The effect of bone marrow transplantation on the osteoblastic differentiation of human bone marrow stromal cells.

Osteoporosis is a serious and relatively common complication of transplantation procedures. However, little is known about the exact mechanism or severity of osteoporosis complicated by bone marrow transplantation (BMT). We conducted both ex vivo and clinical studies to identify the mechanism and extent of bone loss after BMT. In a prospective clinical study, we intended to identify the changes in bone turnover markers and bone mineral density (BMD) after BMT. During a 1-yr follow-up, BMD was measured before BMT and 1 yr after BMT in 67 patients undergoing BMT. Biochemical markers of bone formation and resorption were measured in all patients at short-term intervals during the yearlong follow-up. In ex vivo study, we cultured human bone marrow cells of normal controls and BMT recipients in osteogenic medium and compared their osteogenic potential. Using a DNA fingerprinting method, we also investigated the origin of bone marrow stromal cells that were harvested 3-4 wk after BMT. In a clinical study of 67 patients undergoing BMT, the mean serum carboxy-terminal cross-linked telopeptide of type I collagen increased progressively until 4 wk after BMT. Thereafter, it began to decrease and reached basal values after 1 yr. Serum osteocalcin decreased progressively until 3 wk after BMT and reached basal values after 3 months. One year after BMT, lumbar spine BMD had decreased by 3.3% (P < 0.05), and total proximal femoral BMD had decreased by 8.9% (P < 0.001). For the ex vivo study, bone marrow was obtained from healthy donors (n = 7) and transplant recipients (n = 7). Then, mononuclear cells including marrow stromal cells were isolated and cultured to osteoblastic lineage. Alkaline phosphatase activities of each group were measured by the time course of secondary culture, and the mineralizing potentials were compared between the two groups. Cells cultured in our system showed characteristics of osteoblast-like cells differentiated from marrow stromal cells. They were initially in a fibroblastic-like spindle shape and became cuboidal with the formation of nodules that were later confluent. The cells were stained to both alkaline phosphatase histochemistry and Von Kossa histochemistry, demonstrating that these cells were of osteoblastic lineage differentiating from marrow stromal cells. The mean time required for the near-confluence in the primary culture was 15 and 22.9 d in healthy donors and transplant recipients, respectively (P = 0.003). Alkaline phosphatase activity was significantly lower in the bone marrow recipients than in the healthy donors at d 7 and 10 of the secondary cultures. The period at which peak activity of alkaline phosphatase was reached was also delayed in the osteoblasts derived from BMT recipient bone marrow compared with those of healthy donors. Using Von Kossa histochemistry, much more mineralization was observed in osteoblasts of healthy donors than those of BMT recipients. After BMT, although the peripheral mononuclear cells in the recipients were of donor origin, the bone marrow stromal cells were of recipient origin according to the PCR analysis using YNZ 22 mini-satellite probe. In conclusion, the differentiation of bone marrow stromal cells into osteoblasts was impaired after BMT, and this might contribute to post-BMT bone loss.     

Age-related changes in cortical bone content of insulin-like growth factor binding protein (IGFBP)-3, IGFBP-5, osteoprotegerin,and calcium in postmenopausal osteoporosis: a cross-sectional study

Serum GH and IGF-I levels decline with increasing age, whereas osteoprotegerin (OPG) increases. IGFs as well as OPG are present in bone matrix and mediate the effects of many upstream hormones (e.g. estrogen). To evaluate whether changes in these proteins may to some extent explain the decrease in bone mass in postmenopausal or senile osteoporosis, we measured bone contents of IGF-I, IGF-II, IGF binding protein (IGFBP)-3, IGFBP-5, and OPG in combined extracts obtained after EDTA and guanidine hydrochloride extraction in 60 postmenopausal women aged 47-74 (mean, 63) yr with a previous distal forearm fracture and a hip or spine Z-score less than 0. We found age-related increases in IGFBP-3 (r = 0.35; P < 0.01), IGFBP-5 (r = 0.59; P < 0.001), and OPG (r = 0.36; P < 0.01) in cortical bone, significantly inversely correlated with femoral neck and lumbar spine BMD. A correlation between age and OPG was also detected in trabecular bone (r = 0.27; P < 0.05). A pronounced age-related decrease in cortical calcium contents (r = -0.60; P < 0.001), positively correlated with femoral neck and lumbar spine BMD, was also found. No age-related changes were detected for IGF-I or IGF-II. The present study demonstrates age-related changes in cortical bone contents of IGFBPs, calcium, and OPG, possibly related to the pathophysiology of postmenopausal osteoporosis. As for OPG, our findings probably represent compensatory responses to increased osteoclastic resorption.     

Relationship between circulating cytokine levels and thyroid function following bone marrow transplantation

The relation between thyroid hormone changes and cytokines in bone marrow transplantation (BMT) patients has not been studied. This prospective study was designed to determine the relation between thyroid hormones and cytokine levels after BMT and their effects on the mortality. We studied 80 patients undergoing allogeneic BMT. Serum thyroid hormone parameters and cytokine levels were measured before and serially during 6 months after BMT. Serum T(3) decreased to a nadir 3 weeks post-BMT and serum T(4) was lowest at 3 months post-BMT. Serum thyroid stimulating hormone (TSH) sharply decreased to a nadir at 1 week and recovered. Serum interleukin-6 increased for 2 weeks after BMT and declined thereafter. Serum tumor necrosis factor-alpha increased for 3 weeks after BMT and declined thereafter. After 3 weeks post-BMT, both cytokine levels were negatively correlated with serum T(3) and T(4) levels. A total of 29 patients died before 1 year post-BMT and 51 patients survived longer than 1 year. Those patients who died before 1 year post-BMT had significantly lower levels of T(4) at 3 weeks, 3 and 6 months than surviving patients. In conclusion, increased levels of serum IL-6 and TNF-alpha were negatively correlated with thyroid hormone concentrations in BMT recipients suggesting the role of these cytokines in euthyroid sick syndrome.     

Circulating osteoprotegerin and receptor activator of NF-kappaB ligand system are associated with bone metabolism in middle-aged males

OBJECTIVE: Osteoporosis is a growing health problem in males as well as in females. Sex hormones and insulin-like growth factor-I (IGF-I) have been shown to be the major determinants in male bone metabolism. Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of NF-kappaB ligand (RANKL). OPG and RANKL have been shown to be important regulators of osteoclastogenesis. However, the relationship between the OPG-RANKL system and male bone status in human populations are unclear. Thus, the aim of this study was to investigate the relationship between the OPG-RANKL system and bone mineral metabolism in males. PATIENTS AND MEASUREMENTS: Serum concentrations of OPG, RANKL, oestradiol, total testosterone and IGF-I and bone mineral density (BMD) were measured in 80 Korean males aged 42-70 (mean age, 54.5 year). Enzyme-linked immunosorbent assays were used to determine the serum concentrations of OPG and RANKL. Serum concentrations of oestradiol, total testosterone, IGF-I and bone turnover markers were determined using standard methods. BMD at the lumbar spine and femoral neck were measured by dual energy X-ray absorptiometry. RESULTS: We observed a significant negative correlation between the serum OPG levels and lumbar spine BMD (r =-0.259, P < 0.05) in Spearman correlation analysis. Serum OPG levels and RANKL/OPG ratios were found to be significantly correlated to the serum osteocalcin levels (r =- 0.254, P < 0.05; r = 0.264, P < 0.05) in Spearman correlation analysis. Serum OPG levels were found to be negatively correlated with serum oestradiol levels (r =-0.319, P < 0.01) in Spearman correlation analysis. In addition, a significant positive correlation was found between serum RANKL/OPG ratios and oestradiol levels (r = 0.374, P < 0.001) in Spearman correlation analysis. In contrast, Serum total testosterone and IGF-I levels were not correlated with serum OPG levels or RANKL to OPG ratios in Spearman correlation analysis. In a multiple regression analysis, age, body mass index (BMI), and serum OPG levels were identified as a significant predictor for lumbar spine BMD, and age, BMI, serum OPG and RANKL levels for femoral neck BMD. In another multiple regression analysis, only serum oestradiol level was identified as a significant predictor for serum OPG or RANKL levels. In contrast, Serum total testosterone and IGF-I levels were not correlated with serum OPG or RANKL levels in multiple regression analysis. CONCLUSIONS: Our data show that the circulating OPG-RANKL system is associated with bone metabolism in the male populations. Also, our data suggest that OPG and RANKL may be mediators of the effects of oestradiol in male bone metabolism.     

Recovery of bone mass and normalization of bone turnover in long-term survivors of allogeneic bone marrow transplantation

Osteoporotic fractures are potential long-term complications of bone marrow transplantation (BMT). We previously reported that bone mineral density (BMD) of patients undergoing allogeneic BMT decreased by 6% to 9% during the first 6 months after BMT and that bone turnover rate was still increased 1 year after BMT. BMT patients do not need lifelong immunosuppressive treatment, which should offer favorable circumstances for the recovery of BMD. Thus, 27 (14 women, 13 men) of 29 long-term survivors of our previous study were invited to a follow-up study at a median of 75 months after BMT. From 12 months after BMT the BMD of the lumbar spine had increased by 2.4% (P = 0.002). The respective changes in femoral sites were +4.1% in the femoral neck (P = 0.087), 4.0% in the trochanter (P = 0.095), +4.7% in Ward's triangle (P = 0.072) and +1.4% in the total hip (P = 0.23). The markers of bone formation, serum osteocalcin and type I procollagen aminoterminal propeptide (PINP) had returned to control levels, but out of the markers of bone resorption the mean level of serum type I carboxyterminal telopeptide (ICTP) was 41% higher (P = 0.0001) and that of urinary type I collagen N-terminal telopeptide/creatinine (NTx) 41% lower (P = 0.0002) in patients than in controls. The mean serum 25-hydroxyvitamin D [25(OH)D] was 33% lower in patients (P = 0.0002), most of whom had hypovitaminosis D [serum 25(OH)D < or = 37 nmol/l]. Except for two, males had serum testosterone level lower than before BMT and four men had hypogonadism. In conclusion, in long-term survivors of allogeneic BMT BMD recovers and bone turnover state normalizes as compared to the situation 1 year after BMT. More attention should be paid to the vitamin D status of all recipients and to possible hypogonadism of male patients.     

Osteoprotegerin serum levels in men: correlation with age, estrogen, and testosterone status.

Previous studies have suggested an important role for androgens and estrogens in bone metabolism in men. However, their local mode of action has not been clearly established. Osteoprotegerin (OPG) is a secreted decoy receptor that inhibits osteoclast formation and activity by neutralizing its cognate ligand. To assess the role of OPG on bone metabolism in men, we conducted a study aimed at evaluating OPG serum levels and their correlation with age, bone mineral density, biochemical markers of bone turnover, and testosterone and estradiol levels in 252 men, aged 19-85 yr. Serum concentrations of OPG increased significantly with age (r = 0.41; P = 0.0001), and were positively correlated with free testosterone index and free estradiol index (r = 0.20; P < 0.002 and r = 0.15; P < 0.03, respectively) after adjustment for age and body weight. Beyond the age of 40 yr, OPG serum concentrations were negatively correlated with urinary excretion of total deoxypyridinoline (r = -0.20; P < 0.01) and PTH serum levels (r = -0.23; P < 0.01). In contrast, there was no correlation with biochemical markers of bone formation, 25-hydroxyvitamin D(3) levels, or bone mineral density at any site. Our data reveal that age as well as androgen and estrogen status are significant positive determinants, whereas PTH is a negative determinant, of OPG serum levels in men. These data suggest that OPG may be an important paracrine mediator of bone metabolism in elderly men and highlight the role of estrogens in the homeostasis of the male skeleton.     

Serum osteoprotegerin and its ligand in Paget's disease of bone: relationship to disease activity and effect of treatment with bisphosphonates

OBJECTIVE: To test the following hypotheses: 1) osteoprotegerin (OPG) and receptor activator of nuclear factor kappa B ligand (RANKL) serum levels in patients with Paget's disease are related to disease activity and are different from those in healthy individuals; 2) interleukin-6 (IL-6), a cytokine that has been shown to have higher levels in Paget's disease, modulates these factors; and 3) the antiresorptive effect of bisphosphonates in Paget's disease of bone may be mediated through these local factors. METHODS: The study group comprised 31 patients with Paget's disease who received 400 mg/day of oral tiludronate for 3 months. Serum levels of OPG, RANKL, IL-6, bone alkaline phosphatase (AP), N-terminal type I procollagen propeptide, urinary N-terminal crosslinking telopeptide of type I collagen, and urinary alpha-C-terminal crosslinking telopeptide of type I collagen were measured at baseline and 1 month after the end of therapy. In addition, the RANKL:OPG ratio was calculated, and disease activity was evaluated at baseline by quantitative bone scintigraphy. RESULTS: Mean baseline OPG values were higher in patients with Paget's disease than in healthy control subjects (P < 0.005), but RANKL and IL-6 values and RANKL:OPG ratios in the 2 groups were similar. OPG concentrations decreased significantly after treatment with tiludronate (P < 0.005), whereas no significant changes were observed in serum RANKL values. No correlation was found between either bone markers or quantitative scintigraphic indices and serum levels of OPG, RANKL, IL-6, and RANKL:OPG ratios. Serum OPG decreased significantly only in those patients with baseline OPG values >4.1 pM/liter. CONCLUSION: Serum OPG increases in Paget's disease and decreases after treatment with tiludronate, especially in patients with the highest OPG values. In contrast, RANKL serum levels and RANKL:OPG ratios are unmodified in patients with Paget's disease. Although serum OPG, RANKL, and IL-6 values were unrelated to disease activity, the increase in OPG may reflect a protective mechanism of the skeleton to compensate for increased bone resorption.     

The changes in circulating osteoprotegerin after hormone therapy in postmenopausal women and their relationship with oestrogen responsiveness on bone

OBJECTIVE: Oestrogen replacement reduces the increased rate of bone remodelling after the menopause. Osteoprotegerin (OPG) is a negative regulator of osteoclast-mediated bone resorption. In vitro studies have shown that oestrogen stimulates OPG production. However, the role of OPG in physiological bone remodelling and its regulation by oestrogen in vivo remain controversial. In this study, we analysed the association between changes in serum OPG levels and bone turnover status before and after hormone therapy (HT) in healthy postmenopausal women. PATIENTS AND MEASUREMENTS: Ninety-nine healthy postmenopausal women of Korean ethnicity, aged 42-64 years (52.3 +/- 4.9 years, mean +/- SD) were enrolled in our study. Serum OPG levels were assessed by a highly sensitive sandwich-type enzyme immunoassay. Serum concentrations of osteocalcin (OC) and carboxyterminal telopeptides (CTx) were determined by electrochemiluminescence immunoassays. Bone mineral density (BMD) at the lumbar spine and femoral neck was measured by dual-energy X-ray absorptiometry (DEXA). RESULTS: Baseline levels of OPG correlated neither a the bone formation marker, serum OC, nor with a bone resorption marker, serum CTx. No significant association of baseline OPG was found with baseline BMD measured at the lumbar spine and femoral neck. Serum OPG levels measured after 3 months and 1 year of HT decreased significantly compared to baseline (P < 0.001 in both). The changes in circulating OPG at 3 months of HT correlated with the changes in both serum OC (r = 0.226, P = 0.029) and serum CTx (r = 0.214, P = 0.038) at 3 months after HT. However, there was no significant association between the changes in circulating OPG after 3 months of HT and BMD values of the lumbar spine or femoral neck after 1 year of HT. CONCLUSIONS: Our results suggest that baseline OPG levels do not reflect bone turnover status and that serial measurements of serum OPG after HT are not a useful predictor of the long-term effects of oestrogen on bone density. The decrease in serum concentrations of OPG after HT may occur to compensate for the action of oestrogen in suppressing bone resorption.     

Impact of circulating bone-resorbing cytokines on the subsequent bone loss following bone marrow transplantation

Cytokines including IL-6 and TNF-alpha play an important role in the pathogenesis of postmenopausal osteoporosis. However, the relationship between changes in the cytokine levels and subsequent bone loss in patients undergoing a bone marrow transplantation (BMT) is unclear. A total of 46 patients undergoing an allogeneic BMT were prospectively investigated. The bone turnover markers and the serum cytokines were measured before BMT and serially after BMT. Bone mineral density (BMD) was measured before and 1 year after BMT. At 1 year after BMT, the lumbar spine BMD had decreased by 4.8%, and the total proximal femoral BMD had decreased by 12.3%. The serum IL-6 and TNF-alpha levels increased until 2 and 3 weeks after BMT, respectively. The lumbar BMD was significantly decreased as the serum IL-6 and TNF-alpha levels increased by post-BMT 3 weeks. The lumbar BMD decreased significantly as the cumulative prednisolone and cyclosporine dose increased. Patients with GVHD > or =grade II had higher lumbar bone loss than patients with GVHD 相似文献   

Serum osteoprotegerin as a determinant of bone metabolism in a longitudinal study of human pregnancy and lactation

Osteoprotegerin (OPG) is a soluble decoy receptor that inhibits bone resorption by binding to receptor activator of nuclear factor kappa B ligand. Murine studies suggest that OPG is elevated in pregnancy, but its role in human pregnancy is unknown. We evaluated the relationship among OPG, bone turnover, and bone density in a longitudinal study of planned human pregnancy and lactation (n = 17; age, 20-36 yr). Samples were collected before conception; at 16, 26, and 36 wk gestation; and at 2 and 12 wk postpartum. Indexes of bone resorption included serum beta C-terminal and urinary N-terminal (uNTX) telopeptides of type I collagen. OPG increased by 110 +/- 16% (mean +/- SEM) at 36 wk (P < 0.001), followed by a rapid postpartum decline in both lactating and nonlactating women. Bone resorption was elevated at 36 wk (serum beta C-terminal telopeptides by 76 +/- 17%; urinary N-terminal telopeptides by 219 +/- 41%; P < 0.001). The tissue source of OPG in pregnancy is unknown. Human breast milk contains large amounts of OPG (162 +/- 58 ng/ml in milk vs. 0.42 +/- 0.03 ng/ml in nonpregnant serum). However, the rapid postpartum decline in serum OPG and the low serum OPG in neonates suggest a placental source. There was no correlation between change in OPG and bone turnover or bone mineral density (P > 0.05), and the physiological importance of elevated OPG in human pregnancy remains uncertain.     

Effects of raloxifene therapy on circulating osteoprotegerin and RANK ligand levels in post-menopausal osteoporosis

Previous in vitro studies suggest that the anti-resorptive effect of raloxifene might be mediated by changes in several cytokines involved in the bone remodeling process. In this context, the osteoprotegerin (OPG)- receptor activator of NF kappa B ligand (RANKL) system is considered a key component in the osteoclastogenesis regulation. The aim of this study was to determine the effects of raloxifene treatment on serum concentrations of OPG, receptor RANKL and its relationship with biochemical markers of bone turnover and bone mineral density (BMD) in previously untreated women with post-menopausal osteoporosis. We selected 47 post-menopausal women (mean age 63+/-7 yr) with densitometric criteria of osteoporosis. We determined at baseline, 3, 6, and 12 months anthropometric parameters, biochemical markers of bone turnover, serum levels of 25(OH) D, serum levels of OPG and RANKL. BMD (dual-energy x-ray absorptiometry) in lumbar spine (LS) femoral neck and total hip was measured at baseline and 12 months after raloxifene (60 mg/day) treatment. Serum levels of OPG decreased in the 3rd and 6th month of treatment (p<0.001) and returned to basal levels in the 12th month. There was a significant decrease of RANKL levels and OPG/RANKL ratio after 1 yr of raloxifene treatment. In addition, BMD in LS increased significantly (2.5%) in the 12th month of treatment (p=0.031). Finally, the biochemical markers of bone turnover (total alkaline phosphatase, bone alkaline phosphatase, osteocalcin, tartrate-resistant acid phosphatase, urine cross-linked carboxi-terminal telopeptide of type I collagen) decreased significantly from the 3rd month of treatment. In conclusion, our results support the hypothesis that raloxifene may inhibit osteoclast activity, at least partly modulating the OPG-RANKL system.     

The relationship between circulating osteoprotegerin levels and bone mineral metabolism in healthy women

OBJECTIVE: Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the RANK ligand. Moreover, OPG has been shown to be an important inhibitor of osteoclastogenesis in animal models. However, the relationship between circulating OPG levels and female bone status in human populations is unclear. In this study we undertook to investigate the relationship between circulating OPG levels and bone mineral metabolism in healthy women. PATIENTS AND MEASUREMENTS: Our subjects were 287 women aged 37-73 years (mean age 51.5 years). The serum concentrations of OPG were determined by enzyme-linked immunosorbent assay (ELISA). The biochemical markers of bone turnover and FSH were measured using standard methods. Bone mineral densities at the lumbar spine and femoral neck were measured by dual-energy X-ray absorptiometry. RESULTS: Postmenopausal women had a significantly higher mean value of serum OPG than premenopausal women (1358.5 +/- 32.5 pg/ml vs. 1228.8 +/- 33.3 pg/ml, P < 0.01). Serum OPG levels were positively correlated with age (r = 0.169, P < 0.01), as were urine deoxypyridinoline levels (r = 0.133, P < 0.05) and serum FSH levels (r = 0.187, P < 0.01) in a bivariate correlation analyses. In a multiple regression analysis, only urine calcium excretion was identified as a significant predictor for serum OPG levels. CONCLUSIONS: Circulating OPG levels were found to be associated with urine calcium excretion and menopause in healthy women. Our observations suggest that circulating OPG levels reflect an antiresorptive activity in bone, and they are related to endogenous oestrogen levels.     

Circulating estradiol and osteoprotegerin as determinants of bone turnover and bone density in postmenopausal women

Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of NF kappa B ligand. OPG has been shown to be an important inhibitor of osteoclast differentiation and activation in rodent models. Estrogen is known to suppress bone resorption, and the action of estrogen on bone may be mediated by OPG. The relationship between endogenous estrogen and circulating OPG levels and bone status in human populations is unclear. Thus, the aim of this study was to investigate the relationship between biochemical markers of bone turnover and bone density and circulating OPG and endogenous estradiol levels in a population-based cohort of postmenopausal women. Subjects were 180 women ages 55-91 yr (mean age, 67 yr). Serum estradiol was measured using an auto-analyzer. Serum concentrations of OPG were determined by ELISA. Markers of bone formation and resorption were measured by standard methods. Bone mineral density at total body, total hip, femoral neck, and lumbar spine was measured by dual energy x-ray absorptiometry. There was a significant inverse relationship between estradiol and all bone turnover markers (r-values from -0.46 to -0.23; P < 0.05). Serum estradiol was positively related to absolute bone density at all sites and to change in bone density at the hip and femoral neck by univariate analysis (r-values from 0.15-0.29; P < 0.05). We observed a weak inverse association between OPG and serum-based bone turnover markers (r-values -0.18 and -0.16; P < 0.05). There was a significant positive relationship between OPG and bone mineral density at total body, total hip, and femoral neck (r-values from 0.17-0.2; P < 0.05) by univariate analysis, which was lost after adjustment for age and body mass index. There was a significant weak positive relationship between circulating OPG and serum estradiol (r = 0.18; P < 0.02). We observed no significant relationships between OPG and bone turnover markers measured in urine. We conclude that the variation in circulating endogenous estradiol levels is an important factor contributing to levels of bone turnover and bone density at the menopause. Our observations also suggest that circulating levels of OPG may reflect OPG activity in bone and are related to circulating endogenous levels of estradiol. We have previously reported high levels of variability in urine markers of bone resorption, and we suggest that this could account for the absence of a significant association between these markers and circulating OPG.     

Markedly increased serum erythropoietin levels following conditioning for allogeneic bone marrow transplantation

Serum erythropoietin (EPO) levels were measured by radioimmunoassay in 36 patients undergoing allogeneic bone marrow transplantation (BMT). Serum EPO levels before conditioning treatment for BMT were generally higher than the levels obtained from healthy controls (49 +/- 17 (SEM) and 17 +/- 0.6, respectively). One day prior to BMT, after conditioning by chemotherapy with or without total body irradiation, the mean EPO level was markedly elevated (218 +/- 23 U/l, p less than 0.001) and reached to its highest level at 1 week post-BMT (269 +/- 40 U/l). Although, the EPO levels were significantly lower at 1 month (98 +/- 24 U/l, p less than 0.001), they were still elevated up to 3 months post-BMT, after which they gradually normalized. Patients given methotrexate and cyclosporine for prophylaxis against graft-versus-host disease (GVHD) had significantly lower EPO levels during the first 3 months post-BMT than patients transplanted with T cell-depleted marrow (p less than 0.05). Patients with post-transplant nephrotoxicity had lower, though not statistically significant, EPO levels than patients with normal renal function (p = 0.07). Acute GVHD and number of blood transfusions had no influence on serum EPO levels after BMT.     

Alterations in bone turnover and impaired development of bone mineral density in newly diagnosed children with cancer: a 1-year prospective study.

In the present study, longitudinal changes in bone mineral density, bone turnover, and bone hormonal metabolism were evaluated in newly diagnosed children with cancer. Lumbar spine (L2-L4) and femoral neck bone mineral densities (grams per cm2) were measured by dual energy x-ray absorptiometry in 28 children (age, 2.9-16.0 yr; median, 8.0 yr; 10 acute lymphoblastic leukemias, 18 solid tumors) at diagnosis and after a 1-yr follow-up. Apparent volumetric density (grams per cm3) was calculated to minimize the effect of bone size on BMD. Serum levels of osteocalcin (OC), type I collagen carboxyl-terminal propeptide (PICP), and type I collagen carboxyl-terminal telopeptide were measured serially during the study. Serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, insulin-like growth factor I (IGF-I), and IGF-binding protein-3 were analyzed at diagnosis and at 1-yr follow-up. A significant decrease in femoral bone mineral density and apparent volumetric density was observed during the year after diagnosis [(mean (SD), -10.1% (8.8%) and -11.3% (8.1%) respectively; P < 0.01], whereas age- and sex-matched controls showed annual increments of +5.4% (7.7%; P < 0.01) and +0.7% (5.7%; P = NS) respectively. The markers of bone formation (PICP and OC) were significantly decreased at diagnosis. By the end of the follow-up, PICP and OC were normalized, whereas the marker of bone resorption (type I collagen carboxyl-terminal telopeptide) was significantly increased. Reduced levels of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and IGF-binding protein-3 were observed during the study. To conclude, increased bone resorption and impaired development of femoral bone density were observed in children with cancer during chemotherapy. Deficient accumulation of bone mass may lead to impaired development of peak bone mass and predispose children with cancer to increased risk of osteoporosis and diminished skeletal resistance to fractures later in life.     

Pegvisomant-induced serum insulin-like growth factor-I normalization in patients with acromegaly returns elevated markers of bone turnover to normal

Active acromegaly is associated with increased biochemical markers of bone turnover. Pegvisomant is a GH receptor antagonist that normalizes serum IGF-I in 97% of patients with active acromegaly. We evaluated the effects of pegvisomant-induced serum IGF-I normalization on biochemical markers of bone and soft tissue turnover, as well as levels of PTH and vitamin D metabolites, in 16 patients (nine males; median age, 52 yr; range, 28-78 yr) with active acromegaly (serum IGF-I at least 30% above upper limit of an age-related reference range). Serum procollagen III amino-terminal propeptide (PIIINP) and type I procollagen amino-terminal propeptide, osteocalcin (OC), bone-related alkaline phosphatase, C-terminal cross-linked telopeptide of type I collagen (CTx), albumin-corrected calcium, intact PTH, 25-hydroxy vitamin D, 1,25-dihydroxy vitamin D [1,25-(OH)(2) vit D], urinary type 1 collagen cross-linked N-telopeptide/creatinine ratio, and urinary calcium (24 h collection) were measured (single-batch analysis) at study entry and after IGF-I normalization, along with sera from 32 age- and sex-matched controls. Compared with controls, PIIINP, OC, and CTx were significantly elevated in patients at baseline. Pegvisomant-induced serum IGF-I normalization (699 +/- 76 to 242 +/- 28 micro g/liter, P < 0.001) was associated with a significant decrease in PIIINP, markers of bone formation (type I procollagen amino-terminal propeptide, OC, and bone-related alkaline phosphatase), and resorption (CTx and urinary type 1 collagen cross-linked N-telopeptide/creatinine ratio). 1,25-(OH)(2) vit D decreased and intact PTH increased significantly, but 25-hydroxy vitamin D was unaffected. A significant decline in calculated calcium clearance was observed. The decrease in serum IGF-I correlated positively with the decrease of serum PIIINP (r = 0.7, P < 0.01). After normalization of serum IGF-I, there was no statistical difference between patients and controls for any parameters for which control data were available. In conclusion, GH excess is associated with increased bone and soft tissue turnover. Pegvisomant-induced normalization of serum IGF-I results in a decrease in markers of bone and soft tissue turnover to levels observed in age-matched controls, and these changes are accompanied by an increase in PTH and a decrease in 1,25-(OH)(2) vit D. These data provide further evidence of the effectiveness of pegvisomant in normalizing the altered biological effects of GH hypersecretion.     

Osteogenesis imperfecta types I,III, and IV: effect of pamidronate therapy on bone and mineral metabolism

Cyclical iv therapy with pamidronate improves the clinical course in children and adolescents with osteogenesis imperfecta (OI). In this study we evaluated the effect of this therapy on bone and mineral metabolism in 165 patients with OI types I, III, and IV (age, 2 wk to 17.9 yr; 86 girls and 79 boys). All patients received iv pamidronate infusions on 3 successive days, administered at age-dependent intervals of 2-4 months. During the 3 d of the first infusion cycle, serum concentrations of ionized calcium dropped by 0.14 +/- 0.008 mmol (mean +/- SE; P < 0.001), and serum PTH levels transiently almost doubled (P < 0.001). At the same time, urinary excretion of the bone resorption marker type I collagen N-telopeptide related to creatinine (uNTX/uCr) decreased by 61-73% (P < 0.001). Two to 4 months later, ionized calcium had returned to pretreatment levels, and uNTX/uCr remained 30-35% lower than at baseline (P < 0.001). During 4 yr of pamidronate therapy (n = 40 patients), ionized calcium levels remained stable, but PTH levels increased by about 30% (P < 0.01). uNTX/uCr, expressed as a percentage of the age- and sex-specific mean value in healthy children, decreased from 132 +/- 13% (mean +/- SE) at baseline to 49 +/- 3% after 4 yr of therapy (P < 0.001). In conclusion, serum calcium levels can decrease considerably during and after pamidronate infusions, requiring close monitoring especially at the first infusion cycle. In long-term therapy, bone turnover is suppressed to levels lower than those in healthy children. The consequences of chronically low bone turnover in children with OI are unknown at present.     

IGF-I regulates osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB ligand in vitro and OPG in vivo

IGF-I, a ubiquitous polypeptide, plays a key role in longitudinal bone growth and acquisition. The most predominant effect of skeletal IGF-I is acceleration of the differentiation program for osteoblasts. However, in vivo studies using recombinant human (rh) IGF-I and/or rhGH have demonstrated stimulation of both bone formation and resorption, thereby potentially limiting the usefulness of these peptides in the treatment of osteoporosis. In this study, we hypothesized that IGF-I modulates bone resorption by regulating expression of osteoprotegerin (OPG) and receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL) in bone cells. Using Northern analysis in ST2 cells, we found that human IGF-I suppressed OPG mRNA in a time- and dose-dependent manner: 100 micro g/LIGF-I (13 nM) decreased OPG expression by 37.0 +/- 1.8% (P < 0.002). The half maximal inhibitory dose of IGF-I was reached at 50 micro g/liter ( approximately 6.5 nM) with no effect of IGF-I on OPG message stability. Conditioned media from ST2 cells confirmed that IGF-I decreased secreted OPG, reducing levels by 42%, from 12.1-7 ng/ml at 48 h (P < 0.05). Similarly, IGF-I at 100 micro g/liter (13 nM) increased RANKL mRNA expression to 353 +/- 74% above untreated cells as assessed by real-time PCR. In vivo, low doses of rhGH when administered to elderly postmenopausal women only modestly raised serum IGF-I (to concentrations of 18-26 nM) and did not affect circulating OPG concentrations; however, administration of rhIGF-I (30 micro g/kg.d) for 1 yr to older women resulted in a significant increase in serum IGF-I (to concentrations of 39-45 nM) and a 20% reduction in serum OPG (P < 0.05). In summary, we conclude that IGF-I in a dose- and time-dependent manner regulates OPG and RANKL in vitro and in vivo. These data suggest IGF-I may act as a coupling factor in bone remodeling by activating both bone formation and bone resorption; the latter effect appears to be mediated through the OPG/RANKL system in bone.     

Increased serum osteoprotegerin in disorders characterized by persistent immune activation or glucocorticoid excess--possible role in bone homeostasis.

OBJECTIVE: To investigate the possible role of osteoprotegerin (OPG) in bone metabolism in humans by measuring serum levels of OPG in five well-characterized patient populations with known or suspected pathology in bone homeostasis, but with differences in the pathogenesis of these disturbances. DESIGN: The study comprised 34 patients with Cushing's syndrome (CS), 24 acromegalic patients, 16 patients with growth hormone deficiency (GHD), 29 HIV-infected patients, 25 patients with common variable immunodeficiency (CVI) and 59 age- and sex-matched healthy controls (CTR). METHODS: Serum levels of tumor necrosis factor (TNF)-alpha, OPG, C-terminal telopeptides of Type-I collagen (CTX-I) and osteocalcin were determined in all study subjects as well as cortisol (CS and CTR) and IGF-I (acromegaly, GHD and CTR). RESULTS: OPG levels were significantly elevated in both CVI (median increase approximately 32%, P < 0.05) and HIV-infected patients with especially high levels in the latter group ( approximately 52%, P < 0.001), significantly correlated with increased TNFalpha levels (r = 0.47, P < 0.02). Also CS patients had elevated serum OPG ( approximately 24%, P < 0.01), significantly correlated with increased serum cortisol (r = 0.35, P < 0.05). In contrast, OPG levels in acromegalic and GHD patients were not different from healthy controls. No relationships were found between OPG levels and CTX-I or osteocalcin. CONCLUSIONS: These findings suggest that enhanced OPG levels may be a compensatory response to enhanced osteoclast activity or negative bone remodeling balance in some conditions, but may also be a parameter of enhanced activity in the OPG system possibly correlated to enhanced activity of other members of the TNF family.     

Serum levels of insulin-like growth factor I and the density, volume, and cross-sectional area of cortical bone in children.

Insulin-like growth factor I (IGF-I) is a major regulator of bone growth during childhood. However, beyond knowledge that IGF-I influences longitudinal growth, its associations to changes in the cross-sectional dimensions, the volume, or the material density of bone during growth are unknown. We assessed the relationships between serum IGF-I and measurements of cross-sectional area, cortical bone area, and cortical bone density at the midshaft of the femur in 197 normal healthy white children and adolescents (103 boys and 94 girls; aged 7.8-18.2 yr). Bone determinations were obtained using computed tomography, and levels of IGF-I were measured by RIA after an extraction procedure. IGF-I correlated significantly with both cross-sectional area (r = 0.49; P < 0.0001) and cortical bone area (r = 0.50; P < 0.0001), but did not correlate with the material density of cortical bone (r = -0.08). Multiple regression analyses showed that circulating levels of IGF-I were associated with cross-sectional area (P = 0.03) and cortical bone area (P = 0.04) values, even after correcting for the confounding effects of age, gender, weight, and femoral length. We conclude that IGF-I is a major determinant of the cross-sectional properties of bone, but does not influence the material density of bone, in the appendicular skeleton.