Evidence for both respiratory syncytial virus and measles virus antigens in the osteoclasts of patients with Paget's disease of bone

Recent ultrastructural and immunohistochemical evidence supports the hypothesis that Paget's disease of bone is a slow viral infection of the Paramyxoviridae family. Conflicting evidence for the presence of respiratory syncytial virus (RSV), a pneumovirus, or measles, a morbillivirus, has been reported. By the indirect fluorescent antibody assay, four RSV antisera were compared with four measles antisera on serial sections of pagetic bone or replicate coverslips of cells from pagetic bone grown in culture from 30 patients. Results produced positive immunofluorescence for RSV in 28 of 29 patients and positive immunofluorescence for measles in 11 of 22 patients. Of the 20 patients from whom comparable samples could be tested for antigens, 11 were found to harbor both antigens. These studies support the hypothesis that Paget's disease of bone is a slow viral infection of the Paramyxoviridae family more closely related to the pneumoviruses than the morbilliviruses.     

Demonstration by immunofluorescence and immunoperoxidase of an antigen of the measles type in the osteoclasts of Paget's disease of bone]

The intra nuclear and intra cytoplasmic inclusions described in osteoclasts in PAGET's bone disease are morphologically similar to those observed in subacute sclerosing panencephalitis. Immunological techniques using different specific immune sera demonstrate the presence of an antigenic structure of viral origin in osteoclasts in PAGET's bone disease. A measles or a measles like virus is most likely to be involved and may play a role in the etiology of the disease.     

Hypercalcaemia in Paget's disease of bone.

Albright in 1944 described a syndrome of hypercalcaemia in patients immobilized following fractures through bones affected with Paget's disease. This paper reports a further two cases in which this syndrome was considered the cause of hypercalcaemia with fatal outcome. Both patients had parathyroid adenomata. The literature is reviewed, and it is argued that no firm evidence for the existence of this syndrome has ever been put forward. The finding of hypercalcaemia in Paget's disease of bone should prompt an exhaustive search for its cause.     

Canine distemper virus localised in bone cells of patients with Paget's disease

The technique of in situ hybridisation was applied using radioactively labelled riboprobes to examine for the presence of canine distemper (CDV) and measles (MV) RNA in Paget's disease of bone. The results indicate that in 41% of Paget's patients, CDV RNA could be detected in osteoclasts, osteoblasts, and osteocytes, but not in controls. In contrast, RNA to the measles virus was not detected. We suggest that CDV may in some cases play a role in the aetiology of Paget's disease.     

Prevalence of Paget's disease of bone in Italy.

We examined the prevalence of PDB in Italy from radiological, scintigraphic, and biochemical surveys in two Italian towns. Prevalence rates varied from 0.7% to 2.4%, were higher in males than in females, and slightly differed between the two towns. Unlike previous studies in populations of British descent, no secular trend for a decreasing prevalence emerged. INTRODUCTION: Clinical, radiological, and necropsy data from different countries suggested pronounced geographical variations in the prevalence of Paget's disease of bone (PDB). Despite the impact of the disease on the population, there are limited data on the prevalence of PDB in Italy. MATERIALS AND METHODS: The objective of this study was to estimate the prevalence of PDB in the district of Siena (Central Italy) and Turin (Northern Italy) from radiological, biochemical, and scintigraphic surveys. We examined a sample of 1778 consecutive pelvic radiographs performed between 1999 and 2000 at the Hospital Radiology Unit in Siena and 6609 pelvic radiographs performed in 1986-1987, 1992-1993, and 1999-2002 from the Radiology Department of Molinette Hospital in Turin. In Siena, 7906 consecutive (99m)TC-MDP bone scans performed over a 4-year period (January 2000 to May 2004) were also screened for the presence of PDB, and the prevalence of elevated alkaline phosphatase (ALP) levels (>300 UI/liter) was estimated from 7449 computerized medical records over a 3-year period (January 2000 to February 2003). The finding of PDB on the pelvic radiograph and bone scan was based on standardized radiological criteria. RESULTS: At the end of the radiological surveys, 16/1778 pelvic PDB cases (8 males and 8 females) were observed in Siena and 41/6609 (27 males and 14 females) in Turin. The crude prevalence of the disease was 0.89% in Siena and 0.62% in Turin. Given that pelvic involvement is commonly described in 60-90% of PDB patients, the estimated overall prevalence of PDB ranged from 1.0% to 1.5% in Siena and from 0.7% to 1.0% in Turin. No decrease in the prevalence of PDB was evident after comparison of prevalence rates from different periods. Biochemical analyses showed 296/7449 subjects with elevated ALP levels and normal liver enzymes, 87 of whom had confirmed diagnosis of PDB. The estimated prevalence of biochemical PDB was 1.5%. The scintigraphic survey showed a PDB prevalence of 194/7906 (2.4%), which was significantly higher than the radiological and biochemical estimates. CONCLUSIONS: Our surveys suggest that PDB in Italy has an estimated prevalence of at least 1%, comparable with that observed in United States and other European countries, but lower than that described in Britain and New Zealand. No secular trend for a decreasing prevalence of PDB was observed.     

The diagnosis of Paget's disease of bone.

Paget's disease of the bone is a common disorder and usually presents no diagnostic difficulty. However, atypical cases may cause problems in diagnosis, particularly in younger patients, and this paper describes some of the more unusual modes of presentation mainly related to the osteolytic phase and to accentuation of normal anatomical features. The role of various imaging techniques is discussed, emphasizing that recognition of the plain radiographic changes of Paget's disease remains the key to diagnosis in most cases.     

Bone morphogenetic proteins in bone stimulate osteoclasts and osteoblasts during bone development.

In this study, overexpression of noggin, a BMP antagonist, in developing bone caused significantly decreased osteoclast number as well as bone formation rate, resulting in increased bone mass with immature bone quality. BMP signaling plays important roles in normal bone development and regulation of bone resorption. INTRODUCTION: Bone morphogenetic proteins (BMPs) act on various types of cells. Although involvement of BMP signals in osteoblast differentiation has been studied extensively, the effects of BMPs on osteoclasts have not been widely researched. Consequently, the net effects of BMPs on bone remain unclear. The purpose of this study was to delineate more fully the role of BMPs in skeletal biology. MATERIALS AND METHODS: We generated transgenic mice that express BMP4 or noggin in bone under the control of the 2.3-kb alpha1(I) collagen chain gene (Col1a1) promoter, and analyzed their bone phenotype. We also analyzed bone of transgenic mice expressing BMP4 specifically in cartilage. RESULTS: Mice overexpressing BMP4 in bone developed severe osteopenia with increased osteoclast number. Mice overexpressing noggin, a BMP antagonist, in bone showed increased bone volume associated with decreased bone formation rate and decreased osteoclast number. The noggin-transgenic tibias exhibited reduced periosteal bone formation and reduced resorption of immature bone in marrow spaces, associated with frequent fractures at the diaphysis. Co-culture of primary osteoblasts prepared from noggin-transgenic calvariae and wildtype spleen cells resulted in poor osteoclast formation, which was rescued by addition of recombinant BMP2, suggesting that noggin inhibits osteoclast formation by attenuating BMP activities in noggin-transgenic mice. The expression levels of Rankl were not decreased in primary osteoblasts from noggin transgenic mice. Immunoblot analysis showed increased phosphorylation of Smad1/5/8 in osteoclast precursor cells after 20-minute treatment with BMPs, suggesting that these cells are stimulated by BMPs. Mice overexpressing BMP4 in cartilage had enlarged bones containing thick trabeculae, possibly because of expansion of cartilage anlagen. CONCLUSIONS: Overexpression of noggin in bone revealed that BMP signals regulate bone development through stimulation of osteoblasts and osteoclasts.     

Treatment of Paget's disease of bone with mithramycin.

The hypothesis that Paget's disease of bone is a low grade neoplastic process led us to use the cytotoxic antibiotic mithramycin in its treatment. The dramatic effects observed on the serum calcium and alkaline phosphatase, and urinary hydroxyproline are compatible with the concept that mithramycin is primarily toxic to osteoclasts. Subjective and objective clinical effects establish this agent as useful in the treatment of Paget's disease despite its observed toxicity to other organ systems.     

Bone morphogenetic protein induces bone in the squirrel monkey, but bone matrix does not.

Demineralized bone matrix (DBM) reproducibly induces extraskeletal bone formation in rodents, but its effects in dogs and primates are negative or uncertain. In previous studies on the squirrel monkey, DBM did not induce bone, although the same implants were effective in nude rats. In the present study, the DBM was augmented with recombinant human bone morphogenetic protein-2 (BMP-2). Bone was formed in 10 of 12 monkeys, as verified by histology and calcium content. However, in 4 monkeys, the induced bone mass appeared smaller than the original implant. DBM controls induced microscopic amounts of bone in 2 out of 10 monkeys. In the nude rats, all DBM controls and augmented implants induced bone. The difficulties in achieving bone induction in higher animals may be overcome, at least partially, by using a higher concentration of the inductive protein than is present in DBM.     

Gene-environment interactions in Paget's disease of bone

ObjectivesThis study explored the role of outdoor and indoor air pollutants in Paget's disease of bone (PDB).MethodsWe performed a survey in 140 French-Canadian patients with PDB, including 39 carriers of p.Pro392Leu mutation (SQSTM1 gene) and 113 healthy not mutated controls. The survey covered outdoor air pollution near the residence and indoor air pollutants by focusing on heating fuels and exposure to tobacco smoke. In a subgroup of patients, urinary concentrations of 17 heavy metals and 11 polycyclic aromatic hydrocarbons were measured by mass spectrometry. In light of what we learned from the survey and urinary assays, we explored the in vitro effects of certain toxics on osteoclasts in PDB. We conducted in vitro monocytes differentiation from peripheral blood of more than 40 participants, whose osteoclasts were treated with or without the toxic. The morphology of osteoclasts, their bone resorption abilities, gene and protein expression levels, and cellular oxidative stress levels were assayed.ResultsAn inhibitory effect of cigarette smoke condensate and heavy metals was observed on morphology and bone resorption activity of patients’ osteoclasts. SQSTM1 gene expression was upregulated in osteoclasts from patients with PDB versus healthy controls in presence of cadmium, and SQSTM1 protein expression was upregulated in presence of bismuth and tobacco smoke condensates, in particular in osteoclasts from carriers of the SQSTM1 mutation. Furthermore, high levels of oxidative stress in patients’ osteoclasts were observed.ConclusionsOur in vitro experiments suggest an interaction between SQSTM1 gene and exposure to cadmium and tobacco smoke condensates.