Osteoporosis is an extrahepatic complication of primary biliary cholangitis (PBC) that increases the risk of fractures and mortality. However, Epidemiological studies of osteoporosis in patients with PBC in China and the Asia-Pacific region is lack.

To assess the prevalence and clinical characteristics of osteoporosis in Chinese patients with PBC.

This retrospective analysis included consecutive patients with PBC from a tertiary care center in China who underwent bone mineral density (BMD) assessment using dual-energy X-ray absorptiometry between January 2013 and December 2021. We defined subjects with T-scores ≤ -2.5 in any sites (L1 to L4, femoral neck, or total hip) as having osteoporosis. Demographic, serological, clinical, and histological data were collected. Independent risk factors for osteoporosis were identified by multivariate logistic regression analysis.

A total of 268 patients with PBC [236 women (88.1%); mean age, 56.7 ± 10.6 years; 163 liver biopsies (60.8%)] were included. The overall prevalence of osteoporosis in patients with PBC was 45.5% (122/268), with the prevalence of osteoporosis in women and men being 47.0% and 34.4%, respectively. The prevalence of osteoporosis in postmenopausal women was significantly higher than that in premenopausal women (56.3% vs 21.0%, P < 0.001). Osteoporosis in patients with PBC is associated with age, fatigue, menopausal status, previous steroid therapy, body mass index (BMI), splenomegaly, gastroesophageal varices, ascites, Mayo risk score, histological stage, alanine aminotransferase, albumin, bilirubin, platelet and prothrombin activity. Multivariate regression analysis identified that older age, lower BMI, previous steroid therapy, higher Mayo risk score, and advanced histological stage as the main independent risk factors for osteoporosis in PBC.

Osteoporosis is very common in Chinese patients with PBC, allowing for prior screening of BMD in those PBC patients with older age, lower BMI, previous steroid therapy and advanced liver disease.

Mechanical unloading-induced bone loss is a clinical challenge, and deep understanding for this disease is necessary for developing novel and effective therapies. MicroRNAs (miRNAs) are small non-coding RNAs, and involved in bone remodeling. In the study, we attempted to explore the potential of miR-133a in regulating osteoblast activation and its anti-osteopenia function both in vitro and in vivo. Our in vitro studies at first showed that miR-133a could significantly promote the expression of osteocalcin (OCN), Collagen I, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2) and osterix (Osx), promoting the activation and mineralization of osteoblasts. Then, hindlimb unloading (HU)-challenged mice were established with or without intravenous injection of agomir-miR-133a using an osteoblast-targeting delivery system. We found that miR-133a in osteoblasts significantly alleviated the bone loss, microstructural, and biomechanical property in mice with mechanical unloading, contributing to osteopenia alleviation. Furthermore, both in vitro and in vivo experiments showed that miR-133a could restrain osteoclastogenesis via tartrate-resistant acid phosphatase (TRAP) staining. In conclusion, our results suggested that miR-133a may be a promising factor in mediating the occurrence and progression of osteopenia caused by mechanical unloading, and thus targeting miR-133a could be considered as an effective therapeutic strategy for the suppression of pathological osteopenia.

Denosumab-Prolia®, Xgeva® (Amgen) is a fully human antibody to the receptor activator of the nuclear factor-K ligand (RANKL). Hepatotoxicity is extremely rare, with only one reported case of immune origin. We present a second case of hepatotoxicity resulting from an immune reaction to denosumab. A 43-year-old female was referred to the Endocrinology, Diabetes & Metabolism Department for treatment of low bone mineral density (BMD) following endocrine therapy with letrozole and lucrin because of breast cancer. She developed premature menopause at the age of 36 years when she underwent a left lumpectomy due to an infiltrating duct carcinoma of the breast (T1 NO MO) and was subsequently started on endocrine therapy. Denosumab was started to prevent osteoporosis. On the third year after starting on denosumab and one month after she received the last injection, she became ill. The routine biochemical analysis showed that the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) rose appreciatively to 10 times the upper limit of normal (ULN). The gamma-glutamyl transferase (GGT) level was elevated slightly to 67 U/L (0-38 U/L). The serum gamma-globulin level was elevated to 1.72 g/dL (0.7-1.6 gr/dl), while the total bilirubin (TB) and serum albumin levels were normal. A liver biopsy revealed a moderate to severe chronic inflammatory infiltrate containing MUM-1 positive plasma cells. In addition, numerous CD-3 positive small T lymphocytes and few CD-20 positive B lymphocytes and eosinophils were seen in the portal tracts. Moderate to severe interface hepatitis, bile duct proliferation and mild portal fibrosis were also identified. The results could be consistent with the diagnosis of drug-induced liver injury (DILI).

Osteoporosis is a frequent complication in patients with chronic liver disease, especially in end-stages and in chronic cholestasis, in addition to non-alcoholic fatty liver disease, haemochromatosis and alcoholism. Mechanisms underlying osteoporosis are poorly understood, but osteoporosis mainly results from low bone formation. In this setting, sclerostin, a key regulator of the Wnt/β-catenin signalling pathway which regulates bone formation, in addition to the effects of the retained substances of cholestasis such as bilirubin and bile acids on osteoblastic cells, may influence the decreased bone formation in chronic cholestasis. Similarly, the damaging effects of iron and alcohol on osteoblastic cells may partially explain bone disease in haemochromatosis and alcoholism. A role for proinflammatory cytokines has been proposed in different conditions. Increased bone resorption may occur in cholestatic women with advanced disease. Low vitamin D, poor nutrition and hypogonadism, may be contributing factors to the full picture of bone disorders in chronic liver disease.

Fibrodysplasia Ossificans Progressiva (FOP) is a progressive disease characterized by periods of heterotopic ossification of soft connective tissues, including ligaments. Though progress has been made in recent years in unraveling the underlying mechanism, patient-derived cell models are necessary to test potential treatment options. Periodontal ligament fibroblasts (PLF) from extracted teeth can be used to study deviant bone modeling processes in vitro since these cells are derived from genuine ligaments. They further provide a tool to study the hitherto unknown role of the bone morphogenesis protein receptor type 1 (BMPR-1) Activin A type 1 receptor ACVR1-R206H mutation in osteoclastogenesis. To further validate this potential model, osteogenesis and osteoclastogenesis was studied in the presence of TGF-β/activin receptor inhibitor GW788388. Control and FOP fibroblasts (n=6 of each) were used in osteogenesis and osteoclastogenesis assays in the absence or presence of TGF-β/activin receptor inhibitor GW788388. For osteogenesis, alkaline phosphatase (ALP) activity, alizarin red staining for mineralization and qPCR for expression of osteogenic markers was assessed. TRACP staining, multinuclearity and expression of osteoclastogenesis markers were used as a measure of osteoclast formation. FOP fibroblasts cultured in osteogenic medium displayed a trend of higher ALP activity at 7days. Gene expression of ALP from FOP fibroblasts was significantly higher at 3days. Mineralization was similar at 21days for both groups. GW788388 did not influence mineral deposition in both groups. Osteoclast formation was inhibited by GW788388 on plastic for both controls and FOP. On cortical bone slices, however, osteoclast formation was significantly lowered by GW788388, only in FOP cultures. qPCR revealed strong expression of RANKL at 7days and a significant decline at 14 and 21days in both FOP and control cultures. In contrast to the osteoclastogenesis results, the RANKL/OPG ratio was higher in the presence of GW788388, only in FOP cultures. TGF-β expression was significantly higher at 14 and 21days compared to 7days, possibly signifying a role in later stages of osteoclast formation. Addition of GW788388 strongly decreased TGF-β expression. Our study shows that periodontal ligament fibroblasts from FOP patients displayed at most slightly enhanced in vitro osteogenesis and osteoclastogenesis. This model could be useful to elucidate molecular mechanisms leading to heterotopic ossification in FOP such as in the presence of specific ACVR1-R206H activators as Activin A.

Hepatic osteodystrophy is multifactorial in its pathogenesis. Numerous studies have shown that impairments of the hepatic growth hormone/insulin-like growth factor-1 axis (GH/IGF-1) are common in patients with non-alcoholic fatty liver disease, chronic viral hepatitis, liver cirrhosis, and chronic cholestatic liver disease. Moreover, these conditions are also associated with low bone mineral density (BMD) and greater fracture risk, particularly in cortical bone sites. Hence, we addressed whether disruptions in the GH/IGF-1 axis were causally related to the low bone mass in states of chronic liver disease using a mouse model of liver-specific GH-receptor (GHR) gene deletion (Li-GHRKO). These mice exhibit chronic hepatic steatosis, local inflammation, and reduced BMD. We then employed a crossing strategy to restore liver production of IGF-1 via hepatic IGF-1 transgene (HIT). The resultant Li-GHRKO-HIT mouse model allowed us to dissect the roles of liver-derived IGF-1 in the pathogenesis of osteodystrophy during liver disease. We found that hepatic IGF-1 restored cortical bone acquisition, microarchitecture, and mechanical properties during growth in Li-GHRKO-HIT mice, which was maintained during aging. However, trabecular bone volume was not restored in the Li-GHRKO-HIT mice. We found increased bone resorption indices in vivo as well as increased basal reactive oxygen species and increased mitochondrial stress in osteoblast cultures from Li-GHRKO and the Li-GHRKO-HIT compared with control mice. Changes in systemic markers such as inflammatory cytokines, osteoprotegerin, osteopontin, parathyroid hormone, osteocalcin, or carboxy-terminal collagen cross-links could not fully account for the diminished trabecular bone in the Li-GHRKO-HIT mice. Thus, the reduced serum IGF-1 associated with hepatic osteodystrophy is a main determinant of low cortical but not trabecular bone mass. © 2017 American Society for Bone and Mineral Research.

Critically ill patients are at increased risk of fractures during rehabilitation, and can experience impaired healing of traumatic and surgical bone fractures. In addition, markers of bone resorption are markedly increased in critically ill patients, while markers of bone formation are decreased. In the current study, we have directly investigated the effect of critical illness on bone metabolism and repair. In a human in vitro model of critical illness, Fluorescence-activated cell sorting (FACS) analysis revealed an increase in circulating CD14+/CD11b+ osteoclast precursors in critically ill patient peripheral blood compared to healthy controls. In addition, the formation of osteoclasts was increased in patient peripheral blood mononuclear cell (PBMC) cultures compared to healthy controls, both in the presence and absence of osteoclastogenic factors receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor (M-CSF). Culturing PBMCs with 10% critically ill patient serum further increased osteoclast formation and activity in patient PBMCs only, and neutralization studies revealed that immunoglobulin G (IgG) antibody signaling through the immunoreceptor Fc receptor common γ chain III (FcRγIII) played an important role. When analyzing bone formation, no differences in osteogenic differentiation were observed using human periosteal-derived cells (hPDCs) treated with patient serum in vitro, but a decrease in the expression of vascular endothelial growth factor receptor 1 (VEGF-R1) suggested impaired vascularization. This was confirmed using serum-treated hPDCs implanted onto calcium phosphate scaffolds in a murine in vivo model of bone formation, where decreased vascularization and increased osteoclast activity led to a decrease in bone formation in scaffolds with patient serum-treated hPDCs. Together, these findings may help to define novel therapeutic targets to prevent bone loss and optimize fracture healing in critically ill patients.

The pathophysiology of osteoporosis in patients with Crohn's disease (CD) is still not completely elucidated. In this study, we evaluated osteoclastogenesis from peripheral blood cells of CD patients and studied the role of lymphocytes and inflammatory cytokines in this process. Peripheral blood mononuclear cells from seven patients with quiescent CD and matched healthy controls were isolated, and separated into T cells, B cells, and a T- and B-cell depleted fraction. In various culture combinations, osteoclast formation in the absence of the osteoclastogenic factors RANKL and M-CSF was assessed by scoring the number of tartrate-resistant acid phosphatase (TRACP) positive multinucleated cells (MNCs). Cytokine levels in culture supernatants were measured. Formation of heterogeneous cell clusters in culture was noticed; a process that was inhibited by anti-LFA-1. In CD cultures, mean cluster area was up to threefold higher than in control cultures, and shown to be induced by T cells. Over tenfold higher numbers of TRACP(+) MNCs were found in CD cultures, but exclusively in cultures containing T cells. Formation of cell clusters correlated strongly with formation of TRACP(+) MNCs. Both cell cluster formation and osteoclast formation were related to IL-17 levels in vitro. In conclusion, osteoclastogenesis, preceded by cell cluster formation, is T cell-mediated and increased in patients with quiescent CD. Our findings suggest heterotypic interactions between osteoclast precursors and T cells to be a triggering step in osteoclast formation in CD. Furthermore, our results propose a possible role for IL-17 in osteoclastogenesis in CD patients, and as such in CD-associated bone loss.

Hepatic osteodystrophy (HO) is the generic term defining the group of alterations in bone mineral metabolism found in patients with chronic liver disease. This paper is a global review of HO and its main pathophysiological, epidemiological and therapeutic aspects. Studies examining the most relevant information concerning the prevalence, etiological factors, diagnostic and therapeutic aspects involved in HO were identified by a systematic literature search of the PubMed database. HO generically defines overall alterations in bone mineral density (BMD) (osteoporosis or osteopenia) which appear as a possible complication of chronic liver disease. The origin of HO is multifactorial and its etiology and severity vary in accordance with the underlying liver disease. Its exact prevalence is unknown, but different studies estimate that it could affect from 20% to 50% of patients. The reported mean prevalence of osteoporosis ranges from 13%-60% in chronic cholestasis to 20% in chronic viral hepatitis and 55% in viral cirrhosis. Alcoholic liver disease is not always related to osteopenia. HO has been commonly studied in chronic cholestatic disease (primary biliary cirrhosis and primary sclerosing cholangitis). Several risk factors and pathogenic mechanisms have been associated with the loss of BMD in patients with chronic liver disease. However, little information has been discovered in relationship to most of these mechanisms. Screening for osteopenia and osteoporosis is recommended in advanced chronic liver disease. There is a lack of randomized studies assessing specific management for HO.

Bisphosphonates are widely used for treatment of postmenopausal osteoporosis. Patients with primary biliary cirrhosis often have osteoporosis - either postmenopausal or secondary to the liver disease. No systematic review or meta-analysis has assessed the effects of bisphosphonates for osteoporosis in patients with primary biliary cirrhosis.

To assess the beneficial and harmful effects of bisphosphonates for osteoporosis in primary biliary cirrhosis.

The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, LILACS, clinicaltrials.gov, the WHO International Clinical Trials Registry Platform, and full text searches were conducted until November 2011. Manufacturers and authors were contacted for additional studies during the conductance of the review.

All randomised clinical trials of bisphosphonates in primary biliary cirrhosis compared with placebo or no intervention, or another bisphosphonate, or any other drug.

Two authors extracted data. RevMan Analysis was used for statistical analysis of dichotomous data with risk ratio (RR) or risk difference (RD) and of continuous data with mean difference (MD) or standardised mean difference (SMD), all with 95% confidence intervals (CI). Methodological components were used to assess risk of systematic errors (bias). Trial sequential analysis was also used to control for random errors (play of chance).

Six trials were included. Three trials with 106 participants, of which two trials with high risk of bias, did not demonstrate significant effects of bisphosphonates (etidronate or alendronate) versus placebo or no intervention regarding mortality (RD 0.00; 95% CI -0.12 to 0.12, I² = 0%), fractures (RR 0.87; 95% CI 0.29 to 2.66, I² = 0%), or adverse events (RR 1.00; 95% CI 0.49 to 2.04). Two trials with 62 participants with high risk of bias compared one bisphosphonate (etidronate or alendronate) versus another (alendronate or ibandronate) and found no significant difference regarding mortality (RD -0.03; 95% CI -0.14 to 0.07, I² = 0%), fractures (RR 0.95; 95% CI 0.18 to 5.06, I² = 0%), or adverse events (RR 1.00; 95% CI 0.49 to 2.04, I² = 0%). Bisphosphonates had no significant effect on liver-related mortality, liver transplantation, or liver-related morbidity compared with placebo or no intervention, or another bisphosphonate. Bisphosphonates had no significant effect on bone mineral density compared with placebo or no intervention, or another bisphosphonate. Bisphosphonates compared with placebo or no intervention seem to decrease the urinary amino telopeptides of collagen I (NTx) concentration (MD -16.93 nmol bone collagen equivalents/mmol creatinine; 95% CI -23.77 to -10.10; 2 trials with 88 patients; I² = 0%) and serum osteocalcin (SMD -0.81; 95% CI -1.22 to -0.39; 3 trials with 100 patients; I² = 34 %) concentration. The former result was supported by trial sequential analysis, but not the latter. Alendronate compared with another bisphosphonate (ibandronate) had no significant effect on serum osteocalcin concentration (MD -3.61 ng/ml, 95% CI -9.41 to 2.18; 2 trials with 47 patients; I² = 82%) in a random-effects meta-analysis, but it significantly decreased serum osteocalcin (MD -4.40 ng/ml, 95% CI -6.75 to -2.05; 2 trials with 47 patients; I² = 82%), the procollagen type I N-terminal propeptide (MD -8.79 ng/ml, 95% CI -15.96 to -1.63; 2 trials with 47 patients; I² = 38%), and NTx concentration (MD -14.07 nmol bone collagen equivalents/mmol creatinine, 95% CI -24.23 to -3.90; 2 trials with 46 patients; I²=0%) in a fixed-effect model. The latter two results were not supported by trial sequential analyses. There was no statistically significant difference in the number of patients having bisphosphonates withdrawn due to adverse events compared with placebo or no intervention (RD -0.04; 95% CI -0.21 to 0.12; 2 trials with 46 patients; I² = 0%), or another bisphosphonate (RR 0.56; 95% CI 0.14 to 2.17; 2 trials with 62 patients; I² = 0%). One trial with 32 participants and with high risk of bias compared etidronate versus sodium fluoride without finding significant difference regarding mortality, fractures, adverse events, or bone mineral density. Etidronate compared with sodium fluoride significantly decreased serum osteocalcin, urinary hydroxyproline, and parathyroid hormone concentration.

We did not find evidence to support or refute the use of bisphosphonates for patients with primary biliary cirrhosis. The data seem to indicate a possible positive intervention effect of bisphosphonates on decreasing urinary amino telopeptides of collagen I concentration compared with placebo or no intervention with no risk of random error. There is need for more randomised clinical trials assessing the effects of bisphosphonates for osteoporosis on patient-relevant outcomes in primary biliary cirrhosis.

This study evaluates the effect of alendronate on osteoclastogenesis, cytokine production, and bone resorption in postmenopausal women. We suggest that it acts on mature bone resorbing osteoclasts after 3 months of treatment, whereas, after 1 year, it diminishes their formation by reducing their precursors and serum RANKL.

Osteoclasts are the target cells of bisphosphonates, though the most drug-sensitive steps of their formation and activity have not been determined. The present study evaluates the effect of alendronate on osteoclastogenesis, cytokine production, and bone resorption in postmenopausal women.

The study was conducted on 35 osteoporotic women; 15 were pretreated with alendronate 70 mg/week, whereas, 20 were treated with calcium 1 g/day and vitamin D 800 IU/day. After 3 months, 30 received alendonate 70/mg, vitamin D 2800 IU/week, and calcium 1 g/day for 12 months (combined therapy), whereas, the other five patients remained on calcium 1 g/day and vitamin D 800 IU/day. The following parameters were assessed before and after therapy: changes in bone resorption markers, circulating osteoclast precursors, formation of osteoclasts in peripheral blood mononuclear cell cultures, their viability, and variations in cytokines production.

After 3 months of alendronate, there was no significant reduction in the number of osteoclast precursors, osteoclast formation and viability, and cytokine levels, whereas, there was a significant reduction of bone resorption markers. One year of the combined therapy, on the other hand, reduced osteoclast precursors, osteoclast formation, and serum RANKL, whereas, calcium plus vitamin D alone had no effect.

We suggest that alendronate mainly acts on mature bone resorbing osteoclasts in the short term, whereas, its long-term administration diminishes their formation by reducing their precursors and serum RANKL.

Osteoporosis is a frequent complication in patients with chronic liver disease, especially in end-stages and in cases with chronic cholestasis, hemochromatosis and alcohol abuse. The problem is more critical in transplant patients when bone loss is accelerated during the period immediately after transplantation, leading to a greater incidence of fractures. Advanced age, low body mass index and severity of the liver disease are the main risk factors for bone disease in patients with cholestasis. Mechanisms underlying osteoporosis in chronic liver disease are complex and poorly understood, but osteoporosis mainly results from low bone formation, related to the effects of retained substances of cholestasis, such as bilirubin and bile acids, or to the effects of alcohol on osteoblastic cells. Increased bone resorption has also been described in cholestatic women with advanced disease. Although there is no specific treatment, bisphosphonates associated with supplements of calcium and vitamin D are effective for increasing bone mass in patients with chronic cholestasis and after liver transplantation. The outcome in reducing the incidence of fractures has not been adequately demonstrated essentially because of the low number of patients included in the therapeutic trials. Randomized studies assessing bisphosphonates in larger series of patients, the development of new drugs for osteoporosis and the improvement in the management of liver transplant recipients may change the future.

The influence of osteoporosis and liver disease on fracture risk is not well characterized in patients with primary biliary cirrhosis (PBC). We studied a large series of women with PBC to assess the prevalence and risk factors for fractures and the fracture threshold.

In female patients with PBC (n = 185; age, 55.7 +/- 0.7 years; range 28-79 years), age, duration of PBC, menopausal status, and histologic stage and severity of liver disease were assessed. Vertebral and non-vertebral fractures were recorded in 170 and 172 patients, respectively. Osteoporosis and osteopenia were diagnosed based on densitometry analysis.

The prevalences of vertebral, non-vertebral, and overall fractures were 11.2%, 12.2%, 20.8%, respectively. Osteoporosis was significantly more frequent in patients with PBC than in normal women. Osteoporosis was associated with age, weight, height, histologic stage, severity, and duration of liver damage; fractures were associated with osteoporosis, menopause, age, and height but not with severity of PBC. Osteoporosis was a risk factor for vertebral fracture (odds ratio [OR], 8.48; 95% confidence interval [CI]: 2.67-26.95). Lumbar T score <-1.5 (OR, 8.27; 95% CI: 1.84-37.08) and femoral neck T score <-1.5 (OR, 6.83; 95% CI: 1.48-31.63) were significant risk factors for vertebral fractures.

Fractures, particularly vertebral fractures, are associated with osteoporosis, osteopenia, and T scores less than -1.5, whereas osteoporosis and osteopenia are associated with the severity of liver damage. Patients with T scores less than -1.5 might require additional monitoring and be considered for therapy to prevent fractures.

Osteoporosis is a common complication of many types of liver disease. Research into the pathogenesis of osteoporosis has revealed that the mechanisms of bone loss differ between different types of liver disease. This Review summarizes our current understanding of osteoporosis associated with liver disease and the new advances that have been made in this field. The different mechanisms by which cholestatic and parenchymal liver disease can lead to reduced bone mass, the prevalence of osteopenia and osteoporosis in patients with early and advanced liver disease, and the influence of osteoporotic fractures on patient survival are discussed along with the advances in our understanding of the molecular pathways associated with bone loss. The role of the CSF1-RANKL system and that of the liver molecule, oncofetal fibronectin, a protein that has traditionally been viewed as an extracellular matrix protein are also discussed. The potential impact that these advances may have for the treatment of osteoporosis associated with liver disease is also reviewed.

Tumor cells in the bone microenvironment are able to initiate a vicious cycle of bone degradation by mobilizing osteoclasts, multinucleated cells specialized in bone degradation. c-Src is highly expressed both in tumors and in osteoclasts. Therefore, drugs like AZD0530, designed to inhibit Src activity, could selectively interfere with both tumor and osteoclast activity. Here we explored the effects of AZD0530 on human osteoclast differentiation and activity. The effect on osteoclasts formed in vivo was assessed in mouse fetal calvarial explants and in isolated rabbit osteoclasts, where it dose-dependently inhibited osteoclast activity. Its effect on formation and activity of human osteoclasts in vitro was determined in cocultures of human osteoblasts and peripheral blood mononuclear cells. AZD0530 was most effective in inhibiting osteoclast-like cell formation when present at the onset of osteoclastogenesis, suggesting that Src activity is important during the initial phase of osteoclast formation. Formation of active phosphorylated c-Src, which was highly present in osteoclast-like cells in cocultures and in peripheral blood mononuclear cell monocultures, was significantly reduced by AZD0530. Furthermore, it reversibly prevented osteoclast precursor migration from the osteoblast layer to the bone surface and subsequent formation of actin rings and resorption pits. These data suggest that Src is pivotal for the formation and activity of human osteoclasts, probably through its effect on the distribution of the actin microfilament system. The reversible effect of AZD0530 on osteoclast formation and activity makes it a promising candidate to temper osteoclastic bone degradation in bone diseases with enhanced osteoclast activity such as osteolytic metastatic bone disease.

To determine whether peripheral blood mononuclear cells (PBMCs) from chronic periodontitis patients differ from PBMCs from matched control patients in their capacity to form osteoclast-like cells.

PBMCs from 10 subjects with severe chronic periodontitis and their matched controls were cultured on plastic or on bone slices without or with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor-kappaB ligand (RANKL). The number of tartrate-resistant acid phosphatase-positive (TRACP(+)) multinucleated cells (MNCs) and bone resorption were assessed.

TRACP(+) MNCs were formed under all culture conditions, in patient and control cultures. In periodontitis patients, the formation of TRACP(+) MNC was similar for all three culture conditions; thus supplementation of the cytokines was not needed to induce MNC formation. In control cultures, however, M-CSF or M-CSF/RANKL resulted in higher numbers compared with cultures without cytokines. Upregulations of osteoclast marker mRNA cathepsin K and carbonic anhydrase II confirmed the osteoclastic character. Bone resorption was only observed when PBMCs were cultured in the presence of M-CSF and RANKL.

Our data indicate that PBMCs from periodontitis patients do not need priming by M-CSF to become osteoclast-like cells, suggesting that PBMCs from periodontitis patients are present in the circulation in a different state of activity.