Bisphosphonate-enoxacin inhibit osteoclast formation and function by abrogating RANKL-induced JNK signalling pathways during osteoporosis treatment

AUTHORS

Qiang Xu, Ping Zhan, Xiaofeng Li, Fengbo Mo, Huaen Xu, Yuan Liu, Qi Lai, Bin Zhang,Min Dai, Xuqiang Liu

ABSTRACT

Osteoporosis is an age-related disease characterized by low mineral density, compromised bone strength and increased risk of fragility fracture. Most agents for treating osteoporosis focus primarily on anti-resorption by inhibiting osteoclast activity. Bisphosphonate (BP) is a potent anti-resorptive agent that has been used clinically for decades and is proven to be effective. However, BP has a variety of side effects and is far from being an ideal anti-osteoporosis agent. BP selectively binds to calcium crystals, which are subsequently taken up or released by osteoclasts. Based on the action of BP, we previously demonstrated the inhibitory effect of a novel bone-targeting BP derivative, bisphosphonate-enoxacin (BE). In the current study, we used bone marrow-derived osteoclast cultures to further assess the inhibitory effect of BE on osteoclastogenesis and employed reverse transcription PCR and real-time PCR to examine expression of osteoclast-specific genes. Additionally, we used bone resorption and F-actin immunofluorescence assays to evaluate the effect of BE on osteoclast function and investigated the potential mechanisms affecting osteoclast differentiation and function in vitro. Furthermore, an ovariectomized (OVX) rat model was established to evaluate the therapeutic effects of BE on preventing bone loss. Results showed that BE exerted potent inhibitory effects on osteoclast formation and bone resorption by specifically abrogating RANKL-induced JNK signalling, and that it preserved OVX rat bone mass in vivo without any notable side effects. Collectively, these results indicated that the BP derivative BE may have significant potential as a treatment for osteoporosis and other osteolytic diseases.

Bone Nanomechanical Properties and Relationship to Bone Turnover and Architecture in Patients With Atypical Femur Fractures: A Prospective Nested Case-Control Study

AUTHORS

Lanny V. Griffin,Elizabeth Warner,Saroj Palnitkar,Shijing Qiu,Mahalakshmi Honasoge,Shawna G. Griffin,George Divine,Sudhaker D. Rao

ABSTRACT

Atypical femur fractures (AFFs) are well-established serious complication of long-term bisphosphonate and denosumab therapy in patients with osteopenia or osteoporosis. To elucidate underlying mechanism(s) for the development of AFF, we performed a nested case-control study to investigate bone tissue nanomechanical properties and prevailing bone microstructure and tissue-level remodeling status as assessed by bone histomorphometry. We hypothesized that there would be differences in nanomechanical properties between patients with and without AFF and that bone microstructure and remodeling would be related to nanomechanical properties. Thirty-two full-thickness transiliac bone biopsies were obtained from age- and sex-matched patients on long-term bisphosphonate therapy with (n = 16) and without an AFF (n = 16). Standard histomorphometric measurements were made in each sample on three different bone envelopes (cancellous, intracortical, and endosteal). Iliac bone wall thickness was significantly lower on all three bone surfaces in patients with AFF than in those without AFF. Surface-based bone formation rate was suppressed similarly in both groups in comparison to healthy premenopausal and postmenopausal women, with no significant difference between the two groups. Nanoindentation was used to assess material properties of cortical and cancellous bone separately. Elastic modulus was higher in cortical than in cancellous bone in patients with AFF as well as compared to the elastic modulus of cortical bone from non-AFF patients. However, the elastic modulus of the cancellous bone was not different between AFF and non-AFF groups or between cortical and cancellous bone of non-AFF patients. Resistance to plastic deformation was decreased in cortical bone in both AFF and non-AFF groups compared to cancellous bone, but to a greater extent in AFF patients. We conclude that long-term bisphosphonate therapy is associated with prolonged suppression of bone turnover resulting in altered cortical remodeling and tissue nanomechanical properties leading to AFF.

Local Administration of Bone Morphogenetic Protein-2 and Bisphosphonate During Non-Weight-Bearing Treatment of Ischemic Osteonecrosis of the Femoral Head

Authors

Harry K.W. Kim, MD, MS; Olumide Aruwajoye, MS; Justin Du ; Nobuhiro Kamiya, MD, PhD

Abstract

Background: Non-weight-bearing decreases the femoral head deformity but increases bone resorption without increasing bone formation in an experimental animal model of Legg-Calvé-Perthes disease. We sought to determine if local administration of bone morphogenetic protein (BMP)-2 with or without bisphosphonate can increase the bone formation during the non-weight-bearing treatment in the large animal model of Legg-Calvé-Perthes disease.

Methods: Eighteen piglets were surgically induced with femoral head ischemia. Immediately following the surgery, all animals received an above-the-knee amputation to enforce local non-weight-bearing (NWB). One to two weeks later, six animals received local BMP-2 to the necrotic head (BMP group), six received local BMP-2 and ibandronate (BMP+IB group), and the remaining six received no treatment (NWB group). All animals were killed at eight weeks after the induction of ischemia. Radiographic, microcomputed tomography (micro-CT), and histomorphometric assessments were performed.

Results: Radiographic assessment showed that the femoral heads in the NWB, BMP, and BMP+IB groups had a decrease of 20%, 14%, and 10%, respectively, in their mean epiphyseal quotient in comparison with the normal control group. Micro-CT analyses showed significantly higher femoral head bone volume in the BMP+IB group than in the BMP group (p = 0.02) and the NWB group (p < 0.001). BMP+IB and BMP groups had a significantly higher trabecular number (p < 0.01) and lower trabecular separation (p < 0.02) than the NWB group. In addition, the osteoclast number per bone surface was significantly lower in the BMP+IB group compared with the NWB group. Calcein labeling showed significantly higher bone formation in the BMP and BMP+IB groups than in the NWB group (p < 0.05). Heterotopic ossification was found in the capsule of four hips in the BMP+IB group but not in the BMP group.

Conclusions: Administration of BMP-2 with bisphosphonate best decreased bone resorption and increased new bone formation during non-weight-bearing treatment of ischemic osteonecrosis in a pig model, but heterotopic ossification is a concern.

Clinical Relevance: This preclinical study provides new evidence that BMP-2 with bisphosphonate can effectively prevent the extreme bone loss associated with the non-weight-bearing treatment and increase new bone formation in the femoral head in this animal model of ischemic osteonecrosis.

Link To Article

http://dx.doi.org/10.2106/JBJS.M.01361

Effects of androgen deprivation therapy and bisphosphonate treatment on bone in patients with...

Authors

Colm Morrissey, Martine P. Roudier, Alex Dowell, Lawrence D. True, Melanie Ketchanji, Christopher Welty, Eva Corey, Paul H. Lange, Celestia S. Higano, Robert L. Vessella

Abstract

Qualitative and quantitative bone features were determined in nondecalcified and decalcified bone from 20 predetermined bone sites in each of 44 patients who died with castration resistant prostate cancer (CRPC), some of which received bisphosphonate treatment (BP) in addition to androgen deprivation therapy (ADT). Thirty nine of the 44 patients (89%) had evidence of bone metastases. By histomorphometric analysis, these bone metastases were associated with a range of bone responses from osteoblastic to osteolytic with a wide spectrum of bone responses often seen within an individual patient. Overall, the average bone volume/tissue volume (BV/TV) was 25.7% confirming the characteristic association of an osteoblastic response to prostate cancer bone metastasis when compared to the normal age-matched weighted mean BV/TV of 14.7%. The observed new bone formation was essentially woven bone and this was a localized event. In comparing BV/TV at metastatic sites between patients who had received BP treatment and those that had not, there was a significant difference (28.6% vs 19.3%, respectively). At bone sites that were not invaded by tumor, the average BV/TV was 10.1% indicating significant bone loss due to ADT that was not improved (11%) in those patients who had received BPs. Surprisingly there was no significant difference in the number of osteoclasts present at the metastatic sites between patients treated or not treated with BPs but in bone sites where the patient had been treated with BPs, giant osteoclasts were observed. Overall, 873 paraffin embedded specimens and 661 methylmethacrylate embedded specimens were analyzed. Our results indicate that in CRPC patients, ADT induces serious bone loss even in patients treated with BP. Furthermore, in this cohort of patients, BP treatment increased BV and did not decrease the number of osteoclasts in prostate cancer bone metastases compared to bone metastases from patients who did not receive BP.

Link to Article

http://dx.doi.org/10.1002/jbmr.1749