Biomedical subjects

N A Athanasou

Publications and source records attributed to N A Athanasou.

At least 19 recordsLinked to original sources

PubMed2006

RANKL-dependent and RANKL-independent mechanisms of macrophage-osteoclast differentiation in breast cancer.

The cellular and humoral mechanisms accounting for tumour osteolysis in metastatic breast cancer are uncertain. Osteoclasts, the specialised multinucleated cells responsible for tumour osteolysis, are derived from monocyte/macrophage precursors. Breast cancer-derived tumour-associated macrophages (TAMs) are capable of osteoclast differentiation but the cellular and humoral mechanisms controlling this activity are uncertain. In this study, TAMs were isolated from primary breast cancers and cultured in the presence and absence of cytokines/growth factors influencing osteoclastogenesis. Extensive TAM-osteoclast differentiation occurred only in the presence of RANKL and M-CSF; this process was inhibited by OPG and RANK:Fc, decoy receptors for RANKL. Breast cancer-derived fibroblasts and human bone stromal cells expressed mRNA for RANKL, OPG and TRAIL, and co-culture of these fibroblasts with human monocytes stimulated osteoclast formation by a RANKL-dependent mechanism. Osteoclast formation and lacunar resorption also occurred by a RANKL-independent mechanism when the conditioned medium from breast cancer cells, MDA-MB-231 and MCF-7, was added (with M-CSF) to monocyte cultures. Our findings indicate that TAMs in breast cancer are capable of osteoclast differentiation and that breast cancer-derived fibroblasts and breast cancer cells contribute to this process by producing soluble factors that influence osteoclast formation by RANKL-dependent and RANKL-independent mechanisms respectively.

Aged↗

PubMed2006

Low-grade osteosarcoma of the ethmoid sinus.

Osteosarcoma uncommonly arises in craniofacial bones and has only rarely been reported to arise in the ethmoid sinus. Most primary osteosarcomas arising in paranasal sinuses are high-grade malignancies. A low-grade osteosarcoma arising in the ethmoid sinus has not previously been described. We report the clinical, radiological and histological findings of a case of low-grade (parosteal osteosarcoma-like) osteosarcoma which arose in the ethmoid sinus.

Adult↗

PubMed2006

Malignant melanoma and bone resorption.

The cellular and humoral mechanisms accounting for osteolysis in skeletal metastases of malignant melanoma are uncertain. Osteoclasts, the specialised multinucleated cells that carry out bone resorption, are derived from monocyte/macrophage precursors. We isolated tumour-associated macrophages (TAMs) from metastatic (lymph node/skin) melanomas and cultured them in the presence and absence of osteoclastogenic cytokines and growth factors. The effect of tumour-derived fibroblasts and melanoma cells on osteoclast formation and resorption was also analysed. Melanoma TAMs (CD14+/CD51-) differentiated into osteoclasts (CD14-/CD51+) in the presence of receptor activator for nuclear factor kappaB ligand (RANKL) and macrophage-colony stimulating factor. Tumour-associated macrophage-osteoclast differentiation also occurred via a RANKL-independent pathway when TAMs were cultured with tumour necrosis factor-alpha and interleukin (IL)-1alpha. RT-PCR showed that fibroblasts isolated from metastatic melanomas expressed RANKL messenger RNA and the conditioned medium of cultured melanoma fibroblasts was found to be capable of inducing osteoclast formation in the absence of RANKL; this effect was inhibited by the addition of osteoprotegerin (OPG). We also found that cultured human SK-Mel-29 melanoma cells produce a soluble factor that induces osteoclast differentiation; this effect was not inhibited by OPG. Our findings indicate that TAMs in metastatic melanomas can differentiate into osteoclasts and that melanoma fibroblasts and melanoma tumour cells can induce osteoclast formation by RANKL-dependent and RANKL-independent mechanisms, respectively.

Aged↗

PubMed2006

Toxic osteoblastoma of the scapula.

Osteoblastoma rarely occurs in the scapula, and toxic osteoblastoma is a very rare subtype of this bone-forming tumour. This report details the clinical, radiological and pathological features of a toxic osteoblastoma of the scapula; it is the first reported case to be diagnosed correctly pre-operatively and treated appropriately by excision.

Biopsy↗

PubMed2006

LIGHT (TNFSF14), a novel mediator of bone resorption, is elevated in rheumatoid arthritis.

OBJECTIVE: Human osteoclast formation from mononuclear phagocyte precursors involves interactions between tumor necrosis factor (TNF) ligand superfamily members and their receptors. LIGHT is a transmembrane protein expressed and shed from the surface of activated T cells. Since activated T cells have been implicated in osteoclastogenesis in rheumatoid arthritis (RA), this study sought to determine whether LIGHT can regulate RANKL/cytokine-induced osteoclast formation, to identify the mechanism by which LIGHT influences osteoclastogenesis, and to investigate the presence of LIGHT in the serum of RA patients. METHODS: The effect of LIGHT on human and murine osteoclast formation was assessed in the presence and absence of neutralizing reagents to known osteoclastogenic factors. Serum levels of LIGHT in RA patients were measured by enzyme-linked immunosorbent assay. RESULTS: In the presence and absence of RANKL, LIGHT induced osteoclast formation from both human peripheral blood mononuclear cells and murine macrophage precursors, in a dose-dependent manner, whereas no inhibition was observed by adding osteoprotegerin, RANK:Fc, TNFalpha, or interleukin-8 or by blocking the LIGHT receptors herpesvirus entry mediator or lymphotoxin beta receptor. However, formation of osteoclasts was significantly decreased by the soluble decoy receptor for LIGHT, DcR3, and by blocking antibodies to the p75 component of the TNF receptor. A significant increase in LIGHT levels in the serum of RA patients compared with normal controls was also noted. CONCLUSION: Our results indicate that LIGHT promotes RANKL-mediated osteoclastogenesis and that it can induce osteoclast formation by a mechanism independent of RANKL. The increased concentration of LIGHT in patients with RA raises the possibility that LIGHT may play a role in immunopathogenic conditions that are associated with localized or systemic bone loss.

Animals↗

PubMed2006

Synovial fluid macrophages are capable of osteoclast formation and resorption.

To determine whether synovial fluid (SF) macrophages isolated from the SF of osteoarthritis (OA), rheumatoid arthritis (RA) and pyrophosphate arthropathy (PPA) joints are capable of osteoclast formation, and to investigate the cellular and humoral factors required for this to occur, SF macrophages (CD14+) were isolated from the knee joint SF from patients with OA, RA and PPA and cultured for up to 14 days with macrophage-colony stimulating factor (M-CSF) and soluble receptor activator for nuclear factor-kappaB ligand (RANKL) or tumour-necrosis factor-alpha (TNFalpha) and interleukin-1alpha (IL-1alpha). Osteoclast differentiation was assessed by expression of tartrate-resistant acid phosphatase (TRAP) and vitronectin receptor (VNR), F-actin ring formation and lacunar resorption. Osteoclast formation and lacunar resorption was seen in RANKL-treated cultures of SF macrophages isolated from OA, RA and PPA joints with the largest amount of resorption noted in RA and PPA SF macrophage cultures. In TNFalpha/IL-1alpha-treated RA and PPA SF macrophage cultures, osteoclasts capable of lacunar resorption were also formed. Lacunar resorption was more extensive in RANKL than TNFalpha/IL-1alpha-treated cultures. These findings indicate that SF macrophages are capable of differentiating into mature osteoclasts capable of lacunar resorption. M-CSF in combination with RANKL or TNFalpha/IL-1alpha was required for osteoclast formation. As inflammatory synovial fluids contain an increase in the number of macrophages and an increase in the amounts of RANKL, TNFalpha and IL-1alpha, these findings suggest that one means whereby bone erosions may form in rheumatoid or crystal arthritis is by differentiation of synovial fluid macrophages into osteoclasts.

Aged↗

PubMed2006

Bone stromal cells in pagetic bone and Paget's sarcoma express RANKL and support human osteoclast formation.

Paget's disease is a focal disorder of bone remodelling, in which there is an increase in osteoclast formation. A rare complication of Paget's disease is the development of a sarcoma, most commonly an osteosarcoma. Osteoclast formation occurs in the presence of macrophage-colony stimulating factor and receptor activator for nuclear factor-kappaB ligand (RANKL), and it has been shown that bone stromal cells in Paget's disease can influence osteoclast formation by modulating the expression of RANKL and its decoy receptor, osteoprotegerin (OPG). In this study we show that pagetic bone stromal cells express RANKL and that these cells promote osteoclast formation by a RANKL-dependent mechanism. Osteoclast formation in co-cultures of monocytes and either pagetic bone stromal cells or Paget's sarcoma stromal cells was not only induced by a contact-dependent mechanism but also occurred via the release of a soluble factor. In contrast to bone stromal cells isolated from normal controls, stromal cells isolated from morphologically normal bone in one patient with Paget's disease also stimulated osteoclast formation in this way; this osteoclastogenesis was inhibited by OPG. Our results indicate that Paget's bone stromal cells support osteoclast formation by a RANKL-dependent process which involves not only cell-cell contact but also secretion of soluble RANKL.

Aged↗

PubMed2006

Pathology of the torn rotator cuff tendon. Reduction in potential for repair as tear size increases.

We have studied cellular and vascular changes in different stages of full thickness tears of the rotator cuff. We examined biopsies from the supraspinatus tendon in 40 patients with chronic rotator cuff tears who were undergoing surgery and compared them with biopsies from four uninjured subscapularis tendons. Morphological and immunocytochemical methods using monoclonal antibodies directed against leucocytes, macrophages, mast cells, proliferative and vascular markers were used. Histological changes indicative of repair and inflammation were most evident in small sized rotator cuff tears with increased fibroblast cellularity and intimal hyperplasia, together with increased expression of leucocyte and vascular markers. These reparative and inflammatory changes diminished as the size of the rotator cuff tear increased. Marked oedema and degeneration was seen in large and massive tears, which more often showed chondroid metaplasia and amyloid deposition. There was no association between the age of the patient and the duration of symptoms. In contrast, large and massive tears showed no increase in the number of inflammatory cells and blood vessels. Small sized rotator cuff tears retained the greatest potential to heal, showing increased fibroblast cellularity, blood vessel proliferation and the presence of a significant inflammatory component. Tissue from large and massive tears is of such a degenerative nature that it may be a significant cause of re-rupture after surgical repair and could make healing improbable in this group.

Adult↗

PubMed2005

Arthroplasty membrane-derived fibroblasts directly induce osteoclast formation and osteolysis in aseptic loosening.

PURPOSE: Both macrophages and fibroblasts are the main cell types found in periprosthetic tissues surrounding failed joint arthroplasties. These fibroblasts are known to express RANKL and to produce TNFalpha, factors which promote osteoclast formation and bone resorption. In this study we have analysed the role that arthroplasty membrane-derived fibroblasts (AFb) play in inducing the generation of bone resorbing osteoclasts. METHODS: Fibroblasts were isolated from periprosthetic tissues and co-cultured with human monocytes in an osteoclast differentiation assay in the presence or absence of M-CSF and inhibitors of RANKL (OPG) and/or TNFalpha. RANKL expression by AFbs was determined by RT-PCR and the extent of osteoclast differentiation by the expression of TRAP, VNR and evidence of lacunar resorption. RESULTS: In the presence of M-CSF, large numbers of TRAP(+) and VNR(+) multinucleated cells capable of lacunar resorption, were noted in co-cultures of monocytes and RANKL-expressing AFbs. Cell-cell contact was required for osteoclast formation. The addition of OPG and anti-TNFalpha alone significantly reduced but did not abolish the extent of osteoclast formation, whereas the addition of both together abolished osteoclast formation and lacunar resorption. CONCLUSION: Our results indicate that fibroblasts in periprosthetic tissues are capable of inducing the differentiation of normal human peripheral blood mononuclear cells to mature osteoclasts by a mechanism that involves both RANKL and TNFalpha. Suppression of both RANKL and inflammatory cytokines is likely to be required to control periprosthetic osteolysis.

Aged↗

PubMed2005

Osteonecrosis in retrieved femoral heads after failed resurfacing arthroplasty of the hip.

We present the histological findings of bone retrieved from beneath the femoral components of failed metal-on-metal hip resurfacing arthroplasties. Of a total of 377 patients who underwent resurfacing arthroplasty, 13 required revision; for fracture of the femoral neck in eight, loosening of a component in three and for other reasons in two. None of these cases had shown histological evidence of osteonecrosis in the femoral bone at the time of the initial implantation. Bone from the remnant of the femoral head showed changes of osteonecrosis in all but one case at revision. In two cases of fracture which occurred within a week of implantation, the changes were compatible with early necrosis of the edge of the fracture. In the remaining six fractures, there were changes of established osteonecrosis. In all but one of the non-fracture cases, patchy osteonecrosis was seen. We conclude that histological evidence of osteonecrosis is a common finding in failed resurfaced hips. Given that osteonecrosis is extensive in resurfaced femoral heads which fail by fracture, it is likely to play a role in the causation of these fractures.

Arthroplasty, Replacement, Hip↗

PubMed2004

Transforming growth factor-beta induces osteoclast formation in the absence of RANKL.

Transforming growth factor beta (TGFbeta) is a multifunctional growth factor that is produced by many cells in bone and is abundant in the bone matrix. TGFbeta is known to regulate RANKL-induced osteoclast formation and bone resorbing activity. In this study we sought to determine whether TGFbeta could directly induce osteoclast formation by a RANKL-independent mechanism. We found that the addition of TGFbeta to cultures of human monocytes and RAW 264.7 cells (in the presence of M-CSF and the absence of RANKL, TNFalpha or IL-6/IL-11) was sufficient to induce the formation of TRAP+ and VNR+ cells, which formed actin rings and were capable of extensive lacunar resorption. The addition of osteoprotegerin or antibodies to TNFalpha and its receptors, as well as antibodies to gp130, did not inhibit lacunar resorption, indicating that TGFbeta did not act by stimulating RANKL, TNF or IL-6 production by monocytes. TGFbeta-induced osteoclast formation was qualitatively different from that induced by RANKL with numerous TRAP+/VNR+ mononuclear and small multinucleated cells being formed; these cells produced many small resorption lacunae. Our results indicate that TGFbeta, which is abundant in the bone matrix, can, in the presence of M-CSF, directly induce mononuclear phagocyte osteoclast precursors to differentiate into osteoclastic cells capable of lacunar resorption.

Actins↗

PubMed2004

Heterotopic bone formation following hip arthroplasty in Paget's disease.

Heterotopic bone formation in soft tissues occurs commonly in Paget's disease patients following a primary total hip arthroplasty (THA). The nature of this heterotopic bone has not been documented. In this report, we show that the heterotopic bone removed 14 years after primary THA in a case of Paget's disease was sclerotic, contained prominent mosaic cement lines and showed increased remodelling activity on the bone surface. In addition to these typically Pagetic histological features, it was noted ultrastructurally that the osteoclasts contained characteristic intranuclear viral-like inclusions. In contrast, the foreign body macrophages found in the joint pseudocapsule and pseudomembrane, which are a population of mononuclear precursor cells from which osteoclasts can be formed, did not contain viral-like inclusions. These findings are of interest regarding the pathogenesis of heterotopic bone formation following hip arthroplasty and the ontogeny of Pagetic osteoclasts.

Aged↗

PubMed2004

Expression of a lymphatic endothelial cell marker in benign and malignant vascular tumors.

Tumors of endothelial cell origin are relatively common. Soft tissue tumors and numerous subtypes of benign and malignant vascular tumors have been described; the histogenesis of many of these tumors is uncertain, and distinguishing between benign and malignant vascular tumors, some of which express lymphatic endothelial cell markers, can be problematic. In the present study, immunophenotypic expression of a novel hyaluronan receptor (LYVE-1), which is expressed by endothelial cells of normal lymphatic vessels but not blood vessels, was determined in benign and malignant vascular tumors. It was found that, except in lymphangiomas, intramuscular hemangiomas, and Masson's hemangiomas, endothelial cells in benign blood vessel tumors (including capillary and cavernous hemangiomas, glomus tumors, pyogenic granulomas, and epithelioid hemangiomas) were negative for LYVE-1, and that all angiosarcomas and Kaposi's sarcomas were positive for LYVE-1. Expression of LYVE-1 and other lymphatic endothelial cell markers in relatively few vascular neoplasms has implications for the histogenesis of these lesions, and may prove useful in distinguishing angiosarcoma and Kaposi's sarcoma from most common benign vascular tumors.

Biomarkers, Tumor↗

PubMed2004

Recent advances in osteoclast biology and pathological bone resorption.

The osteoclast is a bone-degrading polykaryon. Recent studies have clarified the differentiation of this cell and the biochemical mechanisms it uses to resorb bone. The osteoclast derives from a monocyte/macrophage precursor. Osteoclast formation requires permissive concentrations of M-CSF and is driven by contact with mesenchymal cells in bone that bear the TNF-family ligand RANKL. Osteoclast precursors express RANK, and the interaction between RANKL and RANK (which is inhibited by OPG) is the major determinant of osteoclast formation. Hormones, such as PTH/PTHrP, glucocorticoids and 1,25(OH)2D3, and humoral factors, including TNFalpha, interleukin-1, TGFss and prostaglandins, influence osteoclast formation by altering expression of these molecular factors. TNFalpha, IL-6 and IL-11 have also been shown to promote osteoclast formation by RANKL-independent processes. RANKL-dependent/independent osteoclast formation is likely to play an important role in conditions where there is pathological bone resorption such as inflammatory arthritis and malignant bone resorption. Osteoclast functional defects cause sclerotic bone disorders, many of which have recently been identified as specific genetic defects. Osteoclasts express specialized proteins including a vacuolar-type H+-ATPase that drives HCl secretion for dissolution of bone mineral. One v-ATPase component, the 116 kD V0 subunit, has several isoforms. Only one isoform, TCIRG1, is up-regulated in osteoclasts. Defects in TCIRG1 are common causes of osteopetrosis. HCl secretion is dependent on chloride channels; a chloride channel homologue, CLCN7, is another common defect in osteopetrosis. Humans who are deficient in carbonic anhydrase II or who have defects in phagocytosis also have variable defects in bone remodelling. Organic bone matrix is degraded by thiol proteinases, principally cathepsin K, and abnormalities in cathepsin K cause another sclerotic bone disorder, pycnodysostosis. Thus, bone turnover in normal subjects depends on relative expression of key cytokines, and defects in osteoclastic turnover usually reflect defects in specific ion transporters or enzymes that play essential roles in bone degradation.

Animals↗

PubMed2003

Subungual melanoma with osteocartilaginous differentiation.

Osteocartilaginous metaplasia is known to occur rarely in melanomas, particularly in subungual melanomas. We present a case of a calcified subungual soft tissue tumour in which biopsy of the lesion showed malignant round and spindle-shaped tumour cells, many of which were associated with the formation of cartilage and osteoid-like material. Subsequent resection showed clear histological evidence of a subungual melanoma. Tumour cells expressed S100, melan-A and neurone-specific enolase but were negative for HMB45. Diagnostic radiological and histological features and the nature of the osteocartilaginous differentiation within this lesion is discussed.

Antigens, Neoplasm↗

PubMed2003

Two distinct cellular mechanisms of osteoclast formation and bone resorption in periprosthetic osteolysis.

PURPOSE: TNFalpha and IL-1alpha are proinflammatory cytokines that are abundant in periprosthetic tissues. These cytokines stimulate bone resorption and have recently been shown to directly induce osteoclast formation in mouse marrow cultures. We examined whether TNFalpha and IL-1alpha can directly induce osteoclast formation from human arthroplasty-derived (CD14(+)) macrophages by a mechanism independent of RANKL-induced osteoclastogenesis. METHODS: TNFalpha and M-CSF (+/-IL-1alpha) were added to cultures of magnetically sorted (CD14(+)) and unsorted (CD14(+)/CD14(-)) cells isolated from the pseudomembrane of loosened hip arthroplasties. Osteoprotegerin (OPG), RANK:Fc and antibodies to TNF receptors (p55 and p75) were added to these cultures to distinguish the pathway of osteoclastogenesis. Osteoclast differentiation was assessed by expression of tartrate-resistant acid phosphatase (TRAP), vitronectin receptor (VNR) and lacunar resorption. RESULTS: The addition of TNFalpha (+/-IL-1alpha) resulted in differentiation of CD14(+) macrophages into TRAP(+) and VNR(+) multinucleated cells capable of extensive lacunar resorption. Both OPG and RANK:Fc (which inhibit RANKL-induced osteoclastogenesis) did not block osteoclastogenesis. The addition of antibodies directed against the p55 receptor subunit of TNF resulted in significant inhibition of osteoclast formation and lacunar resorption. CONCLUSIONS: Our results indicate that, in the presence of M-CSF, TNFalpha is sufficient for inducing human osteoclast differentiation from arthroplasty macrophages and that TNFalpha acts synergistically with IL-1alpha to stimulate lacunar resorption. This process is distinct from the RANK/RANKL signalling pathway and is likely to operate in periprosthetic tissues when there is heavy wear particle deposition and cytokine production.

Acetabulum↗

PubMed2003

Interleukin-6 and interleukin-11 support human osteoclast formation by a RANKL-independent mechanism.

Interleukin-6 (IL-6) and interleukin-11 (IL-11) are known to influence osteoclast formation and bone resorption. In order to determine whether IL-6 and IL-11 could independently support human osteoclast formation, these factors were added to cultures of human peripheral blood mononuclear cells of the monocyte (CD14(+)) fraction in the presence of macrophage colony-stimulating factor (M-CSF). Under these conditions, IL-6 and IL-11 induced the formation of multinucleated cells which were positive for TRAP, VNR, and calcitonin receptor and capable of lacunar resorption. Osteoclastogenesis induced by IL-6 and IL-11 was inhibited by the addition of an anti-gp130 antibody but not by osteoprotegerin. These results indicate that IL-6 and IL-11, which are thought to play a role in several osteolytic bone disorders, are directly capable of inducing osteoclast formation by a RANKL-independent mechanism.

Acid Phosphatase↗

PubMed2003

The effect of particle size and electrical charge on macrophage-osteoclast differentiation and bone resorption.

In aseptic loosening, there is commonly periprosthetic bone loss and a heavy macrophage infiltrate in response to biomaterial wear particles generated from the implant materials. Macrophages which have phagocytosed wear particles are known to be capable of differentiation into bone resorbing osteoclasts. In this investigation we determine the role of particle size and particle charge on this process. Mouse monocytes and macrophages were co-cultured with osteoblast-like UMR106 cells and 1,25 dihydroxyvitamin D3 in the presence or the absence of (i) various sizes of latex beads (0.1, 1, 10 and 100 microm) and (ii) uncharged, positively- or negatively-charged sephadex beads of uniform shape and composition. The extent of osteoclast differentiation by monocytes or foreign body macrophages was determined by the expression of the osteoclast-associated enzyme tartrate-resistant acid phosphatase and lacunar bone resorption. No significant difference in the extent of osteoclast formation and bone resorption was noted in response to particle size. Osteoclast formation was also not significantly different in the presence of positively/negatively charged and uncharged particles. These findings indicate that osteoclast formation is not significantly influenced by particle characteristics, such as particle size. They also add support to the hypothesis that macrophage involvement in periprosthetic osteolysis is not dependent on particle phagocytosis and that it may be induced by particle contact.

Journal Article↗