OBJECTIVETo observe the expression of receptor activator of NF-κB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG) during unloading period of dental implants.

METHODSAn animal model of dental implants was established in Beagle dogs. Bone remodeling was tested at 3, 7, 15, 30, 60 and 90 days after the placement of implants. RANKL and OPG mRNA expression were quantified by real-time PCR. Then mandibular bones were resected and some sections were observed.

RESULTSThe most prominent period of bone remodeling occurred at 7 day after the placement of implants (OPG/RANKL mRNA, 2.15 ± 0.1). The expression of RANKL and OPG increased in a time-dependent manner in both soft and hard tissue. After 7 days they gradually decreased.

CONCLUSIONSBoth OPG and RANKL were expressed in peri-implant tissues, and the changing tendency of RANKL and OPGmRNA was consistent with the change of bone remodeling. The active stage for bone remodelling in peri-implant tissues during unloading period is about 7 days after implantation.

Animals ; Bone Remodeling ; genetics ; Dental Implantation ; Dogs ; Male ; Osteoprotegerin ; genetics ; metabolism ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; metabolism

OBJECTIVETo investigate the influence of surface modification of titanium on OPG/RANKL mRNA expression in human osteoblast-like cells.

METHODSMG-63 osteoblast-like cells were seeded on the titanium plates with surface polishing and with surface modification by sandblasting plus acid-base treatment, with the cells on glass slides as the control. On days 2, 4, 6, and 8 following cell seeding, the cells were harvested for examination of OPG/RANKL mRNA expression using RT-PCR and real-time PCR.

RESULTSThe expression of OPG/RANKL mRNA was sensitive to the surface microphotography. Compared with the other groups, the cells on the titanium plates with sandblasting plus acid-base treatment, which resulted in a porous micro-structure and high roughness, showed significantly up-regulated expression of OPG mRNA. OPG mRNA expression also showed a time-dependent up-regulation, and was the highest on day 8. The expression of the RANKL mRNA in cells on both of the titanium plates was higher than that in the control cells. The peak level of RANKL mRNA expression occurred on day 6 followed by a gradual decrease.

CONCLUSIONA rough and porous surface of the culture plates and prolonged culture time can synergistically up-regulate the ratio of OPG/RANKL mRNA.

Cell Culture Techniques ; Cell Line ; Humans ; Osteoblasts ; cytology ; metabolism ; Osteoprotegerin ; genetics ; metabolism ; Porosity ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Surface Properties ; Tissue Scaffolds ; Titanium ; chemistry ; pharmacology

OBJECTIVETo study the expression profiles of osteoprotegerin (OPG) and receptor activator of nuclear factor-KB ligand (RANKL) in the distraction region and to investigate the mechanism of bone remodelling during mandibular distraction osteogenesis.

METHODSOsteotomies were performed and external distractors were installed on the mandibles of 42 adult male SD rats. After a 5-day latency period, the distractors were activated at a rate of 0.4 mm/day for 6 days, followed by a 4-week consolidation period. Radiographs were taken, and specimens were harvested at the end of the latency period, when distraction was completed, and at of 1, 2, 3 and 4 weeks of the consolidation period. Tartrate-resistant acid phosphatase (TRAP) staining was used to detect the activated osteoclasts. Temporospatial expression of OPG and RANKL was investigated by using immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR). Semi-quantitative analysis was used to characterize OPG,RANKL and RANK/OPG ratio.

RESULTSIn all time points, OPG and RANKL were co-localized in bone marrow lining cells, osteoblasts and newly embedded osteocytes. OPG mRNA expression increased to a peak level when distraction was completed and maintained the level until the end of 2nd week of the consolidation period. RANKL mRNA expression increased steadily until the end of 1 st week of the consolidation period and maintained a peak level until the end of 3rd week, with a slight decrease at the end of 2nd week. The RANKL/OPG ratio increased continuously and reached its highest level at the end of 3rd and 4th week of the consolidation period. TRAP positive osteoclasts were mainly detected at 2, 3 and 4 weeks of the consolidation period in bone marrow cavities and bone surfaces.

CONCLUSIONSThe temporospatial expression patterns of osteoprotegerin and RANKL suggest that osteoblasts and the lineage cell network orchestrates bone remodelling during distraction. Osteogenesis and the most activated bone resorption takes place during 3rd and 4th week of the consolidation phase.

Animals ; Bone Remodeling ; Male ; Mandible ; metabolism ; surgery ; Osteogenesis, Distraction ; Osteoprotegerin ; genetics ; metabolism ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley

Persistent generalized low bone mineral density (BMD) has been reported in patients with adolescent idiopathic scoliosis (AIS). However, the exact mechanisms and causes of the low BMD in AIS patients are largely unknown. The purpose of this study was to examine the relationship between the receptor activator of NF-κB ligand (RANKL)/osteoprotegerin (OPG) levels in osteoblasts (OBs) from AIS patients with low BMD and with comparison made between the patients and controls. Twenty AIS patients and eight age-matched controls were included in the present study. The BMD of lumbar spine and proximal femur was measured in all subjects. OBs from the cancellous bone of each subject was harvested and primarily cultured. The mRNA and protein expression of RANKL and OPG in OBs was detected by RT-PCR and Western blotting. The results showed BMD was lower in AIS patients than in controls. A significantly higher mRNA and protein expression of RANKL was observed in OBs from AIS patients, while no significant difference was found in the expression of OPG between AIS patients and controls. As a result, RANKL/OPG ratio in patients with AIS was remarkably higher than controls. Our study preliminarily demonstrated expression of RANKL was higher in OBs from AIS patients with low BMD as compared with controls, suggesting the unbalanced RANKL/OPG ratio caused by an over-expression of RANKL in OBs may be responsible for the low BMD in AIS patients.
Adolescent ; Bone Density ; genetics ; Child ; Humans ; Osteoblasts ; metabolism ; RANK Ligand ; genetics ; Receptor Activator of Nuclear Factor-kappa B ; genetics ; metabolism ; Scoliosis ; genetics ; Young Adult

OBJECTIVETo evaluate the effects of sonicated extracts of Porphyromonas gingivalis (Pg) on receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) expression in human periodontal ligament cells (HPDLC) and the effect of Pg on bone resorption in periodontitis.

METHODSHPDLC were exposed to 25, 50 mg/L sonicated extracts of Pg for 6 h, HPDLC without treatment served as control. The expression of RANKL-OPG mRNA and protein were examined by real time polymerase chain reaction and Western blotting. OPG protein in the supernatant was examined by enzyme linked immunosorbent assay (ELISA). The data were statistically analyzed by SPSS 13.0 and one-way analysis of variance (ANOVA).

RESULTSWhen HPDLC were exposed to sonicated extracts of Pg, the expression of RANKL mRNA and protein in 25 mg/L and 50 mg/L groups were higher than that of control group (P < 0.05), the expression of OPG mRNA in 50 mg/L group (0.087 ± 0.021) was lower than that of control group (0.240 ± 0.019) (P < 0.05), and OPG protein in 25 mg/L and 50 mg/L groups (0.813 ± 0.007, 0.398 ± 0.009) was lower than that of control group (1.131 ± 0.005) (P < 0.01). OPG protein expression in the supernatant was not significantly different between experimental group and control group.

CONCLUSIONSSonicated extracts of Pg exposed to HPDLC can up-regulate RANKL expression, down-regulate OPG expression and influence bone metabolism.

Adult ; Cells, Cultured ; Humans ; Osteoprotegerin ; genetics ; metabolism ; Periodontal Ligament ; cytology ; metabolism ; Porphyromonas gingivalis ; pathogenicity ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Sonication ; Young Adult

Osteoclasts are multinucleated giant cell, which derived from mononuclear myeloid hematopoietic stem cells with the function of bone absorption. Osteoclasts plays a key role in bone metabolism, therefore the body is very strict to regulation of osteoclastogenesis. Mobilization and differentiation of osteoclast maturation is a complex and sophisticated multi-level regulatory processes. In the relevant regulatory mechanisms, OPG/RANKL/RANK system plays a pivotal role in the process of osteoclast differentiation and maturation. Recent studies revealed that immune cells and osteoclasts were closely connect with each other in the field of bone metabolism, also provide a new therapeutic target for the treatment of bone diseases. The apoptosis of osteoclasts in bone metabolism have been payed more attention,while its mechanism is still not clear, which need further research.
Animals ; Cell Differentiation ; Gene Expression Regulation ; Humans ; Osteoclasts ; cytology ; metabolism ; Osteoprotegerin ; genetics ; metabolism ; RANK Ligand ; metabolism ; Receptor Activator of Nuclear Factor-kappa B ; genetics ; metabolism

OBJECTIVETo evaluate the possible signal transduction mechanism of the mechanical stress induced by the distraction procedure in osteocytes.

METHODSAn animal model of mandibular distraction osteogenesis in rabbits was established. The expressions of c-fos, OPG and OPGL were detected by ultrasensitive S-P immunohistochemical method.

RESULTAt 4 and 8 days after distraction, distraction zone showed strong positive staining of c-fos, which were apparently higher than that in distraction zone of 2, 4 and 6 weeks after consolidation. At 4 and 8 days after distraction and 2 weeks after consolidation, the expression of OPG was strong, and then wore off gradually at 4 and 6 weeks after consolidation. Weak signals of OPGL could be detected at 6 weeks after consolidation only.

CONCLUSIONc-fos, OPG and OPGL are important regulators in distraction osteogenesis. c-fos is interrelated with the mechanical stress induced by the distraction procedure closely, OPG promotes new bone formation, while OPGL plays a more active role in bone remodeling.

Animals ; Mandible ; cytology ; metabolism ; Osteocytes ; metabolism ; Osteogenesis, Distraction ; Osteoprotegerin ; biosynthesis ; genetics ; Proto-Oncogene Proteins c-fos ; biosynthesis ; genetics ; RANK Ligand ; biosynthesis ; genetics ; Rabbits ; Random Allocation

OBJECTIVE: To determine the effect of continuously compressive pressure (CCP) on the expression of receptor activator of nuclear factor kappa B ligand (RANKL) in human periodontal ligament cells (HPDLCs) and to investigate the role of RANKL in alveolar bone rebuilding during orthodontic tooth movement. METHODS: The primary HPDLCs were isolated from human periodontal ligament by explanting enzymatic digestion with trypsin and collagenase to establish a pressure model. Top-bottom axial pressures (1, 2, and 3 g/cm(2)) were laid on HPDLCs for 0.5, 1.5, 6, 12, 24, and 48 h, respectively. The RANKL expression was identified by the reverse transcription-polymerase chain reaction (RT-PCR) at the mRNA level. RESULTS: The expression of RANKL mRNA significantly increased in a time-dependent manner (P<0.01), so did the value of pressure, especially in the 2 g/cm(2) group (P<0.05). CONCLUSION CCP can up-regulate the expression of RANKL mRNA in human periodontal ligament cells.
Compressive Strength ; Humans ; Periodontal Ligament ; cytology ; metabolism ; RANK Ligand ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Receptor Activator of Nuclear Factor-kappa B ; genetics ; metabolism ; Stress, Mechanical

OBJECTIVETo explore the mechanism of Shangke Jiegu Tablet (SJT)in repairing the mandibular defect.

METHODSTotally 72 healthy male New Zealand rabbits were randomly divided into the normal control group (n = 24), the model group (n = 24), and the SJT group (n = 24). Then the mandibular defect model was established. Animals in the normal control group and the model group were fed with normal forage, while those in the SJT group were fed with SJT forage. On the day 7, 14, 28, and 56 after model establishment, 6 rabbits were killed in each group. The bone was collected from the mandibular defect. The gene expressions of osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL) were detected by means of RT-PCR. The positive dyeing strength and area of the bone tissue were detected by means of immunohistochemical technique.

RESULTSCompared with the normal control group, the degree of OPGmRNA expression was remarkably up-regulated on day 7 after model establishment (P < 0.05) and the degree of OPGLmRNA expression was remarkably up-regulated on day 14 after model establishment (P < 0.05) in the model group. Compared with the model group, the degree of OPGmRNA expression was remarkably up-regulated (P < 0.05), and the positive dyeing strength and area of bone tissue were stronger and broader on day 14, 28, and 56 after model establishment in the SJT group. The degree of OPGLmRNA expression was remarkably down-regulated (P < 0.05), and the positive dyeing strength and area of bone tissue were weaker and smaller on day 14 after model establishment in the SJT group. The ratio of OPGmRNA/OPGLmRNA was remarkably up-regulated on day 14, 28, and 56 after model establishment (P < 0.05).

CONCLUSIONThe effect mechanism of promoting mandibular defect repairing by SJT may be correlated to regulating the expressions of OPGmRNA and OPGLmRNA.

Animals ; Drugs, Chinese Herbal ; pharmacology ; Gene Expression ; drug effects ; Ligands ; Male ; Mandibular Injuries ; genetics ; metabolism ; Osteoprotegerin ; metabolism ; RANK Ligand ; metabolism ; Rabbits ; Wound Healing ; drug effects

OBJECTIVETo investigate the expression of receptor activator of nuclear factor-κB (RANK), its ligand RANKL, and osteoprotegerin, and observe the effects of αD3 on their expressions in male rats at different ages.

METHODSWistar rats at 6 weeks, 6 months, and 24 months (n=15) were examined for mRNA expressions of RANK/RANKL and osteoprotegerin in the left proximal femur using RT-PCR and for their protein expressions in the right femur using immunohistochemistry. RANK/RANKL and osteoprotegerin expressions were also detected in another 15 rats aged 24 months following intragastric administration of 0.05 µg/kg αD3 (3 times a week for 10 weeks).

RESULTSCompared with 6-week-old rats, 6-month- and 24-month-old rats showed a 6.2-fold and 7.3-fold increase of RANKL mRNA expression, respectively (P<0.05), and osteoprotegerin mRNA levels increased slightly with age. αD3 treatment resulted in significantly increased expression of RANK in 24-month-old rats with a lowered RANKL/osteoprotegerin ratio. RANKL and osteoprotegerin were co-localized in the osteoblasts and chondrocytes. αD3 treatment also caused an increased expression of osteoprotegerin mRNA in 24-month-old rats.

CONCLUSIONThe age-related increase of the ratio of RANKL/osteoprotegerin mRNA promotes osteoclast activity and bone turnover. αD3 has favorable effect on osteogenesis and suppress bone absorption in the femur possibly by reducing RANK expression and lowering RANKL/osteoprotegerin ratio.

Age Factors ; Animals ; Chondrocytes ; metabolism ; Femur ; metabolism ; Male ; Osteoblasts ; metabolism ; Osteoprotegerin ; genetics ; metabolism ; RANK Ligand ; genetics ; metabolism ; RNA, Messenger ; genetics ; Rats ; Rats, Wistar ; Receptor Activator of Nuclear Factor-kappa B ; genetics ; metabolism