of NAFLD in children with obesity.

Association between serum osteocalcin and body mass index: a systematic review and meta-analysis

PURPOSE

Osteocalcin is considered as a bone-derived hormone affecting on the body fat distribution and body mass index. Several cross-sectional studies have investigated the association between serum osteocalcin and body mass index. The aim of this study was to summarize the evidence on the relationship between serum osteocalcin and body mass index.

METHODS

We conducted a complete search up to November 2016 in PubMed and SCOPUS and reviewed reference list of all relevant articles and reviews. The DerSimonian-Laird method were used to pool effect sizes of eligible studies. The potential sources of heterogeneity were assessed using the standard χ ² test.To find possible the sources of between-study heterogeneity, we carried out subgroup analyses based on sex, and type of study population.

RESULTS

There was a significant inverse association in the overall result of this study between serum osteocalcin levels and BMI(r = -0.161; 95% CI: -0.197, -0.124, p < 0.000). In the subgroup analysis to find the sources of significant heterogeneity between-study, we observed that the type of the study population may be the source of between-study heterogeneity and the most correlation was seen in metabolic syndrome studies (r = -0.265; p = 0.000).

CONCLUSION

Findings from the available data indicated an overall significant inverse association between serum osteocalcin and body mass index. Further studies based on the type of study population are needed to better clarify these associations.

Inflammation and bone mineral density: A Mendelian randomization study

Osteoporosis is a common age-related disorder leading to an increase in osteoporotic fractures and resulting in significant suffering and disability. Inflammation may contribute to osteoporosis, as it does to many other chronic diseases. We examined whether inflammation is etiologically relevant to osteoporosis, assessed from bone mineral density (BMD), as a new potential target of intervention, or whether it is a symptom/biomarker of osteoporosis. We obtained genetic predictors of inflammatory markers from genome-wide association studies and applied them to a large genome wide association study of BMD. Using two-sample Mendelian randomization, we obtained unconfounded estimates of the effect of high-sensitivity C-reactive protein (hsCRP) on BMD at the forearm, femoral neck, and lumbar spine. After removing potentially pleiotropic single nucleotide polymorphisms (SNPs) possibly acting via obesity-related traits, hsCRP, based on 16 SNPs from genes including CRP, was not associated with BMD. A causal relation of hsCRP with lower BMD was not evident in this study.

Coronary Artery Calcium Score and Bone Metabolism: A Pilot Study in Postmenopausal Women

Background

Since 1991 many studies evaluated the link between cardiovascular diseases and osteoporosis, two age-related conditions, but the main common pathologic pathway has not been determined yet. The histological similarity between arterial calcified plaque and bone matrix and involvement of similar cells and mediators provide a special field of research. Therefore in the present study, we aimed to evaluate the relationship between coronary artery calcium score (CACS) as a surrogate marker of atherosclerosis and bone mediators and parameters in postmenopausal women.

Methods

Eleven postmenopausal women who had CACS higher than 80 were enrolled into the study and underwent bone densitometry. In addition, their serum and urine samples were taken for measuring osteoprotegerin, osteocalcin, and β cross laps. Patients' 10-year probability of fracture was calculated by the World Health Organization fracture-risk assessment tool (FRAX).

Results

The regression analysis of our results showed the association between CACS and OC (std β=0.66, 95% confidence interval [CI] 5.47-72.27, P=0.027), femoral bone density (std β=−0.6, 95% CI -6864.34-14.27, P=0.05) and T-score (std β=−0.6, 95% CI −773.08-1.28, P=0.05) which remained significant after adjustment for age, weight, years since menopause and body mass index. No association was found between CACS and osteoprotegerin, spinal bone density and FRAX score.

Conclusions

In conclusion, this pilot study with small sample size showed the potential association between CACS and osteocalcin, femoral bone density and T-score. However, the relationship between CACS and osteoprotegerin, receptor activator of nuclear factor-kappa B ligand, FRAX score and other bone parameters remain to be clarified in larger sample size studies.

Osteocalcin as a potential risk biomarker for cardiovascular and metabolic diseases

Clear evidence supports a role for circulating and locally-produced osteocalcin (OC) in the pathophysiology of cardiovascular (CV) lesions and CV risk, also in combination with metabolic changes, including type 2 diabetes mellitus (T2DM). Reduced plasma OC levels are associated with greater incidence of pathological CV changes, like arterial and valvular calcification, coronary and carotid atherosclerosis and increased carotid intima-media thickness. The actual relationship between OC levels and incidence of major CV events is, however, still unclear. Moreover, reduced circulating OC levels have been mostly associated with insulin resistance, metabolic syndrome or T2DM, indicating relevant OC actions on pancreatic β-cells and insulin secretion and activity. Based on these observations, this review article will attempt to summarize the current evidence on the potential usefulness of circulating OC as a biomarker for CV and metabolic risk, also evaluating the currently open issues in this area of research.

Carboxylated and undercarboxylated osteocalcin in metabolic complications of human obesity and prediabetes

BACKGROUND

Carboxylated osteocalcin (Gla-OC) participates in bone remodeling, whereas the undercarboxylated form (Glu-OC) takes part in energy metabolism. This study was undertaken to compare the blood levels of Glu-OC and Gla-OC in nonobese, healthy obese, and prediabetic volunteers and correlate it with the metabolic markers of insulin resistance and early markers of inflammation.

METHODS

Nonobese (body mass index [BMI] <30 kg/m² ; n = 34) and obese subjects (30 <BMI <40 kg/m² ; n = 98), both sexes, aged 25 to 65 years, were divided into healthy control, normal weight subjects, healthy obese, and obese with biochemical markers of prediabetes. The subgroups with obesity and low or high Gla-OC or Glu-OC were also considered for statistical analysis. After 2 weeks of diet standardization, venous blood was sampled for the determination of Gla-OC, Glu-OC, lipid profile, parameters of inflammation (hsCRP, interleukin 6, sE-selectin, sPECAM-1, and monocyte chemoattractant protein 1), and adipokines (leptin, adiponectin, visfatin, and resistin).

RESULTS

Gla-OC in obese patients was significantly lower compared to nonobese ones (11.36 ± 0.39 vs 12.69 ± 0.90 ng/mL, P = .048) and weakly correlated with hsCRP (r = -0.18, P = .042), visfatin concentration (r = -0.19, P = .033), and BMI (r = -0.17, P = .047). Glu-OC was negatively associated with fasting insulin levels (r = -0.18, P = .049) and reduced in prediabetic individuals compared with healthy obese volunteers (3.04 ± 0.28 vs 4.48 ± 0.57, P = .025).

CONCLUSIONS

Decreased blood concentration of Glu-OC may be a selective early symptom of insulin resistance in obesity, whereas the decreased level of Gla-OC seems to be associated with the appearance of early markers of low grade inflammation accompanying obesity.

The rs2274911 polymorphism in GPRC6A gene is associated with insulin resistance in normal weight and obese subjects

OBJECTIVE

Identification of the novel endocrine role of osteocalcin (OC) and its receptor GPRC6A has given rise to a new branch of research in OC/GPRC6A axis related to glucose metabolism. GPRC6A- and OC-deficient mice share features of the metabolic syndrome, in addition to male infertility. Recently, the polymorphism rs2274911 in GPRC6A was shown to be associated with testicular impairment. We aimed to investigate the role of rs2274911 polymorphism in glucose and lipid metabolism in a cohort of normal weight and obese subjects DESIGN, PATIENTS, SETTINGS: A total of 392 male and females, including 218 obese patients and 174 age-matched normal weight controls, were retrospectively selected.

RESULTS

The distribution of rs2274911 alleles and genotypes did not differ either between normal weight and obese subjects or sexes (all P > 0·05). Age- and OC-adjusted multivariate analysis revealed that, in the normal weight group, fasting insulin and HOMA-IR increased in GA (P = 0·016 and P = 0·025) and AA genotypes (P = 0·033 and P = 0·040) compared with GG homozygotes. In the obese group, AA homozygotes had increased fasting glucose (P = 0·041 vs GG). Triglycerides, fasting insulin and HOMA-IR increased in both GA (P = 0·020, P < 0·001 and P = 0·001) and AA genotype (P = 0·021, P = 0·013 and P = 0·013).

CONCLUSION

In a cohort of normal weight and obese subjects, we found that the nonrare polymorphism rs2274911 in the GPRC6A gene was associated with insulin resistance features, independently of the metabolic phenotype and OC levels.

Serum levels of undercarboxylated osteocalcin are related to cardiovascular risk factors in patients with type 2 diabetes mellitus and healthy subjects

AIM

To determine a potential relationship between serum undercarboxylated (ucOC) concentration and cardiovascular risk factors in type 2 diabetes (T2D) patients and healthy subjects (HS).

METHODS

A cross-sectional study was conducted on 140 subjects classified into two groups, 70 with T2D and 70 HS. Medical history and physical examination with anthropometric measurements were obtained from all subjects. Body fat percentage was determined by bioelectrical impendency analysis. Serum ucOC concentration was determined by enzyme immunoassay, while serum levels of insulin and hsCRP were obtained using high sensitivity enzyme-linked immunosorbent assay. Insulin resistance was determined using the homeostasis model assessment-IR. Lipid profile [triglycerides, total cholesterol (TC), high-density lipoproteins (HDL-c), low density lipoproteins (LDL-c), very low-density lipoproteins] was determined by spectrophotometry and standard formulas when applicable.

RESULTS

The T2D patient group showed significantly higher values of waist circumference, waist-to-hip ratio, systolic blood pressure (SBP), diastolic blood pressure (DBP), current smoking, and alcohol use when compared to the HS group (P < 0.05). We observed a significantly lower serum ucOC concentration in T2D than in HS (1.5 ± 1.4 vs 2.3 ± 1.8, P < 0.05). In the whole study population, ucOC concentration was inversely correlated with body mass index (BMI) (r = -0.236, P < 0.05), fasting plasma glucose (r = -0.283, P < 0.01) and HDL-c (r = -0.255, P < 0.05); and positively correlated with LDL-c/HDL-c ratio (r = 0.306, P < 0.05) and TC/HDL-c ratio (r = 0.284, P < 0.05). In the T2D group, serum ucOC concentration was inversely correlated with BMI (r = -0.310, P < 0.05) and body-fat percentage (r = -0.311, P < 0.05), and positively correlated with DBP (r = 0.450, P < 0.01). In HS group a positive correlation between serum levels of ucOC and SBP (r = 0.277, P < 0.05) was observed.

CONCLUSION

Serum ucOC is a potential marker for cardiovascular risk in Mexicans because it is related to adiposity parameters, blood pressure and lipid profile.

An evaluation of homocysteine, C-reactive protein, lipid levels, neutrophils to lymphocyte ratio in postmenopausal osteopenic women

OBJECTIVE

In the present study, the risk coefficients of serum homocysteine (hcy), lipid levels, C-reactive protein (CRP), neutrophils to lymphocyte ratio (NLR) in postmenopausal osteopenic women were determined.

METHODS

We enrolled 269 patients with postmenopausal women from Hangzhou No.1 Hospital gynecological clinic, who aged 45 to 60 years old and never received menopause hormone therapy. According to the bone mineral density determination results, subjects were divided into normal group (n  =  128), osteopenia group (n  =  141). Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA). Serum hcy, CRP and lipid indexes were determined by enzyme chemiluminescence immunoassay.

RESULTS

The odds ratios (OR) and 95% confidence intervals (CI) of those variables (menopausal age, duration of menopause, LDL, CRP, hcy and NLR) were found significant (p  <  0.05). Menopausal age, duration of menopause, LDL, CRP, hcy and NLR variables were found statistically significant in the analysis of receiver operating characteristic (ROCs).

CONCLUSION

The present study shows that menopause age, duration of menopause, serum LDL, CRP, hcy and NLR levels are risk factors for postmenopausal osteopenic women, which may be used as the indicators of bone loss in postmenopausal women.

Inverse relationship between serum osteocalcin levels and nonalcoholic fatty liver disease in postmenopausal Chinese women with normal blood glucose levels

AIM

Osteocalcin is involved in the progression of nonalcoholic fatty liver disease (NAFLD) in animal models and humans. In this study we investigated the relationship between serum osteocalcin levels and NAFLD in postmenopausal Chinese women.

METHODS

A total of 733 postmenopausal women (age range: 41-78 years) with normal blood glucose levels were enrolled in this cross-sectional study. Women taking lipid-lowering or anti-hypertensive drugs were excluded. Serum osteocalcin levels were assessed using an electrochemiluminescence immunoassay. The degree of NAFLD progression for each subject was assessed through ultrasonography. The fatty liver index (FLI) of each subject was calculated to quantify the degree of liver steatosis.

RESULTS

The median level of serum osteocalcin for all subjects enrolled was 21.99 ng/mL (interquartile range: 17.84-26.55 ng/mL). Subjects with NAFLD had significantly lower serum osteocalcin levels (18.39 ng/mL; range: 16.03-23.64 ng/mL) compared with those without NAFLD (22.31 ng/mL; range: 18.55-27.06 ng/mL; P<0.01). Serum osteocalcin levels decreased with incremental changes in the FLI value divided by the quartile (P-value for trend<0.01). The serum osteocalcin levels showed a negative correlation with the FLI values, even after adjusting for confounding factors (standardized β=-0.124; P<0.01). Binary logistic regression analysis identified an individual's serum osteocalcin level as an independent risk factor for NAFLD (odds ratio: 0.951; 95% confidence interval: 0.911-0.992; P=0.02).

CONCLUSION

Serum osteocalcin levels are inversely correlated with NAFLD in postmenopausal Chinese women with normal blood glucose levels.

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.

Serum Osteocalcin Is Associated with Inflammatory Factors in Metabolic Syndrome: A Population-Based Study in Chinese Males

Osteocalcin (OCN) was potentially associated with inflammatory factors, so we explored the metabolic role in this association in general population. Our findings suggest that OCN was positively associated with IgG while inversely associated with C3, both of which were probably mediated by obesity. Moreover, serum OCN was inversely associated with hsCRP in men with impaired fasting glucose, hyperglycemia, or metabolic syndrome, while its association with IgE was significantly observed in men with a normal metabolic profile.

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.

Osteocalcin, but not deoxypyridinoline, increases in response to isoflurane-induced anaesthesia in young female guinea pigs

The effect of the inhaled anaesthetic isoflurane was investigated on bone biomarkers, both during maturation and on minerals and glucose postpartum. Female guinea pigs (n = 10) were anaesthetized during maturation (5 and 9 weeks) and postpartum (26 weeks of age) with isoflurane during dual-energy X-ray absorptiometry scanning. Blood collection was performed at all ages before and after anaesthesia for measurement of plasma osteocalcin (OC), total deoxypyridinoline (tDPD), and cortisol. Postpartum measurements also included: blood ions, acid-base parameters and glucose, plasma minerals, total alkaline phosphatase (tALP), and albumin. Plasma OC concentration almost doubled after exposure to isoflurane at 5 weeks (30.1 ± 5.0-57.9 ± 11.2 nmol/L, p < 0.001) and at 9 weeks (29.1 ± 7.5-62.9 ± 15.9 nmol/L, p < 0.001), but did not change postpartum (3.7 ± 3.3-4.3 ± 3.9 nmol/L, p = 0.88). There was no effect of isoflurane exposure on plasma tDPD at any age. Plasma cortisol increased after exposure to isoflurane at 9 weeks (1859.6 ± 383.2-2748.0 ± 235.3 nmol/L, p < 0.01) and postpartum (3376.7 ± 322.2-4091.6 ± 195.6 nmol/L, p < 0.001) but not at 5 weeks (2088.3 ± 326.4-2464.1 ± 538.0 nmol/L, p > 0.05). Blood ionized Ca(2+), Na(+) and plasma total Ca did not change, whereas plasma albumin decreased, and inorganic phosphate (PO4) and Cl(-) increased upon exposure to isoflurane. Isoflurane decreased tALP (43.2 ± 6.6-40.2 ± 5.9 IU/L, p = 0.01) and increased glucose (7.5 ± 0.6-10.9 ± 1.7 mmol/L, p < 0.0001) postpartum. Isoflurane inflates the assessment of a bone-derived biomarker, OC, during rapid growth, but not following pregnancy when formation is very low. Measurements prior to anaesthesia are recommended to reflect normal metabolism.

The Relationship between Serum Osteocalcin Concentration and Glucose and Lipid Metabolism in Patients with Type 2 Diabetes Mellitus – The Role of Osteocalcin in Energy Metabolism

BACKGROUND

Recent animal studies have found that the osteocalcin secreted by osteoblasts could participate in glucose and lipid metabolism. Our study aimed to investigate the relationship between serum osteocalcin concentration and glucose and lipid metabolism in patients with type 2 diabetes mellitus.

METHODS

985 patients with type 2 diabetes were divided into the male group (n = 495) and the postmenopausal female group (n = 490). The average ages were 54.42 ± 10.535 and 64.93 ± 9.277, respectively. We collected the parameters of age, duration, fasting plasma glucose, HbA1c, fasting insulin, fasting C peptide, blood lipid, 25 (OH) VD3, parathyroid hormone (PTH), Alkaline phosphatase (ALP), procollagen type 1 N-terminal propeptide (P1NP), β-C-terminal telopeptide of type I collagen (β-CTx), osteocalcin, HOMA-IR, HOMA-β, body mass index (BMI), and waist-to-hip ratio (WHR). The relationship of osteocalcin and these parameters were analyzed by Pearson/Spearman correlation analysis and stepwise multiple regression analysis.

RESULTS

Osteocalcin was negatively correlated with HbA1c (p < 0.05) and it was also an independent relevant factor affecting HbA1c in both groups. Osteocalcin was positively correlated with HOMA-β and it was an independent relevant factor affecting HOMA-β in male group (p < 0.01).

CONCLUSIONS

These findings indicate the association between serum osteocalcin and glucose metabolism and beta cell function. No relationship was found between osteocalcin and insulin resistance and lipid metabolism in type 2 diabetes.

Plasma osteocalcin levels as a predictor of cardiovascular disease in older men and women: a population-based cohort study

OBJECTIVE

The role of osteocalcin (OC) in cardiovascular disease (CVD) is unresolved. We aimed to study the association between plasma OC concentrations and the risk of non-fatal and fatal CVDs. We also aimed to investigate whether such an association, if present, would be mediated by established metabolic risk factors.

DESIGN

A population-based longitudinal cohort study.

METHODS

In 1995/1996, OC was determined in blood samples drawn from 1319 subjects aged 65-88 years participating in the Longitudinal Aging Study Amsterdam in 1995/1996. The self-reported CVD events were collected every 3 years until 2005/2006, and CVD deaths until 1st January 2007. Cox proportional hazards regression was performed, considering potential confounders (smoking, physical activity, and BMI) and mediators (blood pressure, plasma triglycerides, total and HDL cholesterol, fructosamine, and aortic calcification).

RESULTS

During the median 4.1 years follow-up, 709 subjects (53.8%) suffered a CVD event. There was no overall association between OC and CVD: hazard ratio (HR) was 0.97 (95% CI 0.90-1.04) per nmol/l higher plasma OC, adjusted for age and sex. There was a statistical interaction between plasma OC, age, and sex on CVD (P=0.014). In those subjects aged ≥75 years, age-adjusted HRs (95% CI) were 0.86 (0.75-0.99) in men and 1.16 (1.03-1.31) in women per nmol/l higher plasma OC. Adjustment for covariates only slightly attenuated the association in older-old men, but did not affect the association in older-old women.

CONCLUSION

A higher plasma OC concentration was associated with a reduced risk of CVD in older-old men and with an increased risk of CVD in older-old women. We found no evidence that this was mediated by arterial calcification or metabolic risk factors.

Osteocalcin is higher across pregnancy in Caucasian women with gestational diabetes mellitus

OBJECTIVE

The purpose of this study was to investigate circulating concentrations of osteocalcin, a bone-derived protein, while accounting for 25-hydroxyvitamin D (25(OH)D) throughout pregnancy, and whether early gestation concentrations and changes in osteocalcin predict the subsequent diagnosis of gestational diabetes mellitus (GDM).

METHODS

This was a nested case-control study involving 48 GDM and 48 control pregnant Caucasian women (matched for age, season of conception, pre-pregnancy body mass index and pregnancy length). Maternal serum osteocalcin was measured by enzyme-linked immunosorbent assay and 25(OH)D by chemiluminescence throughout pregnancy (11-13 weeks, 24-28 weeks and predelivery). Differences between groups were compared by mixed model analysis of variance. Predictors of diagnosis of GDM were explored using generalized estimating equation models. Neonatal general health outcomes were also compared between groups.

RESULTS

Serum osteocalcin was higher across pregnancy (p=0.006) in women with GDM vs. controls, whereas serum 25(OH)D was not different (p=0.80). Both biomarkers increased with time across pregnancy (p<0.0001). However, serum osteocalcin during early pregnancy and changes in its concentration from early to mid gestation did not predict the development of GDM. There were no significant differences in anthropometry and APGAR (appearance, pulse, grimace, activity, respiration) scores in neonates of controls and cases.

CONCLUSIONS

Serum osteocalcin is elevated in Caucasian women with GDM throughout pregnancy, but was not predictive of the onset of GDM. Larger trials evaluating the role of osteocalcin and the development of GDM appear warranted.

PHEX mimetic (SPR4-peptide) corrects and improves HYP and wild type mice energy-metabolism

CONTEXT

PHEX or DMP1 mutations cause hypophosphatemic-rickets and altered energy metabolism. PHEX binds to DMP1-ASARM-motif to form a complex with α5β3 integrin that suppresses FGF23 expression. ASARM-peptides increase FGF23 by disrupting the PHEX-DMP1-Integrin complex. We used a 4.2 kDa peptide (SPR4) that binds to ASARM-peptide/motif to study the DMP1-PHEX interaction and to assess SPR4 for the treatment of energy metabolism defects in HYP and potentially other bone-mineral disorders.

DESIGN

Subcutaneously transplanted osmotic pumps were used to infuse SPR4-peptide or vehicle (VE) into wild-type mice (WT) and HYP-mice (PHEX mutation) for 4 weeks.

RESULTS

SPR4 partially corrected HYP mice hypophosphatemia and increased serum 1.25(OH)2D3. Serum FGF23 remained high and PTH was unaffected. WT-SPR4 mice developed hypophosphatemia and hypercalcemia with increased PTH, FGF23 and 1.25(OH)2D3. SPR4 increased GAPDH HYP-bone expression 60× and corrected HYP-mice hyperglycemia and hypoinsulinemia. HYP-VE serum uric-acid (UA) levels were reduced and SPR4 infusion suppressed UA levels in WT-mice but not HYP-mice. SPR4 altered leptin, adiponectin, and sympathetic-tone and increased the fat mass/weight ratio for HYP and WT mice. Expression of perlipin-2 a gene involved in obesity was reduced in HYP-VE and WT-SPR4 mice but increased in HYP-SPR4 mice. Also, increased expression of two genes that inhibit insulin-signaling, ENPP1 and ESP, occurred with HYP-VE mice. In contrast, SPR4 reduced expression of both ENPP1 and ESP in WT mice and suppressed ENPP1 in HYP mice. Increased expression of FAM20C and sclerostin occurred with HYP-VE mice. SPR4 suppressed expression of FAM20C and sclerostin in HYP and WT mice.

CONCLUSIONS

ASARM peptides and motifs are physiological substrates for PHEX and modulate osteocyte PHEX-DMP1-α5β3-integrin interactions and thereby FGF23 expression. These interactions also provide a nexus that regulates bone and energy metabolism. SPR4 suppression of sclerostin and/or sequestration of ASARM-peptides improves energy metabolism and may have utility for treating familial rickets, osteoporosis, obesity and diabetes.

Role of adiponectin in mediating the association of osteocalcin with insulin resistance and type 2 diabetes: a cross sectional study in pre- and post-menopausal women

OBJECTIVE

To analyse the association of osteocalcin with insulin resistance and type 2 diabetes and assess the role of adiponectin in these relationships.

METHODS

This study comprised 98 newly diagnosed type 2 diabetic women (51 pre-menopausal and 47 post-menopausal) and 102 age and BMI matched controls (53 pre-menopausal and 49 post-menopausal). Insulin resistance was calculated by homeostasis model assessment-insulin resistance (HOMA-IR).

RESULTS

Osteocalcin was significantly positively correlated with adiponectin in both pre-menopausal (p = 0.0026) and post-menopausal diabetic women (p = 0.0357). Significant negative association between osteocalcin and HOMA-IR was observed only in pre-menopausal diabetic women (p = 0.0019), but the association was partially reduced (p = 0.0219) after additional adjustment for adiponectin. Adiponectin slightly attenuated the inverse association between osteocalcin and presence of type 2 diabetes in both pre- and post-menopausal women.

CONCLUSION

The protective action of osteocalcin against the development of insulin resistance and type 2 diabetes in women may be partially mediated through up-regulation of adiponectin secretion.

Osteocalcin attenuates high fat diet-induced impairment of endothelium-dependent relaxation through Akt/eNOS-dependent pathway

Background

Recent studies have demonstrated a protective effect of osteocalcin (OCN) on glucose homeostasis and metabolic syndrome. However, its role in vascular function remains unknown. This study investigated the contribution of OCN to the pathogenesis of endothelial dysfunction in the thoracic aorta of apolipoprotein E-deficient (ApoE-KO) mice.

Methods

Eight-week-old ApoE–KO mice were given chow or high fat diet (HFD) for 12 weeks with or without daily intraperitoneal injection of OCN. Intraperitoneal glucose tolerance test (IPGTT), insulin tolerance test (ITT),measurement of serum lipid profiles and blood pressure were carried out. Endothelium-dependent relaxation (EDR) was measured by wire myography. Human umbilical vein endothelial cells (HUVECs) were used to study the role of OCN on eNOS levels in vitro. PI3K inhibitor (LY294002) and Akt inhibitor V were used ex-vivo to determine whether PI3K/Akt/eNOS contributes to the beneficial effect of OCN for the vascular or not.

Results

Daily injections of OCN can significantly improve lipid metabolism, glucose tolerance and insulin sensitivity in ApoE-KO mice. In ApoE-KO mice fed with HFD, the OCN-treated mice displayed an improved acetylcholine-stimulated EDR compared to the vehicle-treated group. In addition, compared to vehicle-treated HUVECs, OCN-treated HUVECs displayed increased activation of the Akt-eNOS signaling pathway, as evidenced by significantly higher levels of phosphorylated Akt and eNOS. Furthermore, a similar beneficial effect of OCN on thoracic aorta was observed using ex vivo organ culture of isolated mouse aortic segment. However, this effect was attenuated upon co-incubation with PI3K inhibitor or Akt inhibitor V.

Conclusions

Our study demonstrates that OCN has an endothelial-protective effect in atherosclerosis through mediating the PI3K/Akt/eNOS signaling pathway.

Serum osteocalcin level and its association with carotid atherosclerosis in patients with type 2 diabetes

Objective

To investigate the association of serum osteocalcin with carotid atherosclerosis in patients with type 2 diabetes.

Methods

We performed a cross-sectional community-based study in metropolitan area. Serum total osteocalcin was measured by radioimmunoassay in 382 men and 435 postmenopausal women. The carotid artery intima-media thickness (IMT) and carotid plaques (PLQ) were measured by B-mode ultrasound.

Results

The crude mean of serum osteocalcin concentrations were 4.52±2.43 ng/ml for men and 5.75±2.92 ng/ml for postmenopausal women (P <0.001), respectively. Osteocalcin levels were associated inversely with age, fasting serum insulin, HOMA-IR, ALT, triglycerides, total cholesterol, LDL- cholesterol, CRP (all P<0.001) and positively with adiponectin and HOMA-B (all P<0.05). After multiple adjustment, the odds ratios (ORs) were substantially higher risk for carotid plaques (OR 1.77 for 1 SD decrease in osteocalcin, 95% CI 1.23-2.76, p=0.005). These associations remained significant after further adjustment for potential confounder.

Conclusions

Serum osteocalcin levels is an independent risk factor for carotid atherosclerosis in patients with type 2 diabetes.