Local and systemic factors in the pathogenesis of osteoporosis

Underlying Mechanisms and Treatment of Cellular Senescence-Induced Biological Barrier Interruption and Related Diseases

Given its increasing prevalence, aging is of great concern to researchers worldwide. Cellular senescence is a physiological or pathological cellular state caused by aging and a prominent risk factor for the interruption of the integrity and functionality of human biological barriers. Health barriers play an important role in maintaining microenvironmental homeostasis within the body. The senescence of barrier cells leads to barrier dysfunction and age-related diseases. Cellular senescence has been reported to be a key target for the prevention of age-related barrier diseases, including Alzheimer's disease, Parkinson's disease, age-related macular degeneration, diabetic retinopathy, and preeclampsia. Drugs such as metformin, dasatinib, quercetin, BCL-2 inhibitors, and rapamycin have been shown to intervene in cellular senescence and age-related diseases. In this review, we conclude that cellular senescence is involved in age-related biological barrier impairment. We further outline the cellular pathways and mechanisms underlying barrier impairment caused by cellular senescence and describe age-related barrier diseases associated with senescent cells. Finally, we summarize the currently used anti-senescence pharmacological interventions and discuss their therapeutic potential for preventing age-related barrier diseases.

A 2-year longitudinal study of bone health in adolescent patients with axial spondyloarthritis

PURPOSE

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily affects the axial skeleton and typically has an early onset. Although earlier onset is associated with worse prognosis, there have been few studies of bone mineral density (BMD) in adolescent patients with axSpA.

METHODS

We analysed the clinical characteristics of 43 adolescent patients with axSpA at a baseline assessment and at a follow-up 2 years later. The baseline assessment included age, disease duration, treatment agents, and clinical, radiologic, and laboratory data. BMD of the lumbar spine, femoral neck, and total hip were measured by dual-energy X-ray absorptiometry during both the baseline assessment and the 2-year follow-up. We performed multivariate linear regression analyses to identify factors independently associated with BMD. We analysed the associations between changes in BMD and reductions in inflammatory markers.

RESULTS

The average age of participants was 17.9 years and the mean disease duration was 2.2 years. Of the 43 patients, 10 (23%) had low BMD at any site (lumbar spine, femoral neck, and/or total hip). At baseline, multivariate analysis showed that body mass index (BMI), erythrocyte sedimentation rate (ESR), and spinal structural damage were associated with lumbar spine Z-scores. Increases in BMD in the lumbar spine were correlated with reductions in ESR (r = 0.40, P = 0.02) and C-reactive protein (CRP) (r = 0.40, P = 0.02). Increases in BMD in the total hip were correlated with reductions in CRP (r = 0.38, P = 0.03).

CONCLUSION

In adolescent axSpA patients, bone health was associated with systemic inflammation and the severity of structural damage. Reduced systemic inflammation was associated with improvements in bone health.

Bone mineral density is negatively correlated with ulcerative colitis: a systematic review and meta-analysis

BACKGROUND

Newer epidemiological studies suggest that the incidence of ulcerative colitis might be increasing rapidly. Furthermore, osteoporosis in ulcerative colitis patients has gained great attention, but the epidemiologic evidence remains controversial. Therefore, a meta-analysis was performed to explore the association between bone density and ulcerative colitis.

METHODS

Two investigators used PubMed, EMBASE and the Cochrane Library databases to identify all studies published before August 2019. Depending on the outcomes, investigators divided these studies into four groups (OR, SMD [BMD], SMD [z-score] and SMD [t-score]). To address the use of steroids, which is a major confounding factor in this analysis, another subgroup analysis of studies of steroid-free patients was conducted. Additionally, heterogeneity, sensitivity and stratified analyses were also performed.

RESULTS

A total of 13 cross-sectional studies that involved 1154 participants were included in the present meta-analysis, and three of them were included in the steroid-free subgroup analysis. The pooled OR was 6.41 (95% CI 2.59-15.87) and the pooled SMD (BMD), SMD (t-score) and SMD (z-score) were - 0.24 (95% CI - 0.44 to - 0.04), - 0.55 (95% CI - 0.72 to - 0.37), and - 0.38 (95% CI - 0.56 and - 0.19), respectively. Since steroids are a significant confounder, the pooled SMD of the steroid-free subgroup was - 0.55 (- 0.85 to - 0.25), which revealed a strong negative relationship between bone density and ulcerative colitis in steroid-free patients. Additionally, other subgroup analyses also revealed a strong relationship.

CONCLUSIONS

This meta-analysis provides evidence for the potential association between ulcerative colitis and decreased bone density. It is essential for clinicians to consider bone mineral density in ulcerative colitis patients regardless of steroid-therapy.

Petunidin, a B-ring 5'-O-Methylated Derivative of Delphinidin, Stimulates Osteoblastogenesis and Reduces sRANKL-Induced Bone Loss

Several lines of evidence suggest that oxidative stress is one of the key pathogenic mechanisms of osteoporosis. We aimed to elucidate the bone protective effects of petunidin, one of the most common anthocyanidins, considering its potent antioxidative activity. Petunidin (>5 μg/mL) significantly inhibited osteoclastogenesis and downregulated c-fos, Nfatc1, Mmp9, Ctsk, and Dc-stamp mRNA expression in RAW264.7 cells. Conversely, petunidin (>16 μg/mL) stimulated mineralized matrix formation and gene expression of Bmp2 and Ocn, whereas it suppressed Mmp13, Mmp2, and Mmp9 mRNA expression and proteolytic activities of MMP13 and MMP9 in MC3T3-E1 cells. Micro-CT and bone histomorphometry analyses of sRANKL-induced osteopenic C57BL/6J mice showed that daily oral administration of petunidin (7.5 mg/kg/day) increased bone volume to tissue volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), the ratio of osteoid volume to tissue volume (OV/TV), osteoid thickness (O.Th), the ratio of osteoid surface to bone surface (OS/BS), the ratio of osteoblast surface to bone surface (Ob.S/BS), and the number of osteoblast per unit of bone surface (N.Ob/BS), and decreased trabecular separation (Tb.Sp), the ratio of eroded surface to bone surface (ES/BS), the ratio of osteoclast surface to bone surface (Oc.S/BS), and number of osteoclast per unit of bone surface (N.Oc/BS), compared to untreated mice. Furthermore, histological sections of the femurs showed that oral administration of petunidin to sRANKL-induced osteopenic mice increased the size of osteoblasts located along the bone surface and the volume of osteoid was consistent with the in vitro osteoblast differentiation and MMP inhibition. These results suggest that petunidin is a promising natural agent to improve sRANKL-induced osteopenia in mice through increased osteoid formation, reflecting accelerated osteoblastogenesis, concomitant with suppressed bone resorption.

Effects of One-Year Adjuvant Treatment with Tamoxifen on Bone Mineral Density in Postmenopausal Breast Cancer Women

In this study, the authors have analyzed the possible effects of one-year adjuvant treatment with tamoxifen on bone mineral density in postmenopausal breast cancer women. Bone mineral content was studied by photon absorptiometry (I-125), whereas bone balance was analyzed indirectly by serum PTH, osteocalcin, calcitonin, calcium and alkaline phosphatase levels. Bone mineral content and serum bone-related substances were measured before starting treatment and after one year. Results were analyzed using Student's t test for paired data. No difference was found between the two measurements for bone mineral content, PTH, calcitonin, calcium and alkaline phosphatase levels. Measurements at entry and after one year of treatment showed a statistically significant difference ( P < 0.001) only for osteocalcin. In accordance with other authors, we can conclude that treatment with tamoxifen does not cause an increase in menopausal bone resorption. The finding that osteocalcin levels decreased after one year of therapy with tamoxifen is interesting, but further studies are necessary to clarify the role of such levels in predicting a turnover of bone balance towards osteoblastic activity.

Senescence and aging: Causes, consequences, and therapeutic avenues

Aging is the major risk factor for cancer, cardiovascular disease, diabetes, and neurodegenerative disorders. Although we are far from understanding the biological basis of aging, research suggests that targeting the aging process itself could ameliorate many age-related pathologies. Senescence is a cellular response characterized by a stable growth arrest and other phenotypic alterations that include a proinflammatory secretome. Senescence plays roles in normal development, maintains tissue homeostasis, and limits tumor progression. However, senescence has also been implicated as a major cause of age-related disease. In this regard, recent experimental evidence has shown that the genetic or pharmacological ablation of senescent cells extends life span and improves health span. Here, we review the cellular and molecular links between cellular senescence and aging and discuss the novel therapeutic avenues that this connection opens.

Reexamining the Surfaces of Bone in Boys and Girls During Adolescent Growth: A 12-Year Mixed Longitudinal pQCT Study

We revisit Stanley Garn's theory related to sex differences in endocortical and periosteal apposition during adolescence using a 12-year mixed longitudinal study design. We used peripheral quantitative computed tomography to examine bone parameters in 230 participants (110 boys, 120 girls; aged 11.0 years at baseline). We assessed total (Tt.Ar, mm(2)), cortical (Ct.Ar, mm(2)), and medullary canal area (Me.Ar, mm(2)), Ct.Ar/Tt.Ar, cortical bone mineral density (Ct.BMD, mg/cm(3)), and polar strength-strain index (SSIp , mm(3)) at the tibial midshaft (50% site). We used annual measures of height and chronological age to identify age at peak height velocity (APHV) for each participant. We compared annual accrual rates of bone parameters between boys and girls, aligned on APHV using a linear mixed effects model. At APHV, boys demonstrated greater Tt.Ar (ratio = 1.27; 95% confidence interval [CI] 1.21, 1.32), Ct.Ar (1.24 [1.18, 1.30]), Me.Ar (1.31 [1.22, 1.40]), and SSIp (1.36 [1.28, 1.45]) and less Ct.Ar/Tt.Ar (0.98 [0.96, 1.00]) and Ct.BMD (0.97 [0.96, 0.97]) compared with girls. Boys and girls demonstrated periosteal bone formation and net bone loss at the endocortical surface. Compared with girls, boys demonstrated greater annual accrual rates pre-APHV for Tt.Ar (1.18 [1.02, 1.34]) and Me.Ar (1.34 [1.11, 1.57]), lower annual accrual rates pre-APHV for Ct.Ar/Tt.Ar (0.56 [0.29, 0.83]) and Ct.BMD (-0.07 [-0.17, 0.04]), and similar annual accrual rates pre-APHV for Ct.Ar (1.10 [0.94, 1.26]) and SSIp (1.14 [0.98, 1.30]). Post-APHV, boys demonstrated similar annual accrual rates for Ct.Ar/Tt.Ar (1.01 [0.71, 1.31]) and greater annual accrual rates for all other bone parameters compared with girls (ratio = 1.23 to 2.63; 95% CI 1.11 to 3.45). Our findings support those of Garn and others of accelerated periosteal apposition during adolescence, more evident in boys than girls. However, our findings challenge the notion of greater endocortical apposition in girls, suggesting instead that girls experience diminished endocortical resorption compared with boys.

Association between adult height and tooth loss in a representative sample of Koreans

OBJECTIVES

Evidence suggests that taller individuals have better health than that of shorter individuals. However, evidence for links to tooth loss is scarce. The aim of this study was to examine the association between adult height and tooth loss and to examine the roles of covariates in explaining the association in different birth cohorts in Korea.

METHODS

Using data from the Fourth and Fifth Korea National Health and Nutritional Examination Survey (KNHANES IV and V), the subjects were grouped into two birth cohorts based on their historical context: born from 1920 to 1945 and 1946 to 1962. The dependent variables were loss of 8 or more teeth and total tooth loss (edentulism), while the independent variable was the height quartile. Demographic factors (survey year, age, and gender), early childhood/adult socioeconomic status (SES) (father's education, own education, income, and place of residence), health behaviors (cigarette smoking, binge drinking, frequency of toothbrushing, and regular dental visit), and health problems (diabetes and hypertension) were included in a series of analytical models.

RESULTS

The survey year-, age-, and gender-adjusted prevalence ratios (PR) of the loss of 8 or more teeth for the shortest quartile were 1.23 (95% confidence intervals, CI: 1.13-1.35) for the 1920-1945 birth cohorts and 1.39 (95% CI: 1.20-1.62) for the 1946-1962 birth cohorts. The PRs for edentulousness were 1.64 (95% CI: 1.34-2.02) for the 1920-1945 birth cohorts and 2.26 (95% CI: 1.31-3.91) for the 1946-1962 birth cohorts. These associations were moderately attenuated after adjusting for own education but still significant in the fully adjusted models. After full adjustment for the covariates, those in the shortest height quartiles in the relatively young birth cohorts (1946-1962 birth cohorts) had a 1.93 (95% CI: 1.09-3.43) times greater prevalence of edentulism than that of their tallest counterparts.

CONCLUSIONS

Given that adult height reflects early-life conditions, independent associations between height and tooth loss support the view that early-life circumstances significantly influence oral health outcomes in later life.

Associated bone mineral density and obstructive sleep apnea in chronic obstructive pulmonary disease

BACKGROUND

Osteoporosis is an important issue for patients with chronic obstructive pulmonary disease (COPD). Worse systemic inflammation and reduced exercise capacity have been reported in COPD patients with obstructive sleep apnea (OSA), implying that OSA may be an independent factor for osteoporosis in COPD patients.

METHODS

A total of 66 patients with bone mineral density (BMD) and polysomnography results from a previous COPD cohort (January 2008 to January 2013) were retrospectively enrolled. Clinical characteristics such as medication, pulmonary function, BMD, and results of polysomnography were analyzed.

RESULTS

The BMD in those with OSA was significantly lower than in those without OSA (-1.99±1.63 versus -1.27±1.14, P=0.045). In univariate analysis, body mass index, forced expiratory volume in 1 second, percentage of predicted value, incremental shuttle walk test, apnea-hypopnea index, and oxygen desaturation index (ODI) were significantly associated with BMD. After multivariate linear regression analysis, the ODI was still an independent factor for BMD. In addition, smaller total lung capacity is significantly associated with higher ODI and lower BMD, which implies that lower BMD might cause severer OSA via decreased total lung capacity.

CONCLUSION

OSA may be an independent factor for BMD in patients with COPD, which implies a possible vicious cycle takes place in these patients.

Evaluation of the bone healing process in an experimental tibial bone defect model in ovariectomized rats

The aim of this study was to evaluate the influence of postmenopausal bone loss (induced by ovariectomy) in the process of bone healing in a tibial bone defect model in rats by means of histological evaluation of bone defects and the analysis of the expression of genes and proteins involved in bone consolidation. Twenty female Wistar rats (12 weeks old, weighing ±250 g) were randomly divided into two groups: control group (CG) and ovariectomized group (OG). Rats of OG were submitted to ovariectomy and after 8 weeks post-surgery, all animals were submitted to the tibial bone defect model. The main histological finding analysis revealed that ovariectomized animals showed a higher amount of granulation tissue and immature newly formed bone compared to CG. Furthermore, quantitative histological analysis showed that OG presented a significant decrease in the amount of newly formed bone (p = 0.0351). RT-PCR analysis showed no difference in Runx2, ALP, RANK, RANKL and Osterix gene expression 14-day post-surgery. Interestingly, immunohistochemical evaluation showed that Runx2 was down expressed (p = 0.0001) and RANKL was up expressed (p = 0.0022) in the OG. In conclusion, these data highlight that bone loss induced by ovariectomy causes an impairment in the capacity of bone to heal mainly probably because of alterations in the imbalance of osteoblasts and osteoclasts activities.

In vivo deletion of CAR resulted in high bone mass phenotypes in male mice

Constitutive androstane receptor (CAR) was originally identified as xenobiotic sensor that regulates the expression of cytochrome P450 genes. However, recent studies suggest that this nuclear receptor is also involved in the regulation of energy metabolism including glucose and lipid homeostasis. This study investigated the role of CAR in the regulation of bone mass in vivo using CAR(-/-) mice. Endogenous mRNA expression of CAR was observed in both primary osteoblasts and osteoclast precursors. CAR(-/-) mice have exhibited significant increase in whole body bone mineral density (BMD) by 9.5% (P < 0.01) and 5.5% (P < 0.05) at 10 and 15 weeks of age, respectively, compared with WT mice in males. Microcomputed tomography analysis of proximal tibia demonstrated a significant increase in trabecular bone volume (62.7%), trabecular number (54.1%) in male CAR(-/-) mice compared with WT mice. However, primary culture of calvarial cells exhibited no significant changes in osteogenic differentiation potential between CAR(-/-) and WT. In addition, the number of tartrate-resistant acid-phosphatase positive osteoclasts in the femur and serum level of CTx was not different between CAR(-/-) and WT mice. The higher BMD and microstructural parameters were not observed in female mice. Interestingly, serum level of testosterone in male CAR(-/-) mice was 2.5-fold higher compared with WT mice and the mRNA expressions of Cyp2b9 and 2b10 in the liver, which regulate testosterone metabolism, were significantly down-regulated in male CAR(-/-) mice. Furthermore, the difference in BMD between CAR(-/-) and WT mice disappeared at 8 weeks after performing orchiectomy. CAR(-/-) mice also exhibited significant increase in serum 1,25(OH)2 D3 levels but Cyp 27B1 which converts 25(OH)D3 to 1,25(OH)2 D3 was significantly down-regulated compared to WT mice. These results suggest that in vivo deletion of CAR resulted in higher bone mass, which appears to be a result from reduced metabolism of testosterone due to down-regulation of Cyp2b.

Bone mass and mineral metabolism alterations in adult celiac disease: pathophysiology and clinical approach

Osteoporosis affects many patients with celiac disease (CD), representing the consequence of calcium malabsorption and persistent activation of mucosal inflammation. A slight increase of fracture risk is evident in this condition, particularly in those with overt malabsorption and in postmenopausal state. The adoption of a correct gluten-free diet (GFD) improves bone derangement, but is not able to normalize bone mass in all the patients. Biomarkers effective in the prediction of bone response to gluten-free diet are not yet available and the indications of guidelines are still imperfect and debated. In this review, the pathophysiology of bone loss is correlated to clinical aspects, defining an alternative proposal of management for this condition.

Bone mineral density changes after total knee replacement in women over the age of 65

Background

There are few reports on bone mineral density (BMD) changes of axial bones after total knee replacement (TKR) due to severe osteoarthritis (OA) of the knee joint and its results are controversial. The purpose of our study was to measure the BMD changes of hip and spine in patients receiving TKR due to severe OA and to identify clinical factors relating BMD changes.

Methods

Among 66 female patients above 65 years old who underwent TKR due to severe OA and checked preoperative BMD, 52 patients who checked 1 year follow up BMD were enrolled. We investigated the association of the BMD changes with bilaterality of operation, obesity, preoperative knee functional scores, bisphosphonate medication, and diagnosis of osteoporosis.

Results

We found no correlation between BMD changes and bilaterality of operation, obesity, preoperative knee functional scores and diagnosis of osteoporosis. Spine BMD increased in non-treatment and bisphosphonate treatment group but total hip BMD significantly increased in bisphosphonate treatment group.

Conclusions

Bisphosphonate treatment for 1 year prevents early reduction of hip BMD just after TKR regardless osteoporosis diagnosis. We considered that the bisphosphonate medication would be beneficial to prevention of later hip fracture in elderly patient receiving TKR due to severe OA of knee joints.

Tocotrienol supplementation improves late-phase fracture healing compared to alpha-tocopherol in a rat model of postmenopausal osteoporosis: a biomechanical evaluation

This study investigated the effects of α-tocopherol and palm oil tocotrienol supplementations on bone fracture healing in postmenopausal osteoporosis rats. 32 female Sprague-Dawley rats were divided into four groups. The first group was sham operated (SO), while the others were ovariectomised. After 2 months, the right femora were fractured under anesthesia and fixed with K-wire. The SO and ovariectomised-control rats (OVXC) were given olive oil (vehicle), while both the alpha-tocopherol (ATF) and tocotrienol-enriched fraction (TEF) groups were given alpha-tocopherol and tocotrienol-enriched fraction, respectively, at the dose of 60 mg/kg via oral gavages 6 days per week for 8 weeks. The rats were then euthanized and the femora dissected out for bone biomechanical testing to assess their strength. The callous of the TEF group had significantly higher stress parameter than the SO and OVXC groups. Only the SO group showed significantly higher strain parameter compared to the other treatment groups. The load parameter of the OVXC and ATF groups was significantly lower than the SO group. There was no significant difference in the Young's modulus between the groups. In conclusion, tocotrienol is better than α-tocopherol in improving the biomechanical properties of the fracture callous in postmenopausal osteoporosis rat model.

Bone effects of vitamin D - Discrepancies between in vivo and in vitro studies

Vitamin D was discovered as an anti-rachitic agent, but even at present, there is no direct evidence to support the concept that vitamin D directly stimulates osteoblastic bone formation and mineralization. It appears to be paradoxical, but vitamin D functions in the process of osteoclastic bone resorption. In 1952, Carlsson reported that administration of vitamin D(3) to rats fed a vitamin D-deficient, low calcium diet raised serum calcium levels. Since the diet did not contain appreciable amounts of calcium, the rise in serum calcium was considered to be derived from bone. Since then, this assay has been used as a standard bioassay for vitamin D compounds. Osteoclasts, the cells responsible for bone resorption, develop from hematopoietic cells of the monocyte-macrophage lineage. Several lines of evidence have shown that the active form of vitamin D(3), 1α,25-dihydroxyvitamin D(3) [1α,25(OH)(2)D(3)] is one of the most potent inducers of receptor activator of NF-κB ligand (RANKL), a key molecule for osteoclastogenesis, in vitro. In fact, 1α,25(OH)(2)D(3) strongly induced osteoclast formation and bone resorption in vitro. Nevertheless, 1α,25(OH)(2)D(3) and its prodrug, Alfacalcidol (1α-hydroxyvitamin D(3)) have been used as therapeutic agents for osteoporosis since 1983, because they increase bone mineral density and reduce the incidence of bone fracture in vivo. Furthermore, a new vitamin D analog, Eldecalcitol [2β-(3-hydroxypropoxy)-1α,25(OH)(2)D(3)], has been approved as a new drug for osteoporosis in Japan in January 2011. Interestingly, these beneficial effects of in vivo administration of vitamin D compounds are caused by the suppression of osteoclastic bone resorption. The present review article describes the mechanism of the discrepancy of vitamin D compounds in osteoclastic bone resorption between in vivo and in vitro.

Effects of α-tocopherol on the early phase of osteoporotic fracture healing

Fracture healing is a complex process, which is more complicated if the bone is osteoporotic. One of the vitamin E isomers, α-tocopherol, has been found to prevent osteoporosis and improve bone fracture healing but its role in the healing of osteoporotic fractures is still unclear. We carried out a study on the effects of α-tocopherol supplementation on osteoporotic fracture healing using an ovariectomized rat model, whereby we focused on the early phase of fracture healing, that is, the phase with excessive production of free radicals. Twenty-four female Sprague-Dawley rats were divided into three groups: sham-operated (SO), ovariectomized-control (OVC), and ovariectomized + α-tocopherol supplementation (ATF) groups. The right femora of all the rats were fractured at mid-diaphysis and K-wires were inserted for internal fixation. After 2 weeks of treatment, the rats were euthanized and the femora were dissected out for measurement of callous volume by CT-scan and radiological staging of callous formation and fracture healing. The oxidative parameters of the fractured femora were also measured. The results showed that the callous volume and callous staging were not different between the groups. However, the fracture healing stage of the OVC group was lower than the SO group, while α-tocopherol supplementation in the ATF group had improved the healing until it was comparable to the SO group. The activities of the anti-oxidatant enzymes, superoxide dismutase, and glutathione peroxidase in the ATF group were found to be significantly higher than in the OVC group. In conclusion, α-tocopherol improved fracture healing but had no effect on the callous volume and staging. The improvement in fracture healing may be due to the increased activities of the anti-oxidatant enzymes in the bone during the early phase of fracture healing of osteoporotic bone.

The change of bone mineral density according to treatment agents in patients with ankylosing spondylitis

OBJECTIVES

The aim was to access the effects of treatment on bone mineral density (BMD) by treatment agents in patients with ankylosing spondylitis (AS).

METHODS

We analyzed clinical characteristics of 90 AS patients. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and x-ray of lumbar spine (L-spine) and sacroiliac joint were included in the baseline assessment. The BMDs of right femur and L-spine were measured annually using dual x-ray absorptiometry (DXA). The patients were divided into one of the following four groups by agents exposed for the follow-up period: conventional treatment, bisphosphonate, anti-TNF-α agent or bisphosphonate + anti-TNF-α agent. We evaluated the changes of BMD according to treatment groups.

RESULTS

The average age of disease onset was 30 years and the mean disease duration was 8.2 years. The patients who were assigned to the groups of conventional treatment, bisphosphonate, anti-TNF-α agents and bisphosphonate + anti-TNF-α agents were 40, 20, 19 and 11. BMDs values of both L-spine and femur showed tendencies to the most increase in the group treated with concurrent bisphosphonate and anti-TNF-α agent. However, the change of BMD by treatment agents was significant different only in trochanter (P = 0.001). In patients without syndesmophyte, there was significant difference of BMD change in both L-spine and total proximal femur (P = 0.001, 0.004). The BMD change of trochanter was correlated with the reductions of ESR and CRP (r = 0.239, P = 0.035 and r = 0.233, P = 0.040).

CONCLUSIONS

The BMDs of AS patients increased more by the treatment of concurrent bisphosphonate and anti-TNF-α agents. The gain of bone mass was associated with the reduction of inflammation.

Bone metabolic abnormalities associated with well-controlled type 1 diabetes (IDDM) in young adult women: a disease complication often ignored or neglected

OBJECTIVES

This investigation on a homogenous cohort of young adult Caucasian type 1 diabetic (IDDM) patients (1) aimed at studying the occurrence of low bone mineral density (BMD) at an early stage prior to menopause (i.e., during the first decade after peak bone mass) and (2) elucidating the possible mechanisms underlying IDDM-induced bone complication.

METHODS

Twenty-seven female patients with insulin-treated and well-controlled diabetes, without renal complications, and 32 well-matched healthy controls, aged between 30 and 40 years and fulfilling rigorous inclusion criteria to minimize bone-confounding factors, were enrolled. Areal BMD was evaluated by dual energy X-ray absorptiometry at axial (lumbar spine) and appendicular (femur) sites, using diagnostic WHO reference (T-scores). Osteoblast functions, bone metabolism, related key minerals, and 2 osteoclast-stimulating calciotropic hormones regulating their serum levels were assessed biochemically.

RESULTS

The number of cases with low BMD (T-score below -1.1 SD) was almost 2-fold greater (p < 0.01) in the IDDM group. BMD was significantly lower in this group for 3 lumbar sites (p < 0.01) and femur Ward's triangle (p < 0.05). Bone formation was reduced, as evidenced by the suppressions of osteocalcin (OC; p < 0.01) and IGF-I (p < 0.001). However, bone alkaline phosphatase (bALP) was induced (p < 0.01), in contrast to what is usually observed in cases of reduced bone formation. Correlated total ALP activity was also significantly increased. There was no change in the specific marker of bone resorption (urinary deoxypyridinoline). Serum calcium was significantly elevated, particularly after adjustment for albumin (p < 0.001), despite lower 1,25(OH)(2)D(3) (p < 0.001) and no elevation of PTH. All significant bone-related biochemical changes were significantly correlated with glycosylated hemoglobin, a clinical indicator of long-term glycemic control, indicating a direct effect of the disease.

CONCLUSIONS

Bone loss in the IDDM group results from a decrease in bone formation rather than an increase of bone resorption. The induction of bALP is indicative of impaired osteoblast differentiation and maturation, which delayed (down-regulated) later stages of matrix mineralization, as evidenced by lower OC and BMD.

Effects of calcium supplements on fracture healing in a rat osteoporotic model

Fracture healing is a complex process, which is further complicated if the bone is osteoporotic. Calcium is one of the important minerals in bone and has been found to prevent osteoporosis but its role in fracture healing of osteoporotic bone is still unclear. We carried out a study on the effects of calcium supplementation on the late phase healing of fractured osteoporotic bone using an ovariectomized rat model. Twenty-four female Sprague-Dawley rats were divided into three groups: sham-operated (SO), ovariectomized-control (OVXC), and ovariectomized + calcium supplements (Ca). The right femurs of all the rats were fractured at mid-epiphysis and a K-wire was inserted for internal fixation. After 2 months of treatment, the rats were sacrificed and the femora were dissected out for radiological and biomechanical assessment. As expected, osteoporosis resulted in impaired healing as shown by the poor radiological and biomechanical properties of the OVXC group. CT scans showed significantly lower callus volumes in the SO and Ca groups compared to the OVXC group. Radiological scoring of fracture healing and callus staging of the SO and Ca groups were better than the OVXC group. However, the biomechanical parameters of the Ca group were significantly lower than the SO group and similar to the OVXC group. Therefore, calcium supplements may appear to improve fracture healing of osteoporotic bone but failed to improve strength.

Trabecular bone mechanical properties in patients with fragility fractures

Fragility fractures are generally associated with substantial loss in trabecular bone mass and alterations in structural anisotropy. Despite the high correlations between measures of trabecular mass and mechanical properties, significant overlap in density measures exists between individuals with osteoporosis and those who do not fracture. The purpose of this paper is to provide an analysis of trabecular properties associated with fragility fractures. While accurate measures of bone mass and 3-D orientation have been demonstrated to explain 80% to 90% of the variance in mechanical behavior, clinical and experimental experience suggests the unexplained proportion of variance may be a key determinant in separating high- and low-risk patients. Using a hierarchical perspective, we demonstrate the potential contributions of structural and tissue morphology, material properties, and chemical composition to the apparent mechanical properties of trabecular bone. The results suggest that the propensity for an individual to remodel or adapt to habitual damaging or nondamaging loads may distinguish them in terms of risk for failure.

Inhibitory effects of morinda officinalis extract on bone loss in ovariectomized rats

The present study was undertaken to investigate the protective effects of ethanol extract from the root of Morinda Officinalis (RMO) on ovariectomy-induced bone loss. Administration of RMO extract increased trabecular bone mineral content and bone mineral density of tibia, improved the levels of phosphorus (P), calcium (Ca) and OPG, decreased the levels of DPD/Cr, TRAP, ACTH and corticosterone, but did not reverse the levels of ALP, TNF-α and IL-6 in serum of ovariectomized rats. These findings demonstrated that RMO extract reduced bone loss in ovariectomized rats, probably via the inhibition of bone resorption, but was not involved with bone formation. Anthraquinones and polysaccharides from Morinda officinals could be responsible for their antiosteoporotic activity, and the action mechanism of these constituents needs to be further studied. Therefore, RMO has the potential to develop a clinically useful antiosteoporotic agent.

Bone health in diabetes: considerations for clinical management

BACKGROUND

The metabolic and endocrine alterations of diabetes adversely affect bone quantity and/or quality and may increase fracture risk.

SCOPE

A survey of the scientific literature on diabetes and bone cited on PubMed/MEDLINE and published in English from January 1970 to November 2008.

FINDINGS

Subjects with type 1 diabetes have reduced bone mass and increased risk of fragility fracture, while those with type 2 diabetes, despite having normal or above-normal bone mineral density (BMD), are susceptible to low-trauma fractures, especially hip fractures. A recent meta-analysis, involving 836 000 subjects and 139 000 incident cases of fracture, found that type 2 diabetes was associated with significantly increased risks of non-vertebral (relative risk 1.2), hip (relative risk 1.7) and foot (relative risk 1.3) fracture. The association with hip fracture persisted after adjustment for age, physical activity and body weight, and was more pronounced in men and in those with long-standing diabetes. Insulin has an anabolic effect on bone, and the qualitatively different effects of type 1 and type 2 diabetes on bone mass are consistent with the opposing insulin-secretory states (hypoinsulinaemia vs. hyperinsulinaemia). However, the existence of an elevated fracture risk in type 2 diabetes, despite the underlying hyperinsulinaemia, suggests the involvement of other potential pathogenic influences (e.g., hyperglycaemia, diabetic complications and lifestyle factors) on bone. Animal studies suggest that diabetic bone may be more fragile than non-diabetic bone. Falls arising from diabetes-related comorbidities are another possible cause of low-trauma fracture. Clinical trial findings, supported by bone marker and bone density data, suggest that the oral antidiabetic agents metformin and glibenclamide significantly lower fracture risk, whereas the thiazolidinediones slightly increase fracture risk in postmenopausal women, but not in men, with type 2 diabetes. Recent preclinical studies have helped elucidate the mechanisms underlying the dynamics of bone remodelling, but more research is needed to improve outcomes for patients.

CONCLUSIONS

Bone health is an important consideration in diabetes, and caution should be exercised in prescribing thiazolidinediones to postmenopausal women with low BMD and patients with prior fracture.

Effect of body fat stores on total and regional bone mineral density in perimenopausal Chinese women

Accumulation of body fat is known to be beneficial to bone mass through increased body weight. However, not all the skeleton is loaded by body weight. Therefore, we assume that fat stores would exert different effects on bone mass at different skeletal sites. In this study, 84 perimenopausal Chinese women were recruited. Using dual-energy X-ray absorptiometry, total body fat mass (TBFM), total body lean mass (TBLM), percent body fat (PBF), and total body and regional bone mineral density (BMD) were measured. Correlation analysis indicated that PBF correlated negatively with BMD at ribs and both arms (all P < 0.05). After adjusting for TBLM, PBF had a significantly negative correlation with BMD at head, ribs, both arms, and whole body (all P < 0.05). With adjustment for body weight and height, a significantly negative correlation between PBF and BMD was present, not only at ribs and arms but also at legs and whole body (all P < 0.05, except right leg, at P = 0.094). There was a significantly positive correlation between body weight and leg BMD (all P < 0.001). Body weight was positively correlated with TBFM (r (2) = 0.783, P < 0.001) and TBLM (r (2) = 0.770, P < 0.001). Based on the results, we conclude that increased body fat stores would exert a detrimental effect on BMD, but this effect is more prominent on non-weight-bearing bone. On weight-bearing bone, the detrimental effect of increased body fat could be offset or outweighed by the beneficial effect of increased body weight.

Mortality in the presence of a vertebral fracture, scoliosis, or Scheuermann's disease in the thoracic spine

PURPOSE

Vertebral fractures and scoliosis, unlike Scheuermann's disease, have been associated with increased mortality. Total and cause-specific mortalities of these spinal deformities were studied to produce epidemiologic knowledge.

METHODS

A population of 16,010 Finnish men and women 20 to 92 years of age participated in a health examination from 1973-1976. Their spinal deformities were assessed from chest radiographs by two radiologists. Logistic regression and Cox's model were used to estimate risk ratios and to control confounding. The follow-up period was 30 years.

RESULTS

Vertebral fracture significantly predicted total mortality, and this increase in mortality was due to an excess of cancer and respiratory deaths. The increased risk of cancer death persisted even when those subjects with a history of cancer and the first 5 years of follow-up were excluded to avoid the effect of metastatic fractures, and when confounding was controlled. In this analysis the relative risk of cancer death in subjects with a baseline vertebral fracture was 2.02 (95% confidence interval: 1.23-3.31).

CONCLUSION

Vertebral fracture significantly predicted increased mortality from cancer. To clarify the mechanism, the fractures should be studied further for their associations with defined and site-specific cancer types.

Osteoporosis among patients with type 1 and type 2 diabetes

Both diabetes and fractures are prevalent in adults. The relationship between diabetes and osteoporosis is complex and, although it has been investigated extensively, the subject remains controversial. While low bone mineral density (BMD) is consistently observed in type 1 diabetes, the relationship is less clear in type 2 diabetes, with some studies reporting modestly increased or unchanged BMD. Both type 1 and type 2 diabetes have been associated with a higher risk of fractures. Despite discrepancies between BMD and fracture rates, clinical trials uniformly support the fact that new bone formation and bone microarchitecture and, thus, bone quality, are altered in both types of diabetes. Although a causal association between diabetes and osteoporosis cannot be established on the basis of existing data, it is possible to conclude from many studies and from a better understanding of the physiopathology of diabetes that it can increase the risk of fractures through skeletal (decreased BMD and bone quality) and extraskeletal (increased risk of falls) factors. Even though osteoporosis screening or prophylactic treatment in all patients with type 1 and type 2 diabetes is not being recommended at present, such patient populations should be given general guidelines regarding calcium and vitamin D intakes, exercise and the avoidance of potential risk factors for osteoporosis. The extent of diagnostic and therapeutic interventions should be based on the individual's risk profile for fractures.

Effect of osteoporosis on bone mineral density and fracture repair in a rat femoral fracture model

Osteoporosis (OP) is one of the most prevalent bone diseases worldwide with bone fracture the major clinical consequence. The effect of OP on fracture repair is disputed and although it might be expected for fracture repair to be delayed in osteoporotic individuals, a definitive answer to this question still eludes us. The aim of this study was to clarify the effect of osteoporosis in a rodent fracture model. OP was induced in 3-month-old rats (n = 53) by ovariectomy (OVX) followed by an externally fixated, mid-diaphyseal femoral osteotomy at 6 months (OVX group). A further 40 animals underwent a fracture at 6 months (control group). Animals were sacrificed at 1, 2, 4, 6, and 8 weeks postfracture with outcome measures of histology, biomechanical strength testing, pQCT, relative BMD, and motion detection. OVX animals had significantly lower BMD, slower fracture repair (histologically), reduced stiffness in the fractured femora (8 weeks) and strength in the contralateral femora (6 and 8 weeks), increased body weight, and decreased motion. This study has demonstrated that OVX is associated with decrease in BMD (particularly in trabecular bone) and a reduction in the mechanical properties of intact bone and healing fractures. The histological, biomechanical, and radiological measures of union suggest that OVX delayed fracture healing.

A population-based assessment of rates of bone loss at multiple skeletal sites: evidence for substantial trabecular bone loss in young adult women and men

Using QCT, we made a longitudinal, population-based assessment of rates of bone loss over life at the distal radius, distal tibia, and lumbar spine. Cortical bone loss began in perimenopause in women and later in life in men. In contrast, trabecular bone loss began in young adulthood in both sexes.

INTRODUCTION

Although conventional wisdom holds that bone loss begins at menopause in women and later in life in men, this has not been examined longitudinally in population-based studies using precise technology capable of distinguishing cortical and trabecular bone.

MATERIALS AND METHODS

In an age- and sex-stratified population sample (n = 553), we measured volumetric BMD (vBMD) of trabecular and cortical bone by QCT annually for up to 3 yr at the distal radius (DR) and distal tibia (DT) (n = 552) and trabecular vBMD at baseline and 3 yr at the lumbar spine (LS) (n = 474).

RESULTS

Substantial cortical bone loss began in middle life in women but began mainly after age 75 in men. In contrast, substantial trabecular bone loss began in young adult women and men at all three skeletal sites and continued throughout life with acceleration during perimenopause in women. Women experienced 37% and men experienced 42% of their total lifetime trabecular bone loss before age 50 compared with 6% and 15%, respectively, for cortical bone. Median rates of change in trabecular bone (%/yr) were -0.40, -0.24, and -1.61 in young adult women and -0.38, -0.40, and -0.84 in young adult men at the DR, DT, and LS, respectively (all p < 0.001). The early trabecular bone loss did not consistently correlate with putative causal factors, except for a trend with IGF-related variables at DT in women. However, in postmenopausal women and, to a lesser extent, in older men, higher rates of cortical and trabecular bone loss were associated with lower levels of biologically-active sex steroids and with higher levels of follicle-stimulating hormone and bone turnover markers.

CONCLUSIONS

The late onset of cortical bone loss is temporally associated with sex steroid deficiency. However, the early-onset, substantial trabecular bone loss in both sexes during sex steroid sufficiency is unexplained and indicates that current paradigms on the pathogenesis of osteoporosis are incomplete.

Leukaemia inhibitory factor and bone cell function

A bone-resorbing product of mouse spleen cells found to have differentiation-inducing activity was most probably leukaemia inhibitory factor (LIF). This revealed that LIF is a cytokine active on bone, in addition to its several other sites of action. In organ culture of newborn mouse bone, recombinant LIF promoted bone resorption by a prostaglandin-dependent process. Resorption by isolated rat osteoclasts was also promoted by LIF through an initial action on osteoblasts which was receptor-mediated. Incorporation of [3H]thymidine into DNA was increased by LIF in cells (most probably osteoblasts) of the newborn mouse bones. Osteoblasts have been shown to produce LIF, and the amount is increased by treatment with retinoic acid or TNF-alpha. LIF also acts directly on osteoblasts to inhibit plasminogen activator activity, by stimulating the synthesis of plasminogen activator inhibitor 1 mRNA and protein. The latter actions are very similar to those of TGF-beta. Again like TGF-beta, LIF was ineffective in promoting bone resorption in vitro in fetal rat long bones. These results, together with the in vivo data showing that high circulating levels of LIF in the mouse are accompanied by a substantial increase in trabecular bone mass, indicate that LIF is another cytokine with potent actions on bone and potentially important interactions with other osteotrophic factors.

[Osteoporosis as a first manifestation of systemic mastocytosis. Study of 6 cases]

BACKGROUND AND OBJECTIVE

We describe 6 cases of secondary osteoporosis due to systemic mastocytosis diagnosed in the last 6 years.

RESULTS

Three females and 3 males, age range: 47-66 years, diagnosed with osteoporosis were subsequently diagnosed with systemic mastocytosis. Diagnosis delay: 0.5-17 years. Cutaneous involvement was present in 3 patients, hematologic involvement in 2 patients and gastrointestinal involvement in 2 patients. Histamine levels in urine were elevated in all cases. Four patients had fractures. Treatment with bisphosphonates was started. After 3 years the values of bone mineral density (BMD) improved in the 5 patients evaluated. Two patients had new vertebral fractures and started teriparatide.

CONCLUSIONS

Osteoporosis is an unfrequent initial manifestation of systemic mastocytosis. These patients have a high risk of fractures. Our results suggest that although bisphosphonates improve the bone mineral density the risk of fractures persists.

Arterial stiffness and osteoporosis in chronic obstructive pulmonary disease

RATIONALE

Chronic obstructive pulmonary disease (COPD) is associated with an increased risk of cardiovascular events and osteoporosis. Increased arterial stiffness is an independent predictor of cardiovascular disease.

OBJECTIVES

We tested the hypothesis that patients with COPD would have increased arterial stiffness, which would be associated with osteoporosis and systemic inflammation.

METHODS

We studied 75 clinically stable patients with a range of severity of airway obstruction and 42 healthy smoker or ex-smoker control subjects, free of cardiovascular disease. All subjects underwent spirometry, measurement of aortic pulse wave velocity (PWV) and augmentation index, dual-energy X-ray absorptiometry, and blood sampling for inflammatory mediators.

MEASUREMENTS AND MAIN RESULTS

Mean (SD) aortic PWV was greater in patients, 11.4 (2.7) m/s, than in control subjects, 8.95 (1.7) m/s, p < 0.0001. Inflammatory mediators and augmentation index were also greater in patients. Patients with osteoporosis at the hip had a greater aortic PWV, 13.1 (1.8) m/s, than those without, 11.2 (2.7) m/s, p < 0.05. In patients, aortic PWV was related to age (r = 0.63, p < 0.0001) and log(10) IL-6 (r = 0.31, p < 0.01), and inversely to FEV(1) (r = -0.34, p < 0.01). The strongest predictors of aortic PWV in all subjects were age (p < 0.0001), percent predicted FEV(1) (p < 0.05), mean arterial pressure (p < 0.05), and log(10) IL-6 (p < 0.05).

CONCLUSIONS

Increased arterial stiffness was related to the severity of airflow obstruction and may be a factor in the excess risk for cardiovascular disease in COPD. The increased aortic PWV in patients with osteoporosis and the association with systemic inflammation suggest that age-related bone and vascular changes occur prematurely in COPD.

Fracture healing in osteoporotic fractures: is it really different? A basic science perspective

Osteoporosis is a major health problem characterized by compromised bone strength that predisposes patients to an increased risk of fracture. Osteoporotic patients differ from normal subjects in bone mineral composition, bone mineral content, and crystallinity. Poor bone quality in patients with osteoporosis presents the surgeon with difficult treatment decisions. Much effort has been expended on improving therapies that are expected to preserve bone mass and thus decrease fracture risk. Manipulation of both the local fracture environment in terms of application of growth factors, scaffolds and mesenchymal cells, and systemic administration of agents promoting bone formation and bone strength has been considered as a treatment option from which promising results have recently been reported. Surprisingly, less importance has been given to investigating fracture healing in osteoporosis. Fracture healing is a complex process of bone regeneration, involving a well-orchestrated series of biological events that follow a definable temporal and spatial sequence that may be affected by both biological factors, such as age and osteoporosis, and mechanical factors such as stability of the osteosynthesis. Current studies mainly focus on preventing osteoporotic fractures. In recent years, the literature has provided evidence of altered fracture healing in osteoporotic bone, which may have important implications in evaluating the effects of new osteoporosis treatments on fracture healing. However, the mechanics of this influence of osteoporosis on fracture healing have not yet been clarified and clinical evidence is still lacking.

Advances in the diagnosis and treatment of osteoporosis

Although severely low bone density is relatively rare in the pediatric population, it can be a significant problem in many patients with chronic illness. As peak bone formation occurs during adolescence, it is crucial that pediatricians and other care providers for this patient population recognize the significance of attainment of adequate bone. Dietary intake of vitamin D and calcium should be optimized, and correction of underlying causes of poor bone density should occur whenever possible. Assessment of bone density is difficult, as each technology available has problems, and none of the technologies are well-associated with fracture risk in pediatric patients. Once diagnosis of severely low bone density is established, treatment options are limited and poorly studied. The benefits of bisphosphonate therapy appear to outweigh the risks in patients with low bone density and frequent fragility fractures, and it appears that most improvement with bisphosphonates occurs within the first 2 to 4 years. Evidence, however, is emerging that once off therapy, bone turnover remains decreased for at least several years. During that time, improvements in bone density are decreased. Many questions remain regarding duration of therapy with bisphosphonate therapy and the long-term effects on the children who receive this medication. Anabolic therapies may become important in the future, but there is currently extremely limited information regarding their use in pediatrics.

Osteoimmunology

Osteoimmunology is an interdisciplinary research field combining the exciting fields of osteology and immunology. An observation that contributed enormously to the emergence of osteoimmunology was the accelerated bone loss caused by inflammatory diseases such as rheumatoid arthritis. Receptor activator of nuclear factor kappaB ligand (RANKL), which is the main regulator of osteoclastogenesis, was found to be the primary culprit responsible for the enhanced activation of osteoclasts: activated T cells directly and indirectly increased the expression of RANKL, and thereby promoted osteoclastic activity. Excessive bone loss is not only present in inflammatory diseases but also in autoimmune diseases and cancer. Furthermore, there is accumulating evidence that the very prevalent skeletal disorder osteoporosis is associated with alterations in the immune system. Meanwhile, numerous connections have been discovered in osteoimmunology beyond merely the actions of RANKL. These include the importance of osteoblasts in the maintenance of the hematopoietic stem cell niche and in lymphocyte development as well as the functions of immune cells participating in osteoblast and osteoclast development. Furthermore, research is being done investigating cytokines, chemokines, transcription factors and co-stimulatory molecules which are shared by both systems. Research in osteoimmunology promises the discovery of new strategies and the development of innovative therapeutics to cure or alleviate bone loss in inflammatory and autoimmune diseases as well as in osteoporosis. This review gives an introduction to bone remodeling and the cells governing that process and summarizes the most recent discoveries in the interdisciplinary field of osteoimmunology. Furthermore, an alternative large animal model will be discussed and the pathophysiological alterations of the immune system in osteoporosis will be highlighted.

Mechanisms of osteoporosis in spinal cord injury

Osteoporosis is a known complication of spinal cord injury (SCI), but its mechanism remains unknown. The pathogenesis of osteoporosis after SCI is generally considered disuse. However, although unloading is an important factor in the pathogenesis of osteoporosis after SCI, neural lesion and hormonal changes also seem to be involved in this process. Innervation and neuropeptides play an important role in normal bone remodelling. SCI results in denervation of the sublesional bones and the neural lesion itself may play a pivotal role in the development of osteoporosis after SCI. Although upper limbs are normally loaded and innervated, bone loss also occurs in the upper extremities in patients with paraplegia, indicating that hormonal changes may be associated with osteoporosis after SCI. SCI-mediated hormonal changes may contribute to osteoporosis after SCI by different mechanisms: (1) increased renal elimination and reduced intestinal absorption of calcium leading to a negative calcium balance; (2) vitamin D deficiency plays a role in the pathogenesis of SCI-induced osteoporosis; (3) SCI antagonizes gonadal function and inhibits the osteoanabolic action of sex steroids; (4) hyperleptinaemia after SCI may contribute to the development of osteoporosis; (5) pituitary suppression of TSH may be another contributory factor to bone loss after SCI; and (6) bone loss after SCI may be caused directly, at least in part, by insulin resistance and IGFs. Thus, oversupply of osteoclasts relative to the requirement for bone resorption and/or undersupply of osteoblasts relative to the requirement for cavity repair results in bone loss after SCI. Mechanisms for the osteoporosis following SCI include a range of systems, and osteoporosis after SCI should not be simply considered as disuse osteoporosis. Unloading, neural lesion and hormonal changes after SCI result in severe bone loss. The aim of this review is to improve understanding with regard to the mechanisms of osteoporosis after SCI. The understanding of the pathogenesis of osteoporosis after SCI can help in the consideration of new treatment strategies. Because bone resorption after SCI is very high, intravenous bisphosphonates and denosumab should be considered for the treatment of osteoporosis after SCI.

Efficacy of bone marrow-derived stem cells in strengthening osteoporotic bone in a rabbit model

Osteoporosis might be due to defects in mesenchymal stem cells (MSCs) that lead to reduced proliferation and osteoblast differentiation. We hypothesized that transplantation of MSCs into sites at risk for developing osteoporotic bone could improve bone structure and biomechanics. The aim of this study was to establish an osteoporosis rabbit model by ovariectomy (OVX), characterize the autologous MSCs from the OVX rabbits, and transplant the autologous MSCs into the OVX rabbits. MSCs harvested from bone marrow of normal and OVX rabbits were culture expanded and differentiated in osteogenic medium. Phenotypes were evaluated by collagen I immunostaining, von Kossa staining, and quantitative assays of bone-specific alkaline phosphatase (B-ALP) and osteocalcin (OCN). MSCs were transfected with green fluorescence protein (GFP) and implanted in the gluteus muscle to trace their fate in vivo. Cultured autologous MSCs from OVX rabbits were constructed in calcium alginate gels and then transplanted in the distal femurs. At 4 and 8 weeks after implantation, histomorphometrical and biomechanical analyses were performed on the samples. MSCs from OVX rabbits displayed higher B-ALP activity, but had similar OCN levels as compared to those from sham rabbits. After 8 weeks of implantation, more bone apposition was found in the MSC-alginate-treated group. Histomorphometry indicated increased trabecular thickness. Histology also illustrated improved microstructures with newly formed osteoids and enhanced trabecular thickness. In addition, biomechanical testing revealed stronger stiffness in the MSC-alginate treatment group. Therefore, this study implies that transplantation of MSCs can help to strengthen osteoporotic bone in rabbits.

Strain-dependent variations in the response of cancellous bone to ovariectomy in mice

The goal of this study was to characterize the skeletal response to ovariectomy in mice (129P3, C57BL/6, and B6129PF2) commonly used in gene manipulation studies to evaluate their potential as preclinical models of postmenopausal osteoporosis. The magnitude of cancellous bone loss and cellular indices of increased bone turnover in response to ovariectomy varied with mouse type and skeletal site, but in general, were less pronounced and less consistent than in Sprague-Dawley rats, the established preclinical model for postmenopausal bone loss.

INTRODUCTION

The ovariectomized (OVX) rat is the most widely used preclinical rodent model for postmenopausal osteoporosis. However, the underlying mechanisms of bone disorders, including osteoporosis, have been explored predominantly in the mouse. The purpose of this study was to evaluate mice (129P3 and C57BL/6 inbred strains and their F2 hybrid offspring, B6129PF2), commonly used for gene knockout and overexpression studies, for their potential as preclinical models of postmenopausal bone loss.

MATERIALS AND METHODS

The mice were OVX or sham-operated at 4 months of age and killed at 1 or 3 months after surgery. Lumbar vertebrae and distal femora were subjected to histomorphometric assessment.

RESULTS

Mice in the two strains and the F2 hybrids (will be referred to as strain for the remainder of the abstract) lost vertebral cancellous bone after OVX; bone volume (BV/TV) was 20% and 27% lower at 1 and 3 months after surgery, respectively. The decreased cancellous BV/TV was associated with an increase in osteoclast surface at 1 month after OVX in the 129P3 strain only. Osteoblast surface was increased by 20% with OVX at both 1 and 3 months after surgery, irrespective of mouse strain. However, bone formation rate was not altered by OVX in any of the mouse strains. In contrast to the lumbar vertebrae, cancellous bone loss in response to OVX differed in the distal femur among the three mouse strains. OVX had no significant effect on distal femur BV/TV in the B6129PF2 mouse strain. In the C57BL/6 strain, cancellous BV/TV was reduced by OVX at 1 month after surgery but not at 3 months after surgery, whereas distal femur BV/TV in 129P3 mice was reduced at 3 months after surgery. Osteoclast surface was not affected by OVX at either time-point in the C57BL/6 strain, but was increased by 116% at 1 month after surgery in the 129P3 strain. Osteoblast surface was increased with OVX at 1 month after surgery, irrespective of strain, whereas bone formation rate was not altered by OVX at either time-point in any of the strains.

CONCLUSIONS

The magnitude of cancellous bone loss and cellular indices of increased bone turnover in response to OVX varied with mouse strain and skeletal site, but in general, were less pronounced and less consistent than in the Sprague-Dawley rat. Although mouse models will continue to provide insights into genetic influences on bone mass and turnover, caution should be exercised when using 129P3 and C57BL/6 mice, and their F2 hybrids, as models for postmenopausal bone loss and preclinical testing of potential therapies for osteoporosis.

Serum levels of osteoprotegerin and osteoprotegerin polymorphisms in Gaucher disease

Bone involvement in Gaucher disease causes disability and reduced quality of life; loss of function and pain are important indications for enzyme replacement therapy. The purpose of this study was to ascertain whether osteoprotegerin (OPG), which decreases osteoclast activity, is indicative of incipient bone involvement by comparing OPG serum levels to Gaucher disease severity (SSI) and bone mineral density (BMD), and to correlate bone and disease markers to OPG polymorphisms: OPG1-2(A163G), OPG3-4(T129C) and OPG5-6(C1217T). Of 554 patients, 173 Ashkenazi Jewish patients with non-neuronopathic Gaucher disease were enrolled and 32 healthy Ashkenazi Jews served as controls. Serum OPG levels were detected by enzyme-linked immunosorbent assay and BMD was obtained by dual X-ray absorptiometry. OPG polymorphisms were determined in 63 randomly chosen patients. Serum OPG values for patients were not greater than in controls, but showed a statistically significant trend to increase with age (P = 0.057). No correlation existed between OPG levels and BMD or with genotype or other disease markers. A significant correlation was noted between OPG5-6 genotype and SSI. A significant difference was found between the allele distributions of each OPG polymorphism when compared with Caucasians and Ashkenazi Jews. OPG levels probably do not predict BMD in Gaucher disease and hence are not indicative of osteoporosis in Gaucher disease.

Increased prevalence of radiological spinal deformities in adult patients with GH deficiency: influence of GH replacement therapy

This cross-sectional study shows that a high number of untreated adult patients with GHD develop radiological vertebral deformities. Patients undergoing GH replacement treatment showed a significantly lower prevalence of vertebral deformities versus treated patients in the presence of similar BMD, as assessed by DXA.

INTRODUCTION

In this cross-sectional study, we investigated whether the prevalence and degree of spinal deformities in adults with growth hormone deficiency (GHD) were related to the age of patients, degree of bone turnover, BMD, and recombinant human GH (rhGH) replacement therapy.

MATERIALS AND METHODS

One hundred seven adult hypopituitary patients (67 males and 40 females; mean age, 47 years; range: 16-81 years) with severe GHD and 130 control subjects (39 males, 91 females; mean age: 58.9 years; range: 26-82 years) were evaluated for BMD (DXA) and vertebral deformities (quantitative morphometric analysis). At study entry, 65 patients were on replacement therapy with rhGH, whereas 42 patients had never undergone rhGH.

RESULTS

Vertebral fractures were significantly more frequent in GHD patients versus control subjects (63.6% versus 37.7%; chi2 15.7; p < 0.001). The fracture prevalence, as well as the fracture number, was significantly higher in untreated versus treated patients (78.6% versus 53.8%; chi2: 6.7; p = 0.009), although the two groups of patients did not show any significant difference in median T score. In untreated GHD patients, the prevalence of vertebral deformities was correlated with T score (p = 0.002) and duration of disease (p = 0.003). In treated GHD patients, the prevalence of spinal deformities was correlated only with the timing of the beginning of rhGH replacement.

CONCLUSIONS

This cross-sectional study reports high prevalence of vertebral radiological deformities in adult patients with untreated GHD. The replacement treatment of GHD leads to a significant decrease in fracture rate.

Calcium supplementation does not affect CRP levels in postmenopausal women--a randomized controlled trial

INTRODUCTION

Epidemiological studies suggest that calcium supplementation may decrease the risk of cardiovascular disease.

METHODS

Since the inflammatory marker C-reactive protein (CRP) is a risk factor for cardiovascular disease, and CRP production is potentially responsive to parathyroid hormone, we measured high-sensitivity CRP at baseline and 12 months in a subset of healthy postmenopausal women participating in a randomized controlled trial of the effects of 1 g of calcium daily on the incidence of fractures.

RESULTS

At baseline, we found that CRP correlated positively with indices of body weight and fat and with bone mineral density (BMD) at the total body and total hip sites, but the associations between CRP and BMD were lost after adjustment for body weight. There were consistent associations between levels of CRP and markers of the metabolic syndrome (fat mass, plasma triglycerides, fasting glucose).

CONCLUSION

After 1 year of calcium supplementation, there was no difference between the groups in levels of CRP. We conclude that levels of CRP correlate with anthropometric and biochemical features of insulin resistance, but that they are neither predictive of BMD nor affected by 1 g of calcium supplementation in healthy postmenopausal women.

Increased prevalence of radiological spinal deformities in active acromegaly: a cross-sectional study in postmenopausal women

This cross-sectional study shows that high numbers of postmenopausal women with acromegaly develop vertebral fractures in relation to the activity of disease. In patients with active acromegaly, vertebral fractures occur even in presence of normal BMD, whereas in patients with controlled acromegaly, vertebral fractures are always accompanied by a pathological BMD.

INTRODUCTION

We studied the frequency of radiological vertebral fractures in a cohort of postmenopausal women with active or controlled acromegaly.

MATERIALS AND METHODS

Thirty-six postmenopausal acromegalic patients (15 with active and 21 with controlled disease) were evaluated for BMD, bone metabolism (serum 25-hydroxyvitamin D, PTH, bone-specific alkaline phosphatase [BSALP], and urinary deoxypyridinoline [Dpd]), and vertebral quantitative morphometry. Thirty-six nonacromegalic postmenopausal women, matched for age, were selected among the patients consulting the Bone Center as a control group for BMD evaluation and vertebral quantitative morphometry.

RESULTS

Vertebral fractures were shown in 19 patients (52.8%) and 11 controls (30.6%; chi2: 3.7; p=0.06). Fractured acromegalic women were older and had higher serum IGF-1, Dpd, and BSALP and lower T score and serum vitamin D values compared with nonfractured patients. Moreover, the fractured women had a longer diagnosis and were in the postmenopausal period for a longer period than the nonfractured women. The fracture rate was significantly higher in active than in controlled acromegaly (80% versus 33.3%; chi2: 7.6; p=0.008). The patients with active acromegaly who fractured (12 cases) had significantly higher serum IGF-1 values (356 ng/ml; range: 212-950 versus 120 ng/ml; range: 84-217; p<0.001) and T scores (-1.3 SD, range: -2.9 to +1.3 versus -2.7 SD, range: -3.4 to -1.5, p=0.04) compared with the fractured women whose disease was controlled (7 cases). All fractured women with controlled acromegaly had T scores<-1.0 SD (57.1% of them had osteoporosis, and 42.9% were osteopenic). In contrast, 41.7% of women whose fractures were associated with active disease had a normal T score (>-1.0 SD), whereas osteopenia and osteoporosis were found only in 33.3% and 25.0% of them, respectively.

CONCLUSIONS

This cross-sectional study shows that high numbers of postmenopausal women with acromegaly develop vertebral fractures in relation to the activity of disease. Furthermore, our study shows that, in patients with active acromegaly, vertebral fractures occur even in the presence of normal BMD, whereas in patients with controlled acromegaly, vertebral fractures are always accompanied by a pathological BMD.

Role of endocrine-immune dysregulation in osteoporosis, sarcopenia, frailty and fracture risk

Osteoporosis, a key predictor of hip fractures can be treated using a variety of safe and effective interventions. Nevertheless, optimally effective strategies for the prevention of hip fractures must also incorporate efforts to address a broad range of other potentially reversible factors. Hyperthyroidism, anticonvulsants, caffeine and smoking may decrease bone mass and increase fracture risk at any age. In older individuals it is important to also consider additional risk factors, including long-acting benzodiazepines, poor vision and sarcopenia. The presence of sarcopenia, an age-related decline in muscle bulk and quality enhances the risk of frailty and possibly also hip fracture, particularly if associated with diminished functional mobility, lower quadriceps strength and poor balance or body sway. In this review we examine evidence which indicates the presence of endocrine-immune dysregulation in both osteoporosis and sarcopenia. Post-menopausal declines in serum estrogen and androgen levels contribute to increases in local bone levels of cytoclastic cytokines, followed by increased osteoclastogenesis and bone loss. Similarly, the presence of decreased gonadal hormones and IGF-1, combined with unusually high peripheral levels of cytokines, inflammatory mediators and coagulation markers all enhance the risk of sarcopenia and frailty. We propose that a translational research approach which emphasizes common pathophysiologic mechanisms in osteoporosis and sarcopenia could accelerate the speed of discovery of effective strategies for both frailty and hip fracture prevention.

Insulin-like growth factor-I and parathyroid hormone: potential new therapeutic agents for the treatment of osteoporosis

Millions of men and women worldwide are afflicted by osteoporosis. As this number is projected to increase over the next half century, attempts to forestall the disease process are being tested. Conventional therapies centre on maintaining bone mineral density (BMD) by blocking bone resorption. However, there is a growing need for drugs that can stimulate new bone formation (anabolic agents), thereby reducing future fracture risk. Both parathyroid hormone (PTH) and insulin like growth factor-I (IGF-I) have been the subject of numerous animal and human studies to determine whether these peptides have promise for the treatment of low bone mass. Although the mechanisms of action for these agents are not well delineated, each protein can activate the osteoblast and thereby enhance bone mass. The effects of these drugs on the osteoclast are less well defined. At the current time, there is considerably more interest in PTH than IGF-I, for several reasons. Firstly, animal studies with PTH are more impressive in terms of histomorphometry and biomechanics than IGF-I; secondly, PTH is specific for the skeleton whereas IGF-I is ubiquitous; and thirdly, human studies with PTH have been relatively devoid of significant side-effects. Large scale Phase III trials are now underway in the US and Europe. It is anticipated that at least one of these peptides may prove to have a role in the prevention and treatment of osteoporosis.

Bones in coeliac disease: diagnosis and treatment

Coeliac disease predisposes to metabolic osteopathy. The entity of bone loss is higher in patients with malabsorption at diagnosis but it is also present in asymptomatic or poorly symptomatic patients, occurring in roughly half of them. Calcium malabsorption and the release of proinflammatory cytokines, activating osteoclasts, represent the main mechanisms responsible for bone derangement. In coeliacs, the presence of an increased fracture risk was recently questioned and its importance on clinical grounds was reconsidered, in view of the fact that gluten-free diet generally improves bone mass and, consequently, reduces fracture risk. However, gluten-free diet rarely normalizes bone mass and the co-administration of mineral active drugs may be useful in a subgroup of coeliacs.

Growth hormone replacement is important for the restoration of parathyroid hormone sensitivity and improvement in bone metabolism in older adult growth hormone-deficient patients

Alterations in PTH circadian rhythm and PTH target-organ sensitivity exist in adult GH-deficient (AGHD) patients and may underlie the pathogenesis of AGHD-related osteoporosis. GH replacement (GHR) results in increased bone mineral density, but its benefit in AGHD patients over 60 yr old has been debated. To examine the effect of age on changes in PTH circadian rhythm and target-organ sensitivity after GHR, we recruited 22 AGHD patients (12 were <60 yr of age, and 10 were >60 yr of age). Half-hourly blood samples were collected for PTH, calcium, phosphate, nephrogenous cAMP (marker of renal PTH activity), type-I collagenbeta C-telopeptide (bone resorption marker), and procollagen type-I amino-terminal propeptide (bone formation marker) before and after 1, 3, 6, and 12 months of treatment with GHR. Significant PTH circadian rhythms were present in both age groups throughout the study. After GHR, PTH decreased and nephrogenous cAMP, adjusted calcium, and bone turnover markers increased in both groups, suggesting increased PTH target-organ sensitivity. In younger patients, the changes were significant after 1 month of GHR, but, in older patients, the changes were delayed until 3 months, with maximal changes at 12 months. Older AGHD patients derive benefit from GHR in terms of improvement in PTH sensitivity and bone metabolism. Their response appears delayed and may explain why previous studies have not shown a positive effect of GHR on bone mineral density in older AGHD patients.