Bone Remodeling and Bone Structural Genes in Legg-Calvé-Perthes Disease: The OPG rs2073618 and IL-6 rs1800795 Are Associated with High Risk in Mexican Patients

Legg-Calve-Perthes disease (LCPD) is an idiopathic avascular necrosis of the pediatric femoral head. Bone remodeling and bone structural genes have the potential to contribute to the progression of LCPD when there is disequilibrium between bone resorption and bone formation. A case-control study was performed to search for associations of several common polymorphisms in the genes Receptor Activator for Nuclear Factor κappa B (RANK), Receptor Activator for Nuclear Factor κappa B Ligand (RANKL), osteoprotegerin (OPG), interleukin (IL)-6, and type 1 collagen (COL1A1) with LCPD susceptibility in Mexican children. A total of 23 children with LCPD and 46 healthy controls were genotyped for seven polymorphisms (rs3018362, rs12585014, rs2073618, rs1800795, rs1800796, rs1800012, and rs2586498) in the RANK, RANKL, OPG, IL-6, and COL1A1 genes by real-time polymerase chain reaction with TaqMan probes. The variant allele (C) of IL-6 rs1800795 was associated with increased risk of LCPD (odds ratio [OR]: 3.8, 95% confidence interval [CI]: [1.08-13.54], p = 0.033), adjusting data by body mass index (BMI) and coagulation factor V (FV), the association with increased risk remained (OR: 4.9, 95% CI: [1.14-21.04], p = 0.025). The OPG polymorphism rs2073618, specifically GC-GG carriers, was associated with a more than fourfold increased risk of developing LCPD (OR: 4.34, 95% CI: [1.04-18.12], p = 0.033) when data were adjusted by BMI-FV. There was no significant association between RANK rs3018362, RANKL rs12585014, IL-6 rs1800796, COL1A1 rs1800012, and rs2586498 polymorphisms and LCPD in a sample of Mexican children. The rs1800975 and rs2037618 polymorphisms in the IL-6 and OPG genes, respectively, are informative markers of increased risk of LCPD in Mexican children.

Pathodynamics

Osteoporosis and osteoporosis-related fractures in the aging population are becoming a health care problem and a burden on health service resources available. Osteoporosis is a systemic skeletal disorder that results from an imbalance in bone remodeling, leading to a reduction in bone strength with microarchitectural disruption and skeletal fragility, increasing fracture susceptibility. Osteoporosis is considered a well-known metabolic bone disorder. Although its prevalence is more commonly seen in women than men, it is eventually seen in both genders. In the elderly population, there is an increase in disability and mortality due to osteoporotic fractures.

Mechanisms of thymic repair of in vitro-induced precursor T cells as a haplo-identical HSCT regimen

Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) is currently an effective treatment for malignant hematological disease, but the immune deficiency and severe infection triggered by slow immune reconstitution are the main causes of high mortality and transplant failure. One of these outstanding problems is thymus damage, which is associated with graft-versus-host disease (GVHD), and preconditioning including irradiation and chemotherapy. Therefore, rapid repair of damaged thymus and rapid proliferation of thymus-derived donor T cells after transplantation are key to solving the problem. This study is designed to accelerate the recovery of thymus-derived T cells after transplantation. Wild-type mice with normal immunity were used as recipients in a haplo-HSCT mouse model to mimic clinical haplo-HSCT. A modified cell culture system using Notch ligand Delta4 and IL-7 was established that is capable of inducing and amplifying the differentiation and proliferation of hematopoietic stem cells into precursor T (preT) cells in vitro. Haplo-HSCT protocol included the preT and G-CSF mobilized donor splenic mononuclear cells (MNC) co-infusion or MNC alone. Thymic GVHD, thymic repair, and thymus-derived T cell development were compared in two groups by polychromatic immunofluorescence tracking, flow cytometry and detection of T cell receptor Vβ. The thymus homing and T-cell regeneration of allogenic preT cells were observed. The functions of preT cells in accelerating immune reconstitution, restoring thymic architecture, weakening GVH effects, and enhancing immuno-tolerance after transplantation were demonstrated. Further studies revealed that allogeneic preT cells induced by a culture system containing IL7 and Delta4 highly express ccr9 and RANKL. Interestingly, the RANK expression was promoted after preT cells' thymus homing. These results suggested that the RANK/RANKL pathway may play an important role in thymus homing. Our results provide a potential therapeutic option to optimize haplo-HSCT. It further opened up a new field of T cell therapy for artificial induction of allogeneic precursor T cells in vitro to repair the damaged thymus from irradiation and chemotherapy, and to compensate for the recovery of immune function in patients with immune deficiency caused by multiple reasons.

Treatment of fibrous dysplasia: focus on denosumab

INTRODUCTION

Fibrous dysplasia (FD) is a rare bone disease that is associated with various endocrine conditions, such as McCune Albright syndrome. It manifests as abnormal osteolysis, multiple fractures, or deformities that are reported during disease course. The receptor activator of nuclear factor-kappa B (RANK)/RANK ligand (RANKL) pathway is upregulated in FD and can be targeted with denosumab, a blocking monoclonal antibody.

AREAS COVERED

Preclinical and clinical data on the scientific rationale for using denosumab in FD and on the efficacy and safety of this therapy for this condition have been reviewed, in addition to other therapies.

EXPERT OPINION

Denosumab is a potential therapeutic agent against FD. A combined synergic approach involving theranostics might increase its therapeutic potential.

Estrogens and Progestogens in Triple Negative Breast Cancer: Do They Harm?

Triple-negative breast cancers (TNBC) occur more frequently in younger women and do not express estrogen receptor (ER) nor progesterone receptor (PR), and are therefore often considered hormone-insensitive. Treatment of premenopausal TNBC patients almost always includes chemotherapy, which may lead to premature ovarian insufficiency (POI) and can severely impact quality of life. Hormone replacement therapy (HRT) is contraindicated for patients with a history of hormone-sensitive breast cancer, but the data on safety for TNBC patients is inconclusive, with a few randomized trials showing increased risk-ratios with wide confidence intervals for recurrence after HRT. Here, we review the literature on alternative pathways from the classical ER/PR. We find that for both estrogens and progestogens, potential alternatives exist for exerting their effects on TNBC, ranging from receptor conversion, to alternative receptors capable of binding estrogens, as well as paracrine pathways, such as RANK/RANKL, which can cause progestogens to indirectly stimulate growth and metastasis of TNBC. Finally, HRT may also influence other hormones, such as androgens, and their effects on TNBCs expressing androgen receptors (AR). Concluding, the assumption that TNBC is completely hormone-insensitive is incorrect. However, the direction of the effects of the alternative pathways is not always clear, and will need to be investigated further.

Signaling pathways affected by mutations causing osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous connective tissue disorder characterized by bone fragility and skeletal deformity. To maintain skeletal strength and integrity, bone undergoes constant remodeling of its extracellular matrix (ECM) tightly controlled by osteoclast-mediated bone resorption and osteoblast-mediated bone formation. There are at least 20 recognized OI-forms caused by mutations in the two collagen type I-encoding genes or genes implicated in collagen folding, posttranslational modifications or secretion of collagen, osteoblast differentiation and function, or bone mineralization. The underlying disease mechanisms of non-classical forms of OI that are not caused by collagen type I mutations are not yet completely understood, but an altered ECM structure as well as disturbed intracellular homeostasis seem to be the main defects. The ECM orchestrates local cell behavior in part by regulating bioavailability of signaling molecules through sequestration, release and activation during the constant bone remodeling process. Here, we provide an overview of signaling pathways that are associated with known OI-causing genes and discuss the impact of these genes on signal transduction. These pathways include WNT-, RANK/RANKL-, TGFβ-, MAPK- and integrin-mediated signaling as well as the unfolded protein response.

Effect of Substrate Reduction Therapy in Comparison to Enzyme Replacement Therapy on Immune Aspects and Bone Involvement in Gaucher Disease

Gaucher disease (GD) is caused by mutations in the GBA gene, leading to deficient activity of the lysosomal enzyme glucocerebrosidase. Among all the symptoms across various organ systems, bone disease is a major concern as it causes high morbidity and reduces quality of life. Enzyme replacement therapy (ERT) is the most accepted treatment; however, there are still unmet needs. As an alternative, substrate reduction therapy (SRT) was developed using glucosylceramide synthase inhibitors. In the current study, the effects of ERT vs. SRT were compared, particularly the immunological and bone remodeling aspects. GD subjects were divided into three cohorts based on their treatment at initial visit: ERT, SRT, and untreated (UT). Immunophenotyping showed no significant immune cell alterations between the cohorts. Expression of RANK/RANKL/Osteoprotegerin pathway components on immune cells and the secreted markers of bone turnover were analyzed. In the ERT cohort, no significant changes were observed in RANK, RANKL or serum biomarkers. RANKL on T lymphocytes, Osteopontin and MIP-1β decreased with SRT treatment indicating probable reduction in osteoclast activity. Other secreted factors, Osteocalcin and RANKL/Osteoprotegerin did not change with the treatment status. Insights from the study highlight personalized differences between subjects and possible use of RANK pathway components as markers for bone disease progression.

MiR-143 Inhibits Osteoclastogenesis by Targeting RANK and NF-κB and MAPK Signaling Pathways

OBJECTIVE

To explore the effect of miRNA-143 on osteoclast formation and provide new ideas for the treatment of osteoporosis.

METHODS

Mice macrophage lines RAW264.7 cells after transfection were divided into four groups: control group, RANKL group, RANKL combined with miR-143 mimics group and RANKL combined with miR-NC group. TARCP staining was used to observe the effect of miR-143 on osteoclast formation. The expression of RANK, TRAF6 and NFATc-1 in the upstream of RANKL pathway was detected by real-time quantitative PCR (RT qPCR) and Western blotting (WB). The binding of miR-143 to TNFRSF11A was detected by double Luciferase Reporter Analysis. The effect of miR-143 on the expression of NF-κB (p65, I-κB-α) signal pathway in osteoclasts was detected. The effects of I-BET151 on the expression of osteoclast-specific genes TRACP, MMP 9, CtsK and c-Src were detected.

RESULTS

The positive level of osteoclasts in RANKL group and RANKL combined with miR-NC group was significantly higher than that of RANKL combined with miR-143 mimics group and control group (P < 0.05). The expression levels of RANK, TRAF6, NFATc-1, TRACP, MMP-9, CtsK and c-Src in RANKL group and RANKL combined with miR-NC group were significantly higher than those of RANKL combined with miR-143 mimics group and control group (P < 0.05). The expression levels of I-κB-α were significantly lower than that of RANKL combined with miR-143 mimics group and control group (P<0.05).

CONCLUSION

MiR-143 can inhibit the expression of RANK, TRAF6 and downstream NFATc-1 in the RANKL pathway, thereby inhibiting the RANK/RANKL pathway. MiR-143 can inhibit the signal pathway of NF-κB (p65, I-κB-α). MiR-143 inhibits the expression of osteoclast-specific genes TRACP, MMP 9, CtsK and c-Src. That is to say, miR-143 inhibits osteoclast formation by targeting RANK, NF- κB and MAPK signaling pathways.

Combination of denosumab and immune checkpoint inhibition: experience in 29 patients with metastatic melanoma and bone metastases

BACKGROUND

PD-1 inhibition (PD-1i) is the standard of care in melanoma and other malignancies. In patients with bone metastases of solid tumors, the monoclonal antibody denosumab directed against RANKL is approved for the prevention of skeletal-related events. However, RANKL is not only relevant in osteoclastogenesis, but also has immunological effects. Hence, we aimed at investigating, whether the combination of PD-1i and denosumab produces synergistic effects in metastatic melanoma treatment.

METHODS

We retrospectively collected and analyzed clinical data of metastatic melanoma patients with bone metastases, who received PD-1i and denosumab therapy.

RESULTS

29 patients were identified with a median age of 60.7 years: 20 were male and 9 were female. 20 patients (69%) were in stage IV M1c and 9 (31%) in stage IV M1d; 52% had an increased serum LDH. 24 patients (83%) received PD-1i as first-line therapy and five patients (17%) as second- or third-line therapy. 13 patients received the triple combination nivolumab, ipilimumab and denosumab (N + I+D), 16 patients received PD-1i and denosumab (PD-1i + D). Within a median follow-up time of 19.8 months, 17 patients progressed with a median time to progression of 6 months. The objective response rate was 54% in the N + I + D group and 50% in the PD-1i + D group. Recalcification of bone metastases was radiologically observed in 18 (62%) patients. No unexpected treatment-related adverse events emerged.

CONCLUSIONS

The combination therapy of metastatic melanoma with PD-1i and denosumab was feasible without unexpected safety issues and showed a promising efficacy signal. Further investigation in prospective studies is needed.

Osteoprotegerin mediate RANK/RANKL signaling inhibition eases asthma inflammatory reaction by affecting the survival and function of dendritic cells

INTRODUCTION

Asthma is a chronic inflammatory, heterogeneous airway disease affecting millions of people around the world. Dendritic cells (DCs) are considered the most important antigen-presenting cell in asthma airway inflammatory reaction. But whether osteoprotegerin (OPG) mediate RANK/RANKL signaling inhibition influences asthma development by affecting the survival and function of DCs remains unclear. In this study, we assessed the effects of OPG on DCs and asthma.

MATERIAL AND METHODS

BALB/c mice immunized with ovalbumin (OVA) were challenged thrice with an aerosol of OVA every second day for eight days. Dexamethasone (1.0mg/kg) or OPG (50μg/kg) was administered intraperitoneally to OVA-immunized BALB/c mice on day 24 once a day for nine days. Mice were analyzed for effects of OPG on asthma, inflammatory cell infiltration and cytokine levels in lung tissue. The expression of RANK and β-actin was detected by Western Blot. DCs were isolated from mouse bone morrow. Cell survival was assessed by cell counting. The content of IL-12 was detected by ELISA.

RESULTS

Results showed that OVA increased the number of inflammatory factors in BALF, elevated lung inflammation scores in mice. OPG reversed the alterations induced by OVA in the asthmatic mice. OPG inhibited the survival and function of DC via inhibition of RANK/RANKL signaling.

CONCLUSIONS

This research proved inhibition of RANK/RANKL signaling by OPG could ease the inflammatory reaction in asthma, providing new evidence for the application of OPG on asthma.

Inhibition of NK Reactivity Against Solid Tumors by Platelet-Derived RANKL

NK cells play an important role in tumor immunosurveillance. Their reactivity is governed by various activating and inhibitory surface receptors, which include several members of the TNF/TNF receptor family. For more than 50 years, it has been recognized that tumor immunosurveillance and in particular NK cell antitumor reactivity is largely influenced by platelets, but the underlying mechanisms remain to be fully elucidated. Here we report that upon activation, which reportedly occurs following interaction with cancer cells, platelets upregulate the TNF family member RANKL. Comparative analysis of the expression of RANK among different NK cell subsets and RANKL on platelets in cancer patients and healthy volunteers revealed a distinct malignant phenotype, and platelet-derived RANKL was found to inhibit the activity of normal NK cells against cancer cells. Notably, NK cell antitumor reactivity could be partially restored by application of denosumab, a RANKL-neutralizing antibody approved for treatment of benign and malignant osteolysis. Together, our data not only unravel a novel mechanism of tumor immune evasion mediated by platelets, but they also provide a functional explanation for the clinical observation that denosumab, beyond protecting from bone loss, may prolong disease-free survival in patients with solid tumors.

RANKL/RANK: from bone loss to the prevention of breast cancer

RANK and RANKL, a receptor ligand pair belonging to the tumour necrosis factor family, are the critical regulators of osteoclast development and bone metabolism. Besides their essential function in bone, RANK and RANKL have also been identified as the key factors for the formation of a lactating mammary gland in pregnancy. Mechanistically, RANK and RANKL link the sex hormone progesterone with stem cell expansion and proliferation of mammary epithelial cells. Based on their normal physiology, RANKL/RANK control the onset of hormone-induced breast cancer through the expansion of mammary progenitor cells. Recently, we and others were able to show that RANK and RANKL are also critical regulators of BRCA1-mutation-driven breast cancer. Currently, the preventive strategy for BRCA1-mutation carriers includes preventive mastectomy, associated with wide-ranging risks and psychosocial effects. The search for an alternative non-invasive prevention strategy is therefore of paramount importance. As our work strongly implicates RANK and RANKL as key molecules involved in the initiation of BRCA1-associated breast cancer, we propose that anti-RANKL therapy could be a feasible preventive strategy for women carrying BRCA1 mutations, and by extension to other women with high risk of breast cancer.

Phospholipase C-related, but catalytically inactive protein (PRIP) up-regulates osteoclast differentiation via calcium-calcineurin-NFATc1 signaling

Phospholipase C-related, but catalytically inactive protein (PRIP) was previously identified as a novel inositol 1,4,5-trisphosphate-binding protein with a domain organization similar to that of phospholipase C-δ but lacking phospholipase activity. We recently showed that PRIP gene knock-out (KO) in mice increases bone formation and concomitantly decreases bone resorption, resulting in increased bone mineral density and trabecular bone volume. However, the role of PRIP in osteoclastogenesis has not yet been fully elucidated. Here, we investigated the effects of PRIP on bone remodeling by investigating dynamic tooth movement in mice fitted with orthodontic devices. Morphological analysis indicated that the extent of tooth movement was smaller in the PRIP-KO mice than in wild-type mice. Histological analysis revealed fewer osteoclasts on the bone-resorption side in maxillary bones of PRIP-KO mice, and osteoclast formation assays and flow cytometry indicated lower osteoclast differentiation in bone marrow cells isolated from these mice. The expression of genes implicated in bone resorption was lower in differentiated PRIP-KO cells, and genes involved in osteoclast differentiation, such as the transcription factor NFATc1, exhibited lower expression in immature PRIP-KO cells initiated by M-CSF. Moreover, calcineurin expression and activity were also lower in the PRIP-KO cells. The PRIP-KO cells also displayed fewer M-CSF-induced changes in intracellular Ca²⁺ and exhibited reduced nuclear localization of NFATc1. Up-regulation of intracellular Ca²⁺ restored osteoclastogenesis of the PRIP-KO cells. These results indicate that PRIP deficiency impairs osteoclast differentiation, particularly at the early stages, and that PRIP stimulates osteoclast differentiation through calcium-calcineurin-NFATc1 signaling via regulating intracellular Ca².

State of the art in anti-cancer mAbs

Following Milstein’s discovery, the monoclonal antibodies (mAbs) became a basic tool for biomedical science. In cancer field, since the first mAb was approved by the FDA a great improvement took place making of them a therapeutic option for many cancer types in the current clinical practice. Today, mAbs are being developed to target different molecules with different mechanisms of action and its target potential is unlimited. However, this huge and fast growing new field needs to be organized to better understand the treatment options we have to confront different cancer diseases. Current cancer targeted immunotherapies aim to achieve different goals like the regulation of osteoclast function, the delivery of cytotoxic drugs into tumor cells and the blockade of oncogenic pathways, neo-angiogenesis and immune checkpoints. Here, we reviewed the most relevant therapeutic mAbs for solid tumors available in current clinical practice.

RANK/RANKL expression in prostate cancer

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Expression of RANK and RANKL genes in prostate cancer is higher than non-neoplastic prostate.

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RANK/RANKL expression is not related to pathological features.

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There is no significant correlation of RANK/RANKL expression with biochemical recurrence after radical prostatectomy.

Interactions of the tooth and bone during development

The tooth works as a functional unit with its surrounding bony socket, the alveolar bone. The growth of the tooth and alveolar bone is co-ordinated so that a studied distance always separates the 2, known as the tooth-bone interface (TBI). Lack of mineralization, a crucial feature of the TBI, creates the space for the developing tooth to grow and the soft tissues of the periodontium to develop. We have investigated the interactions between the tooth and its surrounding bone during development, focusing on the impact of the developing alveolar bone on the development of the mouse first molar (M1). During development, TRAP-positive osteoclasts are found to line the TBI as bone starts to be deposited around the tooth, removing the bone as the tooth expands. An enhancement of osteoclastogenesis through RANK-RANKL signaling results in an expansion of the TBI, showing that osteoclasts are essential for defining the size of this region. Isolation of the M1 from the surrounding mesenchyme and alveolar bone leads to an expansion of the tooth germ, driven by increased proliferation, indicating that, during normal development, the growth of the tooth germ is constrained by the surrounding tissues.

Osteoporosis and gastrointestinal disease

Gastrointestinal disease is often overlooked or simply forgotten as a cause of osteoporosis. Yet, the consequences of osteoporotic fractures can be devastating. Although the bulk of the published experience regarding osteoporosis is derived from the postmenopausal population, this review will focus on gastrointestinal disorders implicated in osteoporosis, with an emphasis on inflammatory bowel disease and celiac disease. The unique aspects of gastrointestinal diseases associated with osteoporosis include early onset of disease (and, therefore, prolonged exposure to risk factors for developing osteoporosis, particularly with inflammatory bowel disease and celiac disease), malabsorption, and maldigestion of nutrients necessary for bone health and maintenance (eg, calcium, vitamin D), as well as the impact of glucocorticoids. These factors, when added to smoking, a sedentary lifestyle, hypogonadism, and a family history of osteoporosis, accumulate into an imposing package of predictors for osteoporotic fracture. This paper will review the identification and treatment strategies for patients with gastrointestinal disorders and osteoporosis.

RANKL inhibition improves bone properties in a mouse model of osteogenesis imperfecta

Recently, a new class of agents targeting the receptor activator of nuclear factor-kappaB ligand (RANKL) pathway has been developed for the treatment of osteoporosis and other bone diseases. In the current study, inhibition of the RANKL pathway was evaluated to assess effects on "bone quality" and fracture incidence in an animal model of osteogenesis imperfect (OI), the oim/oim mouse. Juvenile oim/oim ( approximately 6 weeks old) and wildtype (+/+) mice were treated with either a RANKL inhibitor (RANK-Fc) or saline. After treatment, bone density increased significantly in the femurs of both genotypes. Femoral length decreased with RANK-Fc in +/+ mice. Geometric measurements at mid-diaphysis in the oim/oim groups showed increases in the ML periosteal and endosteal diameters and AP cortical thickness in the treated groups. Within +/+ groups, ML cortical thickness and ML femoral periosteal diameter were significantly increased with RANK-Fc. Biomechanical testing revealed increased stiffness in oim/oim and +/+ mice. Total strain was increased with treatment in the +/+ mice. Histologically, RANKL inhibition resulted in retained growth plate cartilage in both genotypes. The average number of fractures sustained by RANK-Fc-treated oim/oim mice was not significantly decreased compared to saline treated oim/oim mice. This preclinical study demonstrated that RANKL inhibition at the current dose improved density and some geometric and biomechanical properties of oim/oim bone, but it did not decrease fracture incidence. Further studies that address commencement of therapy at earlier time points are needed to determine whether this mode of therapy will be clinically useful in OI.