LMS-based continuous pediatric reference values for soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin (OPG) in the HARP cohort

Soluble RANKL (sRANKL) and osteoprotegerin (OPG) are regulators of osteoclast differentiation and activation, but adequate pediatric reference values are lacking. Here we provide LMS (Lambda-Mu-Sigma)-based continuous pediatric reference percentiles for sRANKL, OPG and sRANKL/OPG ratio that will allow calculation of standardized patient z-scores to assess bone modeling in children.

PURPOSE

Soluble receptor activator of nuclear factor kappa B ligand (sRANKL) and osteoprotegerin (OPG) are regulators of osteoclast differentiation and activation and thus bone metabolic turnover in children. Adequate pediatric reference values for their serum/plasma concentrations are lacking. The development of Lambda-Mu-Sigma (LMS)-based continuous reference percentiles for laboratory parameters allow improved data interpretation in clinical practice.

METHODS

A total of 300 children aged 0.1-18 years (166 boys) were enrolled in the HAnnover Reference values for Pediatrics (HARP) study. sRANKL and OPG were assessed by ELISA. LMS-based continuous reference percentiles were generated using RefCurv software.

RESULTS

LMS-based percentiles were established for sRANKL, OPG and sRANKL/OPG ratio, which were all found to be age-dependent. sRANKL and sRANKL/OPG associated with sex. In boys, sRANKL percentiles were highest during infancy, followed by a continuous decline until the age of 7 years and a second peak around age 12-13 years. In girls, a continuous, slow decline of sRANKL percentiles was noticed from infancy onwards until the age of 13 years, followed by a rapid decline until adulthood. OPG percentiles continuously declined from infancy to adulthood. The percentiles for sRANKL/OPG ratio paralleled those of sRANKL. Serum concentrations of sRANKL correlated with OPG and serum phosphate z-scores, while OPG concentrations inversely associated with standardized body weight, BMI, and urinary phosphate to creatinine ratio (each p < 0.05).

CONCLUSION

This is the first report of LMS-based continuous pediatric reference percentiles for sRANKL, OPG and sRANKL/OPG ratio that allows calculation of standardized patient z-scores to assess bone metabolic turnover in children.

Bone mineral density in egyptian children with juvenile idiopathic arthritis: possible correlation to serum RANKL / osteoprotegerin (OPG) ratio and OPG gene polymorphisms

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) are at higher risk of decreased bone mineral density (BMD) compared with healthy children due to genetic, disease and medication-related causes. This study aims to investigate the possible effects of osteoprotegerin (OPG) gene polymorphisms and serum levels of osteoprotegerin (OPG) and receptor activator of nuclear factor κB-ligand (RANKL) and RANKL/OPG ratio on BMD in children with JIA.

METHODS

OPG gene rs2073617, rs3134069, serum RANKL, OPG and RANKL/OPG ratio were evaluated in 60 JIA children and 100 matched healthy controls. BMD was evaluated by lumbar dual energy X-ray absorptiometry (DEXA) according to which patients were classified in 2 groups (DEXA z-score above and below - 2). Composite disease activity was measured using the Juvenile Arthritis Disease Activity Score (JADAS) 27-joints. Articular damage was scored using the juvenile arthritis damage index (JADI).

RESULTS

Patients aged 12.05 ± 3.2 years, included 38 females and 31% had BMD z-score below-2. Systemic-onset JIA was the most frequent phenotype (38%). Genotypes and alleles frequencies of the 2 studied polymorphisms did not differ between patients and controls (p > 0.05 for all) while serum RANKL and RANKL/OPG ratio were significantly higher in patients compared to controls (p = < 0.001 and 0.03 respectively). Patients with BMD < -2 had significantly greater frequencies of rs2073617 TT genotype and T allele (p < 0.001), higher serum RANKL, RANKL/OPG ratio (p = 0.01, 0.002), female predominance (p = 0.02), higher articular and extra-articular damage index (p = 0.008,0.009) and more frequent steroid usage (p = 0.02) compared to patients with BMD z-score >-2. Multivariate analysis showed rs2073617 TT genotype, RANKL/OPG ratio, long disease duration (above 36 months) and use of steroid to be associated with decreased BMD (p = 0.03,0.04,0.01,0.01 respectively) in JIA children.

CONCLUSIONS

Egyptian children with JIA have decreased BMD. rs2073617 TT genotype and T allele, RANKL/OPG ratio are possible determinants of reduced BMD in JIA. Our results underline the importance of frequent monitoring of BMD in JIA children and trying to control disease activity to preserve long term bone health.

Decreased level of soluble receptor activator of nuclear factor-κβ ligand (sRANKL) in overweight and obese children

INTRODUCTION

Childhood obesity contributes to the development of cardiovascular diseases. The molecular pathway - receptor activator of nuclear factor-κβ ligand (RANKL), its receptor RANK and osteoprotegerin (OPG) - takes part not only in bone metabolism but is also involved in the atherosclerosis process. RANKL stimulates osteogenic differentiation and calcification of vascular smooth cells. The associations between the OPG-sRANKL system and various cardiovascular risk factors were displayed. We aimed to evaluate the relationships between serum sRANKL (soluble RANKL) levels and the OPG/sRANKL ratio with cardiometabolic risk factors in overweight and obese children.

MATERIAL AND METHODS

The study included 70 children with overweight and obesity (mean age 13.0 ± 2.8) and 35 age-matched normal weight, healthy peers as a control group. In all patients, anthropometric measurements and laboratory tests were performed. Additionally, an oral glucose tolerance test (OGTT) was made only in overweight and obese children. Atherogenic and insulin resistance indices were calculated.

RESULTS

Overweight and obese children had lower sRANKL levels compared to the control group (median 276.95 vs 325.90, p=0.011), and consequently a higher OPG/sRANKL ratio (0.02 vs 0.01, p = 0.013). The studied children in the lowest quartile of sRANKL levels had higher body weight, Body Mass Index, waist circumference and increased glucose and insulin levels 60 minutes after OGTT and higher uric acid values compared to children in the highest quartile. In multivariable linear regression analysis sRANKL negatively correlated only with uric acid (β = - 0.508, p = 0.041). No association was found for the OPG/sRANKL ratio.

CONCLUSION

Excess fat mass seems to alter the OPG/RANKL ratio mainly by reducing serum sRANKL levels. The correlation between sRANKL and uric acid may suggest a contribution of the OPG-sRANKL system in the cardiometabolic process, but that observation should be confirmed in future studies.

Relationship Between Maternal Bone Biomarkers and Fetal Adiposity Through Normal Pregnancy

PURPOSE

To examine the association of maternal bone markers [sclerostin, soluble receptor activator of nuclear factor-κB ligand (sRANKL), osteocalcin, 25-hydroxyvitamin D3] with fetal intra-abdominal and subcutaneous adipose tissue deposition and birthweight during normal pregnancy.

METHODS

One hundred pregnant women (aged 30.4 ± 5.6 years, mean ± SD) with prepregnancy body mass index = 24.1 ± 4.6 kg/m2 were seen prospectively during each trimester. At each visit they were submitted to anthropometric measurements, a fasting blood sampling, a 75-g oral glucose tolerance test, and a fetal ultrasonogram. At birth, neonates had birth weight measurement.

RESULTS

In the second trimester, maternal sclerostin concentrations correlated positively with fetal abdominal circumference and birth weight; maternal sRANKL concentrations correlated positively with fetal abdominal subcutaneous fat thickness, sagittal abdominal diameter, and abdominal circumference. Fetuses born to mothers with greater (>254 ng/mL), compared to fetuses born to mothers with lower (≤254ng/mL), sRANKL concentrations had greater abdominal circumference, sagittal diameter, and abdominal subcutaneous fat thickness. Maternal serum sclerostin concentrations were the best positive predictors of birth weight. In the third trimester maternal sclerostin concentrations correlated positively with fetal sagittal abdominal diameter; maternal sRANKL concentrations positively correlated with fetal abdominal circumference and fetal abdominal sagittal diameter.

CONCLUSIONS

Maternal bone markers sclerostin and sRANKL may relate to fetal intra-abdominal adipose tissue deposition through as yet unknown direct or indirect mechanisms, thus contributing to birthweight.

Acvr1 deletion in osteoblasts impaired mandibular bone mass through compromised osteoblast differentiation and enhanced sRANKL-induced osteoclastogenesis

Bone morphogenetic protein (BMP) signaling is well known in bone homeostasis. However, the physiological effects of BMP signaling on mandibles are largely unknown, as the mandible has distinct functions and characteristics from other bones. In this study, we investigated the roles of BMP signaling in bone homeostasis of the mandibles by deleting BMP type I receptor Acvr1 in osteoblast lineage cells with Osterix-Cre. We found mandibular bone loss in conditional knockout mice at the ages of postnatal day 21 and 42 in an age-dependent manner. The decreased bone mass was related to compromised osteoblast differentiation together with enhanced osteoclastogenesis, which was secondary to the changes in osteoblasts in vivo. In vitro study revealed that deletion of Acvr1 in the mandibular bone marrow stromal cells (BMSCs) significantly compromised osteoblast differentiation. When wild type bone marrow macrophages were cocultured with BMSCs lacking Acvr1 both directly and indirectly, both proliferation and differentiation of osteoclasts were induced as evidenced by an increase of multinucleated cells, compared with cocultured with control BMSCs. Furthermore, we demonstrated that the increased osteoclastogenesis in vitro was at least partially due to the secretion of soluble receptor activator of nuclear factor-κB ligand (sRANKL), which is probably the reason for the mandibular bone loss in vivo. Overall, our results proposed that ACVR1 played essential roles in maintaining mandibular bone homeostasis through osteoblast differentiation and osteoblast-osteoclast communication via sRANKL.

The impact of nonosteogenic factors on the expression of osteoprotegerin and RANKL during human fracture healing

Objectives

The osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) balance is of the utmost importance in fracture healing. The aim of this study was therefore to investigate the impact of nonosteogenic factors on OPG and RANKL levels.

Methods

Serum obtained from 51 patients with long bone fractures was collected over 48 weeks. The OPG and serum sRANKL (soluble RANKL) concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Smoking habit, diabetes, and alcohol consumption were recorded.

Results

Age and sex greatly influenced preoperative serum levels of OPG and sRANKL but differences were even more pronounced during fracture healing. Statistical significance was observed for overall serum levels of OPG (p = 0.001) and sRANKL (p < 0.001) in older men and women (age greater than 50 years). Interestingly, OPG levels increased over time in older women but decreased over time in older men.

Conclusion

These data suggest that nonosteogenic factors, most significantly age and sex, have a major impact on sRANKL and OPG levels. Given the established association of OPG and sRANKL levels and nonunion, these findings seem to be of clinical relevance.

Cite this article: J. Starlinger, G. Kaiser, A. Thomas, K. Sarahrudi. The impact of nonosteogenic factors on the expression of osteoprotegerin and RANKL during human fracture healing. Bone Joint Res 2019;8:349–356. DOI: 10.1302/2046-3758.87.BJR-2018-0116.R3.

Does idiopathic hypercalciuria affect bone metabolism during childhood? A prospective case-control study

BACKGROUND

A limited number of studies have evaluated biochemical bone metabolism markers in children with idiopathic hypercalciuria, which in adults has been linked with osteopenia. Our aim was to investigate in children with idiopathic hypercalciuria biochemical markers of bone formation and resorption and the osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kB ligand (sRANKL) system which is involved in the osteoclastogenesis process.

METHODS

A prospective study was conducted on 50 children with idiopathic hypercalciuria and 50 healthy age-, sex-, and Tanner stage-matched control subjects. Following the diagnosis, patients were requested to follow a 3-month dietary recommendation for idiopathic hypercalciuria. In patients, at diagnosis and at 3 months of follow-up, and in controls, bone-related hormones and serum/urine biochemical parameters were studied. The bone formation markers (total ALP and osteocalcin) and the bone resorption markers (β-Crosslaps) and the OPG and sRANKL levels were determined.

RESULTS

No differences were found in the bone formation markers or OPG and sRANKL between the children with idiopathic hypercalciuria and controls. The β-Crosslaps and the β-Crosslaps/osteocalcin ratio were higher in the patients at diagnosis than in controls (p = 0.019 and p = 0.029, respectively), with a trend to decrease after the 3-month dietary intervention. The initially increased 24-h urinary Ca in the patients decreased after the 3-month dietary intervention (p = 0.002).

CONCLUSIONS

Children with idiopathic hypercalciuria had biochemical markers compatible with normal bone formation but increased bone resorption. After a 3-month dietary intervention, the trend observed towards decrease in the serum β-Crosslaps may reflect a beneficial response.

sRANKL and its correlation with metabolic syndrome parameters in children

BACKGROUND

Activating receptor ligand for nuclear factor (RANKL) has been identified as a ligand attached to the cell membrane of osteoblasts and odontoclasts.

AIM

To determine a possible association of sRANKL in saliva and serum with the parameters of metabolic syndrome (MS) in paediatric population aged 8-12 years.

DESIGN

This was a clinical, analytical and comparative study. Students between 6 and 12 years with good oral hygiene were included. Anthropometry, clinical analysis, dentobacterial plaque registration were registered as well as sRANKL in total saliva and serum through the ELISA technique.

RESULTS

A total of 43 children were enrolled, with a mean age of 9.7 (±0.8 years). Contrasting the groups by the presence or absence of the waist circumference above the normal limit, the difference in serum sRANKL concentration was statistically significant (P ≤ 0.05). A negative statistical significance was found in the correlation between serum sRANKL and HDLc (r²  = -0.310, P = 0.046). Saliva sRANKL did not show statistical difference between neither gender nor body mass index and was not correlated with any parameter of the MS.

CONCLUSIONS

A good oral hygiene seems to avoid the effects of MS on the oral cavity.

Effects of 17β-estradioland raloxifene on endothelial OPG and RANKL secretion

OBJECTIVES

This study aims to asses the effects of estradiol vs. raloxifene on the levels of osteoprotegerin and soluble Receptor Activator of Nuclear Factor kB Ligand (sRANKL) in Human Umbilical Vein Endothelial Cells (HUVEC) culture in standard and calcifying medium.

MATERIAL AND METHODS

Human Umbilical Vein Endothelial Cells were isolated from human umbilical vein by standard method. The supernatant concentrations of osteoprotegerin (OPG) and sRANKL (ELISA) were determined after incubation with glicerophosphate, estradiol , raloxifene, glicerophoshate and estradiol, glicerophosphate and raloxifene in comparison with control group at four designated time points (0, 1, 2 and 4 days of incubation).

RESULTS

Incubation of estradiol with HUVEC colony lowered the OPG level significantly after day 2 and 4. Meantime, the level of sRANKL was stable. Raloxifene added to standard growth medium also significantly lowered OPG concentration after day 4 only, with no impact on sRANKL concentration. When added to calcifying medium, both estradiol and raloxifene significantly changed OPG level during the experiment. In all treated groups OPG levels were lower than in groups exposed to calcifying medium only. Neither estradiol, nor raloxifene changed sRANKL levels during the experiment.

CONCLUSIONS

Estradiol and raloxifene affect OPG secretion from endothelial cells in vitro which may suggest their modifying role in pathogenesis of vascular calcification in postmenopausal women.

Vaspin and selected indices of bone status in girls with anorexia nervosa

INTRODUCTION

In vitro studies indicate that vaspin may act as a regulator of bone metabolism. The aim of the study was to evaluate the relationship between vaspin and bone metabolism in girls with anorexia nervosa (AN), as well as the potential involvement of OPG and RANKL in this relationship.

MATERIAL AND METHODS

Serum vaspin, OC, CTx, OPG, and sRANKL were determined by ELISA in 50 girls with AN and in 30 healthy controls aged 13 to 17 years.

RESULTS

Girls with AN exhibited significant reduction in body weight, BMI, and Cole index as well as a significant increase in serum level of vaspin compared to healthy participants. These changes were associated with a significant decrease in serum OC and CTx levels and a significant increase in OPG and sRANKL, while the OPG/sRANKL ratio was significantly decreased. BMI and Cole index correlated negatively and significantly with CTx levels in the control group (C), girls with AN, and all study participants (C+AN). Girls with AN showed a significant negative correlation between BMI, the Cole index, and OPG levels. The combination group (C+AN) showed a significant positive correlation between BMI, Cole index, and the OPG/sRANKL ratio. In this group of girls vaspin levels correlated positively and significantly with sRANKL and negatively with body weight, BMI, Cole index, and OPG/sRANKL ratio. Girls with AN showed a significant negative correlation between vaspin levels and the OPG/sRANKL ratio.

CONCLUSIONS

Undernourishment and associated deficit of adipose tissue may result in inadequate vaspin production and bone metabolism disorders in girls with AN. Vaspin acts as a coordinator of the dynamic balance between bone formation and resorption processes; its action is affected by the cytokines of the RANKL/RANK/OPG system. Changes in the relationships between vaspin, bone markers, OPG, and RANKL might contribute to the development of osteoporosis in girls with AN. (Endokrynol Pol 2016; 67 (6): 599-606).

Prognostic Value of Osteoprotegerin and sRANKL in Bronchoalveolar Lavage Fluid of Patients with Advanced Non-small Cell Lung Cancer

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of nuclear factor-kappa B ligand (sRANKL). OPG promotes endothelial cell survival and neoangiogenesis. Dysregulation of the OPG/RANKL system has been detected in several tumors. In the present study, we evaluated the clinical usefulness of OPG and sRANKL assessment in bronchoalveolar lavage fluid (BALF) of patients with advanced non-small cell lung cancer (NSCLC). We measured the concentration of OPG and sRANKL in BALF of 44 NSCLC patients and 15 healthy volunteers taken as control subjects. The OPG content was higher in the NSCLC group than that in controls [0.48 (0.12-1.45) vs. 0.23 (0.14-0.75) pmol/l; p = 0.0001]. There were no significant differences in sRANKL content between the NSCLC and control groups [1.22 (0.74-23.00) vs. 1.12 (0.79-4.39) pmol/l; p = 0.67]. However, we found that the greater the level of sRANKL in NSCLC patients, the shorter the overall survival. We found a correlation between the content of sRANKL and the percentage of lymphocytes in BALF of NSCLC patients (r = 0.52; p = 0.041). We conclude that NSCLC patients have a higher content of OPG in BALF than healthy people. A high level of sRANKL in BALF of NSCLC patients may predict worse survival.

Hormone concentrations throughout uncomplicated pregnancies: a longitudinal study

Background

Evidence suggests that the hormonal milieu of pregnancy is an important determinant of subsequent cancer and other chronic diseases in both the mother and the offspring. Many of the existing maternity and birth cohorts include specimens drawn only once during pregnancy. How well a single blood specimen collected during a pregnancy characterizes exposure to these hormones throughout gestation, and also in subsequent pregnancies, is not well understood.

Methods

We used serial serum samples from 71 pregnant women (25 primiparous, 25 multiparous, and 21 with two consecutive pregnancies) with natural, complication-free pregnancies and a healthy offspring at term who participated in a population-based screening trial for congenital infections in Finland between January 1st, 1988 and June 30, 1989 and provided a blood sample in each trimester.

Results

Hormone levels were more strongly correlated between consecutive trimesters of a pregnancy than between the 1st and 3rd trimester (e.g., estradiol, r_{T1 vs. T2} = 0.51 and r_{T2 vs. T3} = 0.60, p < 0.01; r_{T1 vs. T3} = 0.32, p < 0.05). Concentrations of sRANKL remained stable throughout gestation, whereas estradiol, estrone, progesterone, testosterone, prolactin, and osteoprotegerin increased throughout pregnancy. First trimester hormone concentrations explained less of the variation in the third trimester on their own than second trimester hormone levels (e.g. estradiol R²_T1  = 16 % and R²_T2 = 42 %). Addition of maternal (e.g., smoking) and/or child characteristics (e.g., sex) improved the accuracy of the 3rd trimester estimates for some of the hormones.

Conclusions

One hormone measurement in early pregnancy, in conjunction with maternal and fetal characteristics, permits estimation of 3rd trimester hormone concentrations. Therefore, single hormone measurements available from maternity cohorts are suitable to quantify hormone exposure during pregnancy. To our knowledge, we provide the first data on correlations between hormone concentrations both across trimesters of a single pregnancy, as well as between two subsequent pregnancies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-0937-5) contains supplementary material, which is available to authorized users.

Zoledronic acid increases the circulating soluble RANKL level in mice, with a further increase in lymphocyte-derived soluble RANKL in zoledronic acid- and glucocorticoid-treated mice stimulated with bacterial lipopolysaccharide

The nitrogen-containing bisphosphonate (BP) zoledronic acid (ZA) is a potent antiresorptive drug used in conjunction with standard cancer therapy to treat osteolysis or hypercalcemia due to malignancy. However, it is unclear how ZA influences the circulating levels of bone remodeling factors. The aim of this study was to evaluate the effects of ZA on the serum levels of soluble receptor activator of NF-kB ligand (sRANKL) and osteoprotegerin (OPG). The following four groups of C57BL/6 mice were used (five mice per group): (1) the placebo+phosphate-buffered saline (PBS) group, in which placebo-treated mice were injected once weekly with PBS for 4weeks; (2) the placebo+ZA group, in which placebo-treated mice were injected once weekly with ZA for 4weeks; (3) the prednisolone (PSL)+PBS group, in which PSL-treated mice were injected once weekly with PBS for 4weeks; and (4) the PSL+ZA group, in which PSL-treated mice were injected once weekly with ZA for 4weeks. At the 3-week time point, all mice were subjected to oral inflammatory stimulation with bacterial lipopolysaccharide (LPS). The sera of these mice were obtained every week and the levels of sRANKL and OPG were measured using enzyme-linked immunosorbent assay. At the time of sacrifice, femurs were prepared for micro-computed tomography (micro-CT), histological, and histomorphometric analyses. Our data indicated that ZA administration remarkably reduced bone turnover and significantly increased the basal level of sRANKL. Interestingly, the PSL+ZA group showed a dramatically elevated sRANKL level after LPS stimulation. In contrast, the PSL+ZA group in nonobese diabetic mice with severe combined immunodeficiency disease (NOD-SCID mice), which are characterized by the absence of functional T- and B-lymphocytes, showed no increase in the sRANKL level. Our data suggest that, particularly with combination treatment of ZA and glucocorticoids, surviving lymphocytes might be the source of inflammation-induced sRANKL. Thus, circulating sRANKL levels might be modulated by ZA.

Association between omentin-1, bone metabolism markers, and cytokines of the RANKL/RANK/OPG system in girls with anorexia nervosa

INTRODUCTION

Omentin-1, secreted by visceral adipose tissue, has been indicated in the regulation of bone metabolism in girls with anorexia nervosa (AN). The aim of the study was to evaluate the relationship between omentin-1 and bone metabolism in girls with AN as well as the potential involvement of OPG and RANKL in this relationship.

MATERIAL AND METHODS

Serum omentin-1, OC, CTx, OPG, and sRANKL were determined by ELISA in 49 girls with AN and in 30 healthy controls, aged 13 to 17 years.

RESULTS

Girls with AN exhibited significant reduction in body weight, BMI, and Cole index as well as a significant increase in serum omentin-1 levels, compared to healthy participants. These changes were associated with a significant decrease in serum OC and CTx levels and a significant increase in OPG and sRANKL while the OC/CTx and OPG/sRANKL ratios were significantly decreased. BMI and the Cole index correlated negatively and significantly with omentin-1 levels, positively with CTx levels and the OC/CTx ratio in the control group (C), girls with AN, and all study participants (C + AN). Girls with AN showed a significant negative correlation between BMI, the Cole index, and OPG levels. The combined group (C + AN) showed a significant positive correlation between BMI, the Cole index, and the OPG/sRANKL ratio. Omentin-1 levels correlated negatively and significantly with OC and CTx levels as well as with the OC/CTx and OPG/sRANKL ratios in the C, AN, and C + AN groups.

CONCLUSIONS

The relationship between omentin-1, bone markers, and the OC/CTx and OPG/sRANKL ratios observed in girls with AN indicates the involvement of this adipokine in the regulation of dynamic balance between bone formation and resorption processes. Omentin-1 might exert a negative effect on bone remodelling in girls with AN by inhibiting both bone formation and resorption. The OPG/sRANKL system plays an important role in the latter.

Turbo methanol extract inhibits bone resorption through regulation of T cell function

Marine organisms have bioactive potential which has tremendous pharmaceutical promise. Emerging evidence highlights the importance of the interplay between bone and the immune system of which T lymphocytes and their product act as key regulators of bone resorption. In the present investigation we have analyzed the anti-osteoporotic effect of turbo methanol extract (TME) in the reversal of bone resoprtion. Forty-two female Swiss albino mice were used and randomly assigned into sham-operated group (sham) and six ovariectomized (OVX) subgroups, i.e. OVX with vehicle (OVX) that received daily oral administration of water ad libitum; OVX with estradiol (2mg/kg/day); and OVX with different doses of TME i.e. TME 100mg/kg, TME 50mg/kg, TME 25mg/kg and TME 12.5mg/kg. Oral administration of TME or estradiol started on the second week after ovariectomy for a period of 4weeks. We observed that the administration of TME increased the trabeculation in tibia and reduced the atrophy in the uterus. TME significantly decreased the serum alkaline phosphatase (ALP) and acid phosphatase (ACP) activity in OVX mice. Micro CT analysis revealed that the TME administration preserved the bone volume, connectivity density, trabecular number, trabecular thickness and trabecular separation in OVX mice. Bone mineralization was measured in different groups of mice by Raman spectroscopy. Reversal of bone resorption was observed in TME treated group of mice. To further investigate the mechanism of action of TME, we analyzed the T lymphocyte proliferation and profiles of cytokine TNFα and sRANKL in TME treated ovariectomized mice. Decrease in the elevation of T cell subsets was observed after the supplementation with TME. The extract significantly lowered the T cell proliferation responses to mitogens, phorbol 12-myristate 13-acetate (PMA) and ionomycin (Io) and phytohemagglutinin (PHA). A marked reduction in TNFα and sRANKL secretion in serum and TNFα in cell free supernatants of activated T lymphocytes was observed upon TME administration. TME could significantly inhibit the in vitro osteoclastogenesis and the bone resorption observed using artificial calcium coated slides. Collectively, these results indicate that TME has the potential to inhibit bone resorption and may prove to be a potential candidate for the development of an anti-osteoporosis drug.

Effect of breastfeeding on serum osteoprotegerin and soluble receptor activator of nuclear factor-kappa B ligand in full term neonates

Background

Human breast milk, the sole source of nutrition during the early neonatal period, is rich in nutrients, hormones, growth factors, and immunoactive molecules, which influence the growth, development, and immune status of the newborn infant. It had long been thought that breast milk is an adequate source of anthracitic activity for the newborns and growing child.

Objective

Human milk is a complex biologic fluid which contains nutritional and protective factors such as Osteoprotegerin (OPG), at levels 1000-fold higher than normal human serum. Since OPG and Receptor activator of nuclear factor-kappa B ligand (RANKL) system are tightly involved in bone remodeling and immune activity, the study was designated to evaluate the effect of breastfeeding on serum soluble receptor activator of nuclear factor-kappa B ligand (sRANKL) /OPG ratio in full term neonates in comparison with those of formula feeding full term neonates.

Materials and Methods

In this cross-sectional study serum levels of OPG and sRANKL in 45 breastfed infants were compared to those of 44 formula-fed full term infants. The levels of serum OPG, sRANKL, and Tumor necrosis factor alpha (TNFα) were determined by standard techniques using enzyme-linked immunosorbent assay kits.

Results

The serum levels of OPG were significantly higher (P < 0.001), and the concentrations of TNFα was markedly lower (P = 0.024) in breastfed infants than those of formula-fed infants. No marked differences were observed between the serum levels of sRANKL in the two study groups (P = 0.8).

Conclusions

High OPG and low TNFα levels in serum of breastfed infants are important factors involved in remodeling of bone, and immune activity may prove superiority of breastfeeding over formula feeding during infancy.

OPG and sRANKL serum levels and incident hip fracture in postmenopausal Caucasian women in the Women's Health Initiative Observational Study

PURPOSE

The osteoprotogerin/receptor activator of NF-kappa β/receptor activator of NF-kappa β ligand (OPG/RANK/RANKL) pathway plays a critical role in bone remodeling. This study investigated associations between serum levels of OPG, soluble RANKL (sRANKL), and the ratio of OPG/sRANKL to risk of incident hip fracture.

METHODS

A nested case-control study was conducted among postmenopausal, Caucasian women aged 50-79 at baseline (1993-1998), followed for hip fracture through March 2005 in the Women's Health Initiative Observational Study. 400 incident hip fracture cases were selected and individually matched to 400 controls with no prior fracture or incident hip fracture. Matching factors were baseline age, enrollment date and hormone therapy (HT) exposure. Baseline serum OPG and sRANKL levels were measured using high sensitivity ELISA. Odds ratios were computed for quartiles of each biomarker adjusting for matching factors and hip fracture risk factors.

RESULTS

Serum OPG was significantly associated with older age, low physical activity and poorer physical function in control women. sRANKL was inversely associated with total calcium intake in control women, but not associated with age or other fracture risk factors. The odds ratio for hip fracture comparing the highest to lowest quartiles of OPG was 2.28 (95% confidence interval (CI), 1.45-3.61) after adjusting for the matching variables (p-value for linear trend <0.001), and 1.87 (95% CI, 1.15-3.04; p for linear trend=0.02) after adjusting for self-rated health status, physical activity and physical functioning. No significant associations between sRANKL or the ratio of OPG/sRANKL and hip fracture risk were observed.

CONCLUSION

Serum OPG levels were independently associated with a nearly twofold increased risk of hip fracture in postmenopausal women.

Protective effect of zinc supplementation against cadmium-induced oxidative stress and the RANK/RANKL/OPG system imbalance in the bone tissue of rats

It was investigated whether protective influence of zinc (Zn) against cadmium (Cd)-induced disorders in bone metabolism may be related to its antioxidative properties and impact on the receptor activator of nuclear factor (NF)-κΒ (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system. Numerous indices of oxidative/antioxidative status, and Cd and Zn were determined in the distal femur of the rats administered Zn (30 and 60mg/l) or/and Cd (5 and 50mg/l) for 6months. Soluble RANKL (sRANKL) and OPG were measured in the bone and serum. Zn supplementation importantly protected from Cd-induced oxidative stress preventing protein, DNA, and lipid oxidation in the bone. Moreover, Zn protected from the Cd-induced increase in sRANKL concentration and the sRANKL/OPG ratio, and decrease in OPG concentration in the bone and serum. Numerous correlations were noted between indices of the oxidative/antioxidative bone status, concentrations of sRANKL and OPG in the bone and serum, as well as the bone concentrations of Zn and Cd, and previously reported by us in these animals (Brzóska et al., 2007) indices of bone turnover and bone mineral density. The results allow us to conclude that the ability of Zn to prevent from oxidative stress and the RANK/RANKL/OPG system imbalance may be implicated in the mechanisms of its protective impact against Cd-induced bone damage. This paper is the first report from an in vivo study providing evidence that beneficial Zn impact on the skeleton under exposure to Cd is related to the improvement of the bone tissue oxidative/antioxidative status and mediating the RANK/RANKL/OPG system.