Inhibition of receptor activator of nuclear factor kappa-B ligand-mediated osteoclast differentiation and bone resorption by Gryllus bimaculatus extract: An in vitro study.

Excessive bone-resorbing osteoclast activity during bone remodeling is a major feature of bone diseases, such as osteoporosis. Therefore, the inhibition of osteoclast formation and bone resorption can be an effective therapeutic target for various bone diseases. Gryllus biomaculatus (GB) has recently been approved as an alternative food source because of its high nutritional value and environmental sustainability. Traditionally, GB has been known to have various pharmacological properties, including antipyretic and blood pressure-lowering activity, and it has recently been reported to have various biological activities, including protective effects against inflammation, oxidative stress, insulin resistance, and alcohol-induced liver injury. However, the effect of GB on osteoclast differentiation and bone metabolism has not yet been demonstrated. In this study, we confirmed the inhibitory effect of GB extract (GBE) on the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast formation. To determine the effect of GBE on RANKL-induced osteoclast differentiation and function, we performed TRAP and F-actin staining, as well as a bone-resorbing assay. The intracellular mechanisms of GBE responsible for the regulation of osteoclastogenesis were revealed by Western blot analysis and quantitative real-time polymerase chain reaction. We investigated the relationship between GBE and expression of osteoclast-specific molecules to further elucidate the underlying mechanisms. It was found that GBE significantly suppressed osteoclastogenesis by decreasing the phosphorylation of Akt, p38, JNK, and ERK, as well as Btk-PLCγ2 signaling, in pathways involved in early osteoclastogenesis as well as through the subsequent suppression of c-Fos, NFATc1, and osteoclastogenesis-specific marker genes. Additionally, GBE inhibited the formation of F-actin ring-positive osteoclasts and bone resorption activity of mature osteoclasts. Our findings suggest that GBE is a potential functional food and therapeutic candidate for bone diseases involving osteoclasts.

Novel inhibitor N-cyclopropyl-4-((4-((4-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)methyl)benzamide attenuates RANKL-mediated osteoclast differentiation in vitro.

Both cyclopropyl amide and piperazine sulfonamide functional groups are known for their various biological properties used for drug development. Herein, we synthesized nine new derivatives with different substituent groups incorporating these moieties and screened them for their anti-osteoclast differentiation activity. After analyzing the structure-activity relationship (SAR), the inhibitory effect against osteoclastogenesis was determined to be dependent on the lipophilicity of the compound. Derivative 5b emerged as the most effective dose-dependent inhibitor after TRAP staining with an IC50 of 0.64 µM against RANKL-induced osteoclast cells. 5b was also able to suppress F-acting ring formation and bone resorption activity of osteoclasts in vitro. Finally, well-acknowledged gene and protein osteoclast-specific marker expression levels were decreased after 5b administration on primary murine osteoclast cells.

Bone-modifying agents for reducing bone loss in women with early and locally advanced breast cancer: a network meta-analysis.

BACKGROUND: Bisphosphonates and receptor activator of nuclear factor-kappa B ligand (RANKL)-inhibitors are amongst the bone-modifying agents used as supportive treatment in women with breast cancer who do not have bone metastases. These agents aim to reduce bone loss and the risk of fractures. Bisphosphonates have demonstrated survival benefits, particularly in postmenopausal women. OBJECTIVES: To assess and compare the effects of different bone-modifying agents as supportive treatment to reduce bone mineral density loss and osteoporotic fractures in women with breast cancer without bone metastases and generate a ranking of treatment options using network meta-analyses (NMAs). SEARCH METHODS: We identified studies by electronically searching CENTRAL, MEDLINE and Embase until January 2023. We searched various trial registries and screened abstracts of conference proceedings and reference lists of identified trials. SELECTION CRITERIA: We included randomised controlled trials comparing different bisphosphonates and RANKL-inihibitors with each other or against no further treatment or placebo for women with breast cancer without bone metastases. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data and assessed the risk of bias of included studies and certainty of evidence using GRADE. Outcomes were bone mineral density, quality of life, overall fractures, overall survival and adverse events. We conducted NMAs and generated treatment rankings. MAIN RESULTS: Forty-seven trials (35,163 participants) fulfilled our inclusion criteria; 34 trials (33,793 participants) could be considered in the NMA (8 different treatment options). Bone mineral density We estimated that the bone mineral density of participants with no treatment/placebo measured as total T-score was -1.34. Evidence from the NMA (9 trials; 1166 participants) suggests that treatment with ibandronate (T-score -0.77; MD 0.57, 95% CI -0.05 to 1.19) may slightly increase bone mineral density (low certainty) and treatment with zoledronic acid (T-score -0.45; MD 0.89, 95% CI 0.62 to 1.16) probably slightly increases bone mineral density compared to no treatment/placebo (moderate certainty). Risedronate (T-score -1.08; MD 0.26, 95% CI -0.32 to 0.84) may result in little to no difference compared to no treatment/placebo (low certainty). We are uncertain whether alendronate (T-score 2.36; MD 3.70, 95% CI -2.01 to 9.41) increases bone mineral density compared to no treatment/placebo (very low certainty). Quality of life No quantitative analyses could be performed for quality of life, as only three studies reported this outcome. All three studies showed only minimal differences between the respective interventions examined. Overall fracture rate We estimated that 70 of 1000 participants with no treatment/placebo had fractures. Evidence from the NMA (16 trials; 19,492 participants) indicates that treatment with clodronate or ibandronate (42 of 1000; RR 0.60, 95% CI 0.39 to 0.92; 40 of 1000; RR 0.57, 95% CI 0.38 to 0.86, respectively) decreases the number of fractures compared to no treatment/placebo (high certainty). Denosumab or zoledronic acid (51 of 1000; RR 0.73, 95% CI 0.52 to 1.01; 55 of 1000; RR 0.79, 95% CI 0.56 to 1.11, respectively) probably slightly decreases the number of fractures; and risedronate (39 of 1000; RR 0.56, 95% CI 0.15 to 2.16) probably decreases the number of fractures compared to no treatment/placebo (moderate certainty). Pamidronate (106 of 1000; RR 1.52, 95% CI 0.75 to 3.06) probably increases the number of fractures compared to no treatment/placebo (moderate certainty). Overall survival We estimated that 920 of 1000 participants with no treatment/placebo survived overall. Evidence from the NMA (17 trials; 30,991 participants) suggests that clodronate (924 of 1000; HR 0.95, 95% CI 0.77 to 1.17), denosumab (927 of 1000; HR 0.91, 95% CI 0.69 to 1.21), ibandronate (915 of 1000; HR 1.06, 95% CI 0.83 to 1.34) and zoledronic acid (925 of 1000; HR 0.93, 95% CI 0.76 to 1.14) may result in little to no difference regarding overall survival compared to no treatment/placebo (low certainty). Additionally, we are uncertain whether pamidronate (905 of 1000; HR 1.20, 95% CI 0.81 to 1.78) decreases overall survival compared to no treatment/placebo (very low certainty). Osteonecrosis of the jaw We estimated that 1 of 1000 participants with no treatment/placebo developed osteonecrosis of the jaw. Evidence from the NMA (12 trials; 23,527 participants) suggests that denosumab (25 of 1000; RR 24.70, 95% CI 9.56 to 63.83), ibandronate (6 of 1000; RR 5.77, 95% CI 2.04 to 16.35) and zoledronic acid (9 of 1000; RR 9.41, 95% CI 3.54 to 24.99) probably increases the occurrence of osteonecrosis of the jaw compared to no treatment/placebo (moderate certainty). Additionally, clodronate (3 of 1000; RR 2.65, 95% CI 0.83 to 8.50) may increase the occurrence of osteonecrosis of the jaw compared to no treatment/placebo (low certainty). Renal impairment We estimated that 14 of 1000 participants with no treatment/placebo developed renal impairment. Evidence from the NMA (12 trials; 22,469 participants) suggests that ibandronate (28 of 1000; RR 1.98, 95% CI 1.01 to 3.88) probably increases the occurrence of renal impairment compared to no treatment/placebo (moderate certainty). Zoledronic acid (21 of 1000; RR 1.49, 95% CI 0.87 to 2.58) probably increases the occurrence of renal impairment while clodronate (12 of 1000; RR 0.88, 95% CI 0.55 to 1.39) and denosumab (11 of 1000; RR 0.80, 95% CI 0.54 to 1.19) probably results in little to no difference regarding the occurrence of renal impairment compared to no treatment/placebo (moderate certainty). AUTHORS' CONCLUSIONS: When considering bone-modifying agents for managing bone loss in women with early or locally advanced breast cancer, one has to balance between efficacy and safety. Our findings suggest that bisphosphonates (excluding alendronate and pamidronate) or denosumab compared to no treatment or placebo likely results in increased bone mineral density and reduced fracture rates. Our survival analysis that included pre and postmenopausal women showed little to no difference regarding overall survival. These treatments may lead to more adverse events. Therefore, forming an overall judgement of the best ranked bone-modifying agent is challenging. More head-to-head comparisons, especially comparing denosumab with any bisphosphonate, are needed to address gaps and validate the findings of this review.

STING inhibition alleviates bone resorption in apical periodontitis.

AIM: The goal of this study was to investigate the potential effects of an immunotherapeutic drug targeting STING to suppress the overreactive innate immune response and relieve the bone defect in apical periodontitis. METHODOLOGY: We established an apical periodontitis mouse model in Sting-/- and WT mice in vivo. The progression of apical periodontitis was analysed by micro-CT analysis and H&E staining. The expression level and localization of STING in F4/80+ cells were identified by IHC and immunofluorescence staining. RANKL in periapical tissues was tested by IHC staining. TRAP staining was used to detect osteoclasts. To clarify the effect of STING inhibitor C-176 as an immunotherapeutic drug, mice with apical periodontitis were treated with C-176 and the bone loss was identified by H&E, TRAP, RANKL staining and micro-CT. Bone marrow-derived macrophages (BMMs) were isolated from Sting-/- and WT mice and induced to osteoclasts in a lipopolysaccharide (LPS)-induced inflammatory environment in vitro. Moreover, WT BMMs were treated with C-176 to determine the effect on osteoclast differentiation by TRAP staining. The expression levels of osteoclast-related genes were tested using qRT-PCR. RESULTS: Compared to WT mice, the bone resorption and inflammatory cell infiltration were reduced in exposed Sting-/- mice. In the exposed WT group, STING was activated mainly in F4/80+ macrophages. Histological staining revealed the less osteoclasts and lower expression of osteoclast-related factor RANKL in Sting-/- mice. The treatment of the STING inhibitor C-176 in an apical periodontitis mice model alleviated inflammation progression and bone loss, similar to the effect observed in Sting-/- mice. Expression of RANKL and osteoclast number in periapical tissues were also decreased after C-176 administration. In vitro, TRAP staining showed fewer positive cells and qRT-PCR reflected decreased expression of osteoclastic marker, Src and Acp5 were detected during osteoclastic differentiation in Sting-/- and C-176 treated BMMs. CONCLUSIONS: STING was activated and was proven to be a positive factor in bone loss and osteoclastogenesis in apical periodontitis. The STING inhibitor C-176 administration could alleviate the bone loss via modulating local immune response, which provided immunotherapy to the treatment of apical periodontitis.

[Expert consensus on safety management of bone-modifying agents (2024 edition)].

Bone-modifying agents are a class of drugs that alleviate a series of bone-related events such as pain, pathologic fracture, spinal cord compression, and hypercalcemia caused by bone metastases, and currently include bisphosphonates and RANKL inhibitors. Due to the widespread use of bone-modifying agents, the adverse effects of them are gradually increasing and affecting patients' quality of life. The Breast Cancer Group, Chinese Medical Doctor Association, and the International Medical Society, Chinese Anti-Cancer Association have organized relevant experts to focus on the treatment of bone metastases of advanced malignant tumors based on evidence-based medicine, discuss the management of adverse reactions to bone-modifying agents and form the consensus. Based on the first Expert Consensus on Safety Management of Bone-modifying Agents in China, this consensus added the definition of osteonecrosis of the jaw related to bone-modifying agents, the occurrence of adverse reactions of bone-modifying drugs reported in the literature, and summarized the clinical experience of clinicians in the management of adverse reactions in practice in recent years, and ultimately, the expert group members discussed and proposed reasonable suggestions to guide clinicians in the safety management of bone-modifying agents.

Immune Modulation with RANKL Blockade through Denosumab Treatment in Patients with Cancer.

Denosumab is a fully human mAb that binds receptor activator of NFκB ligand (RANKL). It is routinely administered to patients with cancer to reduce the incidence of new bone metastasis. RANK-RANKL interactions regulate bone turnover by controlling osteoclast recruitment, development, and activity. However, these interactions also can regulate immune cells including dendritic cells and medullary thymic epithelial cells. Inhibition of the latter results in reduced thymic negative selection of T cells and could enhance the generation of tumor-specific T cells. We examined whether administering denosumab could modify modulate circulating immune cells in patients with cancer. Blood was collected from 23 patients with prostate cancer and 3 patients with renal cell carcinoma, all of whom had advanced disease and were receiving denosumab, prior to and during denosumab treatment. Using high-dimensional mass cytometry, we found that denosumab treatment by itself induced modest effects on circulating immune cell frequency and activation. We also found minimal changes in the circulating T-cell repertoire and the frequency of new thymic emigrants with denosumab treatment. However, when we stratified patients by whether they were receiving chemotherapy and/or steroids, patients receiving these concomitant treatments showed significantly greater immune modulation, including an increase in the frequency of natural killer cells early and classical monocytes later. We also saw broad induction of CTLA-4 and TIM3 expression in circulating lymphocytes and some monocyte populations. These findings suggest that denosumab treatment by itself has modest immunomodulatory effects, but when combined with conventional cancer treatments, can lead to the induction of immunologic checkpoints. See related Spotlight by Nasrollahi and Davar, p. 383.

RANK-L inhibitor as a promising agent for refractory extensive craniofacial fibrous dysplasia: A case report.

BACKGROUND: McCune-Albright syndrome is a rare disorder characterized by polyostotic fibrous dysplasia (FD), café-au-lait skin pigmentation, and endocrine dysfunction. Extensive FD in the craniofacial region can present significant challenges in terms of disease control and carries a high risk of permanent visual impairment. METHODS: We present a case of medically and surgically resistant FD that required nine optic nerve decompressions. RESULTS: The condition was ultimately controlled with the use of the denosumab agent. CONCLUSION: The case highlights the importance and potential efficacy of denosumab in resistant FD management, particularly in cases involving sensitive organs.

Temporal patterns of osteoclast formation and activity following withdrawal of RANKL inhibition.

Rebound bone loss following denosumab discontinuation is an important clinical challenge. Current treatment strategies to prevent this fail to suppress the rise and overshoot in osteoclast-mediated bone resorption. In this study, we use a murine model of denosumab treatment and discontinuation to show the temporal changes in osteoclast formation and activity during RANKL inhibition and withdrawal. We show that the cellular processes that drive the formation of osteoclasts and subsequent bone resorption following withdrawal of RANKL inhibition precede the rebound bone loss. Furthermore, a rise in serum TRAP and RANKL levels is detected before markers of bone turnover used in current clinical practice. These mechanistic advances may provide insight into a more defined window of opportunity to intervene with sequential therapy following denosumab discontinuation.

Stopping denosumab, a medication commonly used to improve bone mass by blocking formation of bone resorbing osteoclasts, leads to a rebound loss in the bone which was gained during treatment. Current strategies to prevent this bone loss fail in most cases as they are unable to prevent the rise and overshoot in bone resorption by osteoclasts. Thie stems from an incomplete understanding of how osteoclasts behave during denosumab treatment and after treatment is discontinued. We use a mouse model of this phenomenon to show how osteoclast formation and activity changes throughout this process. We show that increases in the processes that drive the formation of osteoclasts can be detected in the circulation before bone loss occurs. These findings could therefore provide insight into a targeted 'window of opportunity' to intervene and prevent the rebound bone loss following stopping denosumab in patients.

ED-71 Improves Bone Mass in Ovariectomized Rats by Inhibiting Osteoclastogenesis Through EphrinB2-EphB4-RANKL/OPG Axis.

Purpose: Estrogen deficiency is the main reason of postmenopausal osteoporosis. Eldecalcitol (ED-71) is a new active vitamin D analogue clinically used in the treatment of postmenopausal osteoporosis. We aimed to investigate whether EphrinB2-EphB4 and RANKL/RANK/OPG signaling cooperate in mediating the process of osteoporosis by ED-71. Methods: In vivo, the ovariectomized (OVX) rats were administered orally with 30 ng/kg ED-71 once a day for 8 weeks. HE staining, Masson staining and Immunofluorescence staining were used to evaluate bone mass, bone formation, osteoclastogenesis associated factors and the expression of EphrinB2, EphB4, RANKL and OPG. In vitro, H2O2 stimulation was used to simulate the cell environment in osteoporosis. Immunofluorescence, quantitative real time PCR (qRT-PCR), enzyme-linked immunosorbent assay (ELISA) and Western Blot were applied to detect the expression of EphrinB2, EphB4, RANKL and OPG. In osteoblasts, EphB4 was knocked down by EphB4 small-interfering RNA (siRNA) transfection. LY294002 (PI3K inhibitor) or ARQ092 (AKT inhibitor) was used to block PI3K/AKT pathway. An indirect co-culture system of osteoblasts and osteoclasts was established. The mRNA and protein expression of osteoclastogenes is associated factors were tested by qRT-PCR and Western Blot. Results: ED-71 increased bone mass and decreased the number of osteoclasts in OVX rats. Moreover, ED-71 promoted the expression of EphrinB2, EphB4, and decreased the RANKL/OPG ratio in osteoblasts. Osteoclastogenesis was restrained when osteoclasts were indirectly co-cultured with ED-71-treated osteoblasts. After silencing of EphB4 expression in osteoblasts, ED-71 inhibited the expression of P-PI3K and P-AKT and increased the ratio of RANKL/OPG. This reversed the inhibitory effect of ED-71 on osteoclastogenes. Therefore, in ED-71-inhibited osteoclastogenes, EphB4 is a key factor affecting the secretion of RANKL and OPG by osteoblasts. EphB4 suppressed the RANKL/OPG ratio through activating PI3K/AKT signaling in osteoblasts. Conclusion: ED-71 inhibits osteoclastogenesis through EphrinB2-EphB4-RANKL/OPG axis, improving bone mass in ovariectomized rats. PI3K/AKT pathway is involved this process.

Synthesis of Heterocyclic Ring-Fused Bisnoralcohol Derivatives as Novel Small-Molecule Antiosteoporosis Agents.

A series of heterocyclic ring-fused derivatives of bisnoralcohol (BA) were synthesized and evaluated for their inhibitory effects on RANKL-induced osteoclastogenesis. Most of these derivatives possessed potent antiosteoporosis activities in a dose-dependent manner. Among these compounds, 31 (SH442, IC50 = 0.052 µM) exhibited the highest potency, displaying 100% inhibition at 1.0 µM and 82.8% inhibition at an even lower concentration of 0.1 µM, which was much more potent than the lead compound BA (IC50 = 2.325 µM). Cytotoxicity tests suggested that the inhibitory effect of these compounds on RANKL-induced osteoclast differentiation did not result from their cytotoxicity. Mechanistic studies revealed that SH442 inhibited the expression of osteoclastogenesis-related marker genes and proteins, including TRAP, TRAF6, c-Fos, CTSK, and MMP9. Especially, SH442 could significantly attenuate bone loss of ovariectomy mouse in vivo. Therefore, these BA derivatives could be used as promising leads for the development of a new type of antiosteoporosis agent.

Design, Synthesis, and Biological Evaluation of ß-Trifluoroethoxydimethyl Selenides as Potent Antiosteoporosis Agents.

An efficient protocol for the synthesis of ß-trifluoroethoxydimethyl selenides was achieved under mild reaction conditions, and 39 compounds were prepared. All compounds were evaluated for their abilities to inhibit RANKL-induced osteoclastogenesis, compound 4aa exhibited the most potent activity. Further investigations revealed that 4aa could inhibit F-actin ring generation, bone resorption, and osteoclast-specific gene expression in vitro. Western blot analyses demonstrated that compound 4aa abrogated the RANKL-induced mitogen-activated protein kinase and NF-kB-signaling pathways. In addition, 4aa also displayed a notable impact on the osteoblastogenesis of MC3T3-E1 preosteoblasts. In vivo experiments revealed that compound 4aa significantly ameliorated bone loss in an ovariectomized (OVX) mice model. Furthermore, the surface plasmon resonance experiment results revealed that 4aa probably bound to RANKL. Collectively, the above-mentioned findings suggested that compound 4aa as a potential RANKL inhibitor averted OVX-triggered osteoporosis by regulating the inhibition of osteoclast differentiation and stimulation of osteoblast differentiation.

Metástasis en hueso malar de tumor neuroendocrino oncocítico pulmonar / Malar bone metastasis of oncocytic neuroendocrine tumour of the lung

Las metástasis en hueso malar de tumores sólidos infraclaviculares son excepcionales. En aquellos de estirpe neuroendocrina, se debe considerar la expresión de receptores de somatostatina mediante diferentes técnicas de medicina nuclear para realizar terapias dirigidas. Se presenta un caso clínico de un varón de 66 años con neoplasia pulmonar con diferenciación oncocítica, cuyo debut es una metástasis malar de lenta evolución. Es tratado con lanreotido y ácido zolendrónico con enfermedad estable al año de seguimiento

Malar bone metastases of solid infraclavicular tumours are exceptional. Expression of somatostatin receptors should be considered in neuroendocrine strains, in order to carry out targeted therapies. We report a clinical case of a 66-year-old man with a tumour of the lung with oncocytic features, which debut is a malar metastasis of slow evolution. He is treated with Lanreotide and Zolendronic acid with stable disease at 1-year follow-up

Using agents that suppress bone remodeling to treat or prevent joint disease: quo vadis?

Treatment of osteoarthritis (OA) with antiremodeling agents has had a mixed record of results. It is likely that remodeling suppression is only effective when used in the early phases of OA, before significant progression. Animal and human studies largely bear this out. Treatment of young mice with a RANKL inhibitor suppresses bone resorption and prevents OA progression. Likewise, bisphosphonate treatments in rodents and rabbits with induced injury or inflammatory arthritis, reduced cartilage degeneration when administered preemptively, but later administration did not. The increased prevalence of OA in women after the menopause, and presence of estrogen receptors in joint tissues, suggests that treatment with estrogens or Selective Estrogen Receptor Modulators may be effective. However, in clinical trials of knee and hip, results show decreased or increased risk for OA, or no effect. Raloxifene had positive effects in animal models, but no effect in human studies. More recent potential treatments such as strontium ranelate or cathepsin-K inhibitors may be effective, but may work directly on the cartilage rather than through their well-known effects on bone. The conclusion from these studies is that anti-remodeling agents must be administered pre-emptively or in the very early stages of disease to be effective. This means that better imaging techniques or identification of early structural changes in bone that occur before progressive cartilage destruction must be developed. (AU)

Presente y futuro de los anticuerpos monoclonales en el tratamiento de la osteoporosis / Present and future of the treatment of osteoporosis with monoclonal antibodies

El mejor conocimiento de la fisiopatología ósea ha llevado a encontrar nuevas dianas terapéuticas en osteoporosis y se ha conseguido bloquear alguna de ellas con anticuerpos monoclonales. El sistema RANK-RANKL-OPG se considera el elemento efector final de los factores reguladores de la resorción ósea. El denosumab es un anticuerpo monoclonal completamente humanizado (IgG2) con una alta afinidad por el RANKL. Al unirse al RANKL mimetiza la acción de la OPG, impide la interacción RANK-RANKL, bloquea la activación de los osteoclastos e inhibe la resorción ósea. Denosumab ha demostrado en varios ensayos fase III que es un rápido, potente y seguro agente antirresortivo. Administrado por vía subcutánea cada 6 meses, aumenta la densidad mineral ósea y se acompaña de una rápida reducción de los marcadores de resorción ósea. Según los resultados del estudio FREEDOM en mujeres posmenopáusicas con osteoporosis, el tratamiento con 60mg/sc de denosumab cada 6 meses durante 3 años se acompaña de una reducción de riesgo relativo de fractura vertebral del 68% (incidencia del 2,3% en pacientes tratadas con denosumab y del 7,2% en las que recibieron placebo), de fracturas no vertebrales del 20% (incidencia de 6,5% con denosumab frente al 8% con placebo) y de fracturas de cadera del 40% (incidencia de 0,7% con denosumab frente a un 1,2% con placebo). Es un fármaco seguro, con una frecuencia de efectos adversos similares al placebo, aunque parece existir un aumento de efectos adversos cutáneos. Se está investigando el bloqueo mediante anticuerpos monoclonales de antagonistas de la vía de señalización Wnt/β-catenina, y en concreto la utilidad de los anticuerpos antiesclerostina y de los anticuerpos anti-Dkk. Este bloqueo de la vía Wnt/β-catenina tendría una acción anabólica sobre el remodelado óseo (AU)

An improved knowledge of bone physiopathology has led to new therapeutic targets in osteoporosis, blocking some of them with monoclonal antibodies. The RANK-RANKL-OPG system is considered the final effector pathway of bone resorption regulating factors. Denosumab is a humanized monoclonal antibody (IgG2) with a high affinity for RANKL. Upon binding RANKL it simulates the action of OPG, impedes the interaction between RANK-RANKL, blocks osteoclast activation and inhibits bone resorption. Denosumab has shown, in several phase III trials, to be a rapid, potent and safe antiresorptive agent. When administered subcutaneously every 6 months, it increases bone mineral density and is accompanied by a fast reduction in bone remodeling markers. According to the FREEDOM trial, in postmenopausal women with osteoporosis, treatment with 60mg/sc of denosumab every 6 months for 3 years is accompanied by a reduction in the relative risk of fracture of 68% (incidence 2,3% in patients treated with denosumab and 7,2% in the placebo group), 20% in the case of non vertebral fractures (incidence 6,5% with denosumab vs. 8% with placebo) and 40% in hip fractures (incidence 0,7% with denosumab vs. 1,2% with placebo). It is a safe drug, with a frequency of adverse events similar to placebo, although an increased risk for skin reactions. Research is being done into blocking the Wnt/β-catenin pathway with monoclonal antibodies, specifically antisclerostin antibodies and anti-Dkk antibodies. This block of the Wnt/β-catenin pathway would have an anabolic action on bone remodeling (AU)

RANKL inhibition: a promising novel strategy for breast cancer treatment

The cytokine RANKL and its receptor RANK, key proteins in bone remodelling and bone metastasis, are essential for mammary gland development in mice. RANK absence or overexpression results in a lactation defect and a non-functional mammary gland. RANKL signalling mediates progesterone-induced proliferation and expansion of the stem cell compartment in the mouse mammary gland. RANK overexpressing mammary epithelial acini show hallmarks of transformation in a RANKL-dependent manner. Complementary gain- and loss-of-function approaches (RANK transgenic and knock-out mouse models and pharmacological RANKL inhibition) define a direct contribution of this pathway to progestin-driven mammary cancer. Moreover, decreased RANKL signalling attenuates preneoplasic lesions and lung metastasis in the spontaneous model of mammary tumorigenesis MMTV-neu, suggesting that RANK pathway promotes mammary tumorigenesis and metastasis in a wider tumour spectrum and beyond its established role in bone metastasis. In this review, we summarise the role of the RANKL pathway in mammary gland development, breast cancer and metastasis, and discuss the potential application of RANKL inhibition for breast cancer treatment (AU)

The role of Th17 and regulatory T cells (TREGs) in immunomodulation of experimental periapical lesions / Papel das células Th17 e T reguladoras (TREGs) na imunomodulação de lesões periapicais experimentais

A patogênese das lesões periapicais é determinada pelo equilíbrio entre a resposta imune pró-inflamatória do hospedeiro e a resposta anti-inflamatória/reparo. Diferentes subtipos de linfócitos e seus produtos têm sido implicados na patogênese dessas lesões, tais como as células T reguladoras (Tregs) e Th17. Enquanto as Tregs parecem ser potenciais agentes imuno-reguladores, Th17 parece estar associada à maior severidade da doença. Neste estudo, foram investigados o envolvimento de Tregs e Th17, além do impacto de diferentes terapias na progressão de lesões periapicais experimentais. Para isso, lesões periapicais foram induzidas (exposição pulpar e inoculação bacteriana) em camundongos C57BL/6, IL- 17KO e CCR4KO tratados com anticorpos anti-GITR (inibe a função de Treg) ou com CCL22p, partículas de ácido poliláctico-glicólico (induz a migração de Tregs). Além disso, os camundongos WT foram tratados com anti-RANKL utilizando protocolos contínuos ou intermitentes, ou com anti-TNF como controle. Posteriormente, analisou-se o fluxo e fenótipo de Tregs e Th17, perda óssea periapical e expressão de citocinas inflamatórias/imunológicas e marcadores de reparo (RealTimePCRarray, ELISA). A inibição de Tregs (depleção de CCR4 ou terapia anti-GITR), aumentou significantemente a severidade da lesão, associada com o aumento da expressão de citocinas pró-inflamatórias, Th1, Th17 e mediadores de destruição tecidual em paralelo com a diminuição dos marcadores de Treg e de reparo. A liberação local de CCL22 no canal radicular resultou na migração de Treg, dependente de CCR4, levando à modulação da lesão periapical, associada com a diminuição da expressão de marcadores pró-inflamatórios e de destruição tecidual em paralelo com o aumento dos marcadores de Tregs e de reparo. O tratamento anti-RANKL impediu o desenvolvimento da lesão, mas provocou uma resposta inflamatória contínua caracterizada pela elevada expressão de citocinas pró-inflamatórias e mediadores de destruição tecidual e diminuição da expressão dos marcadores de Tregs e de reparo. Este tratamento levou à recidiva da lesão e foi associado com o aumento da razão células TCD4 efetoras/supressoras e com o perfil de expressão gênica de lesões ativas. O tratamento anti-TNF limitou a progressão das lesões e não promoveu sua recidiva após o término da terapia, estando associado à resposta do hospedeiro atenuada. Por fim, a ausência de IL-17 resultou em lesões menos severas, associadas com o aumento da expressão de marcadores de reparo e citocinas anti-inflamatórias, em paralelo com a menor expressão de marcadores de destruição tecidual e citocinas pró-inflamatórias. De fato, observou-se menor concentração de osteoclastos, neutrófilos e células inflamatórias, na ausência de IL-17. Conclui-se, portanto, que as células T reguladoras são essenciais no controle da lesão periapical, enquanto as células Th17 acentuam a severidade dessas lesões. Comparando com outras estratégias clínicas, tais como a terapia anti-RANKL que perpetua a resposta inflamatória do hospedeiro levando a recidiva da lesão, a quimioatração de Treg bem como a inibição de Th17 podem ser estratégias promissoras para o manejo clínico das lesões periapicais.(AU)

The pathogenesis of periapical lesions is determined by the balance between host proinflammatory immune response and counteracting anti-inflammatory and reparative responses. In this context, different subtypes of lymphocytes and their products have been implicated in periapical lesion pathogenesis, such as regulatory T cells (Tregs) and Th17. While Tregs has been demonstrated as potential immunoregulatory agents, Th17 has been correlated with greater severity of disease. In this study, we investigated (in a cause-and-effect manner) the involvement of Tregs and Th17, besides the impact of different therapies in the progression of experimental periapical lesions. With this aim, periapical lesions were induced (pulp exposure and bacterial inoculation) in C57Bl/6 (wild-type), IL-17KO and CCR4KO mice and treated with anti­glucocorticoid-induced TNF receptor family regulated gene (anti-GITR) to inhibit Treg function or alternatively with CCL22-releasing, poly lactic-glycolic acid particles to induce site-specific migration of Tregs. Furthermore, WT mice were treated with anti-RANKL using continuous or intermittent protocols, and with anti-TNF therapy as a control. After treatment, lesions were analyzed for Treg or Th17 influx and phenotype, overall periapical bone loss, and inflammatory/immunologic and wound healing marker expression (RealTimePCRarray, ELISA). Treg inhibition by anti-GITR or CCR4 depletion results in a significant increase in periapical lesion severity, associated with upregulation of proinflammatory, Th1, Th17, and tissue destruction markers in parallel with decreased Treg and healing marker expression. The local release of CCL22 in the root canal system resulted in the promotion of Treg migration in a CCR4-dependent manner, leading to the arrest of periapical lesion progression, associated with down regulation of proinflammatory and tissue destruction markers in parallel with increased Treg and healing marker expression. Anti-RANKL treatment arrested lesion development, but prompted a continuous inflammatory response characterized by unremitting elevated expression of proinflammatory cytokines and tissue destructive mediators, and decreased expression of Tregs and wound healing markers levels. This treatment triggered lesion development relapse and was associated with high TCD4 effector/suppressor cells ratio and active lesions gene expression signature. Anti-TNF treatment limits lesions progression and does not drives lesions relapse upon cessation, being associated with attenuated host response. Finally, the absence of IL-17 results in a significant decrease in periapical lesions severity, associated with upregulation of healing markers and antiinflammatory cytokines, in parallel with decreased expression of tissue destruction markers and proinflammatory cytokines. Indeed, histomorphometric analysis showed lower concentration of osteoclasts, neutrophils and mononuclear cells in periapical lesions without IL-17. Therefore, we concluded that regulatory T cells are essential in the control of apical periodontitis, while Th17 cells accentuate the lesions severity. Compared with other clinical strategies, such as anti-RANKL therapy, which perpetuates the host inflammatory response prompting lesion relapse, chemoattraction of Treg as well as inhibition of Th17 may be promising strategies for the clinical management of periapical lesions.(AU)