Changes in the serum levels of osteoprotegerin and soluble receptor activator for nuclear factor κB ligand after estrogen-progestogen therapy and their relationships with changes in bone mass in postmenopausal women:

Comprehensive assessment of tissue and serum parameters of bone metabolism in a series of orthopaedic patients

Bone diseases represent an increasing health burden worldwide, and basic research remains necessary to better understand the complexity of these pathologies and to improve and expand existing prevention and treatment approaches. In the present study, 216 bone samples from the caput femoris and collum femoris of 108 patients with degenerative or dysplastic coxarthrosis, hip fracture, or osteonecrosis were evaluated for the proportion of trabecular bone (TB) and expression of parathyroid hormone (PTH) type 1 receptor (PTH1R), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-B ligand (RANKL). Serum levels of PTH, OPG, soluble RANKL (sRANKL), alkaline phosphatase (AP), osteocalcin, total procollagen type-1 intact N-terminal propeptide (TP1NP), tartrate-resistant acid phosphatase type 5b (TRAP5b), sclerostin, and C-telopeptide of type-1 collagen (ICTP) were also determined. Age was positively correlated with serum levels of PTH, OPG, and sclerostin but negatively associated with TB and sRANKL. Women exhibited less TB, lower sclerostin and ICTP, and higher TRAP5b. Impaired kidney function was associated with shorter bone decalcification time, less TB, lower sRANKL, and higher serum PTH, OPG, and sclerostin. Furthermore, correlations were observed between bone PTH1R and OPG expression and between serum PTH, OPG, and AP. There were also positive correlations between serum OPG and TP1NP; serum OPG and sclerostin; serum AP, osteocalcin, and TRAP5b; and serum sclerostin and ICTP. Serum OPG was negatively associated with sRANKL. In summary, clear relationships between specific bone metabolism markers were observed, and distinct influences of age, sex, and kidney function, thus underscoring their suitability as diagnostic or prognostic markers.

Serum RANKL, osteoprotegerin (OPG) and RANKL/OPG ratio in children with systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) patients have lower bone mineral density (BMD) compared with healthy individuals because of general, genetic, disease and medication-related factors. The disturbance of the receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) ratio has been reported to be associated with low BMD in many disorders in adults and children alike.

Objectives

The objectives of this study were (i) to assess serum OPG, RANKL and RANKL/OPG ratio levels in SLE children and controls, (ii) to determine whether the cumulative glucocorticoid (CGCS) dose had any effect on the concentration of serum RANKL, OPG and RANKL/OPG ratio, and (iii) to determine the relation of these parameters to BMD.

Methods

We evaluated 50 SLE children and 50 age- and sex-matched healthy controls. RANKL and OPG were assessed in serum and compared between patients and controls. For SLE patients, a univariate followed by multivariable analysis were carried out to detect the possible predictors of the changes in RANKL, OPG and RANKL/OPG ratio levels. Lumbar BMD for all patients was assessed by dual-energy X-ray absorptiometry (DXA) scan and then correlated to different probable correlated factors.

Results

RANKL, OPG and RANKL/OPG ratio were significantly higher in SLE patients ( p ≤ 0.001). Univariate analysis showed significant correlations of RANKL with CGCS ( p ≤ 0.001) and with DXA scan z-score ( p = 0.007): OPG was significantly correlated to Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score ( p = 0.001) and anti-double-stranded DNA ( p = 0.001), whereas RANKL/OPG was significantly correlated to duration of illness and DXA z-score ( p = 0.002). The multivariable analysis showed that DXA z-score was an independent predictor of RANKL and RANKL/OPG ratio ( p = 0.019 and 0.008, respectively), whereas SLEDAI score was an independent predictor of OPG levels. BMD was negatively correlated to disease duration ( p = 0.008) and CGCS dose ( p = 0.015), but no significant correlation has been found between BMD and cumulative SLEDAI score ( p = 0.29).

Conclusions

Serum RANKL/OPG ratio is elevated in Egyptian children with SLE and is considered a risk factor for reduced bone mass in these children. Other risk factors for low BMD include high CGCS dose and disease duration, supporting that osteoporosis in SLE is multifactorial.

Polymorphisms in period genes and bone response to hormone therapy in postmenopausal Korean women

OBJECTIVE

In this study, we aimed to explore the association between polymorphisms in the period (PER) gene and bone response to hormone therapy (HT) in postmenopausal Korean women.

METHODS

The PER1 c.2284C > G, c.2247C > T, PER2 c.3731G > A, PER3 c.2592G > A, c.3083T > C polymorphisms, and PER3 54bp variable number of tandem repeats (VNTR) were analyzed in 509 postmenopausal Korean women who received HT. Bone mineral density (BMD) at the lumbar spine and femoral neck before and after 1 year of HT and serum levels of osteoprotegerin (OPG), soluble receptor activator of the nuclear factor-κB ligand (sRANKL) and bone turnover markers were measured after 6 months of HT.

RESULTS

The PER1 c.2884 C > G polymorphism and PER3 54bp VNTR were associated with annual percent changes in BMD of the femoral neck after 1 year of HT (p < 0.05). Changes in BMD at the femoral neck in the non-CC genotype of the PER1 c.2884C > G polymorphism and in the 4-repeat homozygote of PER3 54bp VNTR were significantly lower than those in CC genotype and non-4-repeat homozygote, respectively. The PER1 c.2884C > G polymorphism was associated with the non-response (>3% BMD loss/year after HT) of HT. The non-CC genotype of the PER1 c.2884C > G polymorphism showed a 1.92-times higher risk of non-response at the lumbar spine and/or femoral neck (p = 0.01) compared with the CC genotype. No significant changes in bone markers after 6 months of HT were noted according to the PER1 c.2884C > G polymorphism.

CONCLUSIONS

The PER1 c.2884C > G polymorphism may be associated with risk of non-response to HT in postmenopausal Korean women.

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.

Cyclic variations of bone resorption mediators and markers in the different phases of the menstrual cycle

Female hormones are very important in regulating bone homeostasis; the drop of estrogen levels occurring at menopause is linked to a dramatic prevalence of bone resorption on formation. Only a small number of studies investigated the relationship between changes in circulating female sex hormones and the markers and mediators of bone homeostasis and they showed conflicting results. To explore such relationships we studied 20 young fertile healthy women, aged between 19 and 32 years. None had received hormone treatment for at least 6 months. We assayed luteinizing hormone, follicle-stimulating hormone, progesterone and 17β-estradiol, as well as the levels of osteoprotegerin (OPG), C-terminal telopeptide of collagen type I (CTx) and RANKL (receptor activator of nuclear factor-B ligand) in samples drawn from every subject at four different times during the menstrual cycle when estrogens are lowest, at the start of the cycle: T 0 (2-4th day); when estrogens are highest, in the pre-ovulatory period: T 14 (12-14th day); when progesterone activity is highest, in the advanced luteal phase: T 26 (24-26th day); and again at the start of the next cycle: T 01 (2-4th day). We observed that CTx levels are highest at the start of the cycle, decreased significantly from T 0 to T 26 (pfwe = 0.0455) and then increased from T 26 to T 01 (pfwe = 0.0415); OPG, on the other hand, which was also highest at the start of the cycle, decreased significantly from T 0 to T 14 (pfwe = 0.02) and then increased, though not significantly, from T 14 to T 01; no variation was observed in RANKL values at any time. We observed inverse correlations between estradiol and OPG levels, which became highly significant at T 01 between estradiol nadir and OPG peak levels (pfw = 0.0095). Furthermore, the increase of estradiol from T 0 to T 14 was negatively correlated with the concomitant decrease of OPG (pfwe = 0.0277), as was the fall of estradiol from T 26 to T 01 with the OPG peak levels, both at T 01 (pfw = 0.0045) and at T 0 (pfwe = 0.0381). We also observed direct correlations between the OPG levels and the variations of progesterone in the preceding intervals, but they never attained statistical significance. We conclude that OPG and CTx fluctuation during the menstrual cycle are likely due to the physiological variations of sex steroids levels.

Increased prevalence of vitamin D insufficiency in patients with breast cancer after neoadjuvant chemotherapy

Patients with locally advanced breast cancer treated with neoadjuvant chemotherapy are at risk of cancer treatment-induced bone loss and consequently of increased skeletal morbidity. In addition, this situation could be worsened by the fact that only a minority of patients with breast cancer have sufficient vitamin D. A comprehensive evaluation of bone homeostasis is critical in this context. We retrospectively evaluated the serum levels of calcium, vitamin D, TRAIL, RANK ligand (RANKL), Osteoprotegerin (OPG), Bone TRAP, CrossLaps and DKK1 in 77 patients (median age: 50 years; range 25-74), with locally advanced breast cancer treated in our institute with anthracyclines-taxane neoadjuvant chemotherapy (7 cycles of 21 days/each) between March 2007 and August 2008. Serum samples were collected before the first (baseline) and the last treatment cycle. Variations and correlations between biomarker levels were evaluated. At baseline, 79.5 % of patients had vitamin D insufficiency (<30 ng/ml), increasing to 97.4 % at the end of the neoadjuvant chemotherapy (p < 0.0001). Calcium and RANKL serum concentrations were also significantly decreased, while OPG was significantly increased, resulting in lower RANKL/OPG ratio. Calcium and vitamin D, RANKL and vitamin D and RANKL and OPG levels were significantly correlated (Spearman's coefficient r = 0.2721, p = 0.0006; r = 0.1916, p = 0.002; and r = -0.179, p = 0.03, respectively). Nearly all included patients suffered from vitamin D insufficiency by the end of the neoadjuvant chemotherapy with changes in the calcium/RANKL/OPG axis that are evocative of deregulation of a functional regulatory mechanism. Further studies are needed to determine how drugs modulate this regulatory mechanism to preserve bone homeostasis in patients with breast cancer.

Osteoprotegerin is associated with hip fracture incidence: the Tromso Study

BACKGROUND

Osteoprotegerin (OPG) is a cytokine essential for the regulation of bone resorption, but large longitudinal studies on its relationship to fracture risk in humans are lacking. In this population-based study of 2740 men and 2857 post-menopausal women, it was examined whether serum OPG was associated with hip fracture incidence. The participants were followed for 15 years.

METHODS

Baseline measurements included height, weight and serum OPG, and information about lifestyle, prevalent diseases and use of medication.

RESULTS

Men with OPG in the highest quartile were 2.79-fold [95% confidence interval (CI) 1.34-5.82] more likely to have a hip fracture during follow-up, compared with those with OPG in the lowest quartile (P-trend over OPG quartiles ≤ 0.001, after adjustments for age and other confounders). In women not using post-menopausal hormone therapy (HT), the risk of hip fracture was 1.64-fold higher (95% CI 0.94-2.86) in the highest quartile compared with the lowest OPG quartile (P-trend over OPG quartiles = 0.05). No relationship was found in post-menopausal women using HT (P-trend over OPG quartiles = 0.23).

CONCLUSIONS

In men, OPG was positively associated with the incidence of hip fracture. In post-menopausal women not using HT a similar, but weaker, relationship was found.

Systemic effects of conjugated equine estrogen vaginal cream on bone turnover markers in postmenopausal women

OBJECTIVE

To evaluate the systemic effect of therapy with conjugated equine estrogen (CEE) vaginal cream on bone turnover markers in postmenopausal women.

METHODS

This study was conducted in 40 spontaneously menopausal women aged 40-60 years who complained of vulvovaginal symptoms. Subjects were instructed to self-administer 1 g CEE vaginal cream (CEE 0.625 mg) once daily for 12 weeks (continuous phase), then twice weekly for the next 12 consecutive weeks (intermittent phase). Serum levels of bone turnover markers and estradiol and the vaginal maturation index were evaluated at baseline, 12 and 24 weeks after treatment initiation.

RESULTS

Levels of C-terminal cross-linked telopeptide of type I collagen (CTx) were significantly decreased at 12 weeks and 24 weeks when compared to baseline values (median (range) 0.435 (0.171-0.859) and 0.391 (0.122-0.714) vs. 0.562 (0.250-1.290) ng/ml (p < 0.001 and < 0.001), respectively), but there was no significant difference between the levels at 12 and 24 weeks. Levels of procollagen type I N-terminal propeptide (P1NP) and osteocalcin levels were significantly decreased after 24 weeks when compared to pretreatment levels (mean (standard deviation) 41.74 (11.76) vs. 50.02 (17.71) ng/ml (p = 0.002) for P1NP and 23.91 (7.11) vs. 27.54 (8.67) ng/ml (p < 0.001) for osteocalcin, respectively). Estradiol levels were significantly increased and the vaginal maturation index was significantly improved after 12 and 24 weeks when compared to baseline.

CONCLUSIONS

CEE vaginal cream significantly decreased the bone resorption marker (CTx) in postmenopausal women after completion of the continuous-treatment phase. There was no significant further decrease after the intermittent phase. The effects on the markers of bone formation and bone turnover (P1NP and osteocalcin) were apparent only at 24 weeks. The two treatment phases moderately increased serum estradiol levels and significantly improved the vaginal maturation index.

The effect of risedronate treatment on serum osteoprotegerin and bone marker levels in postmenopausal women with osteoporosis

BACKGROUND

To evaluate the effect of risedronate treatment on osteoprotegerin (OPG), C-terminal cross-linking telopeptide of type 1 collagen (CTX), osteocalcin (OC), and deoxypyridinoline (DPD).

METHODS

Eighty postmenopausal osteoporotic patients were randomized into two groups. In first group, patients received 35?mg of risedronate once a week and calcium with vitamin D per day. In second group, patients received only calcium with vitamin D per day. Bone turnover markers were measured at baseline, 1st, 3rd and 6th month.

RESULTS

OPG levels were significantly reduced at 1st and 6th month of treatment in both groups, but no statistically significant difference was detected between groups. In the group treated with risedronate, difference in CTX level was observed at 3rd month of treatment, while a difference in DPD and OC levels were observed at 6th month of treatment. The baseline OPG levels correlated with age, menopause duration, and CTX levels. There was no correlation between OPG levels and the levels of the other markers during treatment.

CONCLUSION

The present study showed that using risedronate in treatment of postmenopausal osteoporosis causes no specific changes in OPG levels; therefore, in contrast to some of the studies in the literature OPG may not be useful marker in monitoring of bisphosphonate.

Serum osteoprotegerin levels are related to height loss: the Tromsø Study

Severe loss of body height is often a consequence of osteoporotic vertebral fractures. Osteoprotegerin (OPG) and receptor activator of nuclear factor-kB ligand (RANKL) are cytokines essential for the regulation of bone resorption. The aim of this study was to assess the relationship between the OPG/RANKL system and height loss. A total of 4,435 inhabitants from the municipality of Tromsø, Norway (2,169 men and 2,266 women) were followed for 6 years. Baseline measurements included height, weight, bone mineral density, OPG, RANKL, serum parathyroid hormone and information about lifestyle, prevalent diseases and use of medication. Height was measured again at follow-up, and the loss of height was categorized into 4 groups: ≤1, 1.1-2, 2.1-3, >3 cm. We found increasing height loss with increasing baseline OPG levels in both men and women (P trend = 0.02 and 0.001, respectively), after adjustments for age and other confounders. However, when the women were stratified according to menopausal status and use of hormone replacement therapy (HRT), a significant relationship was present only among postmenopausal women not using HRT (P trend = 0.02). No relations between OPG and height loss were found in post-menopausal HRT-users and premenopausal women (P trend ≥0.39). We conclude that height loss is positively associated with OPG in men and in postmenopausal women not using HRT. No relationship was found between RANKL and height loss.

Bone loss in relation to serum levels of osteoprotegerin and nuclear factor-kappaB ligand: the Tromsø Study

SUMMARY

In this longitudinal study of 4,137 persons, bone mineral density was negatively associated with osteoprotegerin at baseline in both genders. In postmenopausal women not using hormone replacement therapy (HRT), bone-loss increased with increasing osteoprotegerin levels, whereas no relationship was found in men, premenopausal women, or postmenopausal women taking HRT.

INTRODUCTION

In a population-based study of 2,003 men and 2,134 women, the relationship between the osteoprotegerin (OPG)/factor-kappaB ligand (RANKL) system and bone mineral density (BMD) and changes in BMD was examined.

METHODS

Baseline measurements included height, weight, BMD of the forearm, OPG, RANKL, vitamin D, and serum parathyroid hormone (PTH) and information about lifestyle, prevalent diseases, and use of medication. BMD was remeasured at follow-up 6 years later.

RESULTS

BMD was negatively associated with OPG at baseline in both men and women (p trend over OPG levels = 0.01 and 0.007, respectively, after adjustments for age, and other confounders). In postmenopausal women not on hormone replacement therapy, bone loss increased with increasing OPG (p = 0.005), whereas no relationship was found in men, premenopausal women, or postmenopausal women on HRT (p >or= 0.28). BMD at baseline and BMD changes were not related to RANKL levels in any of the groups (p >or= 0.14).

CONCLUSIONS

In postmenopausal women not using HRT, bone loss associated positively with OPG. The results indicate that in women deficient in sex steroids, the OPG/RANKL system may play an important counter regulatory role in order to avoid bone loss and maintain BMD. In men and women replete in sex steroids, the OPG/RANKL system was not associated with BMD.

Serum RANKL, osteoprotegerin (OPG), and RANKL/OPG ratio in nephrotic children

Receptor activator of NF-kB ligand (RANKL) and osteoprotegerin (OPG) play key roles in the pathogenesis of glucocorticoid-induced osteoporosis (GIO). The aim of our study was to determine whether the cumulative glucocorticoid dose (CGCS) in children with idiopathic nephrotic syndrome (INS) has any effect on the concentration of serum RANKL and OPG and the RANKL/OPG ratio. The study population consisted of 90 children with INS, aged 3-20 years, who were treated with GCS. These children were divided into two groups according to the CGCS: low (L)<1 g/kg body weight (BW) and high (H)>or=1 g/kg BW, respectively. The control group (C) consisted of 70 healthy children. RANKL concentration was observed to be significantly higher and OPG significantly lower in INS children than in the reference group: 0.21 (range 0.01-1.36) versus 0.15 (0-1.42) pmol/l (p<0.05), respectively, and 3.76 (1.01-7.25) versus 3.92 (2.39-10.23) pmol/l (p<0.05), respectively. The RANKL/OPG ratio was significantly higher in INS children (p<0.01). The concentration of RANKL, similar to the RANKL/OPG ratio, was significantly higher in Group H children than in Group L children: 0.46 (0.02-1.36 ) versus 0.19 (0.01-1.25) (p<0.01) and 0.14 (0.01-0.71) versus 0.05 (0.002-0.37) (p<0.01), respectively. The concentration of OPG was similar in both groups. There was a positive correlation between CGCS and the concentration of sRANKL as well as the RANKL/OPG ratio (in both cases r=0.33, p<0.05). Based on these results, we suggest that long-term exposure to GCS results in a dose-dependent increase in serum RANKL concentration and the RANKL/OPG ratio, but not in the level of serum OPG.

Relationships among serum receptor of nuclear factor-kappaB ligand, osteoprotegerin, high-sensitivity C-reactive protein, and bone mineral density in postmenopausal women: osteoimmunity versus osteoinflammatory

OBJECTIVE

The aim of this study was to investigate the correlations among circulating osteoprotegerin (OPG), the receptor activator of nuclear factor-kappaB ligand (RANKL), high-sensitivity C-reactive protein (hsCRP), and bone mineral density (BMD) in healthy postmenopausal women.

METHODS

In a population-based study, highly specific enzyme-linked immunosorbent assay methods were used to evaluate the sera of 382 healthy Iranian postmenopausal women (mean age +/- SD, 58.7 +/- 7.5 y) for RANKL, OPG, hsCRP, degradation products of C-terminal telopeptides of type I collagen, and osteocalcin. BMD was determined for the lumbar spine (L2-L4) and the proximal femur using dual-energy x-ray absorptiometry.

RESULTS

Circulating levels of OPG (r = 0.30, P < 0.001) and the RANKL/OPG ratio (r = -0.17, P < 0.001) were significantly associated with age. The geometric mean of hsCRP was 1.89 mg/L (SE, 1.05) in the population studied. There was a significant correlation between log(hsCRP) levels and body mass index (BMI; r = 0.36, P < 0.001). Multivariate linear analyses revealed that age (beta = -0.295, P < 0.001), BMI (beta = 0.464, P < 0.001), RANKL (beta = -0.105, P = 0.014), and OPG (beta = 0.098, P = 0.029) were the independent determinants for lumbar BMD (R(2) = 0.35). Age (beta = -0.250, P < 0.001), BMI (beta = 0.486, P < 0.001), and RANKL (beta = -0.110, P = 0.009) were independently correlated with femoral neck BMD (R(2) = 0.36). Age- and BMI-adjusted analysis by quartiles of log-transformed hsCRP did not reveal an association with BMD, serum levels of biochemical markers of bone turnover, RANKL, or OPG.

CONCLUSIONS

The circulating levels of the RANKL/OPG osteoimmunity system have an association with BMD, but subclinical systemic inflammation may not be involved in bone mass in healthy postmenopausal women.