Yuka Miyatani

Circulating profiles of osteoprotegerin and soluble receptor activator of nuclear factor κB ligand in post-menopausal women

Objective: The aim of this study was to elucidate the detail profiles of circulating osteoprotegerin (OPG) and soluble receptor activator of nuclear factor κB ligand (sRANKL) in post-menopausal women. Methods: Eighty Japanese post-menopausal women were enrolled in this cross-sectional study. Circulating OPG and free fraction of sRANKL (free sRANKL), PTH, calcium and phosphorus, age, years since menopause, body mass index, bone mineral density of the vertebral bodies (LBMD) and bone turnover markers were determined in each subject. Results: In rank order correlation analysis, serum OPG concentrations had a significant positive correlation with age (r=0.291, p=0.024) and a marginal significant negative correlation with LBMD (r=-0.247, p=0.062). However they did not have correlations with LBMD or other parameters after adjustment for age. Serum free sRANKL concentrations had a significant positive correlation with age (r=0.332, p=0.010) and a significant negative correlation with LBMD (r=−0.608, p<0.001). This correlation with LBMD persisted after adjustment for age. In a multiple regression analysis with a stepwise model, the main determinants of LBMD were age and serum free sRANKL (p=0.015 and p=0.006, respectively). Conclusions: We found the increase in circulating OPG and sRANKL with age and a robust negative correlation between circulating free sRANKL and LBMD after adjustment for age. The increase in circulating free sRANKL may reflect directly or indirectly the conditions coexistent with bone loss in post-menopausal women.

Association of serum undercarboxylated osteocalcin with serum estradiol in pre-, peri- and early post-menopausal women

Objective: We investigated changes in serum concentration of undercarboxylated osteocalcin (ucOC), which is a sensitive marker of vitamin K status, and association of ucOC concentration with estradiol concentration in pre-, peri- and early post-menopausal women. Methods: The study population consisted of 193 pre-, peri- and post-menopausal Japanese women aged 39–66 yr. Serum ucOC concentration was measured to assess vitamin K status; serum concentrations of intact osteocalcin (OC) and bone-specific alkaline phosphatase (BAP) were measured as bone formation markers; and urine concentration of N-telopeptide was measured as a bone resorption marker. Serum estradiol and estrone concentrations were measured by a highly sensitive radioimmunoassay. Bone mineral density (BMD) was measured at the lumbar spine. Results: Serum concentration of ucOC in peri-menopausal women was significantly (p=0.0005) higher than that in pre-menopausal women, while serum OC concentration in post-menopausal women for whom 1 yr had passed since menopause was significantly (p=0.0003, p=0.024, respectively) higher than the concentrations in pre-menopausal and peri-menopausal women. Serum ucOC concentration showed a significant negative correlation with estradiol concentration (r=−0.372, p<0.0001) and a significant positive correlation with serum FSH concentration (r=0.324, p<0.0001). Serum OC concentration was positively correlated with serum FSH concentration (r=0.317, p<0.001). Conclusions: The results showed that the change in ucOC concentration during the menopausal transition is different from that in OC concentration. In addition, serum ucOC concentration is closely associated not only with FSH concentration but also estradiol concentration.

Associations of circulating adiponectin with estradiol and monocyte chemotactic protein-1 in postmenopausal women.

Objective: The aim of the present study was to clarify the association of serum adiponectin concentrations with serum 17&bgr;-estradiol concentrations in pre-, peri-, and postmenopausal women. In addition, the associations of serum adiponectin with serum concentrations of proinflammatory and anti-inflammatory cytokines were examined in women during the menopausal transition. Design: A total of 197 women were enrolled in this study: 33 premenopausal women, 80 perimenopausal women, and 84 postmenopausal women. Serum adiponectin concentration was measured by an enzyme-linked immunosorbent assay. Serum concentrations of the proinflammatory cytokines interleukin (IL)-1&bgr;, IL-6, and tumor necrosis factor &agr;, anti-inflammatory cytokine IL-10, and the chemokines IL-8, macrophage inflammatory protein-1&bgr; and monocyte chemotactic protein-1 were measured by using a multiplexed human cytokine assay. Results: Serum adiponectin concentration showed a significant negative correlation with serum estradiol concentration (r = −0.400, P = 0.001) in postmenopausal women but not in pre- and perimenopausal women, and this correlation was significant after adjustment for age and body mass index. Serum adiponectin concentration also showed a significant negative correlation with serum monocyte chemotactic protein-1 concentration (r = −0.244, P = 0.05) in postmenopausal women. Conclusion: An increase in adiponectin level due to a decrease in estradiol results in a reduction in monocyte chemotactic protein-1 level in postmenopausal women, suggesting that adiponectin may be associated with a protective role against insulin resistance and atherosclerosis, which occur in the postmenopausal stage.

Circulating osteoprotegerin is associated with age and systolic blood pressure, but not with lipid profile or fasting glucose, in postmenopausal women.

Objective: Osteoprotegerin (OPG), an inhibitor of osteoclastogenesis and osteoclast activation, has been reported to be linked to vascular biology. The aim of this study was to clarify the relationships between circulating OPG and the risk factors for vascular disorders in postmenopausal women. Design: Eighty Japanese postmenopausal women were enrolled in this cross-sectional study. Clinical parameters (age, number of years since menopause, body mass index, systolic and diastolic blood pressure); serum concentrations of OPG, creatinine, calcium, and phosphorus; serum lipid profile; plasma glucose; and bone mineral density of the L2-4 vertebral bodies were determined for each woman. Results: In rank-order correlation analysis, serum OPG concentrations had significant positive correlations with age (r = 0.29, P = 0.03), systolic blood pressure (r = 0.45, P < 0.01), diastolic blood pressure (r = 0.34, P < 0.01), and serum creatinine (r = 0.29, P = 0.04). Serum OPG concentration also had a marginally significant negative correlation with bone mineral density of the L2-4 vertebral bodies (r = −0.25, P = 0.06). However, serum OPG did not correlate with body mass index, serum lipid profile, or plasma glucose. The correlation of serum OPG with systolic blood pressure persisted after adjustment for both age and serum creatinine. Conclusions: These results suggest that increased circulating OPG in postmenopausal women is closely related to higher systolic blood pressure, which could cause atherosclerosis.

Effect of vitamin K2 treatment on carboxylation of osteocalcin in early postmenopausal women.

Objective. We examined the serum level of undercarboxylated osteocalcin (uc OC), which is a sensitive marker of vitamin K status, and levels of bone turnover markers in early postmenopausal women receiving vitamin K2 treatment with or without vitamin D3. Methods. Thirty-four postmenopausal women with a mean age of 53 years whose bone mineral density (BMD) was less than 0.809 g/cm2 (osteopenia and osteoporosis) were treated with vitamin K2 or with a combination of vitamin K2 and vitamin D3. Seventeen women received daily oral administration of 45 mg vitamin K2 and 17 women received daily oral administration of 45 mg vitamin K2 plus 0.75 µg 1α-hydroxyvitamin D3. Serum levels of uc OC, intact osteocalcin (OC) and bone alkaline phosphatase (BAP), urinary deoxypyridinoline (DPD) levels and BMD at the lumbar spine were measured before and at 1 and 2 years after the start of treatment. Results. Serum uc OC levels in women treated with vitamin K2 alone and with both vitamin K2 and vitamin D3 decreased significantly (p < 0.05). Serum levels of intact OC and BAP in women treated with vitamin K2 did not show significant changes, while those in women who received the combined treatment decreased significantly (p < 0.05). On the other hand, urinary DPD level in women treated with vitamin K2 did not change, while that in women who received the combined treatment tended to decrease (p < 0.1). Conclusion. Serum uc OC levels in early postmenopausal women who received vitamin K2 decreased due to carboxylation of uc OC. Combined treatment with vitamin K2 and vitamin D3 may be effective for sustaining BMD in early postmenopausal women whose bone turnovers are highly activated.

Parathyroid Hormone (1-34) Counteracts the Suppression of Interleukin-11 Expression by Glucocorticoid in Murine Osteoblasts: A Possible Mechanism for Stimulating Osteoblast Differentiation Against Glucocorticoid Excess

Glucocorticoid (GC) excess causes a rapid loss of bone with a reduction in bone formation. Intermittent PTH (1-34) administration stimulates bone formation and counteracts the inhibition of bone formation by GC excess. We have previously demonstrated that mechanical strain enhances interleukin (IL)-11 gene transcription by a rapid induction of ΔFosB expression and protein kinase C (PKC)-δ-mediated phosphorylation of phosphorylated mothers against decapentaplegic (Smad)-1. Because IL-11 suppresses the expression of dickkopf-1 and -2 and stimulates Wnt signaling, IL-11 appears to mediate at least a part of the effect of mechanical strain on osteoblast differentiation and bone formation. The present study was undertaken to examine the effect of PTH(1-34) and GCs on IL-11 expression in murine primary osteoblasts (mPOBs). PTH(1-34) treatment of mPOBs enhanced IL-11 expression in a time- and dose-dependent manner. PTH(1-34) also stimulated ΔFosB expression and Smad1 phosphorylation, which cooperatively stimulated IL-11 gene transcription. PTH(1-34)-induced Smad1 phosphorylation was mediated via PKCδ and was abrogated in mPOBs from PKCδ knockout mice. Dexamethasone suppressed IL-11 gene transcription enhanced by PTH(1-34) without affecting ΔFosB expression or Smad1 phosphorylation, and dexamethasone-GC receptor complex was bound to JunD, which forms heterodimers with ΔFosB. High doses of PTH(1-34) counteracted the effect of dexamethasone on apoptosis of mPOBs, which was blunted by neutralizing anti-IL-11 antibody or IL-11 small interfering RNA. These results demonstrate that PTH(1-34) and GCs interact to regulate IL-11 expression in parallel with osteoblast differentiation and apoptosis and suggest that PTH(1-34) and dexamethasone may regulate osteoblast differentiation and apoptosis via their effect on IL-11 expression.