Interleukin-8 stimulation of osteoclastogenesis and bone resorption is a mechanism for the increased osteolysis of metastatic bone disease

The Role of Mast Cells in Bone Metabolism and Bone Disorders

Mast cells (MCs) are important sensor and effector cells of the immune system that are involved in many physiological and pathological conditions. Increasing evidence suggests that they also play an important role in bone metabolism and bone disorders. MCs are located in the bone marrow and secrete a wide spectrum of mediators, which can be rapidly released upon activation of mature MCs following their differentiation in mucosal or connective tissues. Many of these mediators can exert osteocatabolic effects by promoting osteoclast formation [e.g., histamine, tumor necrosis factor (TNF), interleukin-6 (IL-6)] and/or by inhibiting osteoblast activity (e.g., IL-1, TNF). By contrast, MCs could potentially act in an osteoprotective manner by stimulating osteoblasts (e.g., transforming growth factor-β) or reducing osteoclastogenesis (e.g., IL-12, interferon-γ). Experimental studies investigating MC functions in physiological bone turnover using MC-deficient mouse lines give contradictory results, reporting delayed or increased bone turnover or no influence depending on the mouse model used. By contrast, the involvement of MCs in various pathological conditions affecting bone is evident. MCs may contribute to the pathogenesis of primary and secondary osteoporosis as well as inflammatory disorders, including rheumatoid arthritis and osteoarthritis, because increased numbers of MCs were found in patients suffering from these diseases. The clinical observations could be largely confirmed in experimental studies using MC-deficient mouse models, which also provide mechanistic insights. MCs also regulate bone healing after fracture by influencing the inflammatory response toward the fracture, vascularization, bone formation, and callus remodeling by osteoclasts. This review summarizes the current view and understanding of the role of MCs on bone in both physiological and pathological conditions.

Therapeutic potentials and modulatory mechanisms of fatty acids in bone

Bone metabolism is a lifelong process that includes bone formation and resorption. Osteoblasts and osteoclasts are the predominant cell types associated with bone metabolism, which is facilitated by other cells such as bone marrow mesenchymal stem cells (BMMSCs), osteocytes and chondrocytes. As an important component in our daily diet, fatty acids are mainly categorized as long-chain fatty acids including polyunsaturated fatty acids (LCPUFAs), monounsaturated fatty acids (LCMUFAs), saturated fatty acids (LCSFAs), medium-/short-chain fatty acids (MCFAs/SCFAs) as well as their metabolites. Fatty acids are closely associated with bone metabolism and associated bone disorders. In this review, we summarized the important roles and potential therapeutic implications of fatty acids in multiple bone disorders, reviewed the diverse range of critical effects displayed by fatty acids on bone metabolism, and elucidated their modulatory roles and mechanisms on specific bone cell types. The evidence supporting close implications of fatty acids in bone metabolism and disorders suggests fatty acids as potential therapeutic and nutritional agents for the treatment and prevention of metabolic bone diseases.

A Novel Sulforaphane-Regulated Gene Network in Suppression of Breast Cancer-Induced Osteolytic Bone Resorption

Bone is the most preferred site for colonization of metastatic breast cancer cells for each subtype of the disease. The standard of therapeutic care for breast cancer patients with bone metastasis includes bisphosphonates (e.g., zoledronic acid), which have poor oral bioavailability, and a humanized antibody (denosumab). However, these therapies are palliative, and a subset of patients still develop new bone lesions and/or experience serious adverse effects. Therefore, a safe and orally bioavailable intervention for therapy of osteolytic bone resorption is still a clinically unmet need. This study demonstrates suppression of breast cancer-induced bone resorption by a small molecule (sulforaphane, SFN) that is safe clinically and orally bioavailable. In vitro osteoclast differentiation was inhibited in a dose-dependent manner upon addition of conditioned media from SFN-treated breast cancer cells representative of different subtypes. Targeted microarrays coupled with interrogation of The Cancer Genome Atlas data set revealed a novel SFN-regulated gene signature involving cross-regulation of runt-related transcription factor 2 (RUNX2) and nuclear factor-κB and their downstream effectors. Both RUNX2 and p65/p50 expression were higher in human breast cancer tissues compared with normal mammary tissues. RUNX2 was recruited at the promotor of NFKB1 Inhibition of osteoclast differentiation by SFN was augmented by doxycycline-inducible stable knockdown of RUNX2. Oral SFN administration significantly increased the percentage of bone volume/total volume of affected bones in the intracardiac MDA-MB-231-Luc model indicating in vivo suppression of osteolytic bone resorption by SFN. These results indicate that SFN is a novel inhibitor of breast cancer-induced osteolytic bone resorption in vitro and in vivo.

Serum Levels of Interleukin-8 and Soluble Interleukin-6 Receptor in Patients with Stage-I Multiple Myeloma: A Case-Control Study

Objective:

Multiple myeloma (MM) remains an incurable disease that needs better recognition and further research. Previous studies elucidated the interaction between myeloma cells and showed the necessity of bone marrow stromal cells for the initiation and progression of MM. Many chemokines and their receptors including interleukin-8 (IL-8) and soluble interleukin-6 receptor (sIL-6R) play important roles in this interaction. The main purpose of this study is evaluating the serum level of IL-8 and sIL-6R on stage-I of MM patients and healthy controls.

Methods:

Serum samples from 30 stage-I MM patients (13 males and 17 females) and 30 healthy subjects as controls (13 males and 17 females) were examined in this study. The protein concentrations of serum IL-8 and sIL-6R were assessed by enzyme-linked immunosorbent assay (ELISA).

Results:

The mean level of IL-8 and sIL-6R were significantly elevated in stage-I MM. The mean levels of IL-8 were 1246.57±279.22 ng/ml in stage-I MM and 902.53± 294.61 ng/ml in controls (P<0.001). The mean levels of sIL-6R were 5.39±1.38 ng/ml and 4.1±1.14 ng/ml in stage-I MM and controls, respectively (P<0.001). The mean levels of IL-8 were 1342.18±193.4 ng/ml in patient females and 859± 278.2ng/ml in control females (P <0.001). The mean levels of sIL-6R were 5.21±1.55 ng/ml and 3.91±1.22 ng/ml in patient females and control females, respectively (P=0.01). The mean level of sIL-6R in patient males and control males were 5.63±1.43 ng/ml and 4.34±1.04 ng/ml, respectively (P=0.01). A significant correlation (Pearson’s correlation = 0.45, P=0.008) was observed in the population of females (patients and controls).

Conclusion:

The results of study suggest the possible involvement of IL-8 and the sIL-6R at stage-I MM and can better characterize the role of chemokines and their receptors in the disease process, especially in the early stages.

Myokines: The endocrine coupling of skeletal muscle and bone

Bone and skeletal muscle are integrated organs and their coupling has been considered mainly a mechanical one in which bone serves as attachment site to muscle while muscle applies load to bone and regulates bone metabolism. However, skeletal muscle can affect bone homeostasis also in a non-mechanical fashion, i.e., through its endocrine activity. Being recognized as an endocrine organ itself, skeletal muscle secretes a panel of cytokines and proteins named myokines, synthesized and secreted by myocytes in response to muscle contraction. Myokines exert an autocrine function in regulating muscle metabolism as well as a paracrine/endocrine regulatory function on distant organs and tissues, such as bone, adipose tissue, brain and liver. Physical activity is the primary physiological stimulus for bone anabolism (and/or catabolism) through the production and secretion of myokines, such as IL-6, irisin, IGF-1, FGF2, beside the direct effect of loading. Importantly, exercise-induced myokine can exert an anti-inflammatory action that is able to counteract not only acute inflammation due to an infection, but also a condition of chronic low-grade inflammation raised as consequence of physical inactivity, aging or metabolic disorders (i.e., obesity, type 2 diabetes mellitus). In this review article, we will discuss the effects that some of the most studied exercise-induced myokines exert on bone formation and bone resorption, as well as a brief overview of the anti-inflammatory effects of myokines during the onset pathological conditions characterized by the development a systemic low-grade inflammation, such as sarcopenia, obesity and aging.

Inflammatory Profile and Osteogenic Potential of Fracture Haematoma in Humans

Fracture haematoma forms immediately after fracture and is considered essential for the bone healing process. Its molecular composition has been briefly investigated with our current understanding being based on animal studies. This study aims to analyse the inflammatory cytokine content of fracture haematoma in humans and determine its effect on osteoprogenitor cells. Twenty-three patients were recruited following informed consent. Peripheral blood, fracture haematoma and bone were collected. A Luminex assay on the levels of 34 cytokines was performed and autologous peripheral blood samples served as control. Mesenchymal Stem Cells (MSCs) were isolated following collagenase digestion and functional assays were performed. Gene expression analysis of 84 key osteogenic molecules was performed. Thirty-three inflammatory cytokines were found to be significantly raised in fracture haematoma when compared to peripheral serum (p < 0.05). Amongst the most raised molecules were IL-8, IL-11 and MMP1, -2 and -3. Fracture haematoma did not significantly affect MSC proliferation, but ALP activity and calcium deposition were significantly increased in the MSCs undergoing osteogenic differentiation. Medium supplementations with fracture haematoma resulted in a statistically significant upregulation of osteogenic genes including the EGF, FGF2 and VEGFA. This seems to be the pathway involved in the osteogenic effect of fracture haematoma on bone cells. In conclusion, fracture haematoma is found to be a medium rich in inflammatory and immunomodulatory mediators. At the same time, it contains high levels of anti-inflammatory molecules, regulates osteoclastogenesis, induces angiogenesis and the production of the extracellular matrix. It appears that fracture haematoma does not affect osteoprogenitor cells proliferation as previously thought, but induces an osteogenic phenotype.

MicroRNAs and exosomes: Small molecules with big actions in multiple myeloma pathogenesis

Multiple myeloma (MM), an incurable hematologic malignancy of plasma cells increasing in the bone marrow (BM), has a complex microenvironment made to support proliferation, survival, and drug resistance of tumor cells. MicroRNAs (miRNAs), short non-coding RNAs regulating genes expression at posttranscriptional level, have been indicated to be functionally deregulated or abnormally expressed in MM cells. Moreover, by means of miRNAs, tumor microenvironment also modulates the function of MM cells. Consistently, it has been demonstrated that miRNA levels regulation impairs their interaction with the microenvironment of BM as well as create considerable antitumor feature even capable of overcoming the protective BM milieu. Communication between cancer stromal cells and cancer cells is a key factor in tumor progression. Finding out this interaction is important to develop effective approaches that reverse bone diseases. Exosomes, nano-vehicles having crucial roles in cell-to-cell communication, through targeting their cargos (i.e., miRNAs, mRNAs, DNAs, and proteins), are implicated in MM pathogenesis.

Vibration activates the actin/NF-κB axis and upregulates IL-6 and IL-8 expression in human periodontal ligament cells

We previously reported that mechanical vibration-induced proinflammatory cytokines, interleukin-6 (IL-6) and IL-8, expression in human periodontal ligament (hPDL) cells, however, the underlying mechanism remained unclear. Mechanical stimuli are able to activate cellular responses by inducing the activation of several signaling pathways including cytoskeletal changes and inflammation. The actin cytoskeleton is a highly dynamic network and plays many important roles in intracellular events. Here, we aimed to investigate the involvement of a pivotal mediator of inflammatory responses, nuclear factor-κB (NF-κB), and actin polymerization in vibration-induced upregulation of IL-6 and IL-8 expression in hPDL cells. hPDL cells were pretreated with the NF-κB inhibitor BAY 11-7082 or cytochalasin D, respectively, before exposure to vibration. IL-6 and IL-8 messenger RNA (mRNA) and protein expression were quantified by quantitative polymerase chain reaction and enzyme-linked immunosorbent assays, respectively. Subcellular localization of the NF-κB p65 subunit was visualized by immunofluorescent staining. We found an increase in NF-κB nuclear translocation in vibrated cells compared with control cells. Pretreatment with BAY 11-7082 significantly inhibited vibration-induced IL-6 and IL-8 mRNA and protein expression in hPDL cells. Moreover, pretreatment with cytochalasin D inhibited NF-κB nuclear translocation and attenuated upregulation of IL-6 and IL-8 mRNA and protein in vibrated cells. Therefore, modulation of actin cytoskeletal polymerization in response to vibration may activate the NF-κB signaling pathway and subsequently upregulate IL-6 and IL-8 expression in hPDL cells.

Coordination of Fusion and Trafficking of Pre-osteoclasts at the Marrow-Bone Interface

Fusion is the final osteoclast differentiation step leading to bone resorption. In healthy trabecular bone, osteoclast fusion is restricted to bone surfaces undergoing resorption, and necessarily requires site-specific recruitment of mononucleated pre-osteoclasts originating from the bone marrow. However, the spatiotemporal mechanism coordinating recruitment and fusion is poorly investigated. Herein we identify a collagen/vascular network as a likely structure supporting this mechanism. We therefore used multiplex immunohistochemistry and electron microscopy on human iliac crest bone samples, in combination with functional assays performed in vitro with osteoclasts generated from healthy blood donors. First, we found that putative pre-osteoclasts are in close vicinity of a network of collagen fibers associated with vessels and bone remodeling compartment canopies. Based on 3D-reconstructions of serial sections, we propose that this network may serve as roads leading pre-osteoclasts to resorption sites, as reported for cell migration in other tissues. Importantly, almost all these bone marrow pre-osteoclasts, but only some osteoclasts, express the collagen receptor OSCAR, which is reported to induce fusion competence. Furthermore, differentiating osteoclasts cultured on collagen compared to mineral show higher fusion rates, higher expression of fusogenic cytokines, and a CD47 plasma membrane distribution pattern reported to be typical of a pre-fusion state-thus collectively supporting collagen-induced fusion competence. Finally, these in vitro assays show that collagen induces high cell mobility. The present data lead to a model where collagen fibers/vasculature support the coordination between traffic and fusion of pre-osteoclasts, by serving as a physical road and inducing fusion competence as well as cell mobility.

Ankle loading ameliorates bone loss from breast cancer-associated bone metastasis

Breast cancer is a serious health problem that preferentially metastasizes to bone. We have previously shown that bone loss can be prevented by mechanical loading, but the efficacy of ankle loading for metastasis-linked bone loss has not been investigated. This study showed that body weight was decreased after inoculation of tumor cells, but ankle loading restored a rapid weight loss. The nonloading group exhibited a decrease in bone volume/tissue volume (BV/TV), trabecular thickness, and trabecular number (all P < 0.01) as well as an increase in trabecular separation (P < 0.001). However, ankle loading improved those changes (all P < 0.05). Furthermore, although the nonloading group increased the tumor bearing as well as expression of IL-8 and matrix metalloproteinase 9, ankle loading decreased them. Induction of tumor in the bone elevated the osteoclast number (P < 0.05) as well as the levels of nuclear factor of activated T-cells cytoplasmic 1, NF-κB ligand, cathepsin K, and serum tartrate-resistant acid phosphatase type 5b, but ankle loading reduced osteoclast activity and those levels (all P < 0.05). Tumor bearing was positively correlated with the osteoclast number (P < 0.01) and negatively correlated with BV/TV and the osteoblast number (both P < 0.01). Collectively, these findings demonstrate that ankle loading suppresses tumor growth and osteolysis by inhibiting bone resorption and enhancing bone formation.-Yang, S., Liu, H., Zhu, L., Li, X., Liu, D., Song, X., Yokota, H., Zhang, P. Ankle loading ameliorates bone loss from breast cancer-associated bone metastasis.

6-Shogaol Suppresses 2-Amino-1-Methyl-6-Phenylimidazo [4,5-b] Pyridine (PhIP)-Induced Human 786-O Renal Cell Carcinoma Osteoclastogenic Activity and Metastatic Potential

2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) which can be detected in processed meats and red meats, is a potential carcinogen for renal cell carcinoma (RCC). Approximately 30% of patients with metastatic RCC have bone metastases, and the prognosis of RCC with bone metastases is poor. Thus, the aim of the present study was to investigate whether PhIP induced bone metastases and to develop novel therapeutic agents. Our data revealed that PhIP pre-treatment increased the production of parathyroid hormone-related protein (PTHrP) in human 786-O renal cell carcinoma cells. Subsequently, the cultures of human osteoblasts with PhIP-stimulated condition medium of 786-O increased the expression of the macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL), and decreased the expression of osteoprotegerin (OPG). In addition, PhIP-mediated PTHrP up-regulated as well as increased IL-8 secretion in 786-O cells, and then contributed to 786-O-mediated bone resorption. Furthermore, 6-shogaol, which is an active ingredient in ginger, showed suppressive effects on PhIP-mediated bone resorption. In summary, this is the first study to demonstrate that PhIP pre-treatment increases the stimulatory effect of human renal cell carcinoma 786-O on osteoclastogenesis activity directly by PTHrP. In addition, 6-shogaol treatment reverses PhIP-mediated bone resorption. It suggests that 6-shogaol treatment results in bone resorption activity in the RCC model in vitro.

Effects of pre-applied orthodontic force on the regeneration of periodontal tissues in tooth replantation

Objective

This study aimed to investigate the effect of pre-applied orthodontic force on the regeneration of periodontal ligament (PDL) tissues and the underlying mechanisms in tooth replantation.

Methods

Orthodontic force (50 cN) was applied to the left maxillary first molars of 7-week-old male Sprague–Dawley rats (n = 32); the right maxillary first molars were left untreated to serve as the control group. After 7 days, the first molars on both sides were fully luxated and were immediately replanted in their original sockets. To verify the effects of the pre-applied orthodontic force, we assessed gene expression by using microarray analysis and real-time reverse transcription polymerase chain reaction (RT-PCR), cell proliferation by using proliferating cell nuclear antigen (PCNA) immunofluorescence staining, and morphological changes by using histological analysis.

Results

Application of orthodontic force for 7 days led to the proliferation of PDL tissues, as verified on microarray analysis and PCNA staining. Histological analysis after replantation revealed less root resorption, a better arrangement of PDL fibers, and earlier regeneration of periodontal tissues in the experimental group than in the control group. For the key genes involved in periodontal tissue remodeling, including CXCL2, CCL4, CCL7, MMP3, PCNA, OPG, and RUNX2, quantitative RT-PCR confirmed that messenger RNA levels were higher at 1 or 2 weeks in the experimental group.

Conclusions

These results suggest that the application of orthodontic force prior to tooth replantation enhanced the proliferation and activities of PDL cells and may lead to higher success rates with fewer complications.

S100A4 released from highly bone-metastatic breast cancer cells plays a critical role in osteolysis

Bone destruction induced by breast cancer metastasis causes severe complications, including death, in breast cancer patients. Communication between cancer cells and skeletal cells in metastatic bone microenvironments is a principal element that drives tumor progression and osteolysis. Tumor-derived factors play fundamental roles in this form of communication. To identify soluble factors released from cancer cells in bone metastasis, we established a highly bone-metastatic subline of MDA-MB-231 breast cancer cells. This subline (mtMDA) showed a markedly elevated ability to secrete S100A4 protein, which directly stimulated osteoclast formation via surface receptor RAGE. Recombinant S100A4 stimulated osteoclastogenesis in vitro and bone loss in vivo. Conditioned medium from mtMDA cells in which S100A4 was knocked down had a reduced ability to stimulate osteoclasts. Furthermore, the S100A4 knockdown cells elicited less bone destruction in mice than the control knockdown cells. In addition, administration of an anti-S100A4 monoclonal antibody (mAb) that we developed attenuated the stimulation of osteoclastogenesis and bone loss by mtMDA in mice. Taken together, our results suggest that S100A4 released from breast cancer cells is an important player in the osteolysis caused by breast cancer bone metastasis.

Effects of recombinant bovine interleukin-8 (rbIL-8) treatment on health, metabolism, and lactation performance in Holstein cattle IV: Insulin resistance, dry matter intake, and blood parameters

We have shown in 2 independent studies that cows who received recombinant bovine interleukin-8 (rbIL-8) administered intrauterinely shortly after parturition have a significant and long-lasting increase in milk yield. In the present study, we hypothesized that the increased milk production associated with rbIL-8 treatment is a consequence of increased postpartum dry matter intake (DMI) and orchestrated homeorhetic changes that prioritize milk production. Cows were enrolled into 1 of 3 treatment groups: those assigned to the control group (CTR; n = 70) received an intrauterine (IU) administration of 500 mL of Dulbecco's phosphate-buffered saline (DPBS) solution and 1 mL of DPBS solution intravenously (IV; jugular vein), those assigned to the rbIL-8 IV group (rbIL8-IV, n = 70) received an IV injection of 167 μg of rbIL-8 and 500 mL of DPBS solution IU, and cows assigned to the rbIL-8 IU group (rbIL8-IU, n = 70) received an IU administration with 1,195 μg of rbIL-8 diluted in 499.5 mL of DPBS solution and 1 mL of DPBS solution IV. Animals were housed in a tiestall from calving to 30 d in milk (DIM) to measure DMI. Blood samples were collected daily from calving to 7 DIM and weekly until 28 DIM. Insulin resistance was evaluated using an intravenous glucose tolerance test and intravenous insulin challenge test (IVICT) in a subgroup of cows (n = 20/treatment) at 10 and 11 DIM, respectively. Additionally, liver biopsy samples were taken at 14 DIM from the same subgroup of cows to measure triglyceride levels and cell proliferation and apoptosis. Cows treated with rbIL8-IU produced more milk (CTR = 36.9 ± 1.5; rbIL8-IU = 38.5 ± 1.5; rbIL8-IV = 36.6 ± 1.5 kg/d), energy-corrected milk (CTR = 42.9 ± 0.9; rbIL8-IU = 46.1 ± 0.8; rbIL8-IV = 43.7 ± 0.9 kg/d), and fat-corrected milk (CTR = 44.3 ± 0.9; rbIL8-IU = 47.8 ± 0.9; rbIL8-IV = 45.2 ± 0.9 kg/d) yields when compared with CTR cows, and no differences were observed between rbIL8-IV and CTR cows. The administration of rbIL8-IU significantly increased DMI compared with CTR (CTR = 18.8 ± 0.3; rbIL8-IU = 19.9 ± 0.3; rbIL8-IV = 19.3 ± 0.3 kg/d). Recombinant bIL-8 treatment did not affect glucose, insulin, or fatty acids (i.e., IVICT only) concentrations or their area under the curve in response to an intravenous glucose tolerance test and IVICT when compared with CTR. Moreover, rbIL-8 treatment administered IU or IV increased liver triglyceride levels. Additionally, cows treated with rbIL8-IU tended to have lower odds of developing hyperketonemia (odds ratio = 0.46, 95% confidence interval: 0.19 to 1.10), lower odds of clinical ketosis and displaced abomasum combined (odds ratio = 0.17, 95% confidence interval: 0.03 to 0.89), and lower odds of diseases combined (odds ratio = 0.43, 95% confidence interval: 0.21 to 0.86) when compared with CTR. We conclude that the administration of rbIL8-IU increases DMI, milk production, fat-corrected milk, and energy-corrected milk while improving overall health during the postpartum period. This study supports the use of rbIL-8 administered IU shortly after calving to improve health and production responses in lactating cows.

Effects of recombinant bovine interleukin-8 (rbIL-8) treatment on health, metabolism, and lactation performance in Holstein cattle II: Postpartum uterine health, ketosis, and milk production

To evaluate the effect of recombinant bovine interleukin-8 (rbIL-8) on uterine health and milk production, 2 separate studies were conducted. For study 1, postpartum Holstein cows (n = 213) were randomly allocated into 1 of 3 intrauterine treatment groups: control (CTR, 250 mL of saline solution), low dose (L-IL8, 11.25 µg of rbIL-8 diluted in 250 mL of saline solution), and high dose (H-IL8, 1,125 µg of rbIL-8 diluted in 250 mL of saline solution). Intrauterine delivery of treatments was performed within 12 h of parturition. Cows were evaluated for retained fetal membranes, puerperal metritis, and clinical endometritis. Blood samples were collected immediately before treatment and 1, 2, and 3 d in milk for assessment of IL-8, haptoglobin, fatty acids, and β-hydroxybutyrate concentrations. Treatment with rbIL-8 reduced the incidence of puerperal metritis in multiparous cows (CTR = 34.3, L-IL8 = 8.11, and H-IL8 = 6.35%). Both the L-IL8 and H-IL8 groups produced significantly more milk, fat-corrected milk, and energy-corrected milk yields when compared with placebo-treated controls. A second study was performed to confirm the effect of rbIL-8 on milk production. In study 2, 164 primiparous cows were randomly allocated into 1 of 4 treatment groups: control (CTR, 250 mL of saline solution), low dose (L-IL8, 0.14 µg of rbIL-8), medium dose (M-IL8, 14 µg of rbIL-8), and high dose (H-IL8, 1,400 µg of rbIL-8). Treatments were prepared and administered as described for study 1. Cows in the L-IL8, M-IL8, and H-IL8 groups produced significantly more milk, fat-corrected milk, and energy-corrected milk yields when compared with control cows. In conclusion, treatment with rbIL-8 decreased the incidence of puerperal metritis in multiparous cows. The administration of rbIL-8 was repeatedly associated with a dramatic and long-lasting improvement of lactation performance.

Inflammation time-axis in aseptic loosening of total knee arthroplasty: A preliminary study

OBJECTIVE

Aseptic loosening (AL) is the most frequent long-term reason for revision of total knee arthroplasty (TKA) affecting about 15-20% patients within 20 years after the surgery. Although there is a solid body of evidence about the crucial role of inflammation in the AL pathogenesis, scared information on inflammation signature and its time-axis in tissues around TKA exists.

DESIGN

The inflammation protein signatures in pseudosynovial tissues collected at revision surgery from patients with AL (AL, n = 12) and those with no clinical/radiographic signs of AL (non-AL, n = 9) were investigated by Proximity Extension Assay (PEA)-Immunoassay and immunohistochemistry.

RESULTS

AL tissues had elevated levels of TNF-family members sTNFR2, TNFSF14, sFasL, sBAFF, cytokines/chemokines IL8, CCL2, IL1RA/IL36, sIL6R, and growth factors sAREG, CSF1, comparing to non-AL. High interindividual variability in protein levels was evident particularly in non-AL. Levels of sTNFR2, sBAFF, IL8, sIL6R, and MPO discriminated between AL and non-AL and were associated with the time from index surgery, suggesting the cumulative character of inflammatory osteolytic response to prosthetic byproducts. The source of elevated inflammatory molecules was macrophages and multinucleated osteoclast-like cells in AL and histiocytes and osteoclast-like cells in non-AL tissues, respectively. All proteins were present in higher levels in osteoclast-like cells than in macrophages.

CONCLUSIONS

Our study revealed a differential inflammation signature between AL and non-AL stages of TKA. It also highlighted the unique patient's response to TKA in non-AL stages. Further confirmation of our preliminary results on a larger cohort is needed. Analysis of the time-axis of processes ongoing around TKA implantation may help to understand the mechanisms driving periprosthetic bone resorption needed for diagnostic/preventative strategies.

Cytokine Profile in Patients with Aseptic Loosening of Total Hip Replacements and Its Relation to Metal Release and Metal Allergy

Metal release from total hip replacements (THRs) is associated with aseptic loosening (AL). It has been proposed that the underlying immunological response is caused by a delayed type IV hypersensitivity-like reaction to metals, i.e., metal allergy. The purpose of this study was to investigate the immunological response in patients with AL in relation to metal release and the prevalence of metal allergy. THR patients undergoing revision surgery due to AL or mechanical implant failures were included in the study along with a control group consisting of primary THR patients. Comprehensive cytokine analyses were performed on serum and periimplant tissue samples along with metal analysis using inductive coupled plasma mass spectrometry (ICP-MS). Patient patch testing was done with a series of metals related to orthopedic implant. A distinct cytokine profile was found in the periimplant tissue of patients with AL. Significantly increased levels of the proinflammatory cytokines IL-1β, IL-2, IL-8, IFN-γ and TNF-α, but also the anti-inflammatory IL-10 were detected. A general increase of metal concentrations in the periimplant tissue was observed in both revision groups, while Cr was significantly increased in patient serum with AL. No difference in the prevalence of metal sensitivity was established by patch testing. Increased levels of IL-1β, IL-8, and TNF-α point to an innate immune response. However, the presence of IL-2 and IFN-γ indicates additional involvement of T cell-mediated response in patients with AL, although this could not be detected by patch testing.

Lysophosphatidic acid induces interleukin-6 and CXCL15 secretion from MLO-Y4 cells through activation of the LPA1 receptor and PKCθ signaling pathway

Lysophosphatidic acid (LPA) is a multifunctional phospholipid. Osteocytes are the most abundant cells in bone and can orchestrate bone formation and resorption, in part by producing cytokines that regulate osteoblast and osteoclast differentiation and activity. Interleukin (IL)-6 and IL-8 are two important cytokines that have potent effects on bone fracture healing. Previous studies suggest that platelet-derived LPA may influence fracture healing by inducing osteocyte dendrite outgrowth. However, the biological mechanism through which LPA induces cytokine production in osteocytes is poorly understood. In this study, we report that LPA markedly enhanced IL-6 and CXCL15 (mouse homologue of human IL-8) production in MLO-Y4 cells and that this enhancement was suppressed by the LPA_1/3-selective antagonist Ki16425, the G_i/o protein inhibitor PTX or the protein kinase C (PKC) inhibitor sotrastaurin. We also observed that of all the PKC isoform targets of sotrastaurin, only PKCθ was activated by LPA in MLO-Y4 cells and that this activation was blocked by sotrastaurin, Ki16425 or PTX. Taken together, the results of the present study demonstrate that LPA may be a potent inducer of IL-6 and CXCL15 production in MLO-Y4 cells and that this induction is associated with the activation of LPA₁, G_i/o protein and the PKCθ pathway. These findings may help us better understand the mechanism of fracture healing and contribute to the treatment of bone damage.

Differential gene expression profiles of human periodontal ligament cells preserved in Hank's balanced salt solution and milk

BACKGROUND/AIM

Various types of storage media have been investigated to preserve avulsed teeth. However, the efficacies of storage media mainly focus on the aspect of cell viability. The aim of this study was to evaluate and compare the gene expression profiles of human periodontal ligament cells preserved in Hank's balanced salt solution (HBSS) and milk over different storage durations.

MATERIAL AND METHODS

Human periodontal ligament cells were cultured and preserved in HBSS and milk for 3 and 6 hours. Next, total RNA was isolated. QuantSeq 3' mRNA-Sequencing was used to examine differences in gene expression in HBSS- and milk-grown periodontal ligament cells. Bioinformatics analysis was also performed to predict the function of the differentially expressed genes.

RESULTS

The number of differentially expressed genes shared among all groups was 101. In gene set enrichment analysis, the shared differentially expressed genes in HBSS and milk were associated with the TNF-α signaling pathway (P = 1.07E^-7 ). Seven hallmark gene sets were also identified in HBSS. Moreover, hallmark gene sets associated with hypoxia (P = 7.26E^-5 ) and apoptosis (P = 4.06E^-4 ) were identified in HBSS. In milk, 10 hallmark gene sets along with gene sets for inflammatory response (P = 6.87E^-3 ) were identified.

CONCLUSIONS

Compared to those in milk, genes in HBSS were differentially expressed with increasing storage duration, suggesting that diverse and different gene expression may be involved in HBSS and milk. However, a more detailed functional analysis of these differentially expressed genes in storage solutions should be performed in the future.

The alarmin S100A9 hampers osteoclast differentiation from human circulating precursors by reducing the expression of RANK

The alarmin S100A8/A9 is implicated in sterile inflammation-induced bone resorption and has been shown to increase the bone-resorptive capacity of mature osteoclasts. Here, we investigated the effects of S100A9 on osteoclast differentiation from human CD14⁺ circulating precursors. Hereto, human CD14⁺ monocytes were isolated and differentiated toward osteoclasts with M-CSF and receptor activator of NF-κB (RANK) ligand (RANKL) in the presence or absence of S100A9. Tartrate-resistant acid phosphatase staining showed that exposure to S100A9 during monocyte-to-osteoclast differentiation strongly decreased the numbers of multinucleated osteoclasts. This was underlined by a decreased resorption of a hydroxyapatite-like coating. The thus differentiated cells showed a high mRNA and protein production of proinflammatory factors after 16 h of exposure. In contrast, at d 4, the cells showed a decreased production of the osteoclast-promoting protein TNF-α. Interestingly, S100A9 exposure during the first 16 h of culture only was sufficient to reduce osteoclastogenesis. Using fluorescently labeled RANKL, we showed that, within this time frame, S100A9 inhibited the M-CSF-mediated induction of RANK. Chromatin immunoprecipitation showed that this was associated with changes in various histone marks at the epigenetic level. This S100A9-induced reduction in RANK was in part recovered by blocking TNF-α but not IL-1. Together, our data show that S100A9 impedes monocyte-to-osteoclast differentiation, probably via a reduction in RANK expression.-Di Ceglie, I., Blom, A. B., Davar, R., Logie, C., Martens, J. H. A., Habibi, E., Böttcher, L.-M., Roth, J., Vogl, T., Goodyear, C. S., van der Kraan, P. M., van Lent, P. L., van den Bosch, M. H. The alarmin S100A9 hampers osteoclast differentiation from human circulating precursors by reducing the expression of RANK.

Anti-receptor activator of nuclear factor κB ligand antibody treatment increases osteoclastogenesis-promoting IL-8 in patients with rheumatoid arthritis

The receptor activator of nuclear factor κB ligand (RANKL) is an important factor for osteoclastogenesis and contributes to the pathology of rheumatoid arthritis (RA); thus, the anti-RANKL antibody (Ab) has been expected to protect joint destruction in RA patients. IL-8 also has osteoclastogenic activity; however, the role of IL-8 in the bone pathology of RA as well as the relation between IL-8 and RANKL remain unclear. In the present study, clinical observation revealed serum IL-8 levels of 611 pg ml-1 in RA patients with anti-RANKL Ab and 266 pg ml-1 in the same patients without anti-RANKL Ab. In vitro assay showed that anti-RANKL Ab induced production of IL-8 from pre-osteoclast-like cells (OCLs), and IL-8 promoted the formation of OCLs from peripheral monocytes even without RANKL activity. We further showed that treatment with FK506 (tacrolimus) possibly inhibits the increase in IL-8 levels in RA patients with anti-RANKL Ab, and in vitro assay confirmed that FK506 suppressed IL-8 production in pre-OCLs. These results suggest that inhibition of RANKL induces the change in osteoclastogenesis-promoting factor from RANKL to IL-8, and FK506 may be a valuable combination drug to support the use of anti-RANKL Ab in treatment of RA.

Upregulation of interleukin-8 and activin A induces osteoclastogenesis in ameloblastoma

Ameloblastoma is a common odontogenic benign tumor located in the jaws and is characterized by severe local bone destruction. The current study aimed to investigate the effect of interactions between tumor cells and bone marrow stromal cells (BMSCs) on osteoclast formation in ameloblastoma. The impact of ameloblastoma/BMSC interactions on cytokine production, gene expression and osteoclastogenesis was examined using an immortalized ameloblastoma cell line that the authors' previously established. The results demonstrated that interactions between ameloblastoma cells and BMSCs increased interleukin (IL)‑8 and activin A secretion by BMSCs. IL‑8 expression in BMSCs was modulated by tumor‑derived tumor necrosis factor‑α and IL‑8 contributed to osteoclast formation not only directly but also by stimulating receptor activator of NF‑κB ligand (RANKL) expression in BMSCs. Activin A secretion in BMSCs was stimulated by ameloblastoma cells via cell‑to‑cell‑mediated activation of c‑Jun N‑terminal kinase activation, acting as a cofactor of RANKL to induce osteoclast formation and function. The present study highlights the critical role of communication between BMSCs and ameloblastoma cells in bone resorption in ameloblastoma.

CXCR2: A Novel Mediator of Mammary Tumor Bone Metastasis

Most breast cancer patients die due to bone metastasis. Although metastasis accounts for 5% of the breast cancer cases, it is responsible for most of the deaths. Sometimes even before the detection of a primary tumor, most of the patients have bone and lymph node metastasis. Moreover, at the time of death, breast cancer patients have the bulk of the tumor burden in their bones. Therapy options are available for the treatment of primary tumors, but there are minimal options for treating breast cancer patients who have bone metastasis. C-X-C motif chemokine receptor type 2 (CXCR2) receptor-mediated signaling has been shown to play a critical role during bone-related inflammations and its ligands C-X-C motif chemokine ligand 6 (CXCL6) and 8 (CXCL8) aid in the resorption of bone during bone metastasis. In this study, we tested the hypothesis that CXCR2 contributes to mammary tumor-induced osteolysis and bone metastasis. In the present study, we examined the role of both tumor cell-derived and host-derived CXCR2 in influencing mammary tumor cell bone metastasis. For understanding the role of tumor cell-derived CXCR2, we utilized Cl66 CXCR2 knockdown (Cl66-shCXCR2) and Cl66-Control cells (Cl66-Control) and observed a significant decrease in tumor growth and tumor-induced osteolysis in Cl66-shCXCR2 cells in comparison with the Cl66-Control cells. Next, for understanding the role of host-derived CXCR2, we utilized mice with genomic knockdown of CXCR2 (Cxcr2^-/-) and injected Cl66-Luciferase (Cl66-Luc) or 4T1-Luciferase (4T1-Luc) cells. We observed decreased bone destruction and metastasis in the bone of Cxcr2^-/- mice. Our data suggest the importance of both tumor cell- and host-derived CXCR2 signaling in the bone metastasis of breast cancer cells.

Altered morpho-functional features of bones in autoimmune disease-prone BXSB/MpJ- Yaa mice

IMPACT STATEMENT

Bone disease, such as osteoporosis and rheumatoid arthritis, increases because of the progression of an aging society. Autoimmune disease are important and predisposing factors for the pathogenesis of the bone disease; however, the pathological mechanism is unclear. We have demonstrated that systemic autoimmune disease in BXSB/MpJ- Yaa is closely associated with the morpho-functional abnormalities of bones including bone marrow and has complicated pathology. The abnormalities are characterized by altered regulations of serum calcium, anemia tendency, and hematopoiesis with increased WBCs and decreased PLs, short length and low mass of long bones, imbalance in the populations of osteoclasts and osteoblasts, and increased expression of candidate genes for causing and/or exacerbating their phenotypes. Therefore, BXSB/MpJ- Yaa serves as a model to elucidate bone phenotypes in systemic autoimmune disease that would be affected by the factors in the bone as well as the other immune and/or mineral metabolism organs both in human and experimental medicine.

Correlation of magnetic resonance imaging grades with cytokine levels of synovial fluid of patients with temporomandibular joint disorders: a cross-sectional study

OBJECTIVES

Magnetic resonance imaging (MRI) is a standardized method for assisting joint diagnosis. To validate the reliability of different imaging-based grading systems, this study examined (1) the associations between grading systems for osseous change, joint effusion, and the Wilkes classification of temporomandibular joint (TMJ) disorders and (2) the correlation between cytokines in synovial fluid and imaging-based joint scores.

MATERIALS AND METHODS

Twenty-seven patients, who routinely received numeric rating scale (NRS) and MRI assessment before TMJ arthrocentesis, were enrolled. Each joint was evaluated through the grading criteria for severity of osseous change and joint effusion by blinded observers using MRI. ImageJ was employed for classifying joint effusion. Joint synovial fluid, collected through arthrocentesis, was examined for cytokine expression by using a Luminex multiplex assay. All data were analyzed using the Pearson correlation analysis.

RESULTS

The Wilkes classification was strongly correlated with osseous change scores, but not with joint effusion scores. Joint effusion scores significantly correlated with NRS scores, but not with the Wilkes classification and osseous change scores. Compared with osseous change scores, joint effusion scores had a higher correlation with the levels of inflammatory cytokines (interleukin (IL)-8 and soluble IL-6 receptor (sIL-6R)) and with anti-inflammatory cytokines (soluble tumor necrosis factor receptors I and II (sTNF-RI/II)).

CONCLUSIONS

In patients with TMJ disorders, MRI grades are strongly correlated with NRS scores and levels of cytokines (IL-8, sIL-6R, and sTNF-RI/II) in the synovial fluid.

CLINICAL RELEVANCE

Joint effusion scoring can be a reliable and valid indicator for pathological assessment of TMJ disorders.

Current Advances in Immunomodulatory Biomaterials for Bone Regeneration

Biomaterials with suitable surface modification strategies are contributing significantly to the rapid development of the field of bone tissue engineering. Despite these encouraging results, utilization of biomaterials is poorly translated to human clinical trials potentially due to lack of knowledge about the interaction between biomaterials and the body defense mechanism, the "immune system". The highly complex immune system involves the coordinated action of many immune cells that can produce various inflammatory and anti-inflammatory cytokines. Besides, bone fracture healing initiates with acute inflammation and may later transform to a regenerative or degenerative phase mainly due to the cross-talk between immune cells and other cells in the bone regeneration process. Among various immune cells, macrophages possess a significant role in the immune defense, where their polarization state plays a key role in the wound healing process. Growing evidence shows that the macrophage polarization state is highly sensitive to the biomaterial's physiochemical properties, and advances in biomaterial research now allow well controlled surface properties. This review provides an overview of biomaterial-mediated modulation of the immune response for regulating key bone regeneration events, such as osteogenesis, osteoclastogenesis, and inflammation, and it discusses how these strategies can be utilized for future bone tissue engineering applications.

Multiple myeloma-derived exosomes are enriched of amphiregulin (AREG) and activate the epidermal growth factor pathway in the bone microenvironment leading to osteoclastogenesis

Background

Multiple myeloma (MM) is a clonal plasma cell malignancy associated with osteolytic bone disease. Recently, the role of MM-derived exosomes in the osteoclastogenesis has been demonstrated although the underlying mechanism is still unknown. Since exosomes-derived epidermal growth factor receptor ligands (EGFR) are involved in tumor-associated osteolysis, we hypothesize that the EGFR ligand amphiregulin (AREG) can be delivered by MM-derived exosomes and participate in MM-induced osteoclastogenesis.

Methods

Exosomes were isolated from the conditioned medium of MM1.S cell line and from bone marrow (BM) plasma samples of MM patients. The murine cell line RAW264.7 and primary human CD14⁺ cells were used as osteoclast (OC) sources.

Results

We found that AREG was specifically enriched in exosomes from MM samples and that exosomes-derived AREG led to the activation of EGFR in pre-OC, as showed by the increase of mRNA expression of its downstream SNAIL in both RAW264.7 and CD14⁺ cells. The presence of neutralizing anti-AREG monoclonal antibody (mAb) reverted this effect. Consequently, we showed that the effect of MM-derived exosomes on osteoclast differentiation was inhibited by the pre-treatment of exosomes with anti-AREG mAb. In addition, we demonstrated the ability of MM-derived AREG-enriched exosomes to be internalized into human mesenchymal stromal cells (MSCs) blocking osteoblast (OB) differentiation, increasing MM cell adhesion and the release of the pro-osteoclastogenic cytokine interleukin-8 (IL8). Accordingly, anti-AREG mAb inhibited the release of IL8 by MSCs suggesting that both direct and indirect effects are responsible for AREG-enriched exosomes involvement on MM-induced osteoclastogenesis.

Conclusions

In conclusion, our data indicate that AREG is packed into MM-derived exosomes and implicated in OC differentiation through an indirect mechanism mediated by OBs.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0689-y) contains supplementary material, which is available to authorized users.

Osteoclast-related markers in the hip joint fluid with subchondral insufficiency fracture of the femoral head

Similar to the radiological findings in rapidly destructive arthrosis of the hip joint (RDA), subchondral insufficiency fracture of the femoral head (SIF) can result in progressive femoral head collapse of unknown etiology. We thus examined the osteoclast activity of hip joint fluid in SIF with progressive collapse in comparison with that in RDA. Twenty-nine hip joint fluid samples were obtained intraoperatively with whole femoral heads from 12 SIF patients and 17 RDA patients. SIF cases were classified into subgroups based on the presence of ≥2 mm collapse on preoperative radiographs: SIF with progressive collapse (n = 5) and SIF without progressive collapse (n = 7). The levels of tartrate-resistant acid phosphatase (TRACP)-5b, interleukin-8, vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-9 were measured. The number of multinuclear giant cells at the subchondral region was histopathologically assessed using mid-coronal slice of each femoral head specimen. The median levels of all markers and the median number of multinuclear giant cells in SIF with progressive collapse were significantly higher than those in SIF without progressive collapse, while there were no significant differences in SIF with progressive collapse versus RDA. Regression analysis showed that the number of multinuclear giant cells was positively correlated with the level of TRACP-5b in joint fluid. The present study demonstrated the possible association of increased osteoclast activity with the existing condition of progressive collapse in SIF, which was quite similar to the findings in RDA, indicating that increased osteoclast activity may reflect the condition of progressive collapse in SIF as well as RDA. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2987-2995, 2018.

Localized low-dose rhBMP-2 is effective at promoting bone regeneration in mandibular segmental defects

At least 26% of recent battlefield injuries are to the craniomaxillofacial (CMF) region. Recombinant human bone morphogenetic protein 2 (rhBMP-2) is used to treat CMF open fractures, but several complications have been associated with its use. This study tested the efficacy and safety of a lower (30% recommended) dose of rhBMP-2 to treat mandibular fractures. rhBMP-2 delivered via a polyurethane (PUR) and hydroxyapatite/β-tricalcium phosphate (Mastergraft®) scaffold was evaluated in a 2 cm segmental mandibular defect in minipigs. Bone regeneration was analyzed at 4, 8, and 12 weeks postsurgery using clinical computed tomography (CT) and rhBMP-2, and inflammatory marker concentrations were analyzed in serum and surgery-site drain effluent. CT scans revealed that pigs treated with PUR-Mastergraft® + rhBMP-2 had complete bone bridging, while the negative control group showed incomplete bone-bridging (n = 6). Volumetric analysis of regenerated bone showed that the PUR-Mastergraft® + rhBMP-2 treatment generated significantly more bone than control by 4 weeks, a trend that continued through 12 weeks. Variations in inflammatory analytes were detected in drain effluent samples and saliva but not in serum, suggesting a localized healing response. Importantly, the rhBMP-2 group did not exhibit an excessive increase in inflammatory analytes compared to control. Treatment with low-dose rhBMP-2 increases bone regeneration capacity in pigs with mandibular continuity defects and restores bone quality. Negative complications from rhBMP-2, such as excessive inflammatory analyte levels, were not observed. Together, these results suggest that treatment with low-dose rhBMP-2 is efficacious and may improve safety when treating CMF open fractures. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1491-1503, 2019.

Visfatin alters the cytokine and matrix-degrading enzyme profile during osteogenic and adipogenic MSC differentiation

OBJECTIVES

Age-related bone loss is associated with bone marrow adiposity. Adipokines (e.g., visfatin, resistin, leptin) are adipocyte-derived factors with immunomodulatory properties and might influence differentiation of bone marrow-derived mesenchymal stem cells (MSC) in osteoarthritis (OA) and osteoporosis (OP). Thus, the presence of adipokines and MMPs in bone marrow and their effects on MSC differentiation were analyzed.

METHODS

MSC and ribonucleic acid (RNA) were isolated from femoral heads after hip replacement surgery of OA or osteoporotic femoral neck fracture (FF) patients. Bone structural parameters were evaluated by microcomputed tomography (μCT). MSC were differentiated towards adipocytes or osteoblasts with/without adipokines. Gene expression (adipokines, bone marker genes, MMPs, TIMPs) and cytokine production was evaluated by realtime-polymerase chain reaction (realtime-PCR) and enzyme-linked immunosorbent assay (ELISA). Matrix mineralization was quantified using Alizarin red S staining.

RESULTS

μCT showed an osteoporotic phenotype of FF compared to OA bone (reduced trabecular thickness and increased ratio of bone surface vs volume of solid bone). Visfatin and leptin were increased in FF vs OA. Visfatin induced the secretion of IL-6, IL-8, and MCP-1 during osteogenic and adipogenic differentiation. In contrast to resistin and leptin, visfatin increased MMP2 and MMP13 during adipogenesis. In osteogenically differentiated cells, MMPs and TIMPs were reduced by visfatin. Visfatin significantly increased matrix mineralization during osteogenesis, whereas collagen type I expression was reduced.

CONCLUSION

Visfatin-mediated increase of matrix mineralization and reduced collagen type I expression could contribute to bone fragility. Visfatin is involved in impaired bone remodeling at the adipose tissue/bone interface through induction of proinflammatory factors and dysregulated MMP/TIMP balance during MSC differentiation.

Lysophosphatidic acid enhances breast cancer cells-mediated osteoclastogenesis

Lysophosphatidic acid (LPA) is known to play a critical role in breast cancer metastasis to bone. In this study, we tried to investigate any role of LPA in the regulation of osteoclastogenic cytokines from breast cancer cells and the possibility of these secretory factors in affecting osteoclastogenesis. Effect of secreted cytokines on osteoclastogenesis was analyzed by treating conditioned media from LPA-stimulated breast cancer cells to differentiating osteoclasts. Result demonstrated that IL-8 and IL-11 expression were upregulated in LPA-treated MDA-MB-231 cells. IL-8 was induced in both MDA-MB-231 and MDA-MB-468, however, IL-11 was induced only in MDA-MB-231, suggesting differential LPARs participation in the expression of these cytokines. Expression of IL-8 but not IL-11 was suppressed by inhibitors of PI3K, NFkB, ROCK and PKC pathways. In the case of PKC activation, it was observed that PKCδ and PKCμ might regulate LPA-induced expression of IL-11 and IL-8, respectively, by using specific PKC subtype inhibitors. Finally, conditioned Medium from LPA-stimulated breast cancer cells induced osteoclastogenesis. In conclusion, LPA induced the expression of osteolytic cytokines (IL-8 and IL-11) in breast cancer cells by involving different LPA receptors. Enhanced expression of IL-8 by LPA may be via ROCK, PKCu, PI3K, and NFkB signaling pathways, while enhanced expression of IL-11 might involve PKCδ signaling pathway. LPA has the ability to enhance breast cancer cells-mediated osteoclastogenesis by inducing the secretion of cytokines such as IL-8 and IL-11.

Inhibitory effects of low intensity pulsed ultrasound on osteoclastogenesis induced in vitro by breast cancer cells

Background

Bone tissue is one of the main sites for breast metastasis; patients diagnosed with advanced breast cancer mostly develop bone metastasis characterized by severe osteolytic lesions, which heavily influence their life quality. Low Intensity Pulsed Ultrasound (LIPUS) is a form of mechanical energy able to modulate various molecular pathways both in cancer and in health cells.

The purpose of the present study was to evaluate for the first time, the ability of LIPUS to modulate osteolytic capability of breast cancer cells.

Methods

Two different approaches were employed: a) Indirect method -conditioned medium obtained by MDA-MB-231 cell line treated or untreated with LIPUS was used to induce osteoclast differentiation of murine macrophage Raw264.7 cell line; and b) Direct method -MDA-MB-231 were co-cultured with Raw264.7 cells and treated or untreated with LIPUS.

Results

LIPUS treatment impaired MDA-MB-231 cell dependentosteoclast differentiation and produced a reduction of osteoclast markers such as Cathepsin K, Matrix Metalloproteinase 9 and Tartrate Resistant Acid Phosphatase, suggesting its role as an effective and safe adjuvant in bone metastasis management.

Conclusion

LIPUS treatment could be a good and safety therapeutic adjuvant in osteolyitic bone metastasis not only for the induction properties of bone regeneration, but also for the reduction of osteolysis.

Vibration enhances PGE2 , IL-6, and IL-8 expression in compressed hPDL cells via cyclooxygenase pathway

BACKGROUND

Although vibration combined with orthodontic force may accelerate orthodontic tooth movement, little is known about the mechanisms that regulate the associated cellular responses. The goal of this study was to investigate whether mechanical vibration combined with compressive force regulates cyclooxygenase (COX)-2/prostaglandin E2 (PGE₂ ) and interleukin (IL)-6 and IL-8 messenger RNA (mRNA) and protein expression in human periodontal ligament (hPDL) cells via the COX pathway.

METHODS

The primary cultured hPDL cells were exposed to mechanical vibration, compressive force or a combination of both mechanical vibration and compressive force at 24, 48, and 72 hours. The COX-2, IL-6, IL-8, receptor activator of nuclear factor kappa-Β ligand (RANKL), and osteoprotegrin (OPG) mRNA expressions were determined using quantitative real-time polymerase chain reaction (qPCR). The PGE₂ , IL-6, and IL-8 protein expressions were quantified by enzyme-linked immunosorbent assay (ELISA). To demonstrate whether the expression of PGE₂ , IL-6, and IL-8 was in the COX-dependent pathway, the hPDL cells were treated with indomethacin. To determine whether PGE₂ stimulated the hPDL cells to express IL-6 and IL-8, exogenous PGE₂ was added to the culture media.

RESULTS

The combination of mechanical vibration and compressive force synergistically upregulated RANKL/OPG, COX-2/PGE₂ , IL-6 and IL-8 mRNA, and protein expression. The indomethacin significantly attenuated the increases of PGE₂ , IL-6, and IL-8 expression in cells stimulated with compressive force or mechanical vibration combined with compressive force. In addition, exogenous PGE₂ increased IL-6 and IL-8 mRNA and protein expressions in hPDL cells.

CONCLUSION

Mechanical vibration may enhance alveolar bone resorption at the compression side during orthodontic tooth movement via a mechanism involving the cyclooxygenase pathway.

Cancer Metastases to Bone: Concepts, Mechanisms, and Interactions with Bone Osteoblasts

The skeleton is a unique structure capable of providing support for the body. Bone resorption and deposition are controlled in a tightly regulated balance between osteoblasts and osteoclasts with no net bone gain or loss. However, under conditions of disease, the balance between bone resorption and deposition is upset. Osteoblasts play an important role in bone homeostasis by depositing new bone osteoid into resorption pits. It is becoming increasingly evident that osteoblasts additionally play key roles in cancer cell dissemination to bone and subsequent metastasis. Our laboratory has evidence that when osteoblasts come into contact with disseminated breast cancer cells, the osteoblasts produce factors that initially reduce breast cancer cell proliferation, yet promote cancer cell survival in bone. Other laboratories have demonstrated that osteoblasts both directly and indirectly contribute to dormant cancer cell reactivation in bone. Moreover, we have demonstrated that osteoblasts undergo an inflammatory stress response in late stages of breast cancer, and produce inflammatory cytokines that are maintenance and survival factors for breast cancer cells and osteoclasts. Advances in understanding interactions between osteoblasts, osteoclasts, and bone metastatic cancer cells will aid in controlling and ultimately preventing cancer cell metastasis to bone.

Myeloma-derived macrophage inhibitory factor regulates bone marrow stromal cell-derived IL-6 via c-MYC

Abstract

Multiple myeloma (MM) remains an incurable malignancy despite the recent advancements in its treatment. The protective effects of the niche in which it develops has been well documented; however, little has been done to investigate the MM cell’s ability to ‘re-program’ cells within its environment to benefit disease progression. Here, we show that MM-derived macrophage migratory inhibitory factor (MIF) stimulates bone marrow stromal cells to produce the disease critical cytokines IL-6 and IL-8, prior to any cell-cell contact. Furthermore, we provide evidence that this IL-6/8 production is mediated by the transcription factor cMYC. Pharmacological inhibition of cMYC in vivo using JQ1 led to significantly decreased levels of serum IL-6—a highly positive prognostic marker in MM patients.

Conclusions

Our presented findings show that MM-derived MIF causes BMSC secretion of IL-6 and IL-8 via BMSC cMYC. Furthermore, we show that the cMYC inhibitor JQ1 can reduce BMSC secreted IL-6 in vivo, irrespective of tumor burden. These data provide evidence for the clinical evaluation of both MIF and cMYC inhibitors in the treatment of MM.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0614-4) contains supplementary material, which is available to authorized users.

Osteocyte-Driven Downregulation of Snail Restrains Effects of Drd2 Inhibitors on Mammary Tumor Cells

While bone is a frequent target of breast cancer-associated metastasis, little is known about the effects of tumor-bone interactions on the efficacy of tumor-suppressing agents. Here we examined the effect of two FDA-approved dopamine modulators, fluphenazine and trifluoperazine, on mammary tumor cells, osteoclasts, osteoblasts, and osteocytes. These agents suppressed proliferation and migration of mammary tumor cells chiefly by antagonizing dopamine receptor D2 and reduced bone resorption by downregulating nuclear factor of activated T cells, cytoplasmic 1 (Nfatc1). Three-dimensional spheroid formation assays revealed that tumor cells have high affinity to osteocytes and type I collagen, and interactions with osteocytes as well as administration of fluphenazine and trifluoperazine downregulated Snail and suppressed migratory behaviors. Unlike the inhibitory action of fluphenazine and trifluoperazine on tumor growth, tumor-osteocyte interactions stimulated tumor proliferation by upregulating NFκB and Akt. In the bone microenvironment, osteocytes downregulated Snail and acted as an attractant as well as a stimulant to mammary tumor cells. These results demonstrate that tumor-osteocyte interactions strengthen dopamine receptor-mediated suppression of tumor migration but weaken its inhibition of tumor proliferation in the osteocyte-rich bone microenvironment.Significance: These findings provide novel insight into the cellular cross-talk in the bone microevironment and the effects of dopamine modulators on mammary tumor cells and osteocytes. Cancer Res; 78(14); 3865-76. ©2018 AACR.

Linkage of Infection to Adverse Systemic Complications: Periodontal Disease, Toll-Like Receptors, and Other Pattern Recognition Systems

Toll-like receptors (TLRs) are a group of pattern recognition receptors (PRRs) that provide innate immune sensing of conserved pathogen-associated molecular patterns (PAMPs) to engage early immune recognition of bacteria, viruses, and protozoa. Furthermore, TLRs provide a conduit for initiation of non-infectious inflammation following the sensing of danger-associated molecular patterns (DAMPs) generated as a consequence of cellular injury. Due to their essential role as DAMP and PAMP sensors, TLR signaling also contributes importantly to several systemic diseases including cardiovascular disease, diabetes, and others. The overlapping participation of TLRs in the control of infection, and pathogenesis of systemic diseases, has served as a starting point for research delving into the poorly defined area of infection leading to increased risk of various systemic diseases. Although conflicting studies exist, cardiovascular disease, diabetes, cancer, rheumatoid arthritis, and obesity/metabolic dysfunction have been associated with differing degrees of strength to infectious diseases. Here we will discuss elements of these connections focusing on the contributions of TLR signaling as a consequence of bacterial exposure in the context of the oral infections leading to periodontal disease, and associations with metabolic diseases including atherosclerosis and type 2 diabetes.

Heterogeneity of clinical isolates of chikungunya virus and its impact on the responses of primary human fibroblast-like synoviocytes

Low-passage clinical isolates of chikungunya virus (CHIKV) were found to be a mixture of large- and small-plaque viruses, with small-plaque viruses being the predominant species. To investigate the contribution of plaque variants to the pathology of the joint, primary human fibroblast-like synoviocytes (HFLS) were used. Large- and small-plaque viruses were purified from two clinical isolates, CHIKV-031C and CHIKV-033C, and were designated CHIKV-031L and CHIKV-031S and CHIKV-033L and CHIKV-033S, respectively. The replication efficiencies of these viruses in HFLSs were compared and it was found that CHIKV-031S and CHIKV-033S replicated with the highest efficiency, while the parental clinical isolates had the lowest efficiency. Interestingly, the cytopathic effects (CPE) induced by these viruses correlated with neither the efficiency of replication nor the plaque size. The small-plaque viruses and the clinical isolates induced cell death rapidly, while large-plaque viruses induced slow CPE in which only 50 % of the cells in infected cultures were rounded up and detached on day 5 of infection. The production of proinflammatory cytokines and chemokines from infected HFLSs was evaluated. The results showed that the large-plaque viruses and the clinical isolates, but not small-plaque variants, were potent inducers of IL-6, IL-8 and MCP-1, and were able to migrate monocytes/macrophages efficiently. Sequencing data revealed a number of differences in amino acid sequences between the small- and large-plaque viruses. The results suggest that it is common for clinical isolates of CHIKV to be heterogeneous, while the variants may have distinct roles in the pathology of the joint.

Regulation of Osteoclast Differentiation by Cytokine Networks

Cytokines play a pivotal role in maintaining bone homeostasis. Osteoclasts (OCs), the sole bone resorbing cells, are regulated by numerous cytokines. Macrophage colony-stimulating factor and receptor activator of NF-κB ligand play a central role in OC differentiation, which is also termed osteoclastogenesis. Osteoclastogenic cytokines, including tumor necrosis factor-α, IL-1, IL-6, IL-7, IL-8, IL-11, IL-15, IL-17, IL-23, and IL-34, promote OC differentiation, whereas anti-osteoclastogenic cytokines, including interferon (IFN)-α, IFN-β, IFN-γ, IL-3, IL-4, IL-10, IL-12, IL-27, and IL-33, downregulate OC differentiation. Therefore, dynamic regulation of osteoclastogenic and anti-osteoclastogenic cytokines is important in maintaining the balance between bone-resorbing OCs and bone-forming osteoblasts (OBs), which eventually affects bone integrity. This review outlines the osteoclastogenic and anti-osteoclastogenic properties of cytokines with regard to osteoimmunology, and summarizes our current understanding of the roles these cytokines play in osteoclastogenesis.

Hallmarks of Bone Metastasis

Breast cancer bone metastasis develops as the result of a series of complex interactions between tumor cells, bone marrow cells, and resident bone cells. The net effect of these interactions are the disruption of normal bone homeostasis, often with significantly increased osteoclast and osteoblast activity, which has provided a rational target for controlling tumor progression, with little or no emphasis on tumor eradication. Indeed, the clinical course of metastatic breast cancer is relatively long, with patients likely to experience sequential skeletal-related events (SREs), often over lengthy periods of time, even up to decades. These SREs include bone pain, fractures, and spinal cord compression, all of which may profoundly impair a patient's quality-of-life. Our understanding of the contributions of the host bone and bone marrow cells to the control of tumor progression has grown over the years, yet the focus of virtually all available treatments remains on the control of resident bone cells, primarily osteoclasts. In this perspective, our focus is to move away from the current emphasis on the control of bone cells and focus our attention on the hallmarks of bone metastatic tumor cells and how these differ from primary tumor cells and normal host cells. In our opinion, there remains a largely unmet medical need to develop and utilize therapies that impede metastatic tumor cells while sparing normal host bone and bone marrow cells. This perspective examines the impact of metastatic tumor cells on the bone microenvironment and proposes potential new directions for uncovering the important mechanisms driving metastatic progression in bone based on the hallmarks of bone metastasis.

Implant-Associated Posttraumatic Osteomyelitis: Collateral Damage by Local Host Defense?

Infections following osteosynthesis or total joint replacement, also known as “implant-associated posttraumatic osteomyelitis”, represent a major complication in orthopedic and trauma surgery. While the formation of bacterial biofilms on the implanted osteosynthesis materials is generally accepted as cause of the persistent infection, the molecular mechanisms leading to the progressive and destructive local inflammatory process and eventually to bone degradation, the osteolysis, have not been delineated. Here we provide evidence supporting the hypothesis that it is not the infection per se that causes tissue degradation and osteolysis, but rather the cytotoxic, proteolytic, and proinflammatory effector functions of cells of the host defense, particularly of the infiltrating polymorphonuclear neutrophils.

Secreted factors from metastatic prostate cancer cells stimulate mesenchymal stem cell transition to a pro-tumourigenic 'activated' state that enhances prostate cancer cell migration

Mesenchymal stem cells (MSCs) are a heterogeneous population of multipotent cells that are capable of differentiating into osteocytes, chondrocytes and adipocytes. Recently, MSCs have been found to home to the tumour site and engraft in the tumour stroma. However, it is not yet known whether they have a tumour promoting or suppressive function. We investigated the interaction between prostate cancer cell lines 22Rv1, DU145 and PC3, and bone marrow-derived MSCs. MSCs were 'educated' for extended periods in prostate cancer cell conditioned media and PC3-educated MSCs were found to be the most responsive with a secretory profile rich in pro-inflammatory cytokines. PC3-educated MSCs secreted increased osteopontin (OPN), interleukin-8 (IL-8) and fibroblast growth factor-2 (FGF-2) and decreased soluble fms-like tyrosine kinase-1 (sFlt-1) compared to untreated MSCs. PC3-educated MSCs showed a reduced migration and proliferation capacity that was dependent on exposure to PC3-conditioned medium. Vimentin and α-smooth muscle actin (αSMA) expression was decreased in PC3-educated MSCs compared to untreated MSCs. PC3 and DU145 education of healthy donor and prostate cancer patient-derived MSCs led to a reduced proportion of FAP+ αSMA+ cells contrary to characteristics commonly associated with cancer associated fibroblasts (CAFs). The migration of PC3 cells was increased toward both PC3-educated and DU145-educated MSCs compared to untreated MSCs, while DU145 migration was only enhanced toward patient-derived MSCs. In summary, MSCs developed an altered phenotype in response to prostate cancer conditioned medium which resulted in increased secretion of pro-inflammatory cytokines, modified functional activity and the chemoattraction of prostate cancer cells.

Role of Tumor-Derived Chemokines in Osteolytic Bone Metastasis

Metastasis is the primary cause of mortality and morbidity in cancer patients. The bone marrow is a common destination for many malignant cancers, including breast carcinoma (BC), prostate carcinoma, multiple myeloma, lung carcinoma, uterine cancer, thyroid cancer, bladder cancer, and neuroblastoma. The molecular mechanism by which metastatic cancer are able to recognize, infiltrate, and colonize bone are still unclear. Chemokines are small soluble proteins which under normal physiological conditions mediate chemotactic trafficking of leukocytes to specific tissues in the body. In the context of metastasis, the best characterized role for the chemokine system is in the regulation of primary tumor growth, survival, invasion, and homing to specific secondary sites. However, there is ample evidence that metastatic tumors exploit chemokines to modulate the metastatic niche within bone which ultimately results in osteolytic bone disease. In this review, we examine the role of chemokines in metastatic tumor growth within bone. In particular, the chemokines CCL2, CCL3, IL-8/CXCL8, and CXCL12 are consistently involved in promoting osteoclastogenesis and tumor growth. We will also evaluate the suitability of chemokines as targets for chemotherapy with the use of neutralizing antibodies and chemokine receptor-specific antagonists.

MyD88-mediated innate sensing by oral epithelial cells controls periodontal inflammation

Periodontal diseases are a class of non-resolving inflammatory diseases, initiated by a pathogenic subgingival biofilm, in a susceptible host, which if left untreated can result in soft and hard tissue destruction. Oral epithelial cells are the first line of defense against microbial infection within the oral cavity, whereby they can sense the environment through innate immune receptors including toll-like receptors (TLRs). Therefore, oral epithelial cells directly and indirectly contribute to mucosal homeostasis and inflammation, and disruption of this homeostasis or over-activation of innate immunity can result in initiation and/or exacerbation of localized inflammation as observed in periodontal diseases. Dynamics of TLR signaling outcomes are attributable to several factors including the cell type on which it engaged. Indeed, our previously published data indicates that oral epithelial cells respond in a unique manner when compared to canonical immune cells stimulated in a similar fashion. Thus, the objective of this study was to evaluate the role of oral epithelial cell innate sensing on periodontal disease, using a murine poly-microbial model in an epithelial cell specific knockout of the key TLR-signaling molecule MyD88 (B6^{K5Cre.MyD88plox}). Following knockdown of MyD88 in the oral epithelium, mice were infected with Porphorymonas gingivalis and Aggregatibacter actinomycetemcomitans by oral lavage 4 times per week, every other week for 6 weeks. Loss of oral epithelial cell MyD88 expression resulted in exacerbated bone loss, soft tissue morphological changes, soft tissue infiltration, and soft tissue inflammation following polymicrobial oral infection. Most interestingly while less robust, loss of oral epithelial cell MyD88 also resulted in mild but statistically significant soft tissue inflammation and bone loss even in the absence of a polymicrobial infection. Together these data demonstrate that oral epithelial cell MyD88-dependent TLR signaling regulates the immunological balance within the oral cavity under conditions of health and disease.

An increased concentration of receptor activator of nuclear factor kappa-B ligand pre-dates the onset of rheumatoid arthritis

Objectives

RANK ligand (RANKL) is involved in destruction and osteoporosis in RA. In this study, the relationships between RANKL and ACPA, anti-carbamylated protein antibodies (anti-CarP), cytokines and chemokines were analysed in individuals before the onset of RA symptoms, and their associations with radiological findings at disease onset were assessed.

Methods

This was a case-control study performed within the Medical Biobank of Northern Sweden that included 470 pre-symptomatic individuals [334 women and 136 men; mean (s.d.) age 52.3 (9.4) years] using blood samples donated before symptom onset (pre-dating time; 5.0 years) and 96 controls (60 women and 36 men). Plasma was analysed for RANKL (BioVendor, Karasek, Brno, Czech Republic), anti-CCP2 antibodies (Eurodiagnostics, Malmö, Sweden), anti-CarP antibodies (in-house ELISA), ACPA specificities (ISAC-platform, Phadia AB, Uppsala, Sweden) and cytokines/chemokines (Meso Scale Discovery methods, Rockville, MD, USA). Radiographs of hands and feet were graded using the Larsen score.

Results

The concentration of RANKL was higher in the pre-symptomatic individuals compared with controls; mean (s.e.m.): 0.50 (0.03) vs 0.22 (0.02) nmol/l (P < 0.001). The concentration increased gradually over time until symptom onset but appeared later than ACPA/RF/anti-CarP antibodies. Positivity for these antibodies yielded higher levels of RANKL compared with seronegativity (P < 0.001). RANKL concentrations were significantly associated with IL-6 and IL-10 concentrations. The combination of positivity for RANKL and anti-CarP antibodies resulted in a higher Larsen score at diagnosis β = 6.18 (95% CI: 0.93, 11.43; P = 0.022).

Conclusion

RANKL concentrations were increased several years before symptom onset for RA, particularly in ACPA/RF/anti-CarP-positive individuals, all detectable earlier than RANKL. Positivity for RANKL and anti-CarP antibodies yielded the highest Larsen score at disease onset.

miRNAs in bone tissue correlate to bone mineral density and circulating miRNAs are gender independent in osteoporotic patients

We previously demonstrated the aberrant expression of nine specific miRNAs in serum from osteoporotic patients. In the present study, we further evaluated the expression of these miRNAs in bone tissue, osteoblasts, and osteoclasts from 28 patients. We hypothesize that miRNA expression in serum from osteoporotic patients may be gender-independent. A further hypothesis is that the miRNA expression in bone could be correlated with BMD values. Moreover, intracellular expression of these osteoporosis-related miRNAs may indicate the role of these molecules during osteoporosis. Our results indeed show that miRNA expression in serum was gender-independent except for miR125b-5p. A correlation with BMD was confirmed for miR-21-5p, miR-24-3p, miR-93-5p, miR-100-5p and miR125b-5p with linear correlation coefficients r > 0.9. Intracellular studies revealed a simultaneous up-regulation of miR-21-5p, miR-93-5p, miR-100-5p and miR125b-5p in osteoblasts and in osteoclasts. miR-148a-3p up-regulation in cells was specific for osteoporotic osteoclasts. Altogether, miR-21-5p, miR-93-5p, miR-100-5p, and miR-125b-5p showed significant upregulation in serum, tissue and bone cells of osteoporotic patients. All except miR-125b-5p showed gender independent expression and good correlation to BMD values. Our results suggest that these miRNAs may be important for an earlier diagnosis of osteoporosis.