transforming-growth-factor-alpha and Osteolysis

After an epoch in which was pretended to explain the etiopathogenetic phenomena observed in Cholesteatoma through enzymatic studies, nowadays other investigations focus the topic in the possible presence of immunobiologic alterations at cellular level, so the research work is directed to the occurrence, distribution and activity of several growth factors and leukins. In this paper the AA. made a perusal of the new acquisitions and devote themselves to two important aspects of the cholesteatoma: the biologic behaviour of the squamous cell epithelia with an uncontrolled growth and to the immunobiologic mechanisms responsible for the bone resorption.

Topics: Bone Resorption; Cholesteatoma; Ear, Middle; Epithelial Cells; HLA-DR Antigens; Humans; Keratinocytes; Keratins; Osteolysis; Transforming Growth Factor alpha

The neuropeptide calcitonin gene-related peptide (CGRP) has been described to have an inhibitory effect on endotoxin- and wear particle-induced inflammation in the early stages of periprosthetic osteolysis. In the present study, the crosstalk between immune cells and osteoblasts in osteolytic conditions treated with CGRP has been analyzed to evaluate whether the anti-inflammatory properties of the peptide also have a beneficial, i.e. an anti-resorptive and osteo-anabolic impact on bone metabolism.. MG-63 osteoblast-like cells were co-cultured with THP-1 macrophage-like cells stimulated with either ultra-high molecular weight polyethylene (UHMWPE) particles or different concentrations of bacterial lipopolysaccharides (LPS) and simultaneously treated with CGRP. Inflammation was monitored in terms of measuring the levels of tumor necrosis factor (TNF)-α secretion. Furthermore, the production of the osteoblast markers osteoprotegerin (OPG), receptor activator of nuclear factor κB ligand (RANKL), alkaline phosphatase (ALP) and osteopontin (OPN) was quantified. Also, ALP enzymatic activity was measured.. Stimulation of co-cultured THP-1 macrophages with either high levels of LPS or UHMWPE induced the secretion of TNF-α which could be inhibited by CGRP to a great extent. However, no remarkable changes in the OPG/RANKL ratio or bone ALP activity were observed. Interestingly, OPN was exclusively produced by THP-1 cells, thus acting as a marker of inflammation. In addition, TNF-α production in THP-1 single cell cultures was found to be considerably higher than in co-cultured cells.. In the co-culture system used in the present study, no obvious relation between inflammation, its mitigation by CGRP, and the modulation of bone metabolism became evident. Nonetheless, the results suggest that during the onset of periprosthetic osteolysis the focus might lie on the modulation of inflammatory reactions. Possibly, implant-related inflammation might merely have an impact on osteoclast differentiation rather than on the regulation of osteoblast activity.

Topics: Biomarkers; Bone Density; Bone Remodeling; Calcitonin Gene-Related Peptide; Cell Line, Tumor; Cell Survival; Coculture Techniques; Humans; Inflammation Mediators; Macrophages; Osteoblasts; Osteolysis; Transforming Growth Factor alpha

Osteoclast formation is central to bone metabolism, occurring when myelomonocytic progenitors are stimulated by membrane-bound receptor activator of NFκB ligand (RANKL) on osteoblasts. Osteolytic hormones induce osteoblast RANKL expression, and reduce production of RANKL decoy receptor osteoprotegerin (OPG). However, rather than RANKL and OPG mRNA or protein levels, to measure hormonally-induced osteoclastogenic stimuli the net RANKL activity at the osteoblast surface needs to be determined. To estimate this we developed a cell reporter approach employing pre-osteoclast RAW264.7 cells transfected with luciferase reporter constructs controlled by NFκB (NFκB-RAW) or NFATc1 (NFAT-RAW)-binding promoter elements. Strong signals were induced in these cells by recombinant RANKL over 24h. When NFκB-RAW cells were co-cultured on osteoblastic cells (primary osteoblasts or Kusa O cells) stimulated by osteolytic factors 1,25(OH)(2) vitamin D(3) (1,25(OH)(2)D(3)) and prostaglandin E(2) (PGE(2)), a strong dose dependent signal in NFκB-RAW cells was induced. These signals were completely blocked by soluble recombinant RANKL receptor, RANK.Fc. This osteoblastic RANKL activity was sustained for 3 days in Kusa O cells; with 1,25(OH)(2)D(3) withdrawal, RANKL-induced signal was still detectable 24 h later. However, conditioned medium from stimulated osteoblasts induced no signal. TGFβ treatment inhibited osteoclast formation supported by 1,25(OH)(2)D(3)-treated Kusa O cells, and likewise blocked RANKL-dependent signals in NFAT-RAW co-cultured with these cells. These data indicate net RANKL stimulus at the osteoblast surface is increased by 1,25(OH)(2)D(3) and PGE(2), and suppressed by TGFβ, in line with their effects on RANKL mRNA levels. These results demonstrate the utility of this simple co-culture-based reporter assay for osteoblast RANKL activity.

Topics: Animals; Biological Assay; Calcitriol; Cell Line; Cell Membrane; Coculture Techniques; Dinoprostone; Genes, Reporter; Luciferases; Mice; Mice, Inbred C57BL; NF-kappa B; Osteoblasts; Osteolysis; Osteoprotegerin; Promoter Regions, Genetic; RANK Ligand; Transforming Growth Factor alpha

The immunologic response to prosthetic biomaterial particles is characterized by macrophage-rich inflammatory infiltrate, formation of multinucleated giant cells, and aseptic loosening at the site of arthroplasty. We investigated the in vivo expression and tissue distribution of transforming growth factor alpha, macrophage colony-stimulating factor, and the receptor for colony-stimulating factor-1 at the site of bone erosion in patients with clinically failed orthopaedic implants (n = 30). The expression was further compared with that detected in the inflamed synovial membranes from patients with rheumatoid arthritis or osteoarthritis (n = 15) and one patient with osteoclastoma (giant cell tumour of bone). Immunostaining of the tissue demonstrated positivity for transforming growth factor alpha within the inflammatory macrophage and multinucleated giant cell infiltrate in the diseased synovial membrane and the bone-implant interface. A comparative analysis between the synovium and retrieval interface membranes (pseudosynovium) revealed a high level of expression of transforming growth factor alpha, with intense membrane staining on multinucleated giant cells in all failed arthroplasties with pseudosynovium. In addition, the frequency, antigenic phenotype, and pattern of transforming growth factor alpha expression on multinucleated giant cells in the interface were markedly similar to those observed for multinucleated giant cells in osteoclastoma. Multinucleated giant cells within the interface lacked the expression of macrophage colony-stimulating factor and colony-stimulating factor-1 receptor, whereas those at the bone surfaces exhibited strong immunoreactivity. The predominant expression of transforming growth factor alpha by multinucleated giant cells in the bone-implant interface and its similarity to osteoclastoma highlight the importance of assessing transforming growth factor alpha as a possible contributor to the development of bone-resorbing giant cells at the site of failed orthopaedic implants.

Topics: Arthritis, Rheumatoid; Arthroplasty, Replacement, Hip; Arthroplasty, Replacement, Knee; Bone Neoplasms; Breast Neoplasms; Carcinoma, Ductal, Breast; Fluorescent Antibody Technique, Indirect; Giant Cell Tumor of Bone; Giant Cells; Hip Prosthesis; Humans; Knee Prosthesis; Macrophage Colony-Stimulating Factor; Osteoarthritis; Osteolysis; Receptors, Colony-Stimulating Factor; Synovial Membrane; Transforming Growth Factor alpha