Differences in the time course of the effects of oophorectomy in women on parameters of bone metabolism and interleukin-1 levels in the circulation

Long-Term Prolactin Exposure Differentially Stimulated the Transcellular and Solvent Drag-Induced Calcium Transport in the Duodenum of Ovariectomized Rats

Prolactin, having been shown to stimulate transcellular active and solvent drag-induced calcium transport in the duodenum of female rats, was postulated to improve duodenal calcium transport in estrogen-deficient rats. The aim of the present study was, therefore, to demonstrate the effects of long-term prolactin exposure produced by anterior pituitary (AP) transplantation on the duodenal calcium transport in young (9-week-old) and adult (22-week-old) ovariectomized rats. We found that ovariectomy did not alter the transcellular active duodenal calcium transport in young and adult rats fed normal calcium diet (1.0% w/w Ca) but decreased the solvent drag-induced duodenal calcium transport from 75.50 ± 10.12 to 55.75 ± 4.77 nmol·hr–1 cm–2 (P < 0.05) only in adult rats. Long-term prolactin exposure stimulated the transcellular active calcium transport in young and adult AP-grafted ovariectomized rats fed with normal calcium diet by more than 2-fold from 7.56 ± 0.79 to 16.54 ± 2.05 (P < 0.001) and 9.78 ± 0.72 to 15.99 ± 1.75 (P < 0.001) nmol·hr–1 cm–2, respectively. However, only the solvent drag-induced duodenal calcium transport in young rats was enhanced by prolactin from 95.51 ± 10.64 to 163.20 ± 18.03 nmol·hr–1 cm–2 (P < 0.001) whereas that in adult rats still showed a decreased flux from 75.50 ± 10.12 to 47.77 ± 5.42 nmol·hr–1 cm–2 (P < 0.05). Because oral calcium supplement has been widely used to improve calcium balance in estrogen-deficient animals, the effect of a high-calcium diet (2.0% w/w Ca) was also investigated. The results showed that stimulatory action of long-term prolactin on the transcellular active duodenal calcium transport in both young and adult rats was diminished after being fed a high-calcium diet. The same diet also abolished prolactin-enhanced solvent drag-induced duodenal calcium transport in young and further decreased that in adult AP-grafted ovariectomized rats. We concluded that the solvent drag-induced duodenal calcium transport in adult rats was decreased after ovariectomy. Long-term prolactin exposure stimulated the transcellular active duodenal calcium transport in both young and adult rats whereas enhancing the solvent drag-induced duodenal calcium transport only in young rats. Effects of prolactin were abolished by a high-calcium diet.

Relationship of Bone Densitometry and Bone Resorption Markers With Menopausal Type and Duration

Objective: Menopause age and bone mineral density are positively related and there is a rapid bone loss in the early post-menopausal period. A ratio of 30% of post-menopausal women are affected from osteoporosis developing due to bone loss and this causes 40% risk of fracture in a 50- year old woman.

Materials and Methods: In this sudy, serum osteocalcin and urine deoxypridinoline levels were analyzed in 102 postmenapausal and 48 healthy premenopausal controls who presented to gynecology outpatient clinic. Bone densitometry was obtained from all postmenopausal women. Postmenopausal patients were further divided into four groups according to time since menopause:<5 years, 5-9 years, 10-19 years and >20 years.

Results: Mean (SD) age in 48 premenopausal women was 47.7 (3.7) while it was 56.5 (6.8) in 102 post-menopausal women. 34 out of 102 post-menopausal women had surgical menopause due to bilateral oopheroctomy+hysterectomy while the remaining had natural menopause. No significant difference was found in bone-turnover markers between women with surgical and natural menopause.

Conclusion: Although there was not a statistically significant difference between bone-turnover markers, bone mineral density stays lower in surgical menopausal patients and this difference disappear only after about 20 years. Also bone turnover markers are usually high up to five years after surgical menopause and return to normal levels after then. Thus, our study suggested that oopheroctomy does not cause additional risk to hysterectomy. We also suggest that there is not a long-term relationship between serum bone turnover markers or bone density and the etiology of menopause. (Turk J Rheumatol 2010; 25: 29-33)

Hysterectomy and oophorectomy are unrelated to bone loss in older women

OBJECTIVE

The relation of hysterectomy and oophorectomy to change in bone mineral density (BMD) was examined in older women using and not using estrogen replacement therapy (ERT).

METHODS

Women aged 60-80 years from the Rancho Bernardo Study attended clinic visits in 1988-1991 and 1992-1995 when hysterectomy and oophorectomy were ascertained, ERT use was validated and spine and hip BMD was assessed at both visits with DEXA. Women were either current ERT users or nonusers at both visits.

RESULTS

Among these 447 women, average age was 71 (S.D.=9.0); average years postmenopause was 24.7 (S.D.=10.9). Overall, 122 had a hysterectomy with ovarian conservation and 91 had a hysterectomy with bilateral oophorectomy; 41% reported current ERT use for an average duration of 19.1 years (S.D.=10.8). Hysterectomized women were 2.3 times more likely to report ERT use than intact women (P<0.001). Comparisons adjusted for age, obesity, and age at menopause but not for ERT use showed hysterectomized women had less bone loss per year at the hip than intact women (P<0.05). However, this difference was explained by ERT; after adjustment for ERT, mean hip bone loss per year was -0.57% for intact women, -0.42% for hysterectomized women with ovarian conservation and -0.32% for bilaterally oophorectomized women (P's>0.10). There were no differences by hysterectomy or oophorectomy in bone loss at the spine or femoral neck. For all sites, women using ERT had higher BMD at both visits than nonusers (P's<0.001). Stratification by ERT showed that within users and nonusers, there were no differences in BMD or bone loss at any site by hysterectomy or oophorectomy.

CONCLUSIONS

There are no long term effects of hysterectomy and bilateral oophorectomy on bone loss. Women who use ERT have better BMD than nonusers.

Adverse alterations in bone metabolism are associated with lung infection in adults with cystic fibrosis

Low bone density, fractures, and kyphosis complicate the lives of adults with cystic fibrosis (CF), and inflammatory cytokines (interleukin [IL]-1beta, IL-6, and tumor necrosis factor [TNF]-alpha) that may alter bone metabolism have been previously found to be increased in the lungs and serum of CF patients. The objective of this prospective study was to determine the impact of lung infection on bone physiology in 17 adult CF patients. Serum osteocalcin, a marker of bone formation; urine N-telopeptides of type I collagen and free deoxypyridinoline, both of which are markers of bone breakdown; serum cytokines (TNF-alpha, IL-1beta, and IL-6); and general inflammatory markers (serum C-reactive protein [CRP] and chondrex) were measured at the beginning and end of treatment for an acute exacerbation of lung infection and again 3 wk later. After treatment with conventional antibiotics, decreases in N-telopeptides (147.3 +/- 77.5 [mean +/- SEM] versus 95.5 +/- 57.3 bone collagen equivalents (BCE)/mmol creatinine, p = 0.0014), deoxypyridinoline (8.42 +/- 2.8 versus 6.8 +/- 3.0 mmol/mmol creatinine, p = 0.08), IL-1beta (1.43 +/- 1.13 versus 0.65 +/- 0.63 pg/ml, p = 0.03), IL-6 (9.5 +/- 6.5 versus 4.7 +/- 3.2 pg/ml, p = 0. 012), CRP (43.1 +/- 29.3 versus 23.4 +/- 25.3 mg/ml, p = 0.04), and chondrex (151.7 +/- 111.7 versus 101.4 +/- 67.3 ng/ml, p = 0.014), and increases in osteocalcin levels (14.5 +/- 5.4 versus 22.5 +/- 8. 7 ng/ml, p = 0.010) were observed. Three weeks later, the changes in N-telopeptides and osteocalcin persisted. These data indicate that pulmonary infection, through the elaboration of inflammatory cytokines, may be linked to increased bone resorption and diminished bone formation. These results provide insights into the impact of systemic inflammation on bone health, and suggest novel mechanisms for bone disease in CF.

Osteoporosis. Pathogenesis, diagnosis, and treatment in older adults

Osteoporosis is a major cause of disability and excess mortality in older men and women. Hip fracture incidence accelerates approximately 10 years after menopause in women and after age 70 in men. Approximately 1 million Americans suffer fragility fractures each year at a cost of over 14 billion dollars. The disability, mortality, and cost of hip and vertebral fractures are substantial in the rapidly growing, aging population so that prevention of osteoporosis is a major public health concern. BMD is used to make the diagnosis of osteoporosis before incident fracture and predict fracture risk. Recommendations for treatment and prevention of osteoporosis based on BMD score have been published by the World Health Organization and the National Osteoporosis Foundation. In a process that continues throughout life, bone repairs itself by the coupled action of bone resorption followed by bone formation, sometimes referred to as bone turnover. Osteoblasts and osteoclasts are the primary cells involved in bone formation and resorption, respectively. The process of bone turnover is regulated by hormones, such as PIH and local factors such as IL-1 and prostaglandins. Following attainment of peak bone mass at age 25, bone loss begins, accelerates in women at menopause and slows again but continues into advanced years at a rate of 1% to 2% per year, similar to premenopausal bone loss rate. The leading theories of the mechanism of bone loss in older individuals is calcium deficiency leading to secondary hyperparathyroidism and sex hormone deficiency. Risk factors such as age, gender, ethnic background, smoking, exercise, and nutrition, and medical conditions associated with osteoporosis should be evaluated and modified when possible to prevent further bone loss. Osteoporosis treatment and prevention include weight-bearing exercise, calcium and vitamin D supplementation, estrogen replacement, bisphosphonates, selective estrogen receptor antagonists, and calcitonin. Although there is no currently approved treatment for osteoporosis in men, many of the treatments approved for osteoporosis in women hold promise to be beneficial in men.

Estrogen inhibits interleukin-1beta-induced interleukin-6 production by human osteoblast-like cells

Estrogen supplements are the primary pharmacologic intervention therapy to prevent and treat loss of bone mass (osteoporosis) in postmenopausal women. Furthermore, at sites of local inflammation near bone, estrogen-deficient women are significantly more susceptible to bone loss than are estrogen-sufficient women. In the present study, we investigate whether estrogen modulates osteoblast (MG-63) production of interleukin-6 (IL-6), an osteoclast recruitment and differentiation of cytokine, in the presence of the proinflammatory cytokine, IL-1beta. Using enzyme-linked immunosorbent assay (ELISA), we demonstrate that IL-1beta significantly enhances IL-6 secretion into culture supernatants in a dose-dependent and time-dependent manner. Using reverse-transcriptase polymerase chain reaction (RT-PCR) and ELISA respectively, we demonstrate further that levels of 17beta-estradiol (active metabolite of estrogen) > or = those found in serum of estrogen-sufficient women inhibit steady-state IL-6 mRNA levels as well as inhibit secretion of IL-6 into culture supernatants. One mechanism by which estrogen therapy preserves bone mass in areas of inflammation may be via inhibition of IL-1beta-stimulated obsteoblast-derived IL-6.

Premenopausal ovariectomy-related bone loss: a randomized, double-blind, one-year trial of conjugated estrogen or medroxyprogesterone acetate

The purpose of this study was to contrast the effects of conventional estrogen treatment with medroxyprogesterone on cancellous and cortical bone change in the first year following premenopausal ovariectomy. This 1-year double-blind randomized therapy trial was stratified by osteoporosis family history and performed in an academic medical center and community hospitals. Premenopausal women 45 +/- 5 years old, postovariectomy for benign diseases were provided 600 mg/day of calcium and randomized to daily therapy with conjugated equine estrogen (CEE, 0.6 mg) or medroxyprogesterone (MPA, 10 mg). The primary outcome variable was spinal quantitative computed tomography (QCT) bone density change over 1 year with additional outcomes of dual-energy X-ray absorptiometry (DXA) of proximal femur (FN), whole body (WB), and spine segment (WBS) and N-telopeptide, bone-specific alkaline phosphatase, and other bone marker, hormonal, and weight changes. Results in the 33 women completing the study, whose initial bone densities were normal (QCT 133 mg/cm3, femoral neck 0.94 g/cm2, whole body DXA 1.13 g/cm2), showed annual QCT loss during CEE therapy of -11.5 mg/cm3 (p < 0.0007) and MPA bone loss of -19.7 mg/cm3 (p < 0.0001). Losses were marginally greater on MPA than CEE (p = 0.04). Extremely high postovariectomy (5 days) and pretreatment resorption markers (> 3 SD above premenopausal normal levels) were significantly related to bone loss. Across the year, resorption decreased during CEE but increased on MPA treatment. Significant DXA bone losses were prevented by CEE treatment (-1.4% FN, -.4% WB, and -1.5% WBS, all NS). However, DXA bone loss was not prevented by MPA treatment (-5% FN, -2.8% WB, and -6.1% WBS, all p < 0.03). Average weight gain was significant (+ 3.2 +/- 4.0 kg) and greater on CEE than MPA (+ 4.7 vs. + 2.0 kg, p = 0.049). In conclusion, CEE therapy did not prevent significant 8% cancellous spinal bone loss in the first year following premenopausal ovariectomy, despite supplementation with 600 mg/day of calcium, good control of vasomotor symptoms, and nearly 5 kg of gain in weight. Significant DXA bone loss, however, was prevented by CEE, but not by MPA therapy. These unexpected results were statistically related to high bone resorption following ovariectomy, which CEE suppressed but MPA did not. Bone formation markers increased during MPA therapy but were unchanged during CEE therapy.

Differential expression of insulin-dependent diabetes mellitus-associated HLA-DQA1 alleles in vivo

The strong association of HLA-DQ genes with insulin-dependent diabetes mellitus (IDDM) susceptibility is persuasive evidence of their central role in the etiology of this autoimmune disease. Among other possibilities, it has been proposed that an unbalanced expression of IDDM-associated DQA, and/or DQB alleles may lead to alterations in the composition of alpha beta heterodimers and preferential expression of a particular heterodimer on the antigen-presenting cell surface, leading to self-recognition. In this report, we demonstrate the differential expression of DQA1 alleles in vivo, in particular of the two diabetogenic alleles DQA1*0301 and DQA1*0501. Family studies suggest that unequal HLA-DQA1 allele expression in heterozygous individuals is not associated in cis with the HLA-DQA1 gene, but may be affected by trans-acting determinant(s). We also discuss the segregation of this phenotype in IDDM-affected members. Furthermore, we examined historical samples of PBL from an IDDM-affected individual and an HLA-identical unaffected sibling acting in a kidney transplant program as donor and recipient, respectively. This analysis allowed us to establish that unbalanced expression of DQA1*0301 and DQA1*0501 can be induced by microenvironmental conditions. Inducible differential expression of HLA-DQA1 alleles may account for the discordance in the outcome of autoimmune disease in monozygotic twins and HLA-identical siblings.

Estrogen, cytokines, and pathogenesis of postmenopausal osteoporosis

In summary, available data demonstrate that IL-1 and TNF are the causative agents underlying the bone loss induced by estrogen deficiency. Indeed, these factors are produced in bone and the bone marrow, released in larger amounts from cells of estrogen-deficient subjects, and indispensable for reproducing the effects of estrogen deficiency in bone. These observations support the hypothesis that the bone sparing effect of estrogen is due to the ability of the hormone to block osteoclastogenesis, the activation of mature osteoclasts and, as recently demonstrated, the rate of apoptotic osteoclast death. Although IL-1 and TNF play a prominent causal role in these events, the bone-sparing effect of estrogen is mediated by numerous cytokines which, by simultaneously stimulating multiple target cells, induce effects that are not accounted for by any one single factor (Fig. 2). The ability of estrogen to regulate some, but not all, the cytokines involved in this process is not inconsistent with this hypothesis because cytokines have potent synergistic effects. Thus, a considerable increase in bone resorption may result from a relatively small increase in the concentration of only a few of the bone-resorbing factors present in the bone microenvironment. This concept is best illustrated by the study of Miyaura et al. demonstrating that the concentrations of either IL-1, IL-6, IL-6 receptor, or prostaglandins detected in the bone marrow of OVX mice are insufficient to account for the increased bone resorption caused by estrogen withdrawal. In contrast, the increase in bone resorption induced by OVX can be explained by the cumulative effects of these cytokines. Thus, a better understanding of the cooperative effects of cytokines and a recognition that the contribution of individual cytokines to postmenopausal bone loss varies with the passage of time after menopause are necessary to fully understand the mechanism of action of estrogen in bone. Although the relevance of individual bone-targeting cytokines in species specific, the development of transgenic mice with activatable or deactivatable promoters is likely to result in a further clarification of the integrated action of estrogen-regulated cytokines in human bone cells and lay the foundations for the use of cytokine inhibitors in the treatment of postmenopausal osteoporosis.

Interleukin-1 receptor antagonist and tumor necrosis factor binding protein decrease osteoclast formation and bone resorption in ovariectomized mice

To investigate the contribution of IL-1, IL-6, and TNF to the increased osteoclastogenesis induced by estrogen deficiency, ovariectomized (ovx) mice were treated with either IL-1 receptor antagonist (IL-1ra), a competitive inhibitor of IL-1, TNF binding protein (TNFbp), an inhibitor of TNF, or the anti-IL-6 antibody (Ab) 20F3 for the first 2 wk after surgery. ovx increased the bone marrow cells secretion of IL-1 and TNF, but not IL-6, and the formation of TRAP-positive osteoclast-like multinucleated cells (MNCs) in bone marrow cultures treated with 1,25(OH)2D3. The increase in MNC formation induced by ovx was prevented by in vivo treatment with either 17 beta estradiol, IL-1ra, TNFbp, or anti-IL-6 Ab. However, the percent change in MNC formation induced by the anti-IL-6 Ab was similar in ovx and sham-operated animals, whereas IL-1ra and TNFbp were effective only in ovx mice. MNC formation was also decreased by in vitro treatment of bone marrow cultures with IL-1ra and TNFbp, but not with anti-IL-6 Ab. Ovx also increased bone resorption in vivo and in vitro, as assessed by the urinary excretion of pyridinoline cross links and the formation of resorption pits, respectively. IL-1ra, TNFbp and estrogen decreased bone resorption in vivo and in vitro whereas the anti-IL-6 Ab inhibited bone resorption in vitro but not in vivo. In conclusion, these data indicate that IL-1 and TNF play a direct role in mediating the effects of ovx on osteoclastogenesis and bone resorption. The data also suggest that IL-6 is not essential for increasing bone resorption in the early postovariectomy period.

Circulating levels of cytokines that modulate bone resorption: effects of age and menopause in women

Interleukin 1 alpha (IL-1 alpha), interleukin 1 beta (IL-1 beta), and interleukin 6 (IL-6) are cytokines with potent bone-resorbing effects; some of these biologic effects are opposed by interleukin-1 receptor antagonist (IL-1ra). In vitro and animal model studies suggest that these cytokines are paracrine mediators of the increased bone resorption associated with estrogen deficiency, and increases in their production also could contribute to age-related bone loss. Therefore, we measured serum concentrations of these cytokines in 80 normal women who were 24-87 years old. IL-6 concentration correlated highly with age (p < 0.001) and increased three-fold during life. However, multiple-regression analysis showed no significant correlation between serum IL-6 levels and menopausal status, serum estradiol concentration, or markers for bone turnover (serum bone alkaline phosphatase, osteocalcin, carboxyl-terminal telopeptide of type I collagen, or 24 h urinary free pyridinoline excretion). Serum IL-1 alpha, IL-1 beta, or IL-1ra level did not change with age and, by multiple-regression analysis, did not correlate with markers of bone turnover, except IL-1ra weakly with ICTP. We found no relationship between bone-resorbing cytokines and ovarian function. Although the large age-related increase in serum IL-6 concentration could contribute to age-related bone loss, the lack of correlation with markers for bone turnover argues against this. However, based on the strong evidence in experimental animals that these cytokines are involved in estrogen action on bone, further studies in humans are warranted.