Enhanced Immunoprotective Effects by Anti-IL17 Antibody Translates to Improved Skeletal Parameters Under Estrogen Deficiency Compared to Anti-RANKL and Anti-TNFα Antibodies

Authors

Abdul M Tyagi, Mohd. N Mansoori, Kamini Srivastava, Mohd. P Khan, Jyoti Kureel, Manisha Dixit, Priyanka Shukla, Ritu Trivedi, Naibedya Chattopadhyay and Divya Singh

Abstract

Activated T cell has a key role in the interaction between bone and immune system. T cells produce pro-inflammatory cytokines including, RANKL, TNF-α and IL-17, all of which augment osteoclastogenesis. RANKL and TNF-α are targeted by inhibitors like denosumab, a human monoclonal RANKL antibody and infliximab, which neutralizes TNF-α. IL-17 is also an important mediator of bone loss and an antibody against IL-17 is undergoing phase II clinical trial for rheumatoid arthritis. Although there are few studies showing suppression of Th17 cell differentiation and induction of regulatory T cells (Tregs) by infliximab, however the effect of denosumab remains poorly understood. In this study, we investigated the effects of anti-TNFα, anti-RANKL or anti-IL17 antibody administration to estrogen deficient mice on CD4 + T cell proliferation, CD28 loss, Th17/Treg balance and B lymphopoesis, and finally, the translation of these immunomodulatory effects on skeletal parameters. Adult Balb/c mice were treated with anti-RANKL/-TNFα/-IL17 subcutaneously, twice a week, post-ovariectomy (Ovx) for four weeks. Animals were then autopsied; bone marrow cells collected for FACS and RNA analysis and serum collected for ELISA. Bones were dissected for static and dynamic histomorphometry studies. We observed that while anti-RANKL and anti-TNFα therapies had no effect on Ovx-induced CD4 + T cell proliferation and B lymphopoesis; anti-IL17 effectively suppressed both events with concomitant reversal of CD28 loss. Anti-IL17 antibody reduced pro-inflammatory cytokine production and induced Tregs. All three antibodies restored trabecular microarchitecture with comparable efficacy; however cortical bone parameters, bone biomechanical properties and histomorphometry were best preserved by anti-IL17 antibody likely due to its inhibitory effect on osteoblast apoptosis and increased number of bone lining cells and Wnt10b expression. Based on the superior immunoprotective effects of anti-IL17 which appears to translate to a better skeletal preservation, we propose beginning clinical trials using a humanized antibody against IL-17 for treatment of post-menopausal osteoporosis.

Link To Article

http://dx.doi.org/10.1002/jbmr.2228

Curcumin Inhibits Prostate Cancer Bone Metastasis by Up-Regulating Bone Morphogenic Protein-7 in Vivo

Authors

Thambi Dorai, Janane Diouri, Orla O’Shea, Stephen B. Doty

Abstract

A number of studies have focused on the beneficial properties of Curcumin (diferuloyl methane, used in South Asian cuisine and traditional medicine) such as the chemoprevention of cancer. Recent studies have also indicated that this material has significant benefits for the treatment of cancer and is currently undergoing several clinical trials. We have been interested in the application of this compound as a therapeutic agent for advanced prostate cancer, particularly the skeletal complications in this malignancy. Our earlier work indicated that this compound could inhibit the osteomimetic properties which occur in castration resistant prostate cancer cells, by interfering with the common denominators between these cancer cells and the bone cells in the metastatic tumor microenvironment, namely the osteoblasts and the osteoclast. We predicted that curcumin could break the vicious cycle of reciprocal stimulation that results in uncontrolled osteolysis in the bony matrix. In this work, we have evaluated the potential of this compound in inhibiting the bone metastasis of hormone refractory prostate cancer cells in an established animal model. Our results strongly suggest that curcumin modulates the TGF-β signaling that occurs due to bone matrix degradation by up-regulating the metastasis inhibitory bone morphogenic protein-7 (BMP-7). This enhancement of BMP-7 in the context of TGF-β in the tumor microenvironment is shown to enhance the mesenchymal-to-epithelial transition. Most importantly, we show that as a result of BMP-7 up-regulation, a novel brown/beige adipogenic differentiation program is also up-regulated which plays a role in the inhibition of bone metastasis. Our results suggest that curcumin may subvert the TGF-β signaling to an alternative adipogenic differentiation program in addition to the previously established interference with the osteomimetic properties, thus inhibiting the bone metastatic processes in a chemopreventive as well as therapeutic setting.

Link To Article

http://dx.doi.org/10.4236/jct.2014.54044

Vinculin Regulates Osteoclast Function

Authors

Tomohiro Fukunaga, Wei Zou, Julia T. Warren and Steven L. Teitelbaum

Abstract

Osteoclastic bone resorption depends upon the cell's ability to organize its cytoskeleton. Because vinculin (VCL) is an actin-binding protein, we asked if it participates in skeletal degradation. Thus, we mated VCLfl/fl mice with those expressing cathepsin K-Cre (CtsK-VCL) to delete the gene in mature osteoclasts or lysozyme M-Cre (LysM-VCL) to target all osteoclast lineage cells. VCL-deficient osteoclasts differentiate normally but reflecting cytoskeletal disorganization, form small actin-rings and fail to effectively resorb bone. In keeping with inhibited resorptive function, CtsK-VCL and LysM-VCL mice exhibit a doubling of bone mass. Despite cytoskeletal disorganization, the capacity of VCL-/- osteoclastic cells to normally phosphorylate c-Src in response to αvβ3 integrin ligand is intact. Thus, integrin activated signals are unrelated to the means by which VCL organizes the osteoclast cytoskeleton. WT VCL completely rescues actin-ring formation and bone resorption as does VCLP878A which is incapable of interacting with Arp2/3. As expected, deletion of the VCL tail domain (VCL1-880) which binds actin, does not normalize VCL-/- osteoclasts. The same holds regarding VCLA50I and VCL 811-1066 both of which arrest talin association. Thus, VCL binding talin, but not Arp2/3, is critical for osteoclast function and its selective inhibition retards physiological bone loss.

Link To Article

http://dx.doi.org/10.1074/jbc.M114.550731

How does the amount of surgical insult affect bone around moving teeth?

Authors

Matthew D. McBride, Phillip M. Campbell, Lynne A. Opperman, Paul C. Dechow, Peter H. Buschang

Abstract

Introduction

The purpose of this study was to determine how the amount of surgical insult affects the quantity and maturity of dentoalveolar bone around teeth that have been orthodontically moved.

Methods

A split-mouth design with 8 foxhound dogs was used to evaluate bone surrounding maxillary second premolars that were protracted for 15 days and retained for 7 weeks. The maxillary first premolars were extracted, and the interseptal bone was removed to within 1 mm of the second premolars; on the insult (lesser surgical insult) side, buccal and lingual vertical grooves were made in the extraction socket to undermine the mesial root of the second premolar; the insult+ (greater surgical insult) side was flapped and had modified corticotomies extending to, but not through, the lingual cortex 1 mm distal to the distal root, and 3 to 5 mm apical to both roots. Microcomputed tomography analyses were used to evaluate the material density, bone volume fraction, and trabecular characteristics of surrounding bone. Hematoxylin and eosin sections were used to determine osteoclast numbers, bone surface areas, and bone volumes.

Results

After 7 weeks of consolidation, there was significantly (P <0.05) less bone on the insult+ side; it was less dense and less mature than the bone on the insult side. Relative to the control bone, bone on the insult+ side was significantly less dense but showed no differences in bone volume. Preliminary histologic evaluations indicated increased numbers of osteoclasts and greater bone surface areas on the insult+ side than the insult side, but no differences in bone volume.

Conclusions

Increased surgical insults produce less dense and less mature bone but have no effect on bone volume at 9 weeks after surgery.

Link To Article

http://dx.doi.org/10.1016/j.ajodo.2013.10.020

Entangled Titanium Fibre Balls Combined with Nano Strontium Hydroxyapatite in Repairing Bone Defects

Authors

Ping Liu, Nan Wang, Yongqiang Hao, Qinghua Zhao, Yongmin Qiao, Hui Li, Jipeng Li

Abstract

Objective: To investigate the effect of entangled titanium fibre balls (ETFBs) combined with nano strontium hydroxy-apatite (nano-Sr-HAP) on the repair of bone defects in vivo.

Materials and Methods: Twenty-four 6-month-old, specific pathogen-free, male Sprague-Dawley rats were used. Drill defects were created in bilateral femoral condyles. ETFBs combined with nano-Sr-HAP were selected randomly from 72 samples and implanted into the femoral bone defects of left legs, which served as the experimental group, while ETFBs without nano-Sr-HAP were implanted into right legs for comparison. The bone defects on both sides were X-rayed. The anteroposterior positions and histological procedures and evaluations of each sample were performed at 1, 2, 4 and 8 weeks post-surgery.

Results: Histological results showed that the ETBs allowed new bone to grow within their structure. Additionally, an increase in new bone was seen on the nano-Sr-HAP side compared to the control side. The results of histomorphometric analysis confirmed that the new bone formation on the left side gradually increased with time. There was a statistical increase in new bone at 2, 4 and 8 weeks, and the differences between the two sides were statistically significant at weeks 4 and 8 (p < 0.05 for all comparisons). The results showed that ETFBs possess a unique 3-dimensional interconnective porous structure and have excellent biocompatibility, cell affinity and osteoconductivity, which makes them useful as scaffold materials for repairing bone defects. On the other hand, nano-Sr-HAP improved the bone defect-repairing capacity of the ETFBs, which showed osteoinductive properties.

Link To Article

http://www.karger.com/Article/PDF/359951

Antagonizing the αvβ3 Integrin Inhibits Angiogenesis and Impairs Woven but Not Lamellar Bone Formation Induced by Mechanical Loading

Authors

Ryan E. Tomlinson, Anne H. Schmieder, James D. Quirk, Gregory M. Lanza, and Matthew J. Silva

Abstract

Angiogenesis and osteogenesis are critically linked, though the role of angiogenesis is not well understood in osteogenic mechanical loading. In this study, either damaging or non-damaging cyclic axial compression was used to generate woven bone formation (WBF) or lamellar bone formation (LBF), respectively, at the mid-diaphysis of the adult rat forelimb. αvβ3 integrin targeted nanoparticles or vehicle was injected intravenously following mechanical loading. β3 integrin subunit expression on vasculature was maximal 7 days after damaging mechanical loading, but was still robustly expressed 14 days after loading. Accordingly, targeted nanoparticle delivery in WBF loaded limbs was increased compared to non-loaded limbs. Vascularity was dramatically increased after WBF loading (+700% on day 14) and modestly increased after LBF loading (+50% on day 14). This increase in vascularity was inhibited by nanoparticle treatment in both WBF and LBF loaded limbs at days 7 and 14 after loading. Decreased vascularity led to diminished woven, but not lamellar, bone formation. Decreased woven bone formation resulted in impaired structural properties of the skeletal repair, particularly in post-yield behavior. These results demonstrate that αvβ3 integrin mediated angiogenesis is critical for recovering fracture resistance following bone injury, but is not required for bone modeling after modest mechanical strain.

Link To Article

http://dx.doi.org/10.1002/jbmr.2223