The effect of the alendronate on OPG/RANKL system in differentiated primary human osteoblasts

A mechanistic study on the toluidine blue/ photodynamic therapy inhibition of lipopolysaccharide-induced inflammatory response in rat gingival fibroblasts

The purpose of this research was to investigate the effect of toluidine blue (TB) mediated photodynamic therapy (PDT) on the inhibition of lipopolysaccharide (LPS)-induced inflammation in rat gingival fibroblasts through in vitro experiments. Rat gingival fibroblasts were divided into five groups: (1) control, (2) LPS treatment, (3) laser treatment, (4) TB treatment (1.0 µg/mL), and (5) PDT treatment (TB plus laser irradiation at 320 mW/cm2 for 240 s). After 24 h, cell growth activity was measured using MTT assay. The levels of receptor activator for nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) in the cell culture supernatant were measured using enzyme-linked immunosorbent assay (ELISA). Nuclear proteins were extracted and the phosphorylation levels of phosphorylated nuclear factor-κB/p65 (p-p65) and phosphorylated inhibitor of nuclear factor-κB (p-IκBα) were determined using Western Blot. MTT results showed no significant difference in cell viability between the groups (P > 0.05). After LPS induction, OPG expression decreased, RANKL expression increased, and the OPG/RANKL ratio decreased, which was different from the control group (P < 0.05). After PDT treatment, OPG expression increased, RANKL expression decreased (P < 0.05), and the OPG/RANKL ratio increased (P < 0.05). Compared to the control group, there was no significant difference in OPG and RANKL expression or the OPG/RANKL ratio (P > 0.05). The activation of NF-κB was closely related to the phosphorylation levels of p-p65 and p-IκBα. LPS significantly up-regulated p-p65 and p-IκBα expression (P < 0.05), while PDT treatment decreased their phosphorylation levels (P < 0.05). TB-PDT treatment can inhibit NF-κB signaling pathway activation, decrease RANKL and OPG expression, and reduce the OPG/RANKL ratio, thereby reducing inflammation and playing a role in periodontitis treatment.

Significance of bisphosphonates on angiogenesis in vivo and their effect under geranyl-geraniol addition - could it alter the treatment of bisphosphonate-associated necrosis of the jaw?

PURPOSE

The aim of this study was to contribute to the understanding of the inhibitory effects of bisphosphonates on tissues, with a special focus on angiogenesis. Referring to bisphosphonate-associated osteonecrosis of the jaw (BP-ONJ), it should be shown that the local addition of the isoprenoid geranyl-geraniol (GGOH) prevents vascularization processes.

METHODS

A mouse model with n = 24 animals which received an injection of a collagen matrix was used. In 4 subgroups (n = 6), we examined the effect of zoledronate on the sprouting of capillary-like structures into the matrix, with and without the presence of geranyl-geraniol, as well as testing against control groups with PBS injections or collagen matrix containing PBS instead of GGOH. This was followed by a histological evaluation of the capillary-like structures.

RESULTS

Zoledronate inhibits the sprouting of blood vessels into a collagen matrix in vivo; in the presence of GGOH this effect is significantly weakened by a factor of 3.9 (p = 0.00068).

CONCLUSION

This work commits to the investigation of the pathophysiology of BP-ONJ and shows a possible causal therapeutic path via the topical application of GGOH.

Comparison of the Effects of Denosumab and Alendronate on Cardiovascular and Renal Outcomes in Osteoporotic Patients

A correlation between impaired bone metabolism, chronic kidney disease, and cardiovascular diseases (CVD) has been suggested. This study aimed to compare the effects of denosumab and alendronate, two anti-resorptive agents, on cardiovascular and renal outcomes in osteoporotic patients. Propensity score-matched cohort study comparing denosumab to alendronate users between January 2005 and December 2017 was conducted from a large medical organization in Taiwan. Risks of CVD development and renal function decline were estimated using Cox proportional hazard regression. A total 2523 patients were recruited in each group. No significant difference in cardiovascular events was found between the two groups over a 5-year study period. Stratified analysis results showed that denosumab was likely to exert protective effects against composite CVD in patients with medication possession rate ≥60% (adjusted hazard ratio (AHR), 0.74; p = 0.0493) and myocardial infraction (AHR, 0.42; p = 0.0415). Denosumab was associated with increased risk of renal function decline in male patients (AHR, 1.78; p = 0.0132), patients with renal insufficiency (AHR, 1.5; p = 0.0132), and patients with acute kidney injury during the study period (AHR, 1.53; p = 0.0154). Conclusively, denosumab may exert cardiovascular benefits in patients with good adherence but may have renal disadvantages in certain conditions and thus must be used with caution.

Characterization of neuroblastoma bone invasion/metastasis in established bone metastatic model of SY5Y and KCNR cell lines

OBJECTS

To determine the mechanism of neuroblastoma (NB) bone invasion/metastasis, it is necessary to investigate the bone invasion/metastasis-related factors in the bone invasion/metastasis process. Some evidence has suggested that various proteins were involved in bone osteolytic response. The invasion/metastasis property and gene expression of NB, however, are still unknown.

METHODS

Single-cell suspensions of SY5Y and KCNR cells were injected directly into the femur of nude mice. Radiological and histological analyses, immunohistochemistry analyses, and western blot assay were performed to characterize bone metastasis mechanism in these bone metastasis models.

RESULTS

SY5Y and KCNR NB cells result in osteolytic responses in bone metastasis model. Osteoprotegerin (OPG), receptor activator of NF-kappaB ligand (RANKL), parathyroid hormone-related peptide (PTHrP), endothelin 1 (ET-1), and CXCR4 were examined and compared among in vitro, in vivo, and normal bone, respectively. PTHrP, OPG, RANKL, and ET-1 except CXCR4 in SY5Y and KCNR NB cells xenografts were strikingly upregulated compared with normal bone and NB cells. However, significantly stronger expression of PTHrP and RANKL was presented than ET-1 and OPG; furthermore, the ratios of expression of PTHrP, RANKL to OPG, and ET-1 were also markedly increased in vivo versus in vitro.

CONCLUSIONS

Our study provided evidence that NB cell may enhance bone invasion through PTHrP, OPG, RANKL, and ET-1, especially PTHrP and RANKL which may display stronger effects. CXCR4 appeared not participating in bone invasion, but in tumor growth, and homing to bone. Targeting PTHrP, OPG, ET-1, and RANKL may provide a new insight and method for patient therapy by inhibiting NB bone metastasis and invasiveness.

Alendronate enhances osseous healing in a rat calvarial defect model

AIM

The aim of this study was to evaluate the effect of alendronate on osseous wound healing in an experimental model.

METHODS

Critical size defects were created in calvaria of 40 male Wistar rats. The animals were divided into four groups of 10 animals each: autogenous bone graft group; autogenous bone graft with systemic alendronate group (0.01 mg/kg body weight per day for 8 weeks); autogenous bone graft with local alendronate group (1mg/mL for 5 min); non-treatment (control) group. Animals were sacrificed after 8 weeks; osteoblast number, lamellar bone formation, and area of newly formed bone were analysed.

RESULTS

The osteoblast number significantly increased in the autogenous bone graft with local alendronate group compared to the autogenous bone graft group (p<0.05). Both systemic and local application of the alendronate significantly increased the new bone formation compared to the autogenous bone graft group (p<0.05) with no significant difference between local or systemic use (p>0.05). Local alendronate and autogenous bone graft use significantly increased the total bone area compared to autogenous bone graft alone (p<0.05).

CONCLUSION

Alendronate enhances the new bone formation by autogenous bone graft in the rat calvarial defect model suggesting that the inhibition of the osteoclastic activity allows an increased rate of bone apposition, which could be applicable to the inflammation-induced destruction of the periodontal tissues during disease.

The effect of zoledronate-hydroxyapatite nanocomposites on osteoclasts and osteoblast-like cells in vitro

This study demonstrates that zoledronate containing hydroxyapatite nanocrystals (HA-ZOL) can be synthesized as a single crystalline phase up to a zoledronate content of about 7 wt% by direct synthesis in aqueous solution, at variance with what previously found for alendronate-hydroxyapatite nanocrystals (HA-AL). On increasing zoledronate incorporation, the length of the coherent crystalline domains and the crystal dimensions of hydroxyapatite decrease, whereas the specific surface area increases. Full profile fitting of the powder X-ray diffraction patterns does not indicate major structural modifications, but an increase of the hydroxyapatite unit cell, on increasing zoledronate content. These data, together with a structural similarity between hydroxyapatite and calcium zoledronate, suggest a preferential interaction between zoledronate and the hydroxyapatite faces parallel to the c-axis direction. Osteoblast-like MG-63 cells and human osteoclasts were cultured on HA-ZOL nanocrystals and as a comparison on HA-AL nanocrystals containing almost the same (about 7 wt%) bisphosphonate amount. The beneficial influence of bisphosphonates on osteoblast proliferation and differentiation is enhanced when the tests are performed in co-cultures. Similarly, the reduction of osteoclast proliferation and the increase of Caspase 3 production are dramatically enhanced in co-cultures, which highlight an even greater influence of HA-ZOL than HA-AL on osteoclast apoptosis.