Active identification of vertebral fracture in the FLS model of care

The identification of vertebral fracture is a key point in an FLS. We have analyzed the characteristics of 570 patients according to the route of identification (referral by other doctors, emergency registry or through VFA), concluding that promoting referral by other doctors with a training campaign is effective.

PURPOSE

Vertebral fractures (VF) are associated with increased risk of further VFs. Our objective was to analyze the characteristics of patients with VF seen in a Fracture Liaison Service (FLS).

METHODS

An observational study was carried out on patients with VF referred to the outpatient metabolic clinic (OMC) after a training campaign, identified in the emergency registry, and captured by VF assessment with bone densitometry (DXA-VFA) in patients with non-VFs. Patients with traumatic VF or VF > 1 year, infiltrative or neoplastic disease were excluded. The number and severity of VFs (Genant) were analyzed. Treatment initiation in the first 6 months after baseline visit was reviewed.

RESULTS

Overall, 570 patients were included, mean age 73. The most common route for identifying VF was through referral to OMC (303 cases), followed by the emergency registry (198) and DXA-VFA (69). Osteoporosis by DXA was found in 312 (58%) patients and 259 (45%) had ≥ 2 VFs. The rate of grade 3 VFs was highest among patients on the emergency registry. Those identified through OMC had a higher number of VFs, a higher rate of osteoporosis, more risk factors and greater treatment initiation. Patients with VFs detected by DXA-VFA were mostly women with a single VF and had a lower rate of osteoporosis by DXA.

CONCLUSIONS

We present the distribution of VFs by the route of identification in an FLS. Promoting referral by other doctors with a training campaign may help in the quality improvement of the FLS-based model of care.

Long-term treatment with raloxifene, but not bisphosphonates, reduces circulating sclerostin levels in postmenopausal women

We determined whether suppression of sclerostin levels by estrogen treatment was mediated by anti-resorptive effect. Raloxifene, but not bisphosphonates, suppressed circulating sclerostin concentration, suggesting that sclerostin may mediate the action of estrogen on bone metabolism, independently of their anti-resorptive effects.

INTRODUCTION

Circulating sclerostin concentrations are higher in postmenopausal than in premenopausal women, and estrogen treatment suppresses sclerostin levels in both men and women. We determined whether anti-resorptives may suppress the circulating sclerostin levels.

METHODS

We conducted a retrospective observational study. Eighty postmenopausal women were treated with raloxifene for 19.4 ± 7.7 months (n = 16), bisphosphonates for 19.2 ± 6.7 months (n = 32), or were untreated (n = 32) for 17.1 ± 4.6 months. Plasma sclerostin concentrations were measured before and after treatment.

RESULTS

Plasma sclerostin levels after treatment were significantly lower in the raloxifene than in the control group (55.8 ± 23.4 pmol/l vs. 92.1 ± 50.4 pmol/l, p = 0.046), but were similar between the bisphosphonate and control groups. Relative to baseline, raloxifene treatment markedly reduced plasma sclerostin concentration (-40.7 ± 22.8%, p < 0.001), with respect to both control (-7.5 ± 29.1%) and bisphosphonate (-3.1 ± 35.2%) groups. Changes in bone-specific alkaline phosphatase and osteocalcin levels showed reverse associations with sclerostin concentration changes in the raloxifene (γ = -0.505, p = 0.017) and control (γ = -0.410, p = 0.020) groups.

CONCLUSIONS

Raloxifene, but not bisphosphonates, significantly suppressed circulating sclerostin concentration, suggesting that sclerostin may mediate the action of estrogen on bone metabolism, independently of their anti-resorptive effects.

The Laryngeal Mask Airway Supreme for positive pressure ventilation during laparoscopic cholecystectomy

STUDY OBJECTIVE

To evaluate the Laryngeal Mask Airway Supreme (SLMA) in patients undergoing laparoscopic cholecystectomy.

DESIGN

Prospective observational study.

SETTING

University-affiliated hospital.

PATIENTS

100 ASA physical status 1, 2, and 3 adult patients undergoing laparoscopic cholecystectomy with general anesthesia.

INTERVENTIONS

The SLMA was inserted in all study patients. Patients were placed in the reverse Trendelenburg position.

MEASUREMENTS

Ease of insertion of the device and the drain tube, oropharyngeal leak pressure, frequency of postoperative sore throat, and other adverse events were recorded. The surgeon scored stomach size on an ordinal scale of 0-10 at insertion of the laparoscope and before decompression of the pneumoperitoneum.

MAIN RESULTS

Insertion of the SLMA was successful in all patients (91 pts on the first attempt, 9 pts on the second attempt). Gastric tube insertion was successful in all patients (easy in 97 pts, difficult in 3 pts). Initial mechanical ventilation was adequate in all cases. Mean oropharyngeal leak pressure at the 60 cm H(2)O cuff pressure level was 28.8 cm H(2)O (±5.2; range 18-40 cm H(2)O). Mean airway pressure before pneumoperitoneum was 17.5 cm H(2)O (±3.3; cm; range 11-26 cm H(2)O) and 22.9 cm H(2)O (±4 cm; range 16-32 cm H(2)O) after pneumoperitoneum. Median (range) stomach size on insertion of the laparoscope and change in stomach size during surgery did not interfere with the procedure in any patient. Twelve patients (12%) complained of a mild sore throat postoperatively. No other complications were reported.

CONCLUSIONS

The SLMA is easy to insert and it is an effective ventilatory device for laparoscopic cholecystectomy.

Estradiol rapidly inhibits osteoclastogenesis and RANKL expression in bone marrow cultures in postmenopausal women: a pilot study

We examined RANKL expression and OCL formation in cultured bone marrow cells from eight postmenopausal women in response to E(2). E(2) treatment inhibited the ability of hematopoietic cells to form OCLs in response to RANKL, and decreased RANKL production. These changes are likely involved in the ability of E(2) to influence the development of osteoporosis.

INTRODUCTION

Estrogen (E(2)) deficiency at menopause increases osteoclast (OCL) formation and bone resorption, predisposing women to osteoporosis. We examined receptor activator of NF-kappa B-ligand (RANKL) expression and in vitro OCL formation in cultured bone marrow cells from eight postmenopausal women before and after 3 weeks of E(2) therapy and three untreated premenopausal women.

METHODS

TRAP staining and resorption pit assay determined OCL number and function. Flow cytometry measured the distribution of marrow cell types and expression of RANKL in the macrophage-enriched fraction (R1) and a lymphocyte-enriched fraction (R2).

RESULTS

RANKL (3-100 ng/ml) produced a dose-dependent increase in in vitro OC formation and E(2) therapy significantly (p < 0.01) inhibited OCL formation by 33 to 50%. A small proportion of marrow cells bound anti- RANKL Ab (0.2-4.3%). There was no effect of E(2) on the percentage of cells binding the anti-RANKL Ab in the R1 fraction. In the R2 fraction E(2) treatment decreased the percentage of cells binding anti-RANKL Ab by 68 +/- 9% (p < 0.01).

CONCLUSION

Three weeks of E(2) treatment had a dual action. It inhibited the ability of hematopoietic cells to form OCLs in response to RANKL, and decreased the production of RANKL in cells of the bone marrow. The observed changes in the osteoclastic potential of bone marrow cells are likely involved in the ability of E(2) to regulate bone mass and influence the development of osteoporosis.

Regulation of receptor activator of nuclear factor-kappa B ligand and osteoprotegerin mRNA expression by parathyroid hormone is predominantly mediated by the protein kinase a pathway in murine bone marrow cultures

Parathyroid hormone (PTH) stimulates receptor activator of nuclear factor-kappaB ligand (RANKL) mRNA and inhibits osteoprotegerin (OPG) mRNA expression in murine bone marrow cultures. To understand the mechanisms influencing these responses, we investigated the role of the protein kinase A (PKA) and protein kinase C (PKC) pathways in the regulation of RANKL and OPG mRNA expression in murine bone marrow cultures. Murine bone marrow cells were stimulated with bovine PTH(1-34) and (1-34) amide, which activate both pathways; PTH(3-34), which more selectively activates the PKC and calcium pathways; and human PTH (1-31), which stimulates adenylyl cyclase, but not protein kinase C. We also examined agents that more directly activate either the PKA pathway (forskolin [FSK] and 8-bromo cAMP [8-Br-cAMP]) or the PKC pathway (phorbol 12-myristate 13-acetate [PMA]) in murine bone marrow cultures. After 1 h, RANKL mRNA expression was stimulated to a similar degree by agents that activate either or both the PKA and PKC pathways. However, this effect was sustained for 24 h only with agents that stimulated PKA. OPG mRNA expression was inhibited by all agents that stimulated PKA at 6 h. In contrast, PKC-specific stimulators [PMA and bPTH(3-34)] had no effect on OPG regulation in this culture system. To determine the involvement of the PKC signaling pathway in responses of RANKL, bone marrow cells were pretreated with PMA for 24 h and then treated with PTH(1-34) or FSK for 2 h. PMA pretreatment did not alter the ability of PTH or FSK to stimulate RANKL or inhibit OPG mRNA expression. Treatment of cells with H-89, a PKA inhibitor, significantly reduced the ability of PTH and FSK to induce RANKL and inhibit OPG mRNA expression. Calphostin C, a PKC inhibitor, significantly reduced PMA-stimulated RANKL mRNA expression without altering PTH- or FSK-mediated effects on RANKL or OPG mRNA. Cycloheximide, an inhibitor for protein synthesis, inhibited PTH-stimulated RANKL mRNA expression by 60% without altering the effect of PTH on OPG mRNA expression. To examine the involvement of prostaglandin in PMA-mediated responses, cells were treated with indomethacin, a nonspecific prostaglandin G/H synthase (PGHS) inhibitor, or NS-398, a selective inhibitor of PGHS-2. Neither PGHS inhibitor altered PMA-induced effects on RANKL and OPG mRNA expression. These results demonstrate that the PKA pathway is predominantly involved in the effects of PTH on RANKL mRNA expression in murine bone marrow cultures, but there is also a PKC-mediated response, which is not sustained. Inhibition of OPG by PTH appears to be a selective PKA response.

Interferon-alpha plus ribavirin for 12 months increases the sustained response rates in chronic hepatitis C relapsers

BACKGROUND

The effectiveness and tolerability of combination therapy for 12 months have not been evaluated sufficiently in chronic hepatitis C relapsers to interferon.

AIMS

To evaluate the sustained response to interferon plus ribavirin for 12 months in chronic hepatitis C relapsers.

METHODS

We included 55 chronic hepatitis C relapsers in a 12-month treatment protocol with interferon (3 MU thrice weekly) plus ribavirin (1-1.2 g/day). The effectiveness was evaluated using serum aminotransferase and hepatitis C virus RNA levels, alanine aminotransferase normalization and viraemia clearance after 12 months, defining the end-of-treatment response, and 6 months after completion of therapy, defining the sustained response. Adverse effects were recorded.

RESULTS

End-of-treatment response and sustained response were achieved in 47 (85%) and 37 (67%) patients, respectively; there were 10 (21%) relapsers after combination therapy. Predictive factors of sustained response included the genotype (non-1 95% vs. 1 48%; P < 0.001), lower viraemia (503 917 +/- 553 230 vs. 901 393 +/- 548 267 copies/mL; P < 0.005), higher alanine aminotransferase levels (137 +/- 75 vs. 103 +/- 41 IU/L; P < 0.05) and a lower gamma-glutamyl transpeptidase/alanine aminotransferase ratio (0.30 +/- 0.23 vs. 0.49 +/- 0.39; P < 0.05). Tolerance to therapy was good, with no withdrawals.

CONCLUSIONS

Interferon plus ribavirin treatment for 12 months in chronic hepatitis C relapsers yields high sustained response rates and is well tolerated. The sustained response is related to a non-1 genotype, lower baseline viraemia, higher alanine aminotransferase level and a lower gamma-glutamyl transpeptidase/alanine aminotransferase ratio.

Cellular and molecular interactions between immune system and bone

Functional interdependence between immune and bone systems is reflected in a number of regulatory molecules acting on the cells of both systems and common precursors for bone and immune cells. Therefore, the disturbances of the immune system may affect bone metabolism, and vice versa. This review addresses the roles of two major immune cell populations, T and B lymphocytes, in the regulation of bone metabolism. Experimental models and human diseases demonstrated that T lymphocytes may produce many bone cell regulatory cytokines, including two essential stimulators of osteoclastogenesis: receptor for activation of nuclear factor kappa b (NF-kappa B) (RANK) ligand (RANKL) and macrophage colony-stimulating factor. The effect of T lymphocytes on osteoclastogenesis may be both stimulatory and inhibitory, and depends on the activation stage and pattern of cytokine production. We showed that acute removal of T lymphocytes stimulated osteoclast differentiation in vitro and enhanced new cartilage and bone formation at non-osseous sites in vivo. B lymphocytes may be even more closely related to bone cells, as B lymphopoiesis requires an intimate contact with osteoblastic/stromal cells, and estrogens, powerful regulators of bone mass, are also involved in the differentiation of the B lymphocyte lineage. Also, B lymphocyte progenitors may give rise to functional osteoclasts. Both B and T lymphocytes may act through the RANKL/RANK/osteoprotegerin cytokine system, which has been independently discovered within immune and bone systems. These cytokines have crucial roles in the development and function of osteoclasts, dendritic cells, and T and B lymphocytes, as well as in the thymus and lymph node organogenesis. The cytokines produced by immune cells may affect bone cell function and vice versa, but the full complexity of these interactions awaits further investigation.

Role of B lymphocytes in new bone formation

Although there may be a close relationship between B lymphocytes and osteoclasts, or bone resorbing cells, little is known about the role of B lymphocytes in bone formation. We compared in vivo new bone induction in mice homozygous for the B-cell deficient (microMT) gene knockout, which lack functional B lymphocytes, with bone induction in control wild-type (C57BL/6) mice. Our comparison used two models of new bone induction in vivo: endochondral osteoinduction by subcutaneous implantation of recombinant human bone morphogenetic protein (rhBMP-2) and osteogenic regeneration after tibial bone marrow ablation. The expression of bone-specific proteins (bone sialoprotein, osteopontin, and osteocalcin) and inflammatory/immunomodulatory cytokines (interleukin-1alpha and -1beta, interleukin-6, and tumor necrosis factor-alpha) was assessed by Northern blot analysis or reverse transcription-polymerase chain reaction, respectively. Ossicles induced by rhBMP-2 were larger in volume and mass in microMT knockout mice, but relative volumes of the newly induced bone, cartilage, and bone marrow were similar in the two groups. Six days after tibial bone marrow ablation, microMT knockout mice resorbed the initial blood clot faster and formed more trabecular bone, paralleled by greater levels of bone sialoprotein mRNA than in the wild-type mice. microMT knockout and wild-type mice also differed in the expression pattern of inflammatory/immunomodulatory cytokines during the development of the newly induced bone, suggesting that a genetic lack of B lymphocytes may create a change in the immunological milieu at the site of new bone induction, which stimulates the initial accumulation and proliferation of mesenchymal progenitor.

Depletion of CD4 and CD8 T lymphocytes in mice in vivo enhances 1,25-dihydroxyvitamin D3-stimulated osteoclast-like cell formation in vitro by a mechanism that is dependent on prostaglandin synthesis

To investigate the role of T lymphocytes in osteoclastogenesis, we performed in vivo depletion of CD4 and/or CD8 T lymphocyte subsets and evaluated in vitro osteoclast-like cell (OCL) formation. T lymphocyte depletion (TLD) with mAbs was confirmed 24 h later by flow cytometry. OCL formation was stimulated with 1, 25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) in bone marrow and with recombinant mouse (rm) receptor activator of NF-kappaB ligand (RANK-L) and rmM-CSF in bone marrow and spleen cell cultures. OCL formation was up to 2-fold greater in 1,25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice than in those from intact mice. In contrast, TLD did not alter OCL formation in bone marrow or spleen cell cultures that were stimulated with rmRANK-L and rmM-CSF. The effects of TLD seemed to be mediated by enhanced PG synthesis, because the PGE(2) concentration in the medium of 1, 25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice was 5-fold higher than that in cultures from intact mice, and indomethacin treatment abolished the stimulatory effect of TLD on OCL formation. There was a 2-fold increase in RANK-L expression and an almost complete suppression of osteoprotegerin expression in 1, 25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice compared with those from intact mice. Although there was a small (20%) increase in IL-1alpha expression in 1, 25-(OH)(2)D(3)-stimulated bone marrow cultures from TLD mice, TLD in mice lacking type I IL-1R and wild-type mice produced similar effects on OCL formation. Our data demonstrate that TLD up-regulates OCL formation in vitro by increasing PG production, which, in turn, produces reciprocal changes in RANK-L and osteoprotegerin expression. These results suggest that T lymphocytes influence osteoclastogenesis by altering bone marrow stromal cell function.

Knockout of the murine prostaglandin EP2 receptor impairs osteoclastogenesis in vitro

Prostaglandin E2 (PGE2) stimulates the formation of osteoclast-like tartrate-resistant acid phosphatase-positive multinucleated cells (TRAP + MNC) in vitro. This effect likely results from stimulation of adenylyl cyclase, which is mediated by two PGE2 receptors, designated EP2 and EP4. We used cells from mice in which the EP2 receptor had been disrupted to test its role in the formation of TRAP + MNC. EP2 heterozygous (+/-) mice in a C57BL/6 x 129/SvEv background were bred to produce homozygous null (EP2 -/-) and wild-type (EP2 +/+) mice. PGE2, PTH, or 1,25 dihydroxyvitamin D increased TRAP+ MNC in 7-day cultures of bone marrow cells from EP2 +/+ mice. In cultures from EP2 -/- animals, responses to PGE2, PTH, and 1,25 dihydroxyvitamin D were reduced by 86%, 58%, and 50%, respectively. A selective EP4 receptor antagonist (EP4RA) further inhibited TRAP+ MNC formation in both EP2 +/+ and EP2 -/- cultures. In cocultures of spleen and calvarial osteoblastic cells, the response to PGE2 or PTH was reduced by 92% or 85% when both osteoblastic cells and spleen cells were from EP2 -/- mice, by 88% or 68% when only osteoblastic cells were from EP2 -/- mice and by 58% or 35% when only spleen cells were from EP2 -/- mice. PGE2 increased receptor activator of nuclear factor (NF)-kappaB ligand (RANKL) messenger RNA expression in osteoblastic and bone marrow cell cultures from EP2 +/+ mice 2-fold but had little effect on cells from EP2 -/- mice. Spleen cells cultured with RANKL and macrophage colony stimulating factor produced TRAP+ MNC. PGE2 increased the number of TRAP+ MNC in spleen cell cultures from EP2 +/+ mice but not in cultures from EP2 -/- mice. EP4RA had no effect on the PGE2 response in spleen cell cultures. PGE2 decreased the expression of messenger RNA for granulocyte-macrophage colony stimulating factor in spleen cell cultures from EP2 +/+ mice but had little effect on cells from EP2 -/- mice. These data demonstrate that the prostaglandin EP2 receptor plays a role in the formation of osteoclast-like cells in vitro. A major defect in EP2 -/- mice appears to be in the capacity of osteoblastic cells to stimulate osteoclast formation. In addition, there appears to be a defect in the response of cells of the osteoclastic lineage to PGE2 in EP2 -/- mice.

Prostaglandin G/H synthase-2 is required for maximal formation of osteoclast-like cells in culture

We examined the effect on osteoclast formation of disrupting the prostaglandin G/H synthase genes PGHS-1 and-2. Prostaglandin E(2) (PGE(2)) production was significantly reduced in marrow cultures from mice lacking PGHS-2 (PGHS-2(-/-)) compared with wild-type (PGHS-2(+/+)) cultures. Osteoclast formation, whether stimulated by 1,25-dihydroxyvitamin D(3) (1,25-D) or by parathyroid hormone (PTH), was reduced by 60-70% in PGHS-2(-/-) cultures relative to wild-type cultures, an effect that could be reversed by providing exogenous PGE(2). Cultures from heterozygous mice showed an intermediate response. PGHS inhibitors caused a similar drop in osteoclast formation in wild-type cultures. Co-culture experiments showed that supporting osteoblasts, rather than osteoclast precursors, accounted for the blunted response to 1,25-D and PTH. This lack of response appeared to result from reduced expression of RANK ligand (RANKL) in osteoblasts. We cultured spleen cells with exogenous RANKL and found that osteoclast formation was 50% lower in PGHS-2(-/-) than in wild-type cultures, apparently because the former cells expressed high levels of GM-CSF. Injection of PTH above the calvaria caused hypercalcemia in wild-type but not PGHS-2(-/-) mice. Histological examination of bone from 5-week-old PGHS-2(-/-) mice revealed no abnormalities. Mice lacking PGHS-1 were similar to wild-type mice in all of these parameters. These data suggest that PGHS-2 is not necessary for wild-type bone development but plays a critical role in bone resorption stimulated by 1,25-D and PTH.

Parathyroid hormone stimulates TRANCE and inhibits osteoprotegerin messenger ribonucleic acid expression in murine bone marrow cultures: correlation with osteoclast-like cell formation

We studied the effects of PTH on the expression of tumor necrosis factor-related activation-induced cytokine (TRANCE), osteoprotegerin (OPG), and receptor activator of NF kappaB (RANK) messenger RNA (mRNA) in cultured murine bone marrow, calvaria, and osteoblasts. TRANCE, OPG, and RANK are recently identified regulators of osteoclast formation. Bone marrow cells were cultured with or without PTH(1-34) for 6 days. TRANCE, OPG, and RANK mRNA were measured by RT-PCR. In 6-day cultures, PTH stimulated the number of OCL/well in a dose-dependent manner. A time course showed significant (P < 0.01) increases in OCL/well after 24 h of PTH (100 ng/ml). TRANCE mRNA expression, like OCL formation, increased dose dependently and was maximal, with 10-100 ng/ml PTH. In contrast, OPG mRNA expression was decreased by 0.1 ng/ml PTH (40%) and completely abolished by 1 ng/ml. TRANCE mRNA expression was rapidly stimulated by PTH (maximal response at 1 h, 8.1-fold over control). Expression declined by 40% at 24 h but was still much greater than control at 6 days (4.6-fold) in a time-course study. PTH caused a transient stimulation of OPG mRNA at 1 h (2-fold), which returned to basal levels by 2 h. After 6 h, PTH completely inhibited OPG mRNA. There were only minor effects of PTH on RANK mRNA expression. PTH had less potent effects on TRANCE and OPG mRNA expression in calvaria organ cultures and osteoblasts. In mouse calvaria cultures, TRANCE expression was detectable in controls and was increased 2.9-fold by PTH at 24 h. PTH treatment of calvaria decreased OPG expression by 30% at 6 h. MC3T3 E-1 osteoblastic cells expressed minimal levels of TRANCE mRNA either before or after PTH treatment. OPG mRNA was present in MC3T3 E-1 cells, but levels were not modulated by PTH. In primary osteoblastic cells, PTH stimulated TRANCE mRNA expression 4-fold at 2 h and inhibited OPG mRNA expression by 46%. These results demonstrate a tight correlation between the ability of PTH to stimulate OCL formation in marrow culture and expression of TRANCE (r = 0.87, P < or = 0.05) and OPG mRNA (r = -0.88, P < or = 0.05). Reciprocal regulation of TRANCE and OPG mRNA by PTH preceded its effects on OCL formation by 18-23 h. Hence, it is likely that PTH regulates bone resorption, at least in part, via its effects on TRANCE and OPG expression.

[People accompanying children to pediatric visits: is something changing?]

OBJECTIVE

To find out if the social father-mother stereotypes as regards the care of children are reproduced in the daily practice of Pediatrics Consultations, in order to do so, this study looks at who accompanies children to the consultations and the factors which led to fathers taking their children.

DESIGN

An observational crossover study.

SETTING

Otero Health Center, Oviedo.

PARTICIPANTS

A sample of 300 visits obtained over a year from the consultations of the Pediatrician.

MEASUREMENTS AND MAIN RESULTS

Collected Socioeconomic variables of parents, type of Consultation (Spontaneous or Programmed), who accompanied the child, sufficiency of information brought to the consultation and child management detected. People accompanying children were: Mother only (66.7%; IC 95%: 64.1-74.7), father and mother (14.7%; IC 95%: 11.0-19.3), father only or with others (7.6%; IC 95%: 5.0-11.4). In all cases information was sufficient and child management adequate. Mother came to 70.8% (IC 95%: 60.1-79.7); father to 4.5% (IC 95%: 1.5-11.8) and both to 21.3% (IC 95%: 13.7-31.6) of Programmed Consultations. A Logistic Regression found age of childrens and Education level of father associated with father accompany to consultation.

CONCLUSION

Mother normally accompanies child to pediatrician consultations. Father participates in child care, principally in families with a higher Socioeconomic level.

Osteoclasts and effects of interleukin 4 in development of chronic osteomyelitis

The cellular response to trauma and infection was studied in a murine model of posttraumatic osteomyelitis. Osteoclast response differed markedly depending on whether infection with Staphylococcus aureus accompanied the bone trauma. In animals recovering from sterile trauma, osteoclastic activity that was limited to the damaged or dead bone fragments caused rapid elimination of all recognizable dead bone within 1 week. New bone was laid down in an orderly fashion. Animals with superimposed infection had an intense polymorphonuclear leukocyte response develop. Additionally, osteoclasts behaved as acute inflammatory responders with substantial activity at the margins of the infected site and at previously uninjured tibial cortex adjacent to the infection. Despite the exuberant osteoclast response, bony fragments were not resorbed (for at least 4 weeks after the trauma), that is, sequestra developed, and new bone was laid down over morphologically dead bone and on the cortex (involucrum). When the inhibitory cytokine, interleukin 4 was given in a single dose with the bacterial inoculum, the osteoclast response was moderated with almost complete elimination of osteoclast activity at normal tibial cortex adjacent to the infected site. The limitation of osteoclastic activity did not impair the host's containment of bacterial growth.

Parathyroid hormone induces interleukin-6 heterogeneous nuclear and messenger RNA expression in murine calvarial organ cultures

The cytokine, interleukin-6 (IL-6), is produced by osteoblasts and may in part mediate parathyroid hormone (PTH)-stimulated bone resorption. The goals of the present study were: (1) to examine PTH induction of IL-6 expression in 7-day-old mouse calvarial organ cultures; (2) to assess the role of intracellular signaling pathways in this model; and (3) to determine whether PTH regulates IL-6 expression by a transcriptional mechanism. Northern blot analysis of calvarial RNA showed that PTH(1-34) at 0.1-100 nmol/L induced IL-6 mRNA at 0.5 h with a peak at 2 h. Forskolin at 10 micromol/L and 8-bromocyclic-AMP at 3 mmol/L also induced IL-6 mRNA with a peak at 2 h. Phorbol myristate acetate induced IL-6 expression, whereas ionomycin and PTH(3-34) amide, an N-terminal-truncated PTH analog that has reduced ability to activate the cAMP-PKA pathway, were much less effective. PMA pretreatment of calvariae greatly blocked IL-6 mRNA induction by a subsequent dose of PMA and decreased induction by PTH and forskolin to a much lesser extent. A reverse-transcriptase polymerase chain reaction (RT-PCR) assay was used to measure IL-6 heterogeneous nuclear RNA (hnRNA) and mRNA. A 5' primer spanning exons 1 and 2 and a 3' primer complementary to exon 5 of the murine IL-6 gene were used to detect IL-6 mRNA as a 638 bp product. A 5' primer corresponding to intron 4 of the murine IL-6 gene and the 3' primer were used to detect IL-6 hnRNA as a 370 bp product. RT-PCR of total calvarial RNA showed that the induction of IL-6 hnRNA by PTH and other agonists was similar to their induction of IL-6 mRNA. These data support the conclusion that PTH transcriptionally induces IL-6 gene expression in murine calvarial organ cultures mainly through the cAMP-PKA signaling pathway.

Mice lacking the type I interleukin-1 receptor do not lose bone mass after ovariectomy

We measured the effects of ovariectomy on the bone mass of mice that lacked type I interleukin-1 receptor (IL-I R1 -/- mice) in two genetic backgrounds (C57BL/6 x 129/Sv and C57BL/6) to investigate the role of interleukin-1 in the actions of estrogen on bone. At three weeks after surgery, ovariectomized wild-type mice decreased trabecular bone volume in the proximal humerus by 70% in a C57BL/6 x 129/Sv background and 48% in a C57BL/6 background compared to sham-operated controls. In contrast, there was no significant decrease in trabecular bone mass in IL-1 R1 -/- mice after ovariectomy. The estrogen status of all groups was confirmed by measurement of uterine wet weight. These results demonstrate that a functional IL-1 response pathway is required for mice to lose trabecular bone mass after ovariectomy in this model and they imply that IL-1 is an important mediator of the effects of ovariectomy on bone mass. Hence, therapeutic interventions that block the effects of IL-1 on bone may be beneficial for treating diseases of rapid bone loss such as post-menopausal osteoporosis.

Lack of evidence for an increase in interleukin-6 expression in adult murine bone, bone marrow, and marrow stromal cell cultures after ovariectomy

Interleukin-6 (IL-6) has been implicated as a mediator of postmenopausal bone loss. In vitro studies of bone and bone marrow cells have suggested that estrogen regulates bone turnover by controlling the production of IL-6, a potent stimulator of osteoclastogenesis and bone resorption. To investigate this hypothesis in an in vivo model, we examined the effect of ovariectomy or estrogen replacement on IL-6 mRNA and protein expression in adult mouse bone and bone marrow in vivo and in marrow stromal cell cultures. Eight-week-old CD-1 mice were sham-operated (SHAM), ovariectomized (OVX), or ovariectomized and subcutaneously implanted with 21-day slow-release pellets containing 10 micrograms of 17 beta-estradiol (O + E). Placebo pellets were implanted in the SHAM and OVX mice. Uterine weights at 1, 2, or 3 weeks after surgery were significantly decreased (68-76%) in OVX animals compared with SHAM or O + E. In mice sacrificed at 1 or 3 weeks after surgery, we found by nonquantitative reverse transcribed polymerase chain reaction (RT-PCR), that SHAM, OVX, and O + E calvariae (CALV) constitutively expressed IL-6 mRNA. In contrast, IL-6 mRNA was either barely detectable or absent in the tibia (TIB) and bone marrow (BM). In the mice sacrificed 3 weeks after surgery, we determined by quantitative RT-PCR that IL-6 mRNA in the CALV from the OVX and O + E groups were decreased by 81 and 92%, respectively, compared with SHAM. IL-6 protein levels in the flushed bone marrow (BMSups) were detectable and were not significantly different among the groups. In bone marrow cells that were cultured for 1 week, basal levels of IL-6 protein were low and did not differ significantly among the SHAM, OVX, or O + E groups sacrificed 1, 2, or 3 weeks after surgery. After the addition of hrIL-1 alpha, IL-6 protein levels increased 100- to 1300-fold over control. IL-6 levels in cells from animals sacrificed 2 weeks after surgery were significantly lower in the hrIL-1 alpha-stimulated OVX and O + E groups than in hrIL-1 alpha-stimulated SHAM cell cultures. In conclusion, in this model we could find no increase in IL-6 production with in vivo estrogen withdrawal in calvaria, long bones, bone marrow, or marrow stromal cell cultures. If increases in IL-6 expression are involved in the effects of estrogen withdrawal on bone, the magnitude of these changes are relatively small and below the limits of detection of the assays that we employed.

Interleukin-6 expression and histomorphometry of bones from mice deficient in receptors for interleukin-1 or tumor necrosis factor

We examined the roles of interleukin-1 Type I receptor (IL-1R1) and tumor necrosis factor receptor 1 (TNFR1) in bone metabolism using mice rendered deficient in these receptors by gene targeting. Sections of decalcified paraffin-embedded calvariae and humeri from 11- to 12-week-old mice deficient in IL-1 Type I receptor (IL-1R1-/-) or TNF receptor 1 (TNFR1-/-) were examined by histomorphometry. Wild-type mice (C57BL/6J x 129/J, WILD) served as controls. Interleukin-6 (IL-6) production in primary osteoblastic and bone marrow stromal cell cultures in response to parathyroid hormone (PTH, 100 ng/ml), IL-1 alpha (10 ng/ml), and TNF-alpha (10 ng/ml) was also examined. IL-1R1-/- and TNFR1-/- mice were viable and appeared phenotypically normal. However, the body weights of the IL-1R1-/- mice were 30% less than WILD, while the TNFR1-/- mice weighed 30% more than WILD mice of equivalent age. Calvariae and humeri of IL-1R1-/- and TNFR1-/- mice were normal with respect to trabecular bone volume, osteoclast number, osteoclast surface, growth plate widths, and cortical thickness. Receptor deficiency was confirmed by determining the ability of PTH, IL-1 alpha, and TNF-alpha to stimulate IL-6 in the media of primary calvaria-derived osteoblastic cell cultures from CD-1 and cytokine receptor-deficient mice. After 24 h of treatment, IL-1 alpha and TNF-alpha did not stimulate IL-6 production in osteoblasts from IL-1R1-/- and TNFR1-/- mice, respectively. In contrast, PTH increased IL-6 levels in the cells from all mice. IL-6 protein levels in bone marrow supernatants and conditioned media from untreated bone marrow stromal cells were undetectable in WILD, IL-1R1-/-, and TNFR1-/- mice. PTH, IL-1 alpha and TNF-alpha increased IL-6 mRNA and protein production in the WILD bone marrow stromal cells. In contrast, PTH and TNF-alpha increased IL-6 mRNA and protein levels in IL-1R1-/- bone marrow stromal cells while IL-1 alpha had no effect. These findings demonstrate that normal bone development in mice can occur in the absence of IL-1R1 or TNFR1 expression.

Expression of the calcitonin receptor in bone marrow cell cultures and in bone: a specific marker of the differentiated osteoclast that is regulated by calcitonin

We studied the temporal sequence of osteoclast (OC) differentiation from precursor cells in murine marrow cultures. Two markers of the OC phenotype, calcitonin (CT) receptor (CTR) and tartrate resistant acid phosphatase (TRAP), were assessed. Marrow cells from C57BL/6 mice were cultured for 3, 5, 7, and 9 days with or without 1,25-(OH)2vitamin D3 (10(-8) M). In controls only small numbers of osteoclastic multinucleated cells 9MNCs) formed per well (< 15 per well). In contrast, 1,25-(OH)2D3 strongly stimulated MNC formation (> 80 per well on day 7). Messenger RNA (mRNA) for TRAP was detectable by reverse transcription-polymerase chain reaction amplification in both control and 1,25-(OH)2D3 treated groups at all times. However, TRAP mRNA was detectable in MNCs by the less sensitive in situ hybridization only on days 5, 7, and 9 and only in 1,25-(OH)2D3 treated cells. In control cultures, CTR mRNA was present on day 3 only in nonadherent cells and was not present in adherent cells (where MNCs formed) at any time point. In 1,25-(OH)2D3 treated cultures CTR mRNA was detectable in nonadherent cells on day 3 and in adherent cells on day 5 and thereafter. Peak levels of CTR mRNA were seen in adherent cells on day 7 (15-fold more than day 5 and 4-fold more than day 9). CT (10(-7) M) treatment of 7 day cultures, which had been stimulated to express the osteoclastic phenotype, caused a marked decrease in CTR mRNA expression at 24 h. There was no effect of CT treatment on CTR mRNA expression at 3 h or on TRAP mRNA expression at 3 or 24 h. In neonatal mouse calvaria cultures, CTR mRNA expression was constitutively present and was markedly decreased by 48 h of CT treatment. Similarly, bone resorption in these cultures was inhibited at 24 h by CT treatment, but at 48 and 72 h there was escape from the inhibitory effects of CT on resorption. In the marrow cultures, MNCs were greater than 98% positive for [125I]-salmon calcitonin (sCT) binding and this binding was completely competed away by excess cold sCT (10(-7) M). All primary isolated osteoclasts from 1- to 3-day-old mouse long bones exhibited [125I]-sCT binding and TRAP activity and were strongly positive for CTR and TRAP mRNA by in situ hybridization. Both MNCs that formed in bone marrow cultures and isolated primary osteoclasts formed resorption pits on bone slices.(ABSTRACT TRUNCATED AT 400 WORDS)

Ovariectomy enhances and estrogen replacement inhibits the activity of bone marrow factors that stimulate prostaglandin production in cultured mouse calvariae

To examine PG production in estrogen deficiency, we studied effects on cultured neonatal mouse calvariae of bone marrow supernatants (MSup) from sham-operated (SHAM), ovariectomized (OVX), or 17 beta-estradiol (OVX+E)-treated mice. MSups were obtained 3 wk after OVX when bone density had decreased significantly. 10-60% MSup increased medium PGE2 and levels of mRNA for inducible and constitutive prostaglandin G/H synthase (PGHS-2 and PGHS-1) and cytosolic phospholipase A2 in calvarial cultures. OVX MSups had twofold greater effects on PGHS-2 and medium PGE2 than other MSups. IL-1 receptor antagonist and anti-IL-1 alpha neutralizing antibody decreased MSup-stimulated PGHS-2 mRNA and PGE2 levels and diminished differences among OVX, sham-operated, and OVX+E groups. In contrast, antibodies to IL-1 beta, IL-6, IL-11, and TNF alpha had little effect. There were no significant differences in IL-1 alpha concentrations or IL-1 alpha mRNA levels in MSups or marrow cells. PGHS-2 mRNA in freshly isolated tibiae from OVX mice was slightly greater than from sham-operated. We conclude that bone marrow factors can increase PG production through stimulation of PGHS-2; that OVX increases and estrogen decreases activity of these factors; and that IL-1 alpha activity, together with additional unknown factors, mediates the differential MSup effects.

Monocyte chemoattractant protein-1 expression and monocyte recruitment in osseous inflammation in the mouse

In bone, early events in inflammation involve the production and release of primary proinflammatory cytokines, such as interleukin-1 beta. By activation of target cells, these cytokines are thought to induce a second wave of cytokines, including monocyte chemoattractant protein-1 (MCP-1). MCP-1 is a cytokine that stimulates chemotaxis of monocytes. Experiments were undertaken to examine the expression of MCP-1 in bone-associated cells in vivo. To observe in vivo expression of MCP-1, an inflammatory lesion was created in the murine mandible. Immunohistochemistry experiments using specific antibodies to MCP-1 were conducted to identify MCP-1-expressing cells in inflamed and noninflamed bone. We found that osteoblasts were the principal cells expressing MCP-1 in inflamed bone. There was little or no MCP-1 expression in noninflamed bone. Immunohistochemistry experiments were carried out to assess monocyte recruitment during osseous inflammation. The number of MCP-1-positive cells was significantly correlated to the number of monocytes/macrophages present (n = 15; r = 0.69; P < = 0.01). These in vivo results strongly suggest that MCP-1 is an important mediator involved in the recruitment of monocytes/macrophages in inflamed bone.

Expression of monocyte chemoattractant protein 1 in human osteoblastic cells stimulated by proinflammatory mediators

Monocyte chemoattractant protein 1 (MCP-1) is a member of the chemokine superfamily of genes that induces chemotaxis of monocytes in inflammatory processes. The effects of interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), transforming growth factor beta (TGF-beta), platelet-derived growth factor (PDGF-BB), parathyroid hormone (PTH), and 1,25(OH)2D3 on MCP-1 expression in human osteoblastic cells were compared. Inflammatory or proinflammatory cytokines stimulated the production of MCP-1 in normal human osteoblastic cells as determined by RIA. The osteotrophic mediators PTH and 1,25(OH)2D3 and PDGF-BB had no effect on MCP-1 expression. In further studies, the steady-state mRNA and MCP-1 protein levels in two human osteoblastic cell lines, MG-63 and SaOS-2, were examined. MCP-1 expression at both the protein and mRNA levels was greatly increased by IL-1 beta and TNF-alpha. At the mRNA level, IL-1 beta and TNF-alpha strongly induced MCP-1 expression; TGF-beta and IL-6 induced MCP-1 but to a lesser extent. No significant changes in MCP-1 mRNA or MCP-1 protein secretion were observed when cells were treated with PDGF-BB, PTH, and 1,25(OH)2D3. When tested on preosteoclasts, MCP-1 was shown to have no effect on the formation of multinucleated, tartrate-resistant acid phosphatase (TRAP)-positive osteoclastic cells.

Stimulation of prostaglandin E2 production by interleukin-1 alpha and transforming growth factor alpha in osteoblastic MC3T3-E1 cells

The mechanism by which interleukin-1 (IL-1) and transforming growth factor alpha (TGF-alpha) regulate prostaglandin synthesis has been examined in the clonal mouse osteoblastic cell line MC3T3-E1. Cells were grown in DMEM containing 10% fetal calf serum. Prostaglandin E2 (PGE2) production was determined by radioimmunoassay or by prelabeling cells with [3H]arachidonic acid, followed by high-performance liquid chromatography (HPLC) analysis of the labeled products released into the medium. Prostaglandin G/H synthase (PGHS) mRNAs were quantified by northern blot analysis using [32P]labeled cDNA probes. By HPLC, PGE2 was the major prostanoid produced under basal or stimulated conditions. No release of thromboxane or 6-keto-PGF1 alpha into the medium was detected. PGE2 production was stimulated approximately 7- to 14-fold by IL-1 (1 ng/ml) and 3- to 8-fold by TGF-alpha (30 ng/ml) after 24 h. In combination, however, IL-1 and TGF-alpha caused a synergistic 37- to 71-fold increase in PGE2 accumulation. PGHS-1 mRNA levels were maximally increased approximately 2- to 3-fold by IL-1 and 1.5 to 2.5-fold by TGF-alpha after 24 h; the combination of IL-1 and TGF-alpha produced only an additive 3- to 6-fold increase. Western blotting revealed a corresponding 3-fold increase in immunoreactive PGHS-1 protein in response to combined IL-1 and TGF-alpha. PGHS-2 mRNA was increased 1.4-fold by TGF-alpha at 1 h, and the combination of IL-1 and TGF-alpha caused a 1.7-fold increase.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor alpha stimulates production of leukemia inhibitory factor in human dermal fibroblast cultures

Leukemia inhibitory factor (LIF) is a recently described cytokine with a variety of actions including a possible involvement in immune responses. We determined whether human dermal fibroblast cultures could produce LIF after they were treated with tumor necrosis factor alpha (TNF alpha), a cytokine that is produced as an early inflammatory response of activated monocytes. We found that treatment of the cultures with as little as 0.5 units/ml (1.5 pM) caused a detectable increase in both LIF message and protein as measured by Northern blot assay and ELISA, respectively. Furthermore, increasing concentrations of TNF alpha produced a dose-dependent increase in both steady-state LIF mRNA and protein levels up to a maximum response with 500 units/ml (1.5 nM). Increases in LIF mRNA levels were rapid and could be detected 1 hr after treatment with 500 units/ml of TNF alpha. However, this effect was transient. It reached a maximum at 2 hr and returned almost to baseline at 24 hr. In contrast, levels of LIF protein in the conditioned media of the cultures increased progressively over 24 hr. The LIF produced by these cultures was biologically active and was inhibited by a polyclonal antibody to human LIF in a bioassay. These results demonstrate that LIF is produced by human dermal fibroblasts in response to treatment with TNF alpha, a mediator of acute inflammation. Furthermore, they suggest that production of LIF by these cells may be involved in the development of both the local and generalized immune response.

Production of leukemia inhibitory factor mRNA and protein by malignant and immortalized bone cells

Leukemia inhibitory factor (LIF) is a recently characterized glycoprotein with complex biologic activities on bone cells. We tested various rodent and human immortalized and malignant bone cell lines and primary osteoblast-enriched cell cultures from fetal rat calvarial digests for expression of LIF mRNA and LIF protein. Both human and rodent immortalized and malignant cells expressed a single 4.4 kb mRNA transcript that hybridized to a human LIF cDNA probe in Northern blots. LIF mRNA was undetectable in unstimulated rodent osteoblast-like cells lines MC3T3-E1 and Py1a. However, treatment with LPS (10 micrograms/ml), TGF-beta (1 ng/ml), TNF-alpha (100 ng/ml) or inhibitors of protein synthesis (cycloheximide, emetine, puromycin, and anisomycin) induced the expression of LIF message in these cells. In contrast, primary osteoblast-enriched cells did not express LIF mRNA in Northern blot assays either constitutively or after treatment with TNF-alpha or cycloheximide. The human osteosarcoma cells lines U-2 OS and Saos-2 constitutively expressed LIF mRNA and did not respond to LPS treatment. However, phorbol myristate acetate (PMA), an activator of protein kinase C, was a potent stimulator of LIF message in Saos-2 but not U-2 OS cells. The effects of PMA (0.5 ng/ml) on LIF mRNA in Saos-2 cells were detectable at 1 h and maximal at 6 h. TNF-alpha (100 ng/ml) and inhibitors of protein synthesis also increased LIF mRNA in both Saos-2 and U-2 OS cells. LIF protein was also detected constitutively in the conditioned medium from both Saos and U-2 OS cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of both 92- and 72-kDa gelatinases by bone cells

We investigated the ability of murine bone organ cultures and osteoblast-like bone cells to produce 72- and 92-kDa gelatinase. 4-6 day newborn mouse calvaria cultures were found to release gelatinase activity into their conditioned medium (CM). This activity was increased by four stimulators of resorption, tumor necrosis factor alpha (TNF), interleukin-1 alpha (IL-1), parathyroid hormone (PTH) and the active phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA). Both the 72- and 92-kDa forms of gelatinase were produced by murine bone cultures. In unstimulated bones 72-kDa gelatinase activity was approximately equal to that of the 92-kDa enzyme. IL-1, TNF, PTH and TPA all increased 92-kDa gelatinase activity in the CM of the bone cultures by about 2- to 2.5-fold. In addition TPA and IL-1 also increased 72-kDa gelatinase activity. In unstimulated osteoblast-like MC3T3-E1 cell cultures 72-kDa gelatinase enzyme activity was much greater than 92-kDa activity and was not substantially regulated (less than 40% change) by IL-1, TNF or PTH. In contrast, these agents stimulated 92-kDa gelatinase activity by 2- to 5-fold. As with the MC3T3-E1 cells, primary cells constitutively produced both 72-kDa and 92-kDa gelatinase. This was true for cells with both the most differentiated osteoblast-like phenotype (populations 3 and 4) and the least osteoblast-like phenotype (populations 1 and 2). In unstimulated cultures of all 4-primary populations, 92-kDa gelatinase production was less than 72-kDa and IL-1, TNF and PTH had only small effects on 72-kDa production in any of the populations (less than 60% change).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of transforming growth factor-beta and IL-1 alpha on prostaglandin synthesis in serum-deprived osteoblastic cells

We investigated the effects that the combination of IL-1 alpha and transforming growth factor-beta (TGF-beta) had on PGE2 production in a murine clonal osteoblastic cell line MC3T3-E1 and primary rat calvarial osteoblast-like cells. In serum-supplemented medium, IL-1 alpha was a potent stimulator of PGE2 production in MC3T3-E1 cells (50-fold increase with 0.1 ng/ml). TGF-beta (10 ng/ml) had only a small effect alone and no additional effect on IL-1 alpha-induced responses. In serum-deprived MC3T3-E1 cells, PGE2 responses to IL-1 alpha were either absent or markedly reduced. TGF-beta alone had small effects. However, simultaneous addition of TGF-beta with IL-1 alpha to MC3T3-E1 cells partially restored the ability of IL-1 alpha to generate a PGE2 response (10-fold increase in PGE2 with 0.1 ng/ml of both IL-1 alpha and TGF-beta). As with MC3T3-E1 cells, serum-deprived primary fetal rat calvarial osteoblastic cells also did not respond to IL-1 alpha, unless TGF-beta was present in the medium (sixfold increase in PGE2 with 0.1 ng/ml IL-1 alpha and 10 ng/ml TGF-beta). The synergistic effect of TGF-beta and IL-1 alpha was specific for PGE2 responses, because these factors did not synergistically affect cell proliferation, collagen and noncollagen protein synthesis, or alkaline phosphatase activity. The observed synergy was not associated with changes in the steady state cyclooxygenase (PGH synthase) mRNA levels. However, it did correlate with increased release of [3H]arachidonic acid from prelabeled serum-depleted MC3T3-E1 cells. Hence, the synergistic interactions of IL-1 alpha and TGF-beta on PGE2 appear to occur through an increase in the release of arachidonic acid substrate from phospholipid pools. These effects may be important for both normal bone turnover and the responses of bone to inflammatory and immune stimuli.

Effects of transforming growth factor-beta and IL-1 alpha on prostaglandin synthesis in serum-deprived osteoblastic cells

We investigated the effects that the combination of IL-1 alpha and transforming growth factor-beta (TGF-beta) had on PGE2 production in a murine clonal osteoblastic cell line MC3T3-E1 and primary rat calvarial osteoblast-like cells. In serum-supplemented medium, IL-1 alpha was a potent stimulator of PGE2 production in MC3T3-E1 cells (50-fold increase with 0.1 ng/ml). TGF-beta (10 ng/ml) had only a small effect alone and no additional effect on IL-1 alpha-induced responses. In serum-deprived MC3T3-E1 cells, PGE2 responses to IL-1 alpha were either absent or markedly reduced. TGF-beta alone had small effects. However, simultaneous addition of TGF-beta with IL-1 alpha to MC3T3-E1 cells partially restored the ability of IL-1 alpha to generate a PGE2 response (10-fold increase in PGE2 with 0.1 ng/ml of both IL-1 alpha and TGF-beta). As with MC3T3-E1 cells, serum-deprived primary fetal rat calvarial osteoblastic cells also did not respond to IL-1 alpha, unless TGF-beta was present in the medium (sixfold increase in PGE2 with 0.1 ng/ml IL-1 alpha and 10 ng/ml TGF-beta). The synergistic effect of TGF-beta and IL-1 alpha was specific for PGE2 responses, because these factors did not synergistically affect cell proliferation, collagen and noncollagen protein synthesis, or alkaline phosphatase activity. The observed synergy was not associated with changes in the steady state cyclooxygenase (PGH synthase) mRNA levels. However, it did correlate with increased release of [3H]arachidonic acid from prelabeled serum-depleted MC3T3-E1 cells. Hence, the synergistic interactions of IL-1 alpha and TGF-beta on PGE2 appear to occur through an increase in the release of arachidonic acid substrate from phospholipid pools. These effects may be important for both normal bone turnover and the responses of bone to inflammatory and immune stimuli.

A human periodontal ligament fibroblast clone releases a bone resorption inhibition factor in vitro

The conditioned media (CM) obtained from three lines of cloned human periodontal ligament (PDL) cells were analyzed to determine whether they altered the parathyroid hormone (PTH)-stimulated resorption rates (45Ca release) in 48-hour cultures of 45Ca-labeled rat long bones. One PDL cell line, PDL-5, produced a heat-resistant factor in its CM that inhibited the PTH-stimulated resorption by 43.8 +/- 9.7 (SE) percent (p less than or equal to 0.02), whereas the CM from the other cell lines were without statistically significant effect. The CM from the PDL-5 line did not diminish organ culture viability, as determined by 3H-thymidine incorporation, and did not enhance or diminish the resorption-inhibiting activity of calcitonin added to the PTH-stimulated cultures. The addition of CM from PDL-5 did not alter the bone-resorbing effect of interleukin-1 (IL-1). These results indicate that CM from PDL-5 inhibits only the PTH-induced and not the IL-1-mediated resorption processes, whose mechanisms are therefore likely to differ.

Leukemia inhibitory factor (LIF) inhibits basal bone resorption in fetal rat long bone cultures

Leukemia inhibitory factor (LIF) has a wide variety of biologic actions. In vivo, its net effect on bone is to increase new bone formation. Recently, the sequence of human LIF was found to differ by only a single amino acid from that of human differentiation-inducing factor (D-factor). The effects of LIF on bone appear to be complex since purified murine D-factor and recombinant LIF stimulate bone resorption in cultured newborn mouse calvaria. To examine further the responses of bone to LIF, we studied the effects of recombinant human LIF (glycosylated and nonglycosylated) and recombinant human D-factor (non-glycosylated) on resorption in another in vitro organ culture model, fetal rat long bones. Both LIF preparations and D-factor inhibited basal bone resorption rates by 25% to 44% in these cultures. Resorption rates in maximally inhibited LIF-treated cultures were similar to those in devitalized bones. Inhibitory effects typically occurred at concentrations of greater than or equal to 10 ng/mL (0.5 nM) for the non-glycosylated LIF and D-factor and 1000 U/mL for glycosylated LIF. Neither LIF nor D-factor blocked the resorptive response to interleukin 1 (IL 1) or parathyroid hormone (PTH) nor did they alter total DNA synthesis. Hence, their inhibitory effects appeared to be specific for the mechanisms regulating basal resorptive activity. These results demonstrate that LIF has potent inhibitory actions on basal resorption rates in these cultures. These effects may be important for the anabolic responses that LIF has on bone in vivo. In addition, they may also be involved in the interactions between inflammatory or tumor cells and bone.

Interleukin-1 alpha and phorbol ester inhibit collagen synthesis in osteoblastic MC3T3-E1 cells by a transcriptional mechanism

The effects of recombinant human interleukin-1 alpha (IL-1) on procollagen gene expression were examined in the clonal mouse osteoblastic cell line MC3T3-E1. Cells were grown in Dulbecco's Modified Eagle's Medium containing 10% fetal calf serum and 50 micrograms/ml ascorbic acid. Collagen synthesis was assessed as [3H]proline incorporation into collagenase-digestible protein (CDP). Procollagen mRNA levels were determined by Northern blot analysis using a 32P-labeled alpha 1(I) cDNA. Transcription rates were determined by nuclear run-off assay. IL-1 at 1-1000 pg/ml caused a concentration-dependent inhibition of CDP, which was maximally reduced by 75-80%, and a parallel reduction of procollagen alpha 1(I) mRNA levels. The effects of IL-1 were mimicked by the tumor promoter phorbol 12-myristate 13-acetate (PMA) at 1-100 nM, which inhibited CDP and reduced procollagen alpha 1(I) mRNA levels to a similar extent. The effects of IL-1 and PMA were independent of prostaglandin production, since indomethacin did not alter the inhibitory effect of either agent on CDP. Neither IL-1 (up to 10 ng/ml) nor PMA (100 nM) affected adenylate cyclase activity, while forskolin (10 microM), PTH (10 nM) and prostaglandin E2 (1 microM) stimulated adenylate cyclase activity 3- to 5-fold. However, forskolin (10 microM) and (Bu)2cAMP (100 microM) failed to alter CDP or procollagen alpha 1(I) mRNA levels. IL-1 (1 ng/ml) and PMA (100 nM) reduced transcription of the alpha 1(I) procollagen gene by 70% and 80%, respectively, while alpha 2(I) transcription was decreased by 59% and 53%. Neither IL-1 nor PMA affected transcription of the beta-actin or beta-tubulin genes.(ABSTRACT TRUNCATED AT 250 WORDS)

Production of both interleukin-1 alpha and beta by newborn mouse calvarial cultures

The conditioned medium (CM) from 4-6 day newborn mouse calvarial cultures was found to contain thymocyte comitogen proliferation activity. This activity was blocked by an antiserum to murine interleukin-1 alpha (IL-1 alpha) but not by an antiserum to murine interleukin-1 beta. The release of thymocyte comitogen proliferation activity from the cultures did not appear dependent on endotoxin and was not associated with detectable interleukin-2 activity in the CM. Activity in the CM eluted from a gel filtration column with a peak Mr of 16-18 kD (the Mr of mature murine IL-1 alpha and beta is 17 kD). Western immunoblots of 100-fold concentrated CM demonstrated only a single 33 kD band with an antiserum to murine IL-1 beta and no bands with an antiserum to murine IL-1 alpha. However, this assay was relatively insensitive (limit of detection 1-10 ng compared with 1-10 pg for the thymocyte comitogen proliferation assay). Immunoprecipitation of [35S]methionine-labeled CM with three different anti-IL-1 alpha antisera, a more sensitive assay, demonstrated 15-17 kD bands in all cases. These results demonstrate that 4-6 day newborn mouse calvarial cultures spontaneously release 17 kD IL-1 alpha and 33 kD IL-1 beta into their conditioned medium. It appears that although 17 kD IL-1 alpha is the major bioactive form in the CM, 33 kD IL-1 beta is present in greater amounts. These results also suggest that local production of IL-1 can regulate bone cell function and may play a role in bone growth and remodeling.

The effects of thionapthene-2-carboxylic acid-lysine on the hypercalcemia of malignancy in the rat

Thionapthene-2-carboxylic acid (TNCA) was previously shown to lower serum calcium concentrations in hypercalcemic rats: however, oral administration of TNCA may cause gastric irritation. We have assessed thionapthene-2-carboxylic acid lysine salt (TNLY) for its effects on serum calcium concentration and survival in rats bearing the hypercalcemic Leydig cell tumor. TNLY (0.6-1.8 mmol/kg/day) produced a marked and prolonged dose-related decrease in serum calcium concentration. At the highest dose of 1.8 mmol/kg/day, hypocalcemia occurred. Effects were sustained for 96 hours or longer. In tumor-bearing rats that were not yet hypercalcemic, pretreatment with TNLY (0.9 mmol/kg/day) did not induce hypocalcemia and the onset of hypercalcemia was prevented. Neither TNLY nor dichloromethylene diphosphonate (CL2MDP), a potent inhibitor of bone resorption, significantly prolonged overall survival. We concluded that TNLY is a potent antihypercalcemic agent that warrants further testing for use in the treatment of hypercalcemic disorders.

Interleukin-1 in combination with transforming growth factor-alpha produces enhanced bone resorption in vitro

Interleukin-1 (IL-1) and transforming growth factor-alpha (TGF alpha) both stimulate bone resorption. We examined the effects that the combination of these two agents had on fetal rat long bone cultures. The 48-h resorptive response to recombinant human TGF alpha was markedly enhanced in the presence of IL-1 (either purified from stimulated human monocytes or recombinant human IL-1 alpha) compared to the effects of either agent alone. The enhanced resorptive response to the combination appeared to be dependent on prostaglandin (PG) synthesis, since it was associated with an increase in PGE concentrations in the medium and was completely blocked by either indomethacin or flufenamic acid. Substitution of TGF alpha with epidermal growth factor, a TGF alpha analog, produced identical results. We also found that IL-1 inhibited the mitogenic response of the cultures to TGF alpha. The effects of IL-1 and TGF alpha on PGE concentrations in the medium and DNA synthesis were similar in the osteoblast-like cell line MC3T3-E1. Activated macrophages and certain malignant cells are capable of producing both IL-1 and TGF alpha. Hence, similar interactions could occur in vivo and may regulate some of the effects that either immune or malignant cells have on bone.

Phorbol esters stimulate bone resorption in fetal rat long-bone cultures by mechanisms independent of prostaglandin synthesis

The phorbol esters, 12-O-tetradecanoylphorbol-13-acetate (TPA) and phorbol-12,13-didecanoate, which activate the enzyme protein kinase C, stimulated resorption in fetal rat long-bone cultures at concentrations of 1 and 10 microM. This effect appeared specific for active phorbol esters, since the inactive analogue 4-alpha-phorbol-12,13-didecanoate was without effect. The resorptive responses of fetal rat long-bone cultures to active phorbol esters differed from those previously described in newborn mouse calvaria cultures, since resorption stimulated by TPA in the rat long bones was not inhibited by either indomethacin (10 microM) or flufenamic acid (10 microM). However, calcitonin, an inhibitor of osteoclastic resorption, did decrease the response to TPA. There were some similarities between the response of fetal rat long-bone cultures to TPA and their response to epidermal growth factor (EGF). Like EGF, TPA stimulated DNA synthesis in the bones (measured as the incorporation of [3H]-thymidine) at concentrations below those necessary to stimulate resorption. TPA also did not stimulate resorption in the presence of aphidicolin (10 microM), an inhibitor of DNA synthesis that has been previously shown to block the resorptive response of these cultures to EGF. However, the responses of the cultures to TPA and EGF were not identical, since, unlike the effects of EGF, the stimulatory effects of TPA on DNA synthesis were biphasic. These results demonstrate that active phorbol esters stimulate bone resorption in fetal rat long-bone cultures through mechanisms that do not require prostaglandin synthesis but do appear to be mediated by osteoclasts.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the bone-resorbing activity in the supernatants from phytohemagglutinin-stimulated human peripheral blood mononuclear cells with that of cytokines through the use of an antiserum to interleukin 1

We compared the bone-resorbing activity in the conditioned medium from phytohemagglutinin (PHA)-stimulated human peripheral blood mononuclear cell cultures with that of partially purified human monocyte-derived interleukin 1 (IL-1), human recombinant IL-1 alpha (pI 5) and IL-1 beta (pI 7), human recombinant tumor necrosis factor-alpha (TNF alpha), and PTH in fetal rat long bone cultures. An antiserum to the products of activated human mononuclear cells, including IL-1, completely blocked the bone-resorbing activity of all three forms of IL-1 and of unfractionated PHA-stimulated human peripheral blood mononuclear cell supernatants, but did not inhibit resorption stimulated by recombinant human TNF alpha. This antiserum also had no effect on the resorptive response to 3 nM PTH, but did decrease the response to 1 nM PTH slightly. These results imply that IL-1, but not TNF alpha, mediates the bone-resorbing activity found in the supernatants of PHA-stimulated human peripheral blood mononuclear cell cultures. It is not known whether the small inhibitory effect that the antiserum to IL-1 had on the response to 1 nM PTH resulted from a nonspecific action or an effect of PTH on local IL-1 synthesis in bone. Since cytokines are found in the circulation of normal individuals and are produced at local sites of pathology, these results suggest that they can influence both normal and abnormal skeletal metabolism.

Colony-stimulating factors regulate the development of multinucleated osteoclasts from recently replicated cells in vitro

Osteoclasts mediate the process of bone resorption. However, little is known about the mechanisms that regulate the formation of either osteoclasts or osteoclast precursors. In contrast, colony-stimulating factors (CSFs) are well-known to regulate the formation of myeloid cells and their precursors. Because osteoclasts and myeloid cells may originate from a common stem cell, we examined the effects of two CSFs, granulocyte-macrophage CSF (GM-CSF) and interleukin 3 (IL-3), on bone resorption, osteoclast formation, and the incorporation of recently replicated nuclei into the osteoclasts of mouse bone cultures. CSFs had little effect on the formation rate of osteoclasts or their resorptive activity but significantly decreased the percentage of recently replicated osteoclast progenitor cell nuclei present in the osteoclasts of bones treated with parathyroid hormone. GM-CSF also increased the number of myeloid cells in the marrow space of the cultures and the percentage of these cells derived from recently replicated progenitors. These results demonstrate that GM-CSF and IL-3 can regulate the development of osteoclasts from recently replicated precursor cells in cultured fetal mouse long bones. However, the mechanisms by which CSFs influence osteoclast formation are difficult to determine from these studies because markers for the osteoclast progenitor and precursor do not exist. These data also provide evidence that the differentiation of osteoclast progenitors is regulated by different factors at different points in their ontogeny.

Forskolin has both stimulatory and inhibitory effects on bone resorption in fetal rat long bone cultures

The diterpene forskolin which increases 3',5'-cyclic adenosine monophosphate concentrations (cAMP) in intact cells by directly activating the enzyme adenyl cyclase, was examined for its ability to alter bone resorption in fetal rat long bone cultures. After 48 h, forskolin inhibited resorption at 1.0 and 10 microM. However, after 120 h, it had a small stimulatory effect at 1.0 microM and no net effect on resorption at 10 microM. Isobutyl-methylxanthine (IBMX), which elevates cAMP levels in cells by inhibiting the enzyme 3',5'-cyclic adenosine monophosphate phosphodiesterase, produced a resorptive response which was slightly different from that of forskolin. After both 48 and 120 h, IBMX at 0.1 mM stimulated resorption while at 1.0 mM, it had only inhibitory effects. In bones which were stimulated to resorb with either parathyroid hormone or 1,25(OH)2 vitamin D, forskolin inhibited resorption. The inhibitory effects of forskolin on hormonally stimulated resorption were transient in cultures treated with 1.0 microM but were sustained with 10 microM. Inhibitory responses to forskolin did not appear to result from toxicity since they were completely reversed when forskolin was removed from the media. These results imply that agents which increases 3',5'-cyclic adenosine monophosphate concentrations in bone activate two resorptive pathways: one which is inhibitory and another which is stimulatory.

Effects of DNA and prostaglandin synthesis inhibitors on the stimulation of bone resorption by epidermal growth factor in fetal rat long-bone cultures

We examined two inhibitors of DNA synthesis, hydroxyurea (HU) and aphidicholin (APC), and two inhibitors of prostaglandin cyclooxygenase, indomethacin and flufenamic acid, for their effects on the resorptive responses of fetal rat long-bone cultures to epidermal growth factor (EGF) and parathyroid hormone (PTH). As we have previously found, HU decreased unstimulated 45Ca release but had little effect on the resorptive response to PTH. HU also did not block resorption stimulated by EGF. Addition of the cyclooxygenase inhibitor, indomethacin, did not alter the resorptive responses of unstimulated or PTH-treated cultures in either the presence or absence of HU or the resorptive response of bones cultured with EGF alone. However, indomethacin completely blocked the resorptive response to EGF of bones that were cultured with HU. The effects of indomethacin on EGF-mediated resorption in HU-treated cultures appeared to be related to an inhibition of prostaglandin synthesis since flufenamic acid had similar effects. However, the effects of HU on the resorptive response to EGF may not have resulted solely from its inhibitory action on DNA synthesis since APC, in the absence of cyclooxygenase inhibitors, completely blocked EGF-mediated resorption without significantly affecting the response to PTH. These results demonstrate that the mechanisms regulating PTH- and EGF-mediated resorption in fetal rat long-bone cultures differ, and imply that a component of EGF-mediated resorption in these cultures is dependent on sustained DNA synthesis.

Effects of phosphate on calcium release, lysosomal enzyme activity in the medium, and osteoclast morphometry in cultured fetal rat bones

The relationship between changes in medium phosphate concentration and three indices of cell-mediated resorption in fetal rat bone cultures--calcium release, the activity of the lysosomal enzyme beta-glucuronidase in the medium, and the morphology of osteoclasts--has been investigated. Bones treated with either 1 mM or 4 mM phosphate, with or without parathyroid hormone, were examined. After 2 h of culture we found the predominant effect of changes in medium phosphate to be on non-cell-mediated resorption. However, after 24 h changes in medium phosphate affected both cell-mediated and non-cell-mediated resorptive mechanisms. The 24 h effects of phosphate were not associated with either a change in the activity of beta-glucuronidase in the medium or in the area of the ruffled border of osteoclasts, but 4 mM phosphate did prevent parathyroid hormone from increasing the area of the clear zone of osteoclasts. These results imply that changes in medium phosphate alter cell-mediated resorption by affecting mechanisms that are independent of increases in beta-glucuronidase activity or changes in the ruffled border of osteoclasts but that may involve effects on the clear zone of osteoclasts.

DNA synthesis is not necessary for osteoclastic responses to parathyroid hormone in cultured fetal rat long bones

Osteoclasts, the principal cells mediating bone resorption, are believed to increase their size, number, and resorbing activity in response to parathyroid hormone (PTH) through mechanisms dependent upon the fusion of specific mononuclear precursor cells into either new or existing multinucleated osteoclasts. To address the question of whether these actions of PTH are dependent on the replication of osteoclast precursor cells, we examined the ability of an inhibitor of DNA synthesis, hydroxyurea (HU), to alter bone resorption, osteoclast formation, and DNA synthesis in cultured fetal rat bones treated with PTH. We found that HU significantly reduced [3H]thymidine incorporation into the bones and labeling of osteoclast nuclei by greater than 90%, but did not prevent PTH from stimulating bone resorption, measured as the release of 45Ca, or from increasing the number of osteoclasts in the bones. In bones cultured without PTH, HU decreased the rate of bone resorption, but not the number of osteoclasts per bone. We conclude that in fetal rat bone cultures, PTH can increase osteoclast number and stimulate bone resorption by affecting existing osteoclasts and osteoclast precursors, and that replication of osteoclast precursor cells is not necessary for PTH to stimulate a resorptive response. In unstimulated cultures it appears that HU inhibits bone resorption by affecting mechanisms that are independent of changes in osteoclast number and that may be influenced by cell replication or other unknown factors.

Divalent cation ionophores stimulate resorption and inhibit DNA synthesis in cultured fetal rat bone

Two divalent cation ionophores, A23187 and Ionomycin, which are selective for calcium, stimulated the resorption of fetal rat long bones in organ culture at 0.1 to 1 micromolar but not at higher concentrations. Both agents inhibited DNA synthesis at concentrations that stimulated resorption. These results might explain the differences in ionophore effects on bone previously reported, and they imply that cell replication is not required for osteoclast formation in fetal rat long bone cultures.