Association of estrogen receptor beta gene polymorphism with bone mineral density

Chromosomal mapping of the human estrogen receptor beta (ERbeta) gene by fluorescence in situ hybridization (FISH) reveals that ERbeta is located at human chromosome 14, region q23-24.1, where the aberration of DNA copy number in the bone disorders is frequently involved. Then, we investigated the association between dinucleotide (cytosine-adenine; CA) repeat polymorphism located in the flanking region of ERbeta gene and bone mineral density (BMD) in 204 healthy postmenopausal Japanese women. The genotype was classified into "A" through "O" according to the number of the repeats, from 18 to 32. BMD was expressed in Z score (a deviation from the weight-adjusted average BMD of each age using the standard deviation as a unit). When we separate the subjects into two groups bearing at least one I allele (26 CA repeats) and those who did not, the former subjects had significantly higher Z score of L2-4 BMD (mean +/- standard deviation; 0.674 +/- 1.53 vs 0.128 +/- 1.38; P = 0.027). These data suggest that genetic variation at the ERbeta locus may be associated with some determinants for BMD and the possible involvements of this polymorphism in the cause of postmenopausal osteoporosis in Japanese women.     

Association analysis of vitamin D receptor gene polymorphisms with bone mineral density in young women with Graves' disease

Graves' (GD) hyperthyroidism induces accelerated bone turnover that leads to decreased bone mineral density (BMD). The role of the VDR gene in predisposition to primary osteoporosis has been recognized. Recent studies show associations between the VDR gene polymorphisms and susceptibility to autoimmune diseases. Here we analyzed if VDR gene polymorphisms: BsmI, ApaI, TaqI, and FokI may predispose women with Graves' hyperthyroidism to BMD reduction or to disease development. The subjects were 75 premenopausal female Polish patients with GD and 163 healthy women. The genotyping was performed by the use of the restriction fragment length polymorphism analysis (RFLP). We studied the association of the VDR polymorphisms and their haplotypes with patients' BMD and also SNPs and haplotypes association with Graves' disease. We found a strong linkage disequilibrium for the BsmI, ApaI, and TaqI polymorphims that formed three most frequent haplotypes in Graves' women: baT (47.9%), BAt (34.9%), and bAT (16.4%). We did not show statistically significant association of analyzed VDR polymorphisms or haplotypes with decreased bone mineral density in Graves' patients. However, the presence of F allele had a weak tendency to be associated with Graves' disease (with OR=1.93; 95% CI: 0.97-3.84; p=0.058). In conclusion: VDR gene polymorphisms do not predict the risk of decreased BMD in Polish women with Graves'. It may be speculated that the F allele carriers of the VDR-FokI polymorphism are predisposed to Graves' disease development.     

Relationships between bone and skin atrophies during aging.

Bone mineral density (BMD) was measured in 133 female subjects (age: 61.7 +/- 16.3 years) by dual energy X-ray absorptiometry (DEXA). Vertebral bone mineral density (BMD; L1-L4) and BMD of the whole upper femoral extremity were taken into account. In addition, skinfold thickness was measured with a callipers on the dorsum of the nondominant hand. A significant negative correlation was found between skinfold thickness and age (r = -0.623, p less than 0.0001). Both vertebral and femoral BMD decreased with age and the slopes were similar to those observed by other authors. Skinfold thickness was significantly correlated with vertebral (r = 0.364, p less than 0.0001) and femoral BMD (r = 0.486, p less than 0.0001). Skin and bone are connective tissues whose extracellular matrix mainly contains type I collagen. It is postulated that age-related skin atrophy and bone atrophy have a common genetic mechanism. Skinfold thickness measurement may help in defining the women at risk for osteoporotic bone fractures who should be referred for a DEXA examination.     

Osteoporosis in male hypogonadism: responses to androgen substitution differ among men with primary and secondary hypogonadism

BACKGROUND: No randomized study exists comparing the effects of different modes of androgen substitution on bone mineral density (BMD). METHODS: We performed a prospective, randomized, trial assigning 53 hypogonadal men to the following treatment groups: mesterolone 100 mg p.o. daily, testosterone undecanoate 160 mg p.o. daily, testosterone enanthate 250 mg i.m. every 21 days, or a single subcutaneous implantation of 1,200 mg crystalline testosterone. The BMD was determined by peripheral quantitative computed tomography. RESULTS: At baseline, men with secondary hypogonadism (n = 33) had a lower BMD (-1.52 +/- 0.23 SDS; Z-scores) than men with primary hypogonadism (n = 20, -0.87 +/- 0.23 SDS, p < 0.01). In men with primary hypogonadism, the BMD increased dose dependently (crystalline testosterone +7.0 +/- 1.3%, testosterone enanthate +4.8 +/- 0.2%, testosterone undecanoate +3.4 +/- 2.5%, mesterolone +0.8 +/- 1.6%) after 6 months of therapy. Only secondary hypogonadal men treated with testosterone enanthate experienced an increase of the BMD. CONCLUSIONS: In primary hypogonadal men the BMD responds dose dependently to testosterone substitution, whereas in secondary hypogonadism only testosterone enanthate treatment significantly increased the BMD.     

Adiponectin is associated with bone mineral density in perimenopausal women.

The aim of the current investigation was to investigate any potential effect of fasting plasma adiponectin concentration on bone tissue, and to find possible relationships of fasting plasma adiponectin level with different body composition, insulin sensitivity and physical performance parameters in a group of healthy perimenopausal women. Twenty-one premenopausal and 17 early postmenopausal women participated in this study. The women were matched for body mass index (BMI) and level of mean daily energy expenditure. Women had similar adiponectin (8.4 +/- 3.9 vs. 9.9 +/- 5.4 microg/ml) and leptin values (12.0 +/- 7.7 vs. 14.0 +/- 8.2 ng/ml) before and after menopause. Significant relationships were observed between plasma adiponectin and bone mineral content, total bone mineral density (BMD) and lumbar spine BMD values (r > - 0.36; p < 0.05). Furthermore, adiponectin had a significant negative association with total BMD (beta = - 1.228; p = 0.004) and lumbar spine BMD (beta = - 0.312; p = 0.005) independent of the influence that other measured body compositional, hormonal or physical performance factors may exert on BMD. Adiponectin was also significantly related to waist-to-hip ratio (WHR) (beta = - 2.300; p = 0.002) and fasting insulin resistance index (FIRI) (beta = - 0.006; p = 0.007) in separate regression models. No relationship was observed between leptin and measured bone, physical performance and insulin resistance values. Leptin significantly correlated to BMI (beta = 0.018; p = 0.034), lean body mass (beta = 0.025; p = 0.024) and fat mass (beta = 0.019; p = 0.001) in separate regression models. In conclusion, the results of present study show that circulating adiponectin appears to exert an independent effect on BMD in perimenopausal women and may represent a link between adipose tissue and bone mineral density.     

Association of an aromatase TTTA repeat polymorphism with circulating estrogen, bone structure, and biochemistry in older women

Osteoporosis is a disease that is strongly genetically determined. Aromatase converts androgens to estradiol in postmenopausal women, therefore polymorphisms of the gene for this enzyme may be associated with bone mass and fracture. We investigated the association of the TTTA microsatellite polymorphism in intron 4 of the aromatase (CYP19) gene with bone mineral density (BMD) and fracture in 1,257 women aged 70 yr and greater. The data obtained were stratified based on the presence or absence of a [TTTA]n of 7 (A2), determined from a preliminary analysis of hip dual-energy X-ray absorptiometry BMD, which was present in 27% of the population. The presence of an A2 allele was associated with a higher free estradiol index (0.52 +/- 0.49, P = 0.049) compared with the absence of an A2 allele (0.47 +/- 0.45); higher BMD at all sites of the hip (3.4% total hip, 2.3% femoral neck, 3.6% intertrochanter, 4.1% trochanter) and the lumbar spine (12.7%); higher values for the calcaneal quantitative ultrasound parameters broadband ultrasound (1.3%), speed of sound (0.4%), and stiffness (3.7%); and higher peripheral quantitative computed tomography measures for total (3.4%), trabecular (3.3%), and cortical BMD (3.3%) and the derived stress strain index (SSI) parameters SSI polar (6.4%) and SSI x (6.8%) values. A lower deoxypryridinoline creatinine ratio was observed in subjects with an A2 allele (30.3 +/- 10.4 vs. 27.1 +/- 9.1, P = 0.03). The A2 allele was associated with a lower prevalence of vertebral fracture in subjects who were osteoporotic (odds ratio 0.27, confidence interval 0.09-0.79). Therefore, a common polymorphism of the aromatase gene, perhaps in linkage disequilibrium with a functionally significant CYP19 polymorphism, is associated with bone structure and bone turnover, either by local effects or by effects on circulating bioactive estrogen.     

Vitamin-D receptor genotype does not predict bone mineral density, bone turnover, and growth in prepubertal children.

We examined whether the polymorphism for BsmI restriction enzyme in the vitamin-D receptor (VDR) gene influenced radial (distal third) and lumbar (L2-L4) bone mineral density (BMD), phospho-calcium metabolism (calcium, phosphate, intact parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D), biochemical markers of bone formation (osteocalcin and carboxy-terminal propeptide of type-I procollagen) and bone resorption (carboxy-terminal telopeptide of type-I collagen and urinary cross-linked N-telopeptides of type I collagen), insulin-like growth factor I and insulin-like growth factor-binding protein 3, and growth in 209 healthy prepubertal children (112 males and 97 females) aged 7.1-10.0 years. Genotype frequencies were BB 19%, Bb 46%, and bb 35% in the pooled group of children. Clinical findings, dietary calcium intake, calcium density, and physical activity rate were not different (p NS) among the VDR genotypes. Radial BMD, lumbar BMDarea and lumbar BMD adjusted for the apparent bone volume (BMDvolume), and all the biochemical parameters did not differ (p NS) in relation to the VDR genotype. In conclusion, our data show that polymorphism for BsmI restriction enzyme in the VDR gene is not associated with radial and lumbar BMD, parameters of phospho-calcium metabolism and bone turnover, growth hormone-dependent growth factors, and growth in prepubertal children.     

Effect of growth hormone therapy on IGF-I, bone GLA-protein and bone mineral content in short children with and without chronic renal failure.

Chronic renal failure (CRF) in the young is complicated by, among other conditions, growth retardation, hyperparathyroidism and uremic osteodystrophy. Many children with CRF are now being treated with growth hormone (GH). Since GH has a direct mitogenic effect on osteoblasts in culture, we studied the effects of GH therapy on osteoblastic activity, such as serum alkaline phosphatase (AP), bone GLA-protein (BGP) and bone mass density (BMD) in poorly growing children with and without CRF. Fifteen (4 girls, 11 boys) healthy children with short stature (SS) and 10 (3 girls, 7 boys) children with end-stage renal failure (CRF) 4.5-12.4 years of age were treated with daily subcutaneous injections of GH in a dose of 0.1-0.125 IU/kg/day for 1 year. IGF-I, BGP and BMD of the spine were determined before and after the year of treatment. During GH therapy, a similar increase in height velocity and IGF-I were noted in SS and CRF groups: 3.8 +/- 0.77 to 8.38 +/- 1.25 (p < 0.001) vs. 4.0 +/- 0.6 to 7.14 +/- 1.3 cm/year (p < 0.001) and 7.8 +/- 2.6 to 21.8 +/- 7.5 (p < 0.01) vs. 7.9 +/- 1.3 to 21.5 +/- 5.6 nmol/l (p < 0.01), respectively. AP increased from 205 +/- 27 to 274 +/- 50 IU/l (p < 0.01) in the SS group but not in CRF patients (223 +/- 58 pre- 218 +/- 51 IU/l post-GH therapy).(ABSTRACT TRUNCATED AT 250 WORDS)     

Receptor activator of NF-[kappa]B ligand arrests bone growth and promotes cortical bone resorption in growing rats.

Receptor activator of NF-kappaB ligand (RANKL), produced by osteoblastic lineage cells and activated T cells, is an essential factor for osteoclast differentiation, activation, and survival. Therefore, RANKL is a focal point of therapies targeting bone diseases where there is an imbalance of bone metabolism in favor of bone resorption. The present study assesses the effects of exogenous RANKL on growing bone. RANKL (100 microg x kg-1x day-1 for 7 days) administered to Sprague-Dawley weanling rats caused major deficits in growth, appearance, and bone mineral densities (BMD). Urinary deoxypyridinoline crosslinks, a measure of bone turnover, were higher in the RANKL-treated rats (P = 0.031), and the bone mineral content was lower (P < 0.001). The final BMD in the RANKL-treated rats was lower (P = 0.039) than in the control rats (19 +/- 7 vs. 38 +/- 5 mg/cm3). Moreover, calculated cortical bone density in each bone slice (total BMD - trabecular BMD) indicated there was only 5% cortical bone remaining in RANKL-treated rats. We conclude that therapies targeting RANKL are likely to have effects on cortical as well as trabecular bone density.     

No evidence of association of the osteocalcin gene HindIII polymorphism with bone mineral density in Chinese women

Osteoporosis is a major health problem, mainly characterized by low bone mineral density (BMD). Osteocalcin (also known as BGP, for bone Gla protein) is a significant biomarker of bone turnover and thus the BGP gene has been considered as an important candidate gene for osteoporosis. A few studies on the relationship between variants of the BGP gene and BMD variation, via traditional association and/or linkage methods, have yielded conflicting results. In the present study, we simultaneously tested linkage and/or association of the BGP HindIII polymorphism with BMD in a large cohort of pre-menopausal Chinese women. A total of 1,263 subjects from 402 Chinese nuclear families were examined. Each family consists of both parents and at least one daughter aged between 20-45 years. BMDs at the lumbar spine and hip were measured by dual-energy X-ray absorptiometry (DXA). Using the QTDT (quantitative transmission disequilibrium test) program, we did not detect significant evidence of linkage or association between the BGP HindIII polymorphisms and the BMD variation at any skeletal site. Our data do not support the BGP gene having a major effect on BMD variation in pre-menopausal Chinese women.     

Volumetric bone mineral density in young women with Turner's syndrome treated with estrogens or estrogens plus growth hormone

To explore the effects of estrogen replacement therapy (ERT) and recombinant growth hormone (GH) treatment on bone mineral density (BMD) in Turner's syndrome, we assessed volumetric BMD (vBMD), which is less dependent on body and bone sizes, in these patients at final height. The areal BMD (aBMD) was measured in 26 young women with Turner's syndrome (age range 17.5-25.0 years) by dual-energy X-ray absorptiometry, and vBMD was calculated. Patients were subdivided as group 1 (n = 12; ERT alone) and group 2 (n = 14; GH + ERT). Years of estrogen exposure were not different between the groups (group 1: 6. 4 +/- 1.5 years; group 2: 5.3 +/- 1.7 years); in group 2, GH therapy was 5.3 +/- 1.4 years. Final heights were significantly higher in group 2 than in group 1 (148.1 +/- 3.0 vs. 142.0 +/- 2.8 cm; p < 0. 0001) as well as aBMD (1.073 +/- 0.118 vs. 0.968 +/- 0.122 g/cm(2); p < 0.04). vBMD was higher in group 2 but not significantly different from group 1 (0.374 +/- 0.030 vs. 0.358 +/- 0.027 g/cm(3); p = 0.169). aBMD was reduced with respect to the normative values in both groups (group 1: -1.97 +/- 1.04 SDS, p < 0.0001 vs. 0; group 2: -0.93 +/- 1.01 SDS, p < 0.005 vs. 0), whereas vBMD was not (group 1: -0.07 +/- 0.79 SDS; group 2: 0.42 +/- 0.82 SDS). Our data suggest that: in Turner's syndrome GH administration improves final height and aBMD, but it does not significantly increase vBMD; aBMD reduction in Turner's syndrome is likely due to the impaired growth and reduced bone size; Turner's patients on ERT from adolescence show vBMD values in the normal range in young adulthood.     

Effects of physical training on bone mineral density and bone metabolism

The purpose of this study was to examine the influences of long-term walking training and walking and jumping training on bone mineral density (BMD) and bone metabolism. Data from 28 healthy premenopausal women was assessed. The subjects were divided into the walking group (WG; 17 women mean+/-SE age 35+/-2 years), and the walking and jumping group (WJG; 11 women mean+/-SE age 39+/-1 years). BMD was measured in the lumbar spine and proximal femur using dual energy X-ray absorptiometry (DXA). As markers of bone metabolism, this study was to measure bone formation markers, bone-alkaline phosphatase (B-ALP: measured by enzyme immunoassay/EIA) and osteocalcin (BGP: by radioimmunoassay/RI) as well as bone resorption markers, parathyroid hormone (PTH: measured by/RI) and type I collagen cross-linked N-telopeptides (NTx: by EIA). Despite the significant decrease in body weight (p<0.05), no corresponding decrease in BMD was observed. Moreover, no significant difference in bone markers BGP, PTH, and NTx was observed. B-ALP was significantly increased (p<0.05) after one year, and the rate of this increase was greater in the WJG than in the WG. It is thus concluded that walking training for one year is beneficial for the promotion of bone formation, and that jumping stimulus maintain BMD effectively.     

The lumbar bone mineral density is affected by long-term poor metabolic control in adolescents with type 1 diabetes mellitus

AIM: To analyze whether bone mineral density (BMD) and bone resorption status are influenced by long-term metabolic control and duration of disease in adolescents with long-standing type 1 diabetes mellitus. METHODS: Twenty-seven adolescents (age 13.1 +/- 1.7 years, duration of diabetes 6.9 +/- 3.0 years) were studied. The BMD, expressed as z score, was measured at the lumbar spine (L1-L4) using dual-energy X-ray absorptiometry, while the urinary excretion of total deoxypiridinoline (Dpyd), a marker of bone resorption, was measured by immunoassay and was corrected by creatinine (Cr). Linear and multivariate correlations between lumbar BMD z score or Dpyd/Cr excretion and age and disease variables [short-term (Hb A(1c latest)) or long-term (Hb A(1c whole duration)) metabolic control, duration, 'diabetes impact index' (mean Hb A(1c whole duration) x duration of disease in months)] were sought. RESULTS: In diabetic subjects the mean BMD z score was -0.44 +/- (SD) 1.02 (95% CI: -0.03; -0.84), and the Dpyd/Cr excretion was not increased. A negative correlation was found between lumbar BMD z score and age (r -0.59; p = 0.001), duration (r -0.39; p = 0.04), and the diabetes impact index (r -0.4; p = 0.04). The Dpyd/Cr ratio correlated negatively with age (r -0.40; p = 0.04) and positively with height velocity (r 0.42; p = 0.04). By using multiple linear regression, age showed a significant inverse correlation with lumbar BMD z score (beta = -0.39; p = 0.0005). A negative correlation was found between lumbar BMD z score and Hb A(1c whole duration) (beta = -0.40; p = 0.02) or diabetes impact index (beta = -0.001; p = 0.01). CONCLUSIONS: Poor metabolic control may expose adolescents with long-standing type 1 diabetes to the risk of developing osteopenia in adult age. Optimization of metabolic control in growing diabetic children may prevent osteoporosis in later life.     

Association between parathyroid hormone (PTH)/PTH-related peptide receptor gene polymorphism and the extent of bone mass reduction in primary hyperparathyroidism.

Genetic contributions to bone mineral density (BMD) and bone turnover are well known. In the present study, we analyzed the relationship between polymorphism of parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor gene existing in exon M7 and the clinical characteristics of primary hyperparathyroidism (pHPT). PTH/PTHrP receptor genotypes were analyzed in 92 pHPT patients by direct sequence to determine whether nucleotide 1417 of the cDNA was C or T. BMD levels at the lumbar spine and at the radius before and one year after parathyroidectomy, as well as serum levels of calcium, phosphorus, alkaline phosphatase (ALP) and intact PTH were measured. Although there were no significant differences in serum levels of calcium, phosphorus and intact PTH, ALP was significantly lower in the CT genotype compared with the TT genotype. BMD level at the radius was significantly higher in the CT genotype than in the CC genotype. Moreover, an increase in radial BMD one year after parathyroidectomy was significantly less in CT genotype than two other genotypes (CC, TT). The present study is the first to indicate that the polymorphism of PTH/PTHrP receptor gene is closely related to the extent of bone mass reduction in pHPT and that this polymorphism would be one of the genetic factors responsible for the severity of the pathological state of pHPT.     

One-year spinal bone change in pre- and perimenopausal Japanese women. A prospective observational study

BACKGROUND: This prospective observational study was designed to determine whether the bone mineral density (BMD) of the lumbar spine decreases before menopause. METHODS: The change in BMD of the second through fourth lumbar vertebrae (delta%L2-4BMD) over the course of 12 months was measured in 197 pre- and perimenopausal Japanese women aged 48.2 +/- 2.3 (mean +/- SD) years. RESULTS: Overall, delta%L2-4BMD decreased significantly, with a greater decrease seen in perimenopausal women. This group also had a significantly higher level of FSH (p < 0.05, t = 7.356), a significantly lower level of estradiol (p < 0.05, t = 4.245), and significantly higher levels of the bone metabolic markers, alkaline phosphatase (p < 0.05, t = 3.841), calcium (p < 0.05, t = 3.939), and osteocalcin (p < 0.05, t = -3.295). Overall, there was a significant positive correlation between osteocalcin and delta%L2-4BMD (r = -0.194, p = 0.0479). CONCLUSION: A subset of perimenopausal women with transient decreases in ovarian function that do not respond to increased FSH may be at increased risk for abnormally low BMD, and may benefit from early management of bone mass.     

Conditional expression of constitutively active estrogen receptor α in osteoblasts increases bone mineral density in mice

Estrogen plays an important role in maintaining bone density in women. Estrogen receptor (ER) is expressed in osteoblasts and osteoclasts; however, the precise mechanism of ER in bone is not fully understood. In the present study, we generated a conditional transgenic mouse caERα(ColI) that expresses the constitutively active ERα in osteoblasts using collagen type I promoter-driven Cre transgenic mice. The caERα(ColI) mice showed increased bone mineral density (BMD). Osteoblasts prepared from caERα(ColI) mice expressed high levels of osteoprotegerin and decreased levels of IL-6, both of which are known to regulate osteoclast differentiation. These results suggest that ERα regulates osteoprotegerin and IL-6 production in osteoblasts and modulates BMD. The conditional transgenic mouse model is useful for understanding the in vivo function of ERα.     

The effects of growth hormone on cortical and cancellous bone

Growth hormone (GH) has profound effects on linear bone growth, bone metabolism and bone mass. The GH receptor is found on the cell surface of osteoblasts and osteoclasts, but not on mature osteocytes. In vitro, GH stimulates proliferation, differentiation and extracellular matrix production in osteoblast-like cell lines. GH also stimulates recruitment and bone resorption activity in osteoclast-like cells. GH promotes autocrine/paracrine insulin-like growth factor 1 (IGF-I) production and endocrine (liver-derived) IGF-I production. Some of the GH-induced effects on bone cells can be blocked by IGF-I antibodies, while others cannot. In animal experiments, GH administration increases bone formation and resorption, and enhances cortical bone mass and mechanical strength. When GH induces linear growth, increased cancellous bone volume is seen, but an unaffected cancellous bone volume is found in the absence of linear growth. Patients with acromegaly have increased bone formation and resorption markers. Bone mass results are conflicting because many acromegalics have hypogonadism, but in acromegalics without hypogonadism, increased bone mineral density (BMD) is seen in predominantly cortical bone, and normal BMD in predominantly cancellous bone. Adult patients with growth hormone deficiency have decreased bone mineral content and BMD. GH therapy rapidly increases bone formation and resorption markers. During the first 6-12 months of therapy, declined or unchanged BMD is found in the femoral neck and lumbar spine. All GH trials with a duration of two years or more show enhanced femoral neck and lumbar spine BMD. In osteoporotic patients, GH treatment quickly increases markers for bone formation and resorption. During the first year of treatment, unchanged or decreased BMD values are found, whereas longer treatment periods report enhanced or unchanged BMD values. However, existing trials comprising relatively few patients and limited treatment periods do not allow final conclusions to be drawn regarding the effects of GH on osteoporosis during long-term treatment.