Tartrate-resistant acid phosphatase 5b: a novel serum marker of bone resorption

MiR-503 regulates osteoclastogenesis via targeting RANK

MicroRNAs (miRNAs) play important roles in osteoclastogenesis and bone resorption. However, no study has investigated the role of miRNA in postmenopausal osteoporosis. Here, we report that miR-503 was markedly reduced in circulating progenitors of osteoclasts-CD14(+) peripheral blood mononuclear cells (PBMCs) from postmenopausal osteoporosis patients compared with those from postmenopausal healthy women. Overexpression of miR-503 in CD14(+) PBMCs inhibited receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis. Conversely, silencing of miR-503 in CD14(+) PBMCs promoted osteoclastogenesis. RANK, which is activated by the binding of RANKL and inducing osteoclast differentiation, was confirmed to be a target of miR-503. In vivo, silencing of miR-503 using a specific antagomir in ovariectomy (OVX) mice increased RANK protein expression, promoted bone resorption, and decreased bone mass, whereas overexpression of miR-503 with agomir inhibited bone resorption and prevented bone loss in OVX mice. Thus, our study revealed that miR-503 plays an important role in the pathogenesis of postmenopausal osteoporosis and contributes to a new therapeutic way for osteoporosis.

The role of osteoclasts in bone tissue engineering

The success of scaffold-based bone regeneration approaches strongly depends on the performance of the biomaterial utilized. Within the efforts of regenerative medicine towards a restitutio ad integrum (i.e. complete reconstruction of a diseased tissue), scaffolds should be completely degraded within an adequate period of time. The degradation of synthetic bone substitute materials involves both chemical dissolution (physicochemical degradation) and resorption (cellular degradation by osteoclasts). Responsible for bone resorption are osteoclasts, cells of haematopoietic origin. Osteoclasts play also a crucial role in bone remodelling, which is essential for the regeneration of bone defects. There is, however, surprisingly limited knowledge about the detailed effects of osteoclasts on biomaterials degradation behaviour. This review covers the relevant fundamental knowledge and progress made in the field of osteoclast activity related to biomaterials used for bone regeneration. In vitro studies with osteoclastic precursor cells on synthetic bone substitute materials show that there are specific parameters that inhibit or enhance resorption. Moreover, analyses of the bone-material interface reveal that biomaterials composition has a significant influence on their degradation in contact with osteoclasts. Crystallinity, grain size, surface bioactivity and density of the surface seem to have a less significant effect on osteoclastic activity. In addition, the topography of the scaffold surface can be tailored to affect the development and spreading of osteoclast cells. The present review also highlights possible areas on which future research is needed and which are relevant to enhance our understanding of the complex role of osteoclasts in bone tissue engineering.

Biochemical markers of bone turnover - uses and limitations

Bone turnover markers of resorption and formation are released during the process of bone remodelling. These markers have been extensively studied in a number of therapeutic trials of osteoporosis during the past decade. This has led to better understanding of their physiology, clinical applications and possible ways to optimize analytical techniques. Bone markers can complement the results of bone mineral density in the management of osteoporosis, but their use in clinical practice is challenged by pre-analytical and analytical variability. This review will discuss different types of bone markers, their limitations, use in different metabolic bone diseases and current recommendations from the International Osteoporosis Foundation and the International Federation of Clinical Chemistry and Laboratory Medicine bone marker standards working group.

Detection of Bone Metastases in Breast Cancer (BC) Patients by Serum Tartrate-Resistant Acid Phosphatase 5b (TRACP 5b), a Bone Resorption Marker and Serum Alkaline Phosphatase (ALP), a Bone Formation Marker, in Lieu of Whole Body Skeletal Scintigraphy with Technetium99m MDP

Bone metastases are a serious problem in patients with advanced cancer disease and their presence usually signifies serious morbidity prior to the patient's death. In breast cancer patients the incidence of bone metastasis is observed to be very high at 70 %, as seen during post-mortem examination. Bone metastasis is difficult to diagnose, treat or follow clinically without radiological tools. This study was designed to evaluate the utility of a novel bone resorption marker-serum tartrate-resistant acid phosphatase 5b (TRACP5b) and the bone formation marker such as serum total alkaline phosphatase (ALP), in comparison with whole body skeletal scintigraphy with Technetium99m MDP for the diagnosis of bone metastases (BM) in breast cancer (BC) patients. This study is intended to help the clinician to diagnose bone metastasis without resorting to radiological tools, as they are not cost effective and carry the risk of radiation.

EXPERIMENTAL DESIGN

Four groups of samples were analysed. 1st group consists 52 normal female (cancer free women), 2nd group consists 38 BC patients without bone metastasis, 3rd group consists 27 breast cancer patients with limited bone metastasis (3 or less than 3 skeletal lesions) and 4th group consists 35 breast cancer patients with extensive bone metastasis (4 or more than 4 skeletal lesions), conformed by whole body skeletal scintigraphy with Technetium99m MDP. One way ANOVA was used to compare serum TRACP5b and serum ALP among these groups. Both serum TRACP5b and serum ALP are not markedly elevated in limited bone metastasis but are strongly elevated in extensive bone metastasis (p < 0.0001). As seen in this study the biochemical bone resorption marker, serum TRACP5b, abnormally increased in extensive bone metastasis of breast cancer patients and can be used as a specific marker for bone metastasis in lieu of radiological tools.

Appliance-induced osteopenia of dentoalveolar bone in the rat: effect of reduced bone strains on serum bone markers and the multifunctional hormone leptin

To understand, in greater detail, the molecular mechanisms regulating the complex relationship between mechanical strain and alveolar bone metabolism during orthodontic treatment, passive cross-arch palatal springs were bonded to the maxillary molars of 6-wk-old rats, which were killed after 4 and 8 d. Outcome measures included serum assays for markers of bone formation and resorption and for the multifunctional hormone leptin, and histomorphometry of the inter-radicular bone. The concentration of the bone-formation marker alkaline phosphatase (ALP) was significantly reduced at both time points in the appliance group, accompanied by a 50% reduction in inter-radicular bone volume; however, osteocalcin (bone Gla protein) levels remained unaffected. Bone collagen deoxypyridinoline (DPD) crosslinks increased 2.3-fold at 4 d only, indicating a transient increase in bone resorption; in contrast, the level of the osteoclast-specific marker, tartrate-resistant acid phosphatase 5b (TRACP 5b), was unchanged. Leptin levels closely paralleled ALP reductions at both time points, suggesting an important role in the mechanostat negative-feedback loop required to normalize bone mass. These data suggest that an orthodontic appliance, in addition to remodeling the periodontal ligament (PDL)-bone interface, may exert unexpected side-effects on the tooth-supporting alveolar bone, and highlights the importance of recognizing that bone strains can have negative, as well as positive, effects on bone mass.

Clinical significance of serum BAP, TRACP 5b and ICTP as bone metabolic markers for bone metastasis screening in lung cancer patients

BACKGROUND

We investigated the clinical significance of serum bone-specific alkaline phosphatase (BAP), tartrate-resistant acid phosphatase isoform 5b (TRACP 5b) and type I collagen carboxyterminal telopeptide (ICTP) as bone metabolic markers for bone metastasis (BM) screening in lung cancer patients.

METHODS

Newly diagnosed advanced lung cancer patients with (N = 130) and without (N = 135) BM were enrolled in the study. Serum BAP, TRACP 5b and ICTP were measured before the treatment.

RESULTS

BAP, TRACP 5b and ICTP values were higher in patients with BM compared with patients without BM (all P < 0.0001). Area under ROC curve (AUC) of BAP, TRACP 5b and ICTP was 0.760, 0.753 and 0.835 (all P < 0.0001), respectively. The cut-off values for BAP, TRACP 5b and ICTP were 21.8 μg/l, 7.8 U/l and 8.8 μg/l, respectively. When TRACP 5b and ICTP were combined, AUC was elevated to 0.895 (P < 0.0001), and the cut-off values were TRACP 5b 7.6 U/l and ICTP 8.4 μg/l.

CONCLUSIONS

We conclude that serum BAP, TRACP 5b and ICTP may serve as useful tools for BM screening in lung cancer patients.

Effects of fluoride and cadmium co-exposure on bone in male rats

Although cadmium (Cd) and fluoride may both have adverse effects on bone, most studies focus on a single agent. In this study, we investigated the effects of cadmium and fluoride on bone at a relative low level. Sprague-Dawley male rats were assigned randomly into four groups which were given sodium chloride, cadmium (50mg/L), and fluoride (20mg/L) alone, or in combination via drinking water. At the 12th week, urine, blood, and bone tissues were collected for biomarker assay, biomechanical assay, and histological assay. Cadmium had significantly adverse effects on bone mineral density, bone biomechanical property, and bone microstructure. Fluoride slightly increased vertebral bone mineral density but negatively affected bone biomechanical property and bone microstructure. Fluoride could reverse the decrease of vertebral bone mineral density caused by cadmium but could not improve the damage of bone biomechanical property and microstructure caused by cadmium. Tartrate-resistant acid phosphatase 5b levels in rats treated with cadmium and fluoride or in combination were 1-2.5 folds higher than the control. Our data suggest that low level of fluoride could reverse the decrease of vertebral bone mineral density caused by cadmium exposure but has no influence on appendicular skeleton damage caused by cadmium.

The clinical utility of bone marker measurements in osteoporosis

Osteoporosis is characterised by low bone mass and structural deterioration of bone tissue, resulting in increased fragility and susceptibility to fracture. Osteoporotic fractures are a significant cause of morbidity and mortality. Direct medical costs from such fractures in the UK are currently estimated at over two billion pounds per year, resulting in a substantial healthcare burden that is expected to rise exponentially due to increasing life expectancy. Currently bone mineral density is the WHO standard for diagnosis of osteoporosis, but poor sensitivity means that potential fractures will be missed if it is used alone. During the past decade considerable progress has been made in the identification and characterisation of specific biomarkers to aid the management of metabolic bone disease. Technological developments have greatly enhanced assay performance producing reliable, rapid, non-invasive cost effective assays with improved sensitivity and specificity. We now have a greater understanding of the need to regulate pre-analytical sample collection to minimise the effects of biological variation. However, bone turnover markers (BTMs) still have limited clinical utility. It is not routinely recommended to use BTMs to select those at risk of fractures, but baseline measurements of resorption markers are useful before commencement of anti-resorptive treatment and can be checked 3–6 months later to monitor response and adherence to treatment. Similarly, formation markers can be used to monitor bone forming agents. BTMs may also be useful when monitoring patients during treatment holidays and aid in the decision as to when therapy should be recommenced. Recent recommendations by the Bone Marker Standards Working Group propose to standardise research and include a specific marker of bone resorption (CTX) and bone formation (P1NP) in all future studies. It is hoped that improved research in turn will lead to optimised markers for the clinical management of osteoporosis and other bone diseases.

The beneficial effect of icaritin on osteoporotic bone is dependent on the treatment initiation timing in adult ovariectomized rats

BACKGROUND

Epimedium-derived flavonoids (EFs) have a potential to treat established osteoporosis in postmenopausal women. However, one of the main disadvantages of the compound is the high volume and dosage during long-term administration period. Meanwhile, the beneficial effect of EFs on osteoporotic bone depends greatly on the intervention timing. Whether icaritin (ICT), an active molecular compound from EFs, can exert beneficial effect on osteoporotic bone and whether the beneficial effect is also dependent on the intervention timing remain unknown.

OBJECTIVE

The objective of this study was to evaluate the effect of the early and late ICT treatment on bone turnover markers, trabecular architecture, bone remodeling, biomechanics, colony formation of bone marrow stromal cells and osteoblast, adipocyte and osteoclast-related gene expression in adult ovariectomized rats.

METHODS

Eighty 9-month-old female rats (n=8/group) were sham-operated (Sham) or ovariectomized (OVX). The OVX rats were subjected to ICT treatment initiation at 1 month (early treatment) and 3 months (late treatment) post-operation, respectively. The vehicle-treated Sham and OVX rats starting at month 1 and month 3 post-operation served as the corresponding controls (Sham and OVX controls) for early and late ICT treatment, respectively. Those Sham and OVX rats sacrificed immediately before early and late ICT treatment served as the pretreatment baseline controls. Both ICT and vehicle treatments lasted for 2 months. The bone turnover markers, trabecular architecture, bone remodeling and bone biomechanical properties were analyzed with biochemistry, microCT, histomorphometry and mechanical testing, respectively. The population of bone marrow stromal cells (BMSCs) and osteoblasts were evaluated with colony formation assays, respectively. The expression levels of osteoblast, adipocyte and osteoclast-related genes in bone marrow were assessed by real-time polymerase chain reaction (PCR), respectively.

RESULTS

At the tissue level, early ICT treatment remarkably restored the trabecular bone mass, trabecular architecture and bone biomechanical properties towards pretreatment Sham levels, and significantly increased bone formation from pretreatment OVX level and markedly inhibited bone resorption towards pretreatment Sham level, whereas late ICT treatment failed to have any effect. At the cellular and molecular level, early ICT treatment significantly increased the number of osteoblastic colonies and the level of osteoblast-related gene expression compared to pretreatment OVX levels and remarkably decreased adipocyte and osteoclast-related gene expression towards pretreatment Sham levels. Late ICT treatment failed to have beneficial effect on any of these parameters.

CONCLUSION

ICT can exert anabolic and anti-resorptive effect on osteoporotic bone. The beneficial effect of ICT treatment is dependent on the intervention timing in established osteoporosis induced by estrogen depletion.

miR-148a regulates osteoclastogenesis by targeting V-maf musculoaponeurotic fibrosarcoma oncogene homolog B

MicroRNAs (miRNAs) play crucial roles in bone metabolism. In the present study, we found that miR-148a is dramatically upregulated during osteoclastic differentiation of circulating CD14+ peripheral blood mononuclear cells (PBMCs) induced by macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL). Overexpression of miR-148a in CD14+ PBMCs promoted osteoclastogenesis, whereas inhibition of miR-148a attenuated osteoclastogenesis. V-maf musculoaponeurotic fibrosarcoma oncogene homolog B (MAFB) is a transcription factor negatively regulating RANKL-induced osteoclastogenesis. miR-148a directly targeted MAFB mRNA by binding to the 3' untranslated region (3'UTR) and repressed MAFB protein expression. In vivo, our study showed that silencing of miR-148a using a specific antagomir-inhibited bone resorption and increased bone mass in mice receiving ovariectomy (OVX) and in sham-operated control mice. Furthermore, our results showed that miR-148a levels significantly increased in CD14+ PBMCs from lupus patients and resulted in enhanced osteoclastogenesis, which contributed to the lower bone mineral density (BMD) in lupus patients compared with normal controls. Thus, our study provides a new insight into the roles of miRNAs in osteoclastogenesis, and contributes to a new therapeutic pathway for osteoporosis.

Expression of osteoprotegerin from a replicating adenovirus inhibits the progression of prostate cancer bone metastases in a murine model

Metastatic involvement of the skeleton is a frequent consequence of advanced prostate cancer. These skeletal metastases cause a number of debilitating complications and are refractory to current treatments. New therapeutic options are being explored, including conditionally replicating adenoviruses (CRAds). CRAds are engineered to selectively replicate in and destroy tumor cells and can be 'armed' with exogenous transgenes for enhanced potency. We hypothesized that a CRAd armed with osteoprotegerin (OPG), an inhibitor of osteoclastogenesis, would inhibit the progression of prostate cancer bone metastases by directly lysing tumor cells and by reducing osteoclast activity. Although prostate cancer bone metastases are predominantly osteoblastic in nature, increased osteoclast activity is critical for the growth of these lesions. Ad5-Δ24-sOPG-Fc-RGD is a CRAd that carries a fusion of the ligand-binding domains of OPG and the Fc region of human IgG1 in place of the viral E3B genes. To circumvent low tumor cell expression of the native adenoviral receptor, an arginine-glycine-aspartic acid (RGD) peptide insertion within the viral fiber knob allows infection of cells expressing α(v) integrins. A 24-base pair deletion (Δ24) within viral E1A limits replication to cells with aberrant retinoblastoma cell cycle regulator/tumor suppressor expression. We have confirmed that Ad5-Δ24-sOPG-Fc-RGD replicates within and destroys prostate cancer cells and, in both murine and human coculture models, that infection of prostate cancer cells inhibits osteoclastogenesis in vitro. In a murine model, progression of advanced prostate cancer bone metastases was inhibited by treatment with Ad5-Δ24-sOPG-Fc-RGD but not by an unarmed control CRAd.

Targeting of the osteoclastogenic RANKL-RANK axis prevents osteoporotic bone loss and soft tissue calcification in coxsackievirus B3-infected mice

Bone mineralization is a normal physiological process, whereas ectopic calcification of soft tissues is a pathological process that leads to irreversible tissue damage. We have established a coxsackievirus B3 (CVB3)-infected mouse model that manifests both osteoporosis and ectopic calcification specifically in heart, pancreas, and lung. The CVB3-infected mice showed increased serum concentrations of both cytokines including IL-1β, TNF-α, and the receptor activator of NF-κB ligand (RANKL) that stimulate osteoclast formation and of the osteoclast-derived protein tartrate-resistant acid phosphatase 5b. They exhibited more osteoclasts in bone, with no change in the number of osteoblasts, and a decrease in bone formation and the serum concentration of osteoblast-produced osteocalcin. These results indicate that CVB3-induced osteoporosis is likely due to upregulation of osteoclast formation and function, in addition to decreased osteoblast activity. In addition, the serum in the CVB3-infected mice contained a high inorganic phosphate content, which causes ectopic calcification. RANKL treatment induced an increase in the in vitro cardiac fibroblast calcification by inorganic phosphate via the upregulation of osteogenic BMP2, SPARC, Runx2, Fra-1, and NF-κB signaling. We finally observed that i.p. administration of RANK-Fc, a recombinant antagonist of RANKL, prevented bone loss as well as ectopic calcification in CVB3-infected mice. Thus, our results indicate that RANKL may contribute to both abnormal calcium deposition in soft tissues and calcium depletion in bone. In addition, our animal model should provide a tool for the development of new therapeutic agents for calcium disturbance in soft and hard tissues.

Regulation of inflammatory responses and fibroblast-like synoviocyte apoptosis by calcineurin-binding protein 1 in mice with collagen-induced arthritis

OBJECTIVE

Calcineurin-binding protein 1 (CABIN-1) regulates calcineurin phosphatase activity as well as the activation, apoptosis, and inflammatory responses of fibroblast-like synoviocytes (FLS), which actively participate in the chronic inflammatory responses in rheumatoid arthritis (RA). However, the mechanism of action of CABIN-1 in FLS apoptosis is not clear. This study was undertaken to define the regulatory role of CABIN-1 in FLS from mice with collagen-induced arthritis (CIA).

METHODS

Transgenic mice overexpressing human CABIN-1 in joint tissue under the control of a type II collagen promoter were generated. Expression of human CABIN-1 (hCABIN-1) in joints and FLS was determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. The expression of cytokines, matrix metalloproteinases (MMPs), and apoptosis-related genes in FLS was determined by enzyme-linked immunosorbent assay, gelatin zymography, and RT-PCR, respectively. Joints were stained with hematoxylin and eosin and with tartrate-resistant acid phosphatase for histologic analysis.

RESULTS

Human CABIN-1-transgenic mice with CIA had less severe arthritis than wild-type mice with CIA, as assessed according to hind paw thickness and histologic features. The milder arthritis was accompanied by significantly enhanced apoptosis in transgenic mice, evidenced by a significantly greater number of TUNEL-positive cells in synovial tissue. Expression of inflammatory cytokines and MMPs in the transgenic mice with CIA was reduced, and they exhibited decreased Akt activation and increased expression of p53, caspase 3, caspase 9, and Bax.

CONCLUSION

Our findings demonstrate that hCABIN-1 plays a critical role in promoting apoptosis of FLS and in attenuating inflammation and cartilage and bone destruction in RA. These results help elucidate the pathogenic mechanisms of RA and suggest that CABIN-1 is a potential target for treatment of this disease.

Chronically inadequate sleep results in abnormal bone formation and abnormal bone marrow in rats

Insufficient sleep over long durations of the lifespan is believed to adversely affect proper development and healthful aging, although how this might become manifested is unknown. In the present study, rats were repeatedly sleep-restricted during 72 days to permit maladaptations to evolve, thereby permitting study. Densitometric and histomorphometric analyses were performed on harvested bone. In sleep-restricted rats, bone lined by osteoid was reduced 45-fold and osteoid thickness was decreased, compared with controls. This corresponded to a decrease in osteoblast number and activity. The percentage of bone lined by osteoclasts did not differ from that of controls. Plasma concentrations of an osteoclast marker (TRACP 5b) were increased in sleep-restricted rats, indicating increased bone resorption. The low amount of new bone formation without a reduction in bone resorption is diagnostic of osteopenia. Bone mineral density was decreased in femurs from sleep-restricted rats compared with controls, indicating osteoporosis. Red marrow in sleep-restricted rats contained only 37% of the fat and more than twice the number of megakaryocytes compared with that of the control rats. These findings in marrow suggest changed plasticity and increased hematopoiesis. Plasma concentrations of insulin-like growth factor-1, a known, major mediator of osteoblast differentiation and the proliferation of progenitor cells, was decreased by 30% in sleep-restricted rats. Taken together, these findings suggest that chronically inadequate sleep affects bone metabolism and bone marrow composition in ways that have implications for development, aging, bone healing and repair, and blood cell differentiation.

Effect of combined sex hormone replacement on bone/cartilage turnover in a murine model of osteoarthritis

Background

Estrogens act on estrogen receptors distributed in articular cartilages, synovial membrane, and ligaments, which are thought to be related with degenerative changes. Meanwhile, progesterone is known to have a weak anabolic action on bone formation This study evaluates the effects of estrogen and progesterone hormone on bone/cartilage turnover in ovariectomized (OVX) rats.

Methods

Thirty-five 7-month-old female Sprague-Dawley rats were randomly divided into 5 groups and then ovariectomized bilaterally except the sham control group. The first and the second group acting as controls did not receive hormonal therapy, the third group received estrogen, the fourth group received progesterone, and the fifth group received combination of both hormones 10 weeks after surgery. Evaluations were done using the serum levels of cartilage oligomeric matrix protein (COMP) for cartilage turnover, collagen type I C-telopeptide (CTX-1) and osteocalcin (OC) for bone turnover at 11, 15, 19 weeks after OVX and histology using the Osteoarthritis Research Society International (OARSI) osteoarthritis (OA) cartilage histopathology assessment system.

Results

Significantly less cartilage degradation (decreased levels of COMP) was found in the combined hormone treated group in comparison with OVX group. Similarly, both hormonal treatment resulted in increased bone formation and decreased bone resorption i.e., a low overall bone turnover status (decrease in the serum OC and CTX-1 levels).

Conclusions

Combined estrogen and progesterone therapy was found to be convincing in terms of reducing the severity of OA in this experimental model.

Post-mortem analysis of bone marrow osteoclasts using tartrate-resistant acid phosphatase staining: does histochemistry work and correlate with time since death?

Aims

In bone marrow (BM) biopsies, tartrate-resistant acid phosphatase (TRAP) staining represents the gold standard for the characterisation of osteoclasts. TRAP is one of the few enzymes that is histochemically detectable on formalin-fixed paraffin-embedded tissue. This study investigated whether TRAP is also able to visualise BM osteoclasts in autopsy tissue. It was hypothesised that, due to a progressive loss of enzymatic activity in osteoclasts post-mortem, TRAP staining could allow the time of death of a patient to be determined.

Methods

TRAP-stained BM slides of 96 cases including 51 pathology and 23 forensic autopsies and 22 biopsies were histologically evaluated and their staining intensity (SI) semi-quantitatively graded. In the autopsy cases, the results were correlated with the post-mortem interval (PMI, time span in days between death and autopsy).

Results

TRAP staining intensities (TRAP-SIs) did not differ between men and women and showed a steady decrease with age. TRAP-SIs were significantly stronger in biopsies than in autopsy cases. Among the autopsies, TRAP-SIs were highly variable and not dependent on PMI, except for three forensic cases with PMI ≥7 days which showed a complete loss of TRAP stainability. On the whole, the TRAP-SIs of pathology and forensic cases did not differ significantly.

Conclusions

This study clearly shows that BM osteoclasts stay TRAP-positive for 7 days post-mortem, although with markedly reduced TRAP-SIs compared with biopsies. Since TRAP-SIs were not correlated with the duration of PMI, TRAP staining of BM osteoclasts cannot serve as a tool to determine the time of death of a patient.

Dual inhibition of canonical and noncanonical NF-κB pathways demonstrates significant antitumor activities in multiple myeloma

PURPOSE

NF-κB transcription factor plays a key role in the pathogenesis of multiple myeloma in the context of the bone marrow microenvironment. Both canonical and noncanonical pathways contribute to total NF-κB activity. Recent studies have shown a critical role for the noncanonical pathway: selective inhibitors of the canonical pathway present a limited activity, mutations of the noncanonical pathway are frequent, and bortezomib-induced cytotoxicity cannot be fully attributed to inhibition of canonical NF-κB activity.

EXPERIMENTAL DESIGN

Multiple myeloma cell lines, primary patient cells, and the human multiple myeloma xenograft murine model were used to examine the biologic impact of dual inhibition of both canonical and noncanonical NF-κB pathways.

RESULTS

We show that PBS-1086 induces potent cytotoxicity in multiple myeloma cells but not in peripheral blood mononuclear cells. PBS-1086 overcomes the proliferative and antiapoptotic effects of the bone marrow milieu, associated with inhibition of NF-κB activity. Moreover, PBS-1086 strongly enhances the cytotoxicity of bortezomib in bortezomib-resistant multiple myeloma cell lines and patient multiple myeloma cells. PBS-1086 also inhibits osteoclastogenesis through an inhibition of RANK ligand (RANKL)-induced NF-κB activation. Finally, in a xenograft model of human multiple myeloma in the bone marrow milieu, PBS-1086 shows significant in vivo anti-multiple myeloma activity and prolongs host survival, associated with apoptosis and inhibition of both NF-κB pathways in tumor cells.

CONCLUSIONS

Our data show that PBS-1086 is a promising dual inhibitor of the canonical and noncanonical NF-κB pathways. Our preclinical study therefore provides the framework for clinical evaluation of PBS-1086 in combination with bortezomib for the treatment of multiple myeloma and related bone lesions.

Bruton tyrosine kinase inhibition is a novel therapeutic strategy targeting tumor in the bone marrow microenvironment in multiple myeloma

Bruton tyrosine kinase (Btk) has a well-defined role in B-cell development, whereas its expression in osteoclasts (OCs) further suggests a role in osteoclastogenesis. Here we investigated effects of PCI-32765, an oral and selective Btk inhibitor, on osteoclastogenesis as well as on multiple myeloma (MM) growth within the BM microenvironment. PCI-32765 blocked RANKL/M-CSF-induced phosphorylation of Btk and downstream PLC-γ2 in OCs, resulting in diminished TRAP5b (ED50 = 17 nM) and bone resorption activity. PCI-32765 also inhibited secretion of multiple cytokines and chemokines from OC and BM stromal cell cultures from both normal donors (ED50 = 0.5 nM) and MM patients. It decreased SDF-1-induced migration of MM cells, and down-regulated MIP1-α/CCL3 in MM cells. It also blocked MM cell growth and survival triggered by IL-6 or coculture with BM stromal cells or OCs in vitro. Importantly, PCI-32765 treatment significantly inhibits in vivo MM cell growth (P < .03) and MM cell-induced osteolysis of implanted human bone chips in SCID mice. Moreover, PCI-32765 prevents in vitro colony formation by stem-like cells from MM patients. Together, these results delineate functional sequelae of Btk activation mediating osteolysis and growth of MM cells, supporting evaluation of PCI-32765 as a novel therapeutic in MM.

Relationship between sex hormone fluctuations and biomarkers of bone resorption in bovine plasma during the oestrous cycle

The objective of this study was to determine the potential influence of fluctuations in the sex hormones progesterone and oestradiol-17β (E(2)), on biomarkers of bone resorption (hydroxyproline [HYP] and tartrate-resistant acid phosphatase isoform 5b [TRAP5b]) during the oestrous cycle of Holstein cows. Over the course of the study, plasma HYP concentrations did not change and alterations in the concentration of TRAP5b negatively correlated with E(2) levels: enhanced TRAP5b activity correlated with decreased E(2) concentrations below a defined level. This finding enhances the understanding of calcium homeostasis in post-partum dairy cows.

Effect of green tea and Tai Chi on bone health in postmenopausal osteopenic women: a 6-month randomized placebo-controlled trial

Postmenopausal women with osteopenia received green tea polyphenols (GTP) supplement and/or Tai Chi exercise for 6 months. Bone turnover biomarkers, calcium metabolism, and muscle strength were measured. This study showed that GTP supplementation and Tai Chi exercise increased bone formation biomarkers and improved bone turnover rate. Tai Chi exercise increased serum parathyroid hormone. GTP supplementation, Tai Chi exercise, and the combination of the two all improved muscle strength in postmenopausal women with osteopenia.

INTRODUCTION

This study evaluated the effect of GTP supplementation and Tai Chi (TC) exercise on serum markers of bone turnover (bone-specific alkaline phosphatase, BAP, and tartrate-resistant acid phosphatase, TRAP), calcium metabolism, and muscle strength in postmenopausal osteopenic women.

METHODS

One hundred and seventy-one postmenopausal osteopenic women were randomly assigned to four groups: (1) placebo (500 mg starch/day), (2) GTP (500 mg GTP/day), (3) placebo + TC (placebo plus TC training at 60 min/session, three sessions/week), and (4) GTP + TC (GTP plus TC training). Overnight fasting blood and urine samples were collected at baseline, 1, 3, and 6 months for biomarker analyses. Muscle strength was evaluated at baseline, 3, and 6 months. One hundred and fifty subjects completed the 6-month study.

RESULTS

Significant increases in BAP level due to GTP intake (at 1 month) and TC (at 3 months) were observed. Significant increases in the change of BAP/TRAP ratio due to GTP (at 3 months) and TC (at 6 months) were also observed. Significant main effect of TC on the elevation in serum parathyroid hormone level was observed at 1 and 3 months. At 6 months, muscle strength significantly improved due to GTP, TC, and GTP + TC interventions. Neither GTP nor TC affected serum TRAP, serum and urinary calcium, and inorganic phosphate.

CONCLUSION

In summary, GTP supplementation and TC exercise increased BAP and improved BAP/TRAP ratio. TC exercise increased serum parathyroid hormone. GTP supplementation, TC exercise, and the combination of the two all improved muscle strength in postmenopausal women with osteopenia.

Role of carotenoid β-cryptoxanthin in bone homeostasis

Bone homeostasis is maintained through a balance between osteoblastic bone formation and osteoclastic bone resorption. Aging induces bone loss due to decreased osteoblastic bone formation and increased osteoclastic bone resorption. Osteoporosis with its accompanying decrease in bone mass is widely recognized as a major public health problem. Nutritional factors may play a role in the prevention of bone loss with aging. Among various carotenoids (carotene and xanthophylls including beta (β)-cryptoxanthin, lutein, lycopene, β-carotene, astaxanthin, and rutin), β-cryptoxanthin, which is abundant in Satsuma mandarin orange (Citrus unshiu MARC.), has been found to have a stimulatory effect on bone calcification in vitro. β-cryptoxanthin has stimulatory effects on osteoblastic bone formation and inhibitory effects on osteoclastic bone resorption in vitro, thereby increasing bone mass. β-cryptoxanthin has an effect on the gene expression of various proteins that are related osteoblastic bone formation and osteoclastic bone resororption in vitro. The intake of β-cryptoxanthin may have a preventive effect on bone loss in animal models for osteoporosis and in healthy human or postmenopausal women. Epidemiological studies suggest a potential role of β-cryptoxanthin as a sustainable nutritional approach to improving bone health of human subjects. β-Cryptoxanthin may be an osteogenic factor in preventing osteoporosis in human subjects.

Increased numbers of nonattached osteoclasts after long-term zoledronic acid therapy in mice

Osteoclasts are key players in the maintenance of bone, which is an endocrine target and organ. Bisphosphonates, used for the management of metastatic bone diseases and osteoporosis, suppress osteoclasts. However, the impact of continuously suppressed osteoclasts is unknown. In this study, mice received zoledronic acid (ZA) for 13 months, nearly half the lifespan of mice, and the effects of continual osteoclast suppression on the bone environment and oral wound healing were determined. ZA therapy suppressed osteoclasts, resulting in significantly more bone mass compared with control. Despite continuous and intense suppression of bone loss in mice receiving ZA, serum calcium levels were maintained in the normal range. No differences were noted in serum tartrate-resistant acid phosphatase (TRAP) 5b levels between ZA-treated and control mice. Histomorphometric analyses of bones revealed that ZA therapy significantly decreased osteoclasts on the bone surface but, instead, substantially increased TRAP(+) mononuclear cells and osteoclasts that were not on the bone surface. When oral trauma was induced, such TRAP(+) mononuclear and nonattached osteoclasts increased considerably with increased inflammatory cell infiltration in the wounds. As a result, oral wound healing was hindered at the connective tissue level. Healing of the epithelium was unaffected. These findings indicate that the continual suppression of osteoclasts does not affect serum calcium levels and that long-term ZA therapy stimulates nonattached osteoclast and TRAP(+) mononuclear cell formation that are expanded rapidly in response to oral trauma. Caution should be exercised when using the serum TRAcP5b to estimate the efficacy of antiresorptive therapy.

Is a daily supplementation with 40 microgram vitamin D3 sufficient? A randomised controlled trial

PURPOSE

The effect of 40 μg (1,600 IU) per day of vitamin D(3) on serum 25-hydroxyvitamin D (25(OH)D) and markers of bone and mineral metabolism was evaluated.

METHODS

This intervention study was designed as a double-blind randomised controlled trial. Forty-five community-dwelling subjects (32 females), age 55-84 years, at 58° North latitude were supplemented for 1 year with 40 μg vitamin D(3) plus 1,000 mg calcium per day, or with 1,000 mg calcium per day for controls. Safety parameters and 25(OH)D, intact parathyroid hormone (PTH), ionized calcium, bone-specific alkaline phosphatase (BALP), and tartrate-resistant acid phosphatase isoform 5b (TRACP5b) were measured over the study period.

RESULTS

All subjects supplemented with vitamin D(3) reached a 25(OH)D level above 50 nmol/L. Mean (SD) serum 25(OH)D increased from 50.4 (13.5) nmol/L to 84.2 (17.5) nmol/L, range 55.0-125.0 nmol/L in the vitamin D(3) supplemented group and the corresponding levels for the control group were 47.3 (14.1) nmol/L and 45.7 (13.4) nmol/L, range 26.0-73.0 nmol/L. No serious adverse event was recorded and the highest 25(OH)D level reached, 125.0 nmol/L, is well below toxic levels. BALP and TRACP5b did not change significantly over the study period.

CONCLUSIONS

This trial suggests that a daily supplementation with 40 μg vitamin D(3) is sufficient to secure a 25(OH)D level of 50 nmol/L. No side effects were observed in the study group.

Effects of cadmium on bone microstructure and serum tartrate-resistant acid phosphatase 5b in male rats

This study investigated the effects of cadmium on bone microstructure and serum tartrate-resistant acid phosphatase 5b (Tracp 5b) in male rats. Sprague-Dawley male rats were divided into three groups that were given CdCl2 by subcutaneous injection at doses of 0, 0.1 and 0.5 mg/kg body weight (bw) for 12 weeks, respectively. Before killing at the 12th week, microcomputed tomography scanning was performed on the proximal tibia, and urine samples were collected from all of the rats. All rats were then killed, and their blood was collected for biomarkers assay. Bone tissues were dissected for mineral density determinations and histology. The concentration of cadmium in the blood, urine and bone of rats treated with cadmium were significantly higher than in the control group. The bone mineral density, bone mineral concentrations and bone microstructure index of rats treated with cadmium at 0.5 mg/kg bw were clearly lower than in the control rats. Histological investigation also revealed damage to the bone microstructure caused by cadmium. Tracp 5b concentrations in rats treated with cadmium were dose dependently higher than the control. The concentration of cadmium in blood, urine and bone was significantly correlated with Tracp 5b and bone microstructure parameters. Cadmium was shown to induce bone microstructure damage, especially to trabecular bone. The elevated concentrations of serum Tracp 5b suggest that bone resorption mediated via osteoclasts is an important mechanism for the toxic effects of cadmium on bone.

Biochemical markers in osteoporosis: usefulness in clinical practice

Currently, the measurement of bone remodeling biomarkers is an innovate proposal in clinical evaluation of patients with osteoporosis. Its use may identify patients at increased risk of fracture as well as monitoring therapeutic efficacy. Because they constitute a relatively inexpensive non-invasive measurement, its use should be widespread for serial and frequent measurements of bone turnover. However, their analytical and biological variability limits their clinical applicability.

Suitability of tartrate-resistant acid phosphatase type 5b as a screening marker for bone mineral density in community-dwelling elderly individuals

Osteoporosis is a common disorder in aging populations that imposes considerable health problems. Tartrate-resistant acid phosphatase type 5b (TRAP-5b) is derived from osteoclasts, and is involved in normal bone homeostasis. Recently, a novel assay system for TRAP-5b, the fragments absorbed immunocapture enzymatic assay method, has been developed. To evaluate the suitability of TRAP-5b as a screening marker for bone mineral density (BMD), we explored the correlations between serum TRAP-5b concentrations and laboratory findings, body mass index, or BMD in 462 community-dwelling elderly individuals (249 men and 213 women, age 73.4±6.5 years) who participated in a regular medical screening program. By multivariate linear regression analysis adjusted for confounding factors, TRAP-5b was significantly correlated with body mass index (β=-0.005, p=0.043), alkaline phosphatase, a marker for osteoid formation and calcification (β=0.001, p<0.001), and triglyceride (β=-0.097, p=0.016) in men, and with body mass index (β=-0.009, p=0.025), alkaline phosphatase (β=0.001, p<0.001), calcium (β=-0.059, p=0.039), and bone trabecular area ratio (β=-0.47, p=0.025) in women. In conclusion, the elevated serum level of TRAP-5b is independently correlated with the decreased BMD in women, but not in men. Because measurement of TRAP-5b is not affected by food intake, and blood samples can be collected at any time of the day, we suggest the suitability of serum TRAP-5b as a simple marker for the evaluation of BMD in women.

Identification of CXCL13 as a marker for rheumatoid arthritis outcome using an in silico model of the rheumatic joint

OBJECTIVE

Rheumatoid arthritis (RA) is characterized by inflammation and joint destruction, with the degree of damage varying greatly among patients. Prediction of disease severity using known clinical and serologic risk factors is inaccurate. This study was undertaken to identify new serologic markers for RA severity using an in silico model of the rheumatic joint.

METHODS

An in silico model of a prototypical rheumatic joint was used to predict candidate markers associated with erosiveness. The following 4 markers were chosen for validation: tartrate-resistant acid phosphatase 5b (TRAP-5b), N-telopeptide of type I collagen (NTX), angiopoietin 2 (Ang-2), and CXCL13. Serum from 74 RA patients was used to study whether radiologic joint destruction (total erosion score and total Sharp/van der Heijde score [SHS]) after 4 years of disease was associated with serum levels at the time of diagnosis. Serum marker levels were determined using enzyme-linked immunosorbent assays. For confirmation, baseline serum levels were analyzed for an association with progression of joint damage over 7 years of followup in a cohort of 155 patients with early RA.

RESULTS

Comparison of high and low quartiles of erosion score and SHS at 4 years showed a difference in baseline serum CXCL13 level (P = 0.011 and P = 0.018, respectively). In the confirmation cohort, elevated baseline CXCL13 levels were associated with increased rates of joint destruction during 7 years of followup (P < 0.001 unadjusted and P ≤ 0.004 with adjustment for C-reactive protein level). Analyzing anti-CCP-2-positive and anti-CCP-2–negative RA separately yielded a significant result only in the anti-CCP-2-negative group (P ≤ 0.001).

CONCLUSION

Our findings indicate that CXCL13 is a novel serologic marker predictive of RA severity.This marker was identified with the help of an in silicomodel of the RA joint.

Osteal macrophages promote in vivo intramembranous bone healing in a mouse tibial injury model

Bone-lining tissues contain a population of resident macrophages termed osteomacs that interact with osteoblasts in vivo and control mineralization in vitro. The role of osteomacs in bone repair was investigated using a mouse tibial bone injury model that heals primarily through intramembranous ossification and progresses through all major phases of stabilized fracture repair. Immunohistochemical studies revealed that at least two macrophage populations, F4/80(+) Mac-2(-/low) TRACP(-) osteomacs and F4/80(+) Mac-2(hi) TRACP(-) inflammatory macrophages, were present within the bone injury site and persisted throughout the healing time course. In vivo depletion of osteomacs/macrophages (either using the Mafia transgenic mouse model or clodronate liposome delivery) or osteoclasts (recombinant osteoprotegerin treatment) established that osteomacs were required for deposition of collagen type 1(+) (CT1(+)) matrix and bone mineralization in the tibial injury model, as assessed by quantitative immunohistology and micro-computed tomography. Conversely, administration of the macrophage growth factor colony-stimulating factor 1 (CSF-1) increased the number of osteomacs/macrophages at the injury site significantly with a concurrent increase in new CT1(+) matrix deposition and enhanced mineralization. This study establishes osteomacs as participants in intramembranous bone healing and as targets for primary anabolic bone therapies.

Bone turnover in passive smoking female rat: relationships to change in bone mineral density

Background

Many studies have identified smoking as a risk factor for osteoporosis, but it is unclear whether passive smoking has an effect on bone mineral density and bone turnover and if such an effect could cause osteoporosis.The purpose of the study was to investigate the effect of passive smoking on bone mineral density (BMD) and bone turnover and the relationship between BMD and bone turnover in female rat.

Methods

Forty-eight female Wistar rats were randomized into six groups: 2-month, 3-month,4-month smoke-exposed rats and their controls. A rat model of passive cigarette smoking was prepared by breeding female rats in a cigarette-smoking box for 2, 3 or 4 months. Serums were analyzed for levels of osteocalcin, bone-specific alkaline phosphatase (b-ALP) and Tartrate-resistant acid phosphatase 5b (TRACP 5b). BMD was assessed at lumbar vertebrae and femur by dual energy X-ray absorptiometry in passive smoking rats and in control rats.

Results

BMD of lumbar spine and femur was lower in 4-month smoke-exposed female rats than that in controls. However, there was no significant difference in serum osteocalcin levels between smoke-exposed rats and controls. Significantly lower b-ALP and higher TRACP 5b were found in the 3-month or 4-month smoke-exposed rats compared to controls. Subsequent analysis showed that b-ALP positively correlated with BMD of the lumbar vertebrae(r = 0.764, P = 0.027) and femur(r = 0.899, P = 0.002) in 4-month smoke-exposed female rats. Furthermore, TRACP 5b levels negatively correlated with BMD of lumbar vertebrae (r = -0.871, P = 0.005) and femur (r = -0.715, P = 0.046) in 4-month smoke-exposed female rats.

Conclusion

Our data suggest that smoke exposure can inhibit bone formation and increase bone resorption. The hazardous effects of passive smoking on bone status are associated with increased bone turnover in female rat.

Severe nutritional iron-deficiency anaemia has a negative effect on some bone turnover biomarkers in rats

BACKGROUND

The role of iron (Fe) in bone formation and disease have not received much attention, a fact that is interesting given the known biochemical role that this mineral has upon collagen maturation together with the high prevalence of Fe-deficiency anaemia worldwide.

AIM

To investigate the changes in bone formation, resorption and mineral content in developing rats with induced nutritional Fe-deficiency anaemia.

METHODS

Thirty male Wistar rats were divided into two groups, a control group receiving AIN-93G diet with normal-Fe content and an anaemic group receiving AIN-93G diet with low-Fe content for 40 days. Both diets were prepared with an adequate calcium (Ca) and phosphorus (P) content. The most representative serum bone turnover biomarkers and femur and sternum calcium and phosphorus content, together with sternum Fe content were determined in both experimental groups.

RESULTS

In anaemic rats, bone matrix formation diminished as revealed by the lower amount of procollagen type I N-terminal propeptide. Bone resorption process increased in Fe deficiency as shown by the increase of serum parathyroid hormone, tartrate-resistant acid phosphatase and levels of degradation products from C-terminal telopeptides of type I collagen released to the serum. In addition, mineralization process was affected by Fe deficiency, because Ca and P content in femur decreased markedly.

CONCLUSIONS

Fe-deficiency anaemia had a significant impact upon bone, affecting bone mineralization, decreasing the matrix formation and increasing bone resorption, therefore it is of great interest to assess bone status in situation of Fe-deficiency anaemia.

Serum tartrate-resistant acid phosphatase isoform 5a (TRACP5a) as a potential risk marker in cardiovascular disease

OBJECTIVE

This study was undertaken to determine the association between serum tartrate-resistant acid phosphatase 5a (TRACP5a) and cardiovascular disease (CVD) risk.

METHODS

Four hundred patients were enrolled including, 291 asymptomatic subjects grouped by the number of traditional risk factors, 36 patients undergoing cardiac arteriography, 34 undergoing percutaneous cardiac intervention, and 39 with acute myocardial infarction. Serum was collected at baseline and, in arteriograpy and intervention groups, periodically for 1 week afterward. In addition to laboratory and clinical evaluation for risk assessment, serum TRACP5a, C-reactive protein (CRP) and interleukin-6 (IL-6) were determined.

RESULTS

All biomarkers rose with increasing CVD risk. Only serum TRACP5a, logCRP and cholesterol were elevated in symptomatic patients. Serum TRACP5a was higher in men and correlated with age, logCRP, logIL-6 and log-triglycerides, and in symptomatic patients, with the number of diseased coronary arteries. IL-6 and CRP showed acute phase responses, whereas TRACP5a did not change over 1 week after arteriography or intervention. After adjustment for all other variables and risk factors, TRACP5a and logCRP were the only biomarkers to associate with symptomatic disease. TRACP5a was more specific than CRP to predict myocardial infarction among all subjects.

CONCLUSIONS

Serum TRACP5a is a macrophage-derived inflammation marker associated with CVD risk, and with coronary vessel disease and its severity and may be a useful marker for screening and assessment of CVD risk.

Hyperadiponectinemia enhances bone formation in mice

BACKGROUND

There is growing evidence that adiponectin, a physiologically active polypeptide secreted by adipocytes, controls not only adipose tissue but also bone metabolism. However, a role for adiponectin in bone development remains controversial.

METHODS

We therefore investigated the endocrine effects of adiponectin on bone metabolism using 12-week-old male transgenic (Ad-Tg) mice with significant hyperadiponectinemia overexpressing human full-length adiponectin in the liver.

RESULTS

In Ad-Tg mice, the serum level of osteocalcin was significantly increased, but the levels of RANKL, osteoprotegerin, and TRAP5b were not. Bone mass was significantly greater in Ad-Tg mice with increased bone formation. In contrast, bone resorption parameters including the number of osteoclasts and eroded surface area did not differ between Ad-Tg and their littermates.

CONCLUSIONS

These findings demonstrate that hyperadiponectinemia enhances bone formation in mice.

The bone marrow microenvironment contributes to type I diabetes induced osteoblast death

Type I diabetes increases an individual's risk for bone loss and fracture, predominantly through suppression of osteoblast activity (bone formation). During diabetes onset, levels of blood glucose and pro-inflammatory cytokines (including tumor necrosis factor α (TNFα)) increased. At the same time, levels of osteoblast markers are rapidly decreased and stay decreased chronically (i.e., 40 days later) at which point bone loss is clearly evident. We hypothesized that early bone marrow inflammation can promote osteoblast death and hence reduced osteoblast markers. Indeed, examination of type I diabetic mouse bones demonstrates a greater than twofold increase in osteoblast TUNEL staining and increased expression of pro-apoptotic factors. Osteoblast death was amplified in both pharmacologic and spontaneous diabetic mouse models. Given the known signaling and inter-relationships between marrow cells and osteoblasts, we examined the role of diabetic marrow in causing the osteoblast death. Co-culture studies demonstrate that compared to control marrow cells, diabetic bone marrow cells increase osteoblast (MC3T3 and bone marrow derived) caspase 3 activity and the ratio of Bax/Bcl-2 expression. Mouse blood glucose levels positively correlated with bone marrow induced osteoblast death and negatively correlated with osteocalcin expression in bone, suggesting a relationship between type I diabetes, bone marrow and osteoblast death. TNF expression was elevated in diabetic marrow (but not co-cultured osteoblasts); therefore, we treated co-cultures with TNFα neutralizing antibodies. The antibody protected osteoblasts from bone marrow induced death. Taken together, our findings implicate the bone marrow microenvironment and TNFα in mediating osteoblast death and contributing to type I diabetic bone loss.

Assessment of bone remodelling in childhood-onset systemic lupus erythematosus

OBJECTIVE

To identify predictors of bone remodelling in children and young adults with SLE.

METHODS

Ninety subjects with SLE aged 8-22 years underwent yearly measurements of height, bone age, bone turnover markers, serum Type I IFNs, SLEDAI and BMD. Predictors of bone turnover were examined using serum osteocalcin as a marker of bone formation and both serum tartrate-resistant acid phosphatase (TRAP) and urine N-telopeptide (NTx) as markers of bone resorption.

RESULTS

Subjects demonstrated short stature, high BMI and bone age delay. A spine BMD Z-score of less than -2.0 was seen in 16.1% of subject visits. Serum osteocalcin was negatively correlated with glucocorticoid dose (Spearman rank correlation coefficient R = -0.34, P < 0.0001) but was not associated with SLEDAI after adjustment for confounders. Serum TRAP was negatively associated with SLEDAI, even after controlling for confounders (P = 0.04). Similar results were obtained for urine NTx. There was a negative association between TRAP and serum IFN-β (P = 0.03).

CONCLUSIONS

In this population of children and young adults with moderate lupus disease activity, glucocorticoid dose was a negative predictor of bone formation, whereas lupus disease activity was not. Interestingly, lupus disease activity was a negative predictor of bone resorption, suggesting that lupus disease activity is not the primary factor contributing to the bone deficits of childhood-onset SLE. The potential protective role of IFN-β and the effects of SLE treatment on bone loss require further study.

Bone metabolism markers in sports medicine

Bone mass can be viewed as the net product of two counteracting metabolic processes, bone formation and bone resorption, which allow the skeleton to carry out its principal functions: mechanical support of the body, calcium dynamic deposition and haemopoiesis. Besides radiological methods, several blood and urinary molecules have been identified as markers of bone metabolic activity for estimating the rates and direction of the biological activities governing bone turnover. The advantages for the use of bone metabolism markers are that they are potentially less dangerous than radiological determinations, are more sensitive to changes in bone metabolism than radiological methods and are easily collected and analysed. The disadvantages are that they have high biological variability. Physical exercise is a known source of bone turnover and is recommended for preventing osteoporosis and bone metabolism problems. There are numerous experiments on bone metabolism markers after acute exercise, but not after long-term training and during or after a whole competition season. Moreover, few studies on bone metabolism markers have evaluated their performance in elite and top-level athletes, who have a higher bone turnover than sedentary individuals. Despite discrepant results among studies, most have shown that short exercise is insufficient for modifying serum concentrations of bone metabolism markers. Marker variations are more evident after several hours or days after exercise, bone formation markers are more sensitive than bone resorption markers, and stimulation of osteoblast and/or osteoclast functions is exercise dependent but the response is not immediate. The response depends on the type of exercise; the markers seem to be less sensitive to resistance exercise and the intensity of exercise is not discriminate. Comparisons between trained subjects and untrained controls have demonstrated the influence of exercise on bone turnover. During training, carboxy-terminal collagen cross-links (CTx), a bone resorption marker, was shown to be less sensitive than amino-terminal cross-linking telopeptide of type I collagen (NTx) and urinary pyridinolines, which were sensitive to anaerobic exercise. Whereas, the bone formation markers, bone alkaline phosphatase (BAP) and osteocalcin (OC) changed after 1 month and 2 months of an exercise programme, respectively. After 2 months, while BAP normalized, it was found to be sensitive to aerobic exercise and OC was found to be sensitive to anaerobic exercise. After prolonged training and competition, bone formation markers are found to change in sedentary subjects enrolled in a physical activity programme. Professional athletes show changes in bone formation markers depending on programme intensity, whereas bone resorption appears to stabilize. Crucial for long-term training, are the characteristics of exercise (e.g. weight-bearing, impact).

Differential expression of tartrate-resistant acid phosphatase isoforms 5a and 5b by tumor and stromal cells in human metastatic bone disease

Tartrate-resistant acid phosphatase (TRAP) exists in human serum as two major isoforms, monomeric 5a and proteolytically processed enzymatically active 5b. The 5b isoform is secreted by osteoclasts and has recently been advocated as a serum marker for bone metastasis in breast cancer patients. The 5a isoform, on the other hand, is not bone-derived and has been proposed to be a marker of activated macrophages and chronic inflammation. In this study, expression of TRAP protein and enzymatic activity in bone metastases from different primary sites was examined. TRAP activity was high in bone metastases from prostate cancer, intermediate in breast cancer, and low in lung and kidney cancers. The partially purified TRAP from breast cancer bone metastasis samples exhibited the enzymatic characteristics of purple acid phosphatase. Both 5a and 5b isoforms were expressed in bone metastases of different histogenetic origins, i.e. prostate, breast, lung and kidney, and also a novel previously unreported 42 kDa variant of the TRAP 5a isoform was identified in bone metastases. This novel TRAP 5a isoform was absent in human bone, indicating that the 42 kDa variant is specific to metastatic cancer tissue. Immunohistochemistry revealed that metastatic cancer cells were the predominant source of TRAP 5a, whereas tumor-associated macrophages and occasionally multinucleated giant cells in the tumor stroma preferentially expressed the proteolytically processed TRAP 5b variant. Our results indicate the presence of a previously unstudied variant of monomeric TRAP 5a in cancer cells, which may have functional and diagnostic implications. Moreover, the presence of TRAP-positive macrophages in bone metastases could, together with cancer cells and osteoclasts, contribute to the elevated levels of serum TRAP activity observed in patients with bone metastases.

Serum tartrate-resistant acid phosphatase 5b (TRACP5b) activity as a biomarker for bone metastasis in non-small cell lung cancer patients

BACKGROUND

Diagnosis and follow-up of bone metastasis (BMet) in non-small cell lung cancer (NSCLC) patients usually rely on symptoms and image studies. A serum marker of bone resorption may improve the quality of treatment in such patients. Tartrate-resistant acid phosphatase 5b (TRACP5b) is a specific marker for osteoclasts and we proposed it can be used as a marker of BMet in NSCLC patients.

METHODS

In November 2002 till August 2008 serum samples were obtained from 141 newly diagnosed stage IIIA, IIIB or IV NSCLC patients and 41 normal subjects. All patients received baseline bone scintinography examination and evaluation of clinical symptoms as a standard of BMet diagnosis. Patients were divided into 2 groups by having BMet (Group I, n = 72) or not (Group II, n = 69). An in-house immunoassay using a TRACP-specific monoclonal antibody, 14G6, was used to measure the serum TRACP5b activity at pH 6.1.

RESULTS

The mean serum TRACP5b activities of Group I, Group II and normal subjects were 3.50 ± 2.2 3U/l, 2.09 ± 0.72 U/l and 2.33 ± 0.52 U/l, respectively. After adjusting for age, stage, gender, and histology in a generalized linear model, Group I has significantly higher TRACP5b activity than Group II (p < 0.001). The receiver operating characteristic analysis established a cutoff value of 2.551 U/l to identify BMet in NSCLC patients with a sensitivity of 63.9% and a specificity of 76.8%. TRACP5b activity declined in patients who responded to treatment (p = 0.047), and elevated in patients who developed new BMet (p = 0.05).

CONCLUSIONS

Serum TRACP5b activity test is a potentially useful adjunct in diagnosing and monitoring BMet in NSCLC. Further study is warranted to establish its real value in diagnosis and monitoring of BMet in NSCLC patients.

Oleoyl serine, an endogenous N-acyl amide, modulates bone remodeling and mass

Bone mass is determined by a continuous remodeling process, whereby the mineralized matrix is being removed by osteoclasts and subsequently replaced with newly formed bone tissue produced by osteoblasts. Here we report the presence of endogenous amides of long-chain fatty acids with amino acids or with ethanolamine (N-acyl amides) in mouse bone. Of these compounds, N-oleoyl-l-serine (OS) had the highest activity in an osteoblast proliferation assay. In these cells, OS triggers a Gi-protein-coupled receptor and Erk1/2. It also mitigates osteoclast number by promoting osteoclast apoptosis through the inhibition of Erk1/2 phosphorylation and receptor activator of nuclear-κB ligand (RANKL) expression in bone marrow stromal cells and osteoblasts. In intact mice, OS moderately increases bone volume density mainly by inhibiting bone resorption. However, in a mouse ovariectomy (OVX) model for osteoporosis, OS effectively rescues bone loss by increasing bone formation and markedly restraining bone resorption. The differential effect of exogenous OS in the OVX vs. intact animals is apparently a result of an OVX-induced decrease in skeletal OS levels. These data show that OS is a previously unexplored lipid regulator of bone remodeling. It represents a lead to antiosteoporotic drug discovery, advantageous to currently available therapies, which are essentially either proformative or antiresorptive.

A20 suppresses inflammatory responses and bone destruction in human fibroblast-like synoviocytes and in mice with collagen-induced arthritis

OBJECTIVE

Nuclear factor-kappaB (NF-kappaB) has been implicated as a therapeutic target for the treatment of rheumatoid arthritis (RA). The purpose of this study was to determine whether A20, a universal inhibitor of NF-kappaB, might have antiarthritic effects.

METHODS

An adenovirus containing A20 complementary DNA (AdA20) was used to deliver A20 to human rheumatoid fibroblast-like synoviocytes (FLS) in vitro as well as to mice with collagen-induced arthritis (CIA) in vivo via intraarticular injection into the ankle joints bilaterally.

RESULTS

In vitro experiments demonstrated that AdA20 suppressed NF-kappaB activation, chemokine production, and matrix metalloproteinase secretion induced by tumor necrosis factor alpha in FLS. Mice with CIA that were treated with AdA20 had a lower cumulative disease incidence and severity of arthritis, based on hind paw thickness, radiologic and histopathologic findings, and inflammatory cytokine levels, than did control virus-injected mice. The protective effects of AdA20 were mediated by the inhibition of the NF-kappaB signaling pathway. The severity of arthritis was also significantly decreased in the untreated front paws, indicating a beneficial systemic effect of local suppression of NF-kappaB. Surprisingly, mice treated with AdA20 after the onset of CIA had significantly decreased arthritis severity from the onset of clinical signs to the end of the study.

CONCLUSION

These results suggest that using A20 to block the NF-kappaB pathway in rheumatoid joints reduces both the inflammatory response and the tissue destruction. The development of an immunoregulatory strategy based on A20 may therefore have therapeutic potential in the treatment of RA.