Histochemistry of tartrate-resistant acid phosphatase and carbonic anhydrase isoenzyme II in osteoclast-like giant cells in bone tumours

Giant Cells of Various Lesions Are Characterised by Different Expression Patterns of HLA-Molecules and Molecules Involved in the Cell Cycle, Bone Metabolism, and Lineage Affiliation: An Immunohistochemical Study with a Review of the Literature

Giant cells (GCs) are thought to originate from the fusion of monocytic lineage cells and arise amid multiple backgrounds. To compare GCs of different origins, we immunohistochemically characterised the GCs of reactive and neoplastic lesions (n = 47). We studied the expression of 15 molecules including HLA class II molecules those relevant to the cell cycle, bone metabolism and lineage affiliation. HLA-DR was detectable in the GCs of sarcoidosis, sarcoid-like lesions, tuberculosis, and foreign body granuloma. Cyclin D1 was expressed by the GCs of neoplastic lesions as well as the GCs of bony callus, fibroid epulis, and brown tumours. While cyclin E was detected in the GCs of all lesions, p16 and p21 showed a heterogeneous expression pattern. RANK was expressed by the GCs of all lesions except sarcoid-like lesions and xanthogranuloma. All GCs were RANK-L-negative, and the GCs of all lesions were osteoprotegerin-positive. Osteonectin was limited to the GCs of chondroblastoma. Osteopontin and TRAP were detected in the GCs of all lesions except xanthogranuloma. RUNX2 was heterogeneously expressed in the reactive and neoplastic cohort. The GCs of all lesions except foreign body granuloma expressed CD68, and all GCs were CD163- and langerin-negative. This profiling points to a functional diversity of GCs despite their similar morphology.

Cell cytoskeleton and proliferation study for the RANKL-induced RAW264.7 differentiation

Although document studies (including ours) have been reported the achieved in vitro osteoclastic cellular model establishment from the RAW264.7 cell lineage, there was no study directly reported that American Type Culture Collection (ATCC) cell bank has various RAW264.7 cell lineages. Besides that, for our knowledge there was only one study compared the two different RAW264.7TIB-71 and RAW264.7CRL-2278 cell lineages for their osteoclastic differentiation, and they concluded that the RAW264.7CRL-2278 demonstrated to generate much osteoclast than RAW264.7TIB-71 . However, on the contrary to their results we noticed the fusion of RAW264.7TIB-71 in our previous studies was much compromising. Therefore, we try to explore the two cell lineages for their properties in osteoclastic differentiation with an in-depth cellular cytoskeletal study. Our current study has showed that comparing to the RAW264.7CRL-2278 , RAW264.7TIB-71 demonstrated a much higher efficacies for RANKL-stimulated osteoclastic differentiation. Besides that, in our depth cytoskeletal studies, we found that the RANKL-induced RAW264.7TIB-71 cells could finally differentiate into mature osteoclasts. However, regardless the various pre-treatment conditions, there was no mature osteoclast formed in RANKL-induced RAW264.7CRL-2278 cell lineage.

Interleukin 17A: a Janus-faced regulator of osteoporosis

Interleukin (IL)-17A is a well-described mediator of bone resorption in inflammatory diseases, and postmenopausal osteoporosis is associated with increased serum levels of IL-17A. Ovariectomy (OVX) can be used as a model to study bone loss induced by estrogen deficiency and the role of IL-17A in osteoporosis development has previously been investigated using various methods to inhibit IL-17A signaling in this model. However, the studies show opposing results. While some publications reported IL-17A as a mediator of OVX-induced osteoporosis, others found a bone-protective role for IL-17 receptor signaling. In this study, we provide an explanation for the discrepancies in previous literature and show for the first time that loss of IL-17A has differential effects on OVX-induced osteoporosis; with IL-17A being important for cortical but not trabecular bone loss. Interestingly, the decrease in trabecular bone after OVX in IL-17A knock-out mice, was accompanied by increased adipogenesis depicted by elevated leptin levels. Additionally, the bone marrow adipose tissue expanded, and the bone-turnover decreased in ovariectomized mice lacking IL-17A compared to ovariectomized WT mice. Our results increase the understanding of how IL-17A signaling influences bone remodeling in the different bone compartments, which is of importance for the development of new treatments of post-menopausal osteoporosis.

Increased bone mass in a mouse model with low fat mass

Mice with impaired acute inflammatory responses within adipose tissue display reduced diet-induced fat mass gain associated with glucose intolerance and systemic inflammation. Therefore, acute adipose tissue inflammation is needed for a healthy expansion of adipose tissue. Because inflammatory disorders are associated with bone loss, we hypothesized that impaired acute adipose tissue inflammation leading to increased systemic inflammation results in a lower bone mass. To test this hypothesis, we used mice overexpressing an adenoviral protein complex, the receptor internalization and degradation (RID) complex that inhibits proinflammatory signaling, under the control of the aP2 promotor (RID tg mice), resulting in suppressed inflammatory signaling in adipocytes. As expected, RID tg mice had lower high-fat diet-induced weight and fat mass gain and higher systemic inflammation than littermate wild-type control mice. Contrary to our hypothesis, RID tg mice had increased bone mass in long bones and vertebrae, affecting trabecular and cortical parameters, as well as improved humeral biomechanical properties. We did not find any differences in bone formation or resorption parameters as determined by histology or enzyme immunoassay. However, bone marrow adiposity, often negatively associated with bone mass, was decreased in male RID tg mice as determined by histological analysis of tibia. In conclusion, mice with reduced fat mass due to impaired adipose tissue inflammation have increased bone mass.

Trabecular bone loss in collagen antibody-induced arthritis

Introduction

Postmenopausal women with rheumatoid arthritis (RA) have increased risk of developing osteoporosis due to chronic inflammation and estrogen deprivation. Collagen antibody-induced arthritis (CAIA), an experimental polyarthritis model representing the effector phase of arthritis, is mainly mediated by the innate immune system. Compared to the widely used collagen-induced arthritis model, CAIA is conveniently short and can be used in C57BL/6 mice, enabling studies with knock-out mice. However, the impact on bone of the CAIA model in C57BL/6 mice has not previously been studied. Therefore, the aim of this study was to determine if CAIA can be used to study postmenopausal arthritis-induced osteoporosis.

Methods

CAIA was induced by administration of collagen-type II antibodies and lipopolysaccharide to ovariectomized female C57BL/6J mice. Control mice received lipopolysaccharide, but no antibodies. Nine days later, femurs were collected for high-resolution micro-CT and histomorphometry. Serum was used to assess cartilage breakdown and levels of complement. Frequencies of immune cell subsets from bone marrow and lymph nodes were analyzed by flow cytometery.

Results

Trabecular bone mass was decreased and associated with increased number of osteoclasts per bone surface in the CAIA model. Also, the frequency of interleukin-17⁺ cells in lymph nodes was increased in CAIA.

Conclusion

The present study show that CAIA, a short reproducible arthritis model that is compatible with C57BL/6 mice, is associated with increased number of osteoclasts and trabecular bone loss.

Carbonic anhydrases II and XII are up-regulated in osteoclast-like cells in advanced human atherosclerotic plaques-Tampere Vascular Study

BACKGROUND AND AIMS

Carbonic anhydrases (CA) play a central role in osteoclast function and bone remodeling by catalyzing the formation of bicarbonate and proton from carbon dioxide. According to previous histochemical studies, advanced atherosclerotic plaques share similarities with bone. However, whether CAs are expressed in plaques is not known.

METHODS AND RESULTS

Whole genome expression array of arterial samples (n = 24) confirmed that several genes indicating osteoblastogenesis and osteoclastogenesis were up-regulated in plaques when compared to control vessel samples from internal thoracic arteries (n = 6), including CA2 and CA12, expression of which was also verified with quantitative reverse transcription polymerase chain reaction (RT-PCR). In atherosclerotic plaques there was 11.6-fold (P < 0.0001) and 11.4-fold (P < 0.0001) up-regulation of CA2 and CA12, compared to controls, respectively. According to quantitative PCR, CA2 expression was elevated in carotid (12.3-fold, P < 0.0001), femoral (13.2-fold, P < 0.01), and aortic plaques (7.5-fold, P < 0.0001). CA12 expression was elevated in carotid (11.6-fold, P < 0.0001), femoral (11.5-fold, P < 0.01), and aortic plaques (9.7-fold, P < 0.0001). CAII, CAXII, and CD68 and tartrate-resistant acid phosphatase (TRAP), a marker of osteoclast-like cells, were found to be co-localized in multinucleated giant cells in the atherosclerotic plaques using immunohistochemistry and double-staining immunofluorescence analysis.

CONCLUSIONS

The present findings provide evidence for the involvement of CAs in advanced atherosclerosis in osteoclast-like cells of monocyte-macrophage lineage.

Giant Cell Tumour of Bone in a Cat with Extraskeletal Metastases: Pathological and Immunohistochemical Study

A case of giant cell tumour of bone (GCTb) in the lung and in a subcutaneous mass located in the right flank, with a probable primary origin in the mid-diaphysis of the right tibia, was described in a 8-year-old female cat. Numerous multinucleated giant cells were homogeneously distributed among a population of ovoid or spindle-shaped mononuclear cells. All of them were positive for vimentin suggesting a mesenchymal origin. Spindle-shaped tumour cells resemble fibroblastic cells, showing collagen fibres in their vicinity. Ovoid mononuclear cells are similar to macrophages, with a cytoplasm rich in electron-dense lysosomes. Multinucleated giant cells appear morphologically similar to osteoclasts. These findings are supported for the positive reaction to tartrate-resistant acid phosphatase (TRAP) and lysozyme, encountered only in ovoid and multinucleated giant cells. No immunoreactivity against human oestrogen receptors was observed in the nuclei of any neoplastic cells.

Receptor activator of NF-kappaB ligand (RANKL) is expressed in chondroblastoma: possible involvement in osteoclastic giant cell recruitment

AIMS

Chondroblastoma is a rare, locally aggressive bone tumour that causes osteolytic destruction at the epiphyseal end of the affected bone. It is possible that tumour cells may stimulate osteoclastogenesis and osteolytic destruction through the production of receptor activator of NF-kappaB ligand (RANKL), which is a key molecule essential for regulating osteoclast formation and activity. Therefore, the expression of RANKL at both the mRNA and the protein level was investigated in chondroblastoma tumour tissue obtained from patients.

METHODS

The expression of RANKL gene transcripts was analysed by the reverse transcription-polymerase chain reaction (RT-PCR), and the cellular localisation of RANKL mRNA and protein was demonstrated by means of in situ hybridisation and immunohistochemistry.

RESULTS

RT-PCR analysis indicated that RANKL mRNA was present in all chondroblastoma specimens and normal cancellous bone samples, but not in normal articular cartilage and chondrosarcoma tissues. In contrast, gene transcripts of osteoprotegerin (OPG), the decoy receptor of RANKL, were detected in all types of tissues. The chondroid origin of neoplastic mononuclear cells in chondroblastoma was confirmed by positive S-100 immunohistochemical staining. Both RANKL mRNA and protein were exclusively expressed in these neoplastic mononuclear cells.

CONCLUSIONS

These findings suggest that RANKL may be involved in the tumour cell induced recruitment of osteoclast-like cells and consequent osteolytic bone destruction in chondroblastoma.

Primary giant cell tumor of soft tissue

BACKGROUND

Primary giant cell tumor of soft tissue, also known as soft tissue giant cell tumor of low malignant potential, is a rare soft tissue tumor located in both superficial and deep soft tissue. Histologically, these lesions bear a close resemblance to their bony counterparts, giant cell tumor of bone, with round to spindle-shaped cells intimately admixed with uniformly scattered osteoclast-like multinucleated giant cells. In 1989 in the dermatology literature, two malignant giant cell tumors of soft parts were described that filled the dermis and extended into the subcutaneous tissue.

METHODS

The authors report the rare occurrence of a giant cell tumor of soft tissue occurring primarily in the dermis that lacks overtly malignant features and clinically was thought to be an epidermal inclusion cyst.

RESULTS

Light microscopy revealed a non-encapsulated cellular dermal tumor containing numerous osteoclast-like giant cells. Cytologic atypia was minimal and the mitotic count averaged 2-3/10 HPF. The histologic differential diagnosis is also discussed.

CONCLUSION

Giant cell tumor of soft tissue is a rare neoplasm of the skin, however, recognition of this tumor is important due to its behavior as a low-grade malignancy.

Autocrine regulation of osteoclast formation and bone resorption by IL-1 alpha and TNF alpha

Bone resorption is regulated by the cytokines within marrow cells that mediate osteoclast formation and activation. IL-1 and TNF induce bone resorption by stimulating the production of osteoclast-like multinucleated cells and by increasing the bone-resorbing activity of formed osteoclasts. This study was designed to detect IL-1 and TNF in osteoclasts in vitro and to determine whether these cytokines up-regulate osteoclast differentiation and bone resorption. The production of IL-1 alpha, -beta, and TNF alpha, beta in osteoclasts was examined immunohistochemically and by in situ hybridization. In the co-culture of C57BL/6N mouse bone marrow and MC3T3-G2/PA6 cells, a colony of osteoclasts formed, and IL-1 alpha and TNF alpha were detected. However, IL-1 beta and TNF beta were not detected. To investigate the role of IL-1 alpha and TNF alpha from osteoclasts, we enumerated TRAP-positive cells and measured the resorption pit areas in the presence of antibodies against IL-1 alpha and TNF alpha. The addition of antibodies against IL-1 alpha and TNF alpha to the co-culture system decreased the number of TRAP-positive colonies at seven days after incubation (anti-IL-1 alpha, 25.0 +/- 2.3%; anti-TNF alpha, 41.7 +/- 3.7%; anti-IL-1 alpha + anti-TNF alpha, 40.5 +/- 1.3%; and control, 100%), and the ratio of mononuclear to multinuclear cells had changed (anti-IL-1 alpha, 90:10; anti-TNF alpha, 75:25; anti-IL-1 alpha+ anti-TNF alpha, 88:12; and control, 60:40). The total pit areas per dentin slice also decreased with the addition of antibodies (anti-IL-1 alpha, 28,828; anti-TNF alpha, 49,249; anti-IL-1 alpha + anti-TNF alpha, 30,685; and control, 303,139 mm2). These results suggest that local production of IL-1 alpha and TNF alpha by osteoclasts is an important mechanism for regulating the osteoclast differentiation and bone resorptive process.

Methods for the differentiation of giant cells in canine and feline neoplasias in paraffin sections

In the following study cells with at least two cell nuclei are addressed as giant cells. In 47 biopsies of feline neoplasias (fibrosarcoma, haemangioendothelsarcoma, mammary adenocarcinoma, osteoidsarcoma, complex sarcoma), and 25 biopsies of canine neoplasias (malignant seminoma, mammary adenocarcinoma, haemangioendothelsarcoma, fibrosarcoma, osteoblastic sarcoma, complex sarcoma) giant cells are distinguished either as neoplastic giant cells or as reactive (non-neoplastic) giant cells. Cell nuclei of neoplastic giant cells which are labelled with the monoclonal antibody MIB 1 are mitotic active; cell nuclei are polymorph and can show atypical mitosis; the cytoplasmic reaction with tartrate resistant acid phosphatase (TRAP) is negative. Negative reactions with MIB 1, positive TRAP staining and homogeneous cell nuclei are distinctive for osteoclast-like glant cells. Other non-neoplastic giant cells (e.g. foreign body cells, Langhans-giant cells) are negative with both MIB 1 and TRAP. Double staining of paraffin sections is possible. Routine formalin-fixation, embedding in paraffin and decalcifying tissue samples do not interfere with MIB 1 immunoreactions or TRAP reactions. Methodological modifications that were necessary for the preparation of paraffin sections from canine and feline tissue samples are discussed. As the presence of neoplastic giant tumour cells is an index for a poor prognosis in human medicine, not only the entity of the tumour must be named, but also the exact significance of the giant cell type:, e.g. fibrosarcoma with osteoclast-like giant cells, hepatic carcinoma with reactive giant cells, malignant seminoma with neoplastic giant cells, angiosarcoma with both neoplastic giant cells and osteoclast-like giant cells. This would enable the classification of further neoplasias dealing with clinical courses of the diseases. Over the past years our stains have remained stable. It is possible to carry out retrospective investigations with archived tissue samples and make permanent preparations. A reclassification and a refined form of diagnosis (tumour and giant cell type) would be recommended.