Receptor Activator Of Nuclear Factor kappa-B Ligand Research Articles

OPG/RANK/RANKL Axis in Egyptian Children With Acute Lymphoblastic Leukemia After Maintenance Therapy: Relationship to Bone Mineral and Vitamin D Status.

Policies to maximize peak bone mass in survivor's children of acute lymphoblastic leukemia (ALL) have been recognized as a priority area for research. The present study aimed to evaluate the relationship between osteoprotegerin (OPG)/receptor activator of nuclear factor kappa-B (RANK)/RANK ligand (RANKL) axis, vitamin D status, and serum magnesium in ALL survivors. Sixty ALL survivors treated with chemotherapy and 60 age and sex-matched controls were included. Vitamin D and parathyroid hormone, RANK, RANKL, and OPG levels were immunoassayed, in addition to serum calcium, phosphorus, magnesium levels, and alkaline phosphatase activity assessment. Furthermore, standard anthropometric measurement, history of fractures since treatment and clinical assessment were recorded. History of bone fractures after the start of therapy was detected in 17 ALL subjects (28.33%). Significantly lower vitamin D, magnesium, calcium, and OPG levels, meanwhile, significantly higher serum parathyroid hormone, RANK, and RANKL levels were detected in survivors compared with the control group. Vitamin D level was significantly positively correlated with magnesium, calcium, and OPG levels. Meanwhile, negatively correlated with RANK and RANKL levels. ALL survivors had a high prevalence of impaired vitamin D status, decreased Mg, and altered OPG/RANK/RANKL axis with impaired bone remodeling. The results herein may open the door for new interventional actions in ALL survivors to protect against bone resorption.

Effects of Co-exposure to Fluoride and Arsenic on TRAF-6 Signaling and NF-κB Pathway ofBoneMetabolism.

Little is known about the combined effect of fluoride (F)and arsenic (As) on bone metabolism. This study aims to explore the effect of co-exposure to F and As on the expressions of TNF receptor-associated factor 6 (TRAF-6), nuclear factor-kappa B (NF-κB), and the related factors in cell and animal experiments. With the rats exposed to different doses of F, As, and combined F-As, we found that F exposure doses were positively correlated with the protein expression of receptor activator of nuclear factor-kappa B ligand (RANKL), receptor activator of nuclear factor-kappa B (RANK), TRAF-6, NF-κB, and nuclear factor of activated T cells (NFAT-c1) (P < 0.001). As exposure doses were negatively correlated with RANK, TRAF-6, NF-κB, and NFAT-c1 (P < 0.001). The effect of F and As interaction on the protein expression of RANKL, TRAF-6, NF-κB, and NFAT-c1 was significant in bone tissue (P < 0.05). In the cellular experiment, F could promote the mRNA expression of RANK, TRAF-6, and NFAT-c1. A higher concentration of As could inhibit the mRNA expression of Tartrate-resistant acid phosphatase (TRAP), RANK, TRAF-6, and NFAT-c1. The effect of F and As interaction on the mRNA expression of TRAP, RANK, TRAF-6, and NFATc1 in osteoclasts was significant (P < 0.001). In conclusion, the expression of TRAF-6 and NF-κB pathway was affected by F and As co-exposure in osteogenic differentiation, and As could antagonize the promoting effect of F on the expression of TRAF-6, TRAP, RANKL, RANK, NF-κB, and NFAT-c1 in these exposure levels. These results could provide a scientific basis for understanding the interaction of F and As in bone formation.

Assessment of Bone Disease in Multiple Myeloma Patients After Autologous Stem Cell Transplant

Background : Detection of lytic bone lesions is crucial in the workup for multiple myeloma (MM) and very often dictates the decision to start treatment. Modern imaging techniques such as MRI, PET, and CT offer superior detection of myeloma bone disease and extramedullary manifestations of plasma cell dyscrasias. Autologous stem cell transplant (ASCT) is regarded as frontline therapy in candidate patients. Recent advances in understanding of myeloma bone disease showed that the receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG) system plays a key role in this regard. Objectives : to assess the response of bone disease in patients with multiple myeloma using whole body low dose CT (WBLD CT) scan after different modalities of treatment including autologous stem cell transplant. Patients and method : This is a prospective cohort study in which patients with multiple myeloma had baseline WBLD CT scan with basic evaluation. They were then received induction chemotherapy with and then grouped into two groups according to the modality of consolidation (ASCT vs no ASCT). Both groups had second WBLD CT and were compared for the osteolytic lesions concerning size and site. Results : 20 patients were included in the study (12 males, 8 females), 8 treated with chemotherapeutic protocols (mainly bortezomib based) (group A) while 12 patients underwent ASCT during their course of treatment (group B). The improved score was found only in two patients, one in each group. Conclusion : myeloma bone disease needs to be assessed initially and promptly prevented and treated since it increases morbidity and mortality. Using newer imaging modalities like WBLD CT, MRI, PET scan is encouraged over conventional X ray skeletal survey.

Tripeptide IRW (Ile-Arg-Trp) as a Potential Nutraceutical Intervention in Osteoporosis.

Bone health is an important medical concern in rapidly aging demographics worldwide. Excessive bone resorption, due to enhanced activity of osteoclasts, is a major underlying cause of bone disorders such as osteoporosis. Inflammation and oxidative stress are key factors contributing to increased osteoclastic activity. Like increased activity of osteoclasts, depletion of osteoblasts also contributes to weakened structural integrity of bone. Considering the epidemiology of bone disorders and aging demographics there is a substantial need for novel bone health therapeutics. IRW (Ile-Arg-Trp), an egg-derived tripeptide, exhibits a spectrum of pharmacological activity. In our recent work, we have shown that IRW inhibits osteoclastogenesis and promotes osteogenesis in the mouse macrophage RAW 264.7 and MC3T3-E1 cells. IRW treatment (25 and 50 μM) significantly inhibited osteoclastogenesis-associated factors [TRAF6 (TNF Receptor Associated Factor 6), Fos Proto-Oncogene (c-Fos), Nuclear Factor of Activated T Cells 1 (NFATc1), and cathepsin K] and upregulated osteogenesis-associated factors [RUNX2 (Runt-related transcription factor 2) and RANKL (Receptor activator of nuclear factor kappa-B ligand)] in the two cell lines. Currently, we are conducting studies to analyze the impact of IRW on Angiotensin II (Ang II)-induced stress in vitro and in vivo. In summary, our recent work presents the ability of IRW to prevent LPS-induced inflammatory bone resorption and activation of osteogenesis activity via multiple signaling pathways.

Modelling stromal compartments to recapitulate the ameloblastoma tumour microenvironment

Tumour development and progression is dependent upon tumour cell interaction with the tissue stroma. Bioengineering the tumour-stroma microenvironment (TME) into 3D biomimetic models is crucial to gain insight into tumour cell development and progression pathways and identify therapeutic targets. Ameloblastoma is a benign but locally aggressive epithelial odontogenic neoplasm that mainly occurs in the jawbone and can cause significant morbidity and sometimes death. The molecular mechanisms for ameloblastoma progression are poorly understood. A spatial model recapitulating the tumour and stroma was engineered to show that without a relevant stromal population, tumour invasion is quantitatively decreased. Where a relevant stroma was engineered in dense collagen populated by gingival fibroblasts, enhanced receptor activator of nuclear factor kappa-B ligand (RANKL) expression was observed and histopathological properties, including ameloblastoma tumour islands, developed and were quantified. Using human osteoblasts (bone stroma) further enhanced the biomimicry of ameloblastoma histopathological phenotypes. This work demonstrates the importance of the two key stromal populations, osteoblasts, and gingival fibroblasts, for accurate 3D biomimetic ameloblastoma modelling.

Evaluation of Receptor Activator of Nuclear Factor Kappa B Ligand, Osteoprotegerin, Osteopontin, and Tumor Necrosis Factor Alpha on Chronic Apical Periodontitis in Smokers

IntroductionSmoking can be considered a risk factor for chronic apical periodontitis (CAP). This study compared the immunoexpression of biomarkers receptor activator of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG), osteopontin (OPN), and tumor necrosis factor alpha (TNF-α) in CAP in smokers and nonsmokers. MethodsTwelve smokers and 12 nonsmokers diagnosed with CAP and indicated for tooth extraction were selected. Exclusion factors were teeth with a diagnosis of root fracture, previous endodontic treatment, or endoperiodontal injury, in addition to individuals with systemic diseases, under 18 years of age, users of anti-inflammatory and/or antibiotics in the last 3 months, and drug users. Specimens were processed for histopathologic and immunohistochemical analysis. ResultsQualitative analysis of RANKL expression showed 66.66% weak/moderate and 33.33% strong in smokers and 100% weak/moderate in nonsmokers. OPG and OPN expressions were 100% negative to focal in the smoker group and 50% negative to focal and 50% weak/moderate in the nonsmoker group. TNF-α was 25% negative to focal and 75% weak/moderate in the smoker group and 33.33% negative to focal and 66.66% weak/moderate in the nonsmoker group. Quantitative analysis of the data using the Mann-Whitney U test showed that there was a significant difference in the immunoexpression of RANKL (P < .05), OPG (P < .05), and OPN (P < .05), but there was no statistical difference in the immunoexpression of TNF-α (P > .05) between the 2 groups. ConclusionsThese findings suggest that smoking is capable of altering the inflammatory response, influencing the evolution of CAP.

Evaluation of culture conditions for osteoclastogenesis in RAW264.7 cells.

Osteoclasts are the only multinucleated cells in vivo responsible for bone resorption and are vital for regulating bone remodeling and maintaining bone mass. The RAW264.7 cell line is widely used to study osteoclastic differentiation and biological molecular mechanism. However, protocols for inducing osteoclast formation in RAW264.7 cells vary considerably between laboratories, hindering the replication of results. Therefore, we tested the influence of culture conditions on osteoclast differentiation, including cell density and receptor activator of nuclear factor kappa-B ligand (RANKL) concentrations with or without macrophage colony-stimulating factors (M-CSF). Tartrate-resistant acid phosphatase (TRAP) staining was used to detect the morphology of osteoclasts. qPCR was used to detect gene expression of osteoclast-specific gene marker cathepsin K (CTSK), osteoclast transcription factors c-Fos and nuclear factor of activated T cells, cytoplasmic 1 (NFATc1). The bone resorption function was evaluated by a scanning electron microscope (SEM). RANKL treatment increased multinucleated osteoclasts formation and increased CTSK, c-Fos and NFATc1 gene expression. Compared with RANKL treatment, M-CSF significantly decreased multinucleated osteoclasts formation, reduced CTSK gene expression and had little effect on c-Fos and NFATc1 gene expression. Concerning bone resorption activity, RANKL treatment increased bone resorption pits on bovine bone slices. Significantly higher levels of osteoclastogenesis were observed with RAW264.7-cell density of 2×104 cells/well in 24-well plates. Our results suggest that the addition of 50 ng/ml M-CSF has no positive effect on osteoclastogenesis. RANKL treatment and cell density contribute to osteoclast formation, and the optimal conditions are beneficial when exploring osteoclast function and mechanism.

Chinese Herbal Medicine 'Diwu' Suppresses Myeloma Bone Disease Via ERK/MAPK Signaling Pathway By Targeting CCL3

Background： Multiple myeloma (MM) associated bone disease (MBD) is largely dependent on the bone marrow microenvironment (BME). The cross-talk between MM cells, bone marrow mesenchymal cells and myeloid progenitors affects the osteoclastogenesis. Traditional Chinese medicine 'Diwu' is effective for patients with arthritis and inflammation, also occasionally uses as one ingredient treating MM. But the effects of 'Diwu' in MBD are largely unknown. The aim of this study is to investigate the role and underlying mechanism of 'Diwu' in regulating BME and osteoclast differentiation. Methods： Myeloma cell lines RPMI-8226, NCI-H929, U266 and MM1 were treated with 'Diwu' extract. Killing effects was evaluated by the half inhibitory dose (IC50) value and proportion of apoptotic MM cells. RNA-seq was applied in 'Diwu' treated myeloma cells to identify MBD associated signaling pathways. RPMI-8226 was co-cultured with mesenchymal stromal cell (MSC) line HS5. Human monocyte cell line THP-1 was treated with CCL3 and M-CSF to form osteoclasts determined by tartrate-resistant acid phosphatase (TRACP) staining. Primary human MSCs were cultured into osteogenic or adipogenic differentiation, determined by alizarin red staining and oil red staining, respectively. RNAi technology was applied to knock down CCL3. The expression of osteoclast-specific genes TRACP and MAPK pathway-related genes was tested using quantitative real-time PCR. Phosphorylation and expression of MEK1, ERK, FOS were measured by Western Blot. The myeloma-bearing NOD/SCID mice were treated with intragastric 'Diwu'. Serum C-terminal telopeptide of type 1 collagen (CTXI) and propeptide of type I procollagen (PINP) was tested by ELISA. The tibia of mice was fixed and stained to analyze the differentiation and maturation of osteoblasts and osteoclasts. Micro-CT was used for bone destruction measurement. Results： 'Diwu' inhibited MM cells proliferation (IC50, 29.22-364.7μg/ml) in a dose-dependent manner and promoted apoptosis by upregulating protein expression of CASP3, BCL2. 'Diwu' decreased the secretion of chemokine (C-C motif) ligand 3 (CCL3) and receptor activator of nuclear factor-kappa B ligand (RANKL) in myeloma-MSC co-cultured system by diminishing the direct attachment and interaction of these two cells. The mRNA and protein levels of osteoclast-specific genes such as TRACP, and the phosphorylation and expression of MEK1, ERK, FOS in osteoclast were all reduced after 'Diwu' treatment. We observed improved osteogenic activation rather than lipid formation in hMSC differentiation. The level of TRACP isoform 5b (TRACP-5b) was significantly downregulated in mouse serum after 'Diwu' treatment for 14 days. Conclusions: Altogether, our results demonstrated that effective extract of Chinese herbal medicine 'Diwu' could simultaneously inhibit myeloma cells and suppress osteoclast formation, indicating an important role of 'Diwu' in regulating BM microenvironment. It is possible to translate 'Diwu' into clinical application as an oral agent for myeloma bone disease. Key words： 'Diwu'; Myeloma Bone Disease; Bone Marrow Microenvironment; CCL3; ERK/MAPK

Factor VIII and Von Willebrand Factor Inhibit Osteoclastogenesis in a Humanized Cell Culture Model

Background: Patients with hemophilia A suffer from decreased bone mineral density. It is unknown whether the absence of factor VIII (FVIII) might play a direct causative role. Aim: To investigate the effect of recombinant FVIII (rFVIII, simoctocog alfa) and von Willebrand factor (vWF) on osteoclastogenesis in a humanized two-dimensional (2D) cell culture model. Simoctocog alfa is a rFVIII product manufactured using a human cell line without chemical modification or protein fusion. Methods: CD14+ monocytes from male donors were cultured for 14 days with 10% human serum under the influence of macrophage-colony stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL), in the presence and absence of osteoprotegerin (OPG). On days 0, 4, 7 and 11 cells were incubated with 10 IU/ml rFVIII, 10 IU/ml vWF or 10 IU/ml rFVIII/vWF. Tartrate-resistant acid phosphatase (TRAP) activity was measured in the supernatant on day 14 using a colorimetric assay with p-nitrophenylphosphate (pNPP) as substrate. Data were normalized to the condition with mCSF/RANKL alone, or mCSF/RANKL/OPG. Quantitative PCR of cathepsin K (CATK) and nuclear factor of activated T cells (NFATc) was performed. Results: In the absence of OPG, osteoclastogenesis was significantly reduced by the addition of vWF (p<0.001) or the combination rFVIII/VWF (p<0.001). In the presence of OPG, addition of vWF (p<0.001), rFVIII (p<0.05), or the combination rFVIII/VWF (p<0.01) significantly reduced osteoclastogenesis. Similar results were obtained for analyses of CATK and NFATc gene expression. Conclusion: We demonstrated an inhibitory effect of rFVIII, vWF and rFVIII/VWF on osteoclastogenesis in an in vitro model using human serum as opposed to the more commonly used fetal calf serum. As osteoclastogenesis has a high donor-to-donor variation, we are currently testing more donors to see if dependencies on age or blood type exist. These data provide a first insight into mechanisms underlying the reduced bone mass observed in patients with hemophilia A. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Bone resorption during therapy with denosumab in patients with rheumatoid arthritis, positive for the main immunological markers

Objective. Inflammation in rheumatoid arthritis (RA) leads to the development of local and generalized bone loss. Rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibodies (ACCP) are believed to play a negative role in the radiological progression of RA. The use of such antiresorptive therapy as denosumab – monoclonal antibodies to RANKL (receptor activator of nuclear factor kappa-B ligand), reduces the activity of osteoclasts, increases bone mineral density (BMD), and also potentially affects the erosive process at RA. The aim of the study is to evaluate the effect of denosumab therapy on BMD and erosion count in patients with RA and osteoporosis (OP) in consideration of the positivity in the RF and ACCP in serum and the baseline RA activity. Materials and methods. The 12-month prospective study of the efficacy of denosumab therapy (60 mg subcutaneously every 6 months) in patients with RA and OP included 66 postmenopausal women; age – 59.4±7.5 years, duration of RA – 17.8±10.6 years, RF-positive – 47 (72%) patients, ACCP-positive – 48 (74%) patients. At baseline and after 12 months, dual-energy X-ray absorptiometry was performed with an assessment of BMD in the lumbar spine (L1– L4), proximal femur (hip neck and total hip), distal forearm; X-ray of the hands and distal parts of the feet in direct projection, followed by assessment of erosive-destructive changes according to the Sharp/van der Heijde method. Results. A significant increase in BMD was established in all studied sites of the skeleton despite the positivity of the RF and ACCP (for the hip neck p=0.05), while a significant increase in BMD in the RF- and ACCP-negative group was detected only in L1–L4 site. The progression of the increase in erosion count was noted in the RF- and ACCP-positive group while in the RF- and ACCP-negative group this indicator did not change. Regardless of the baseline activity of RA (by DAS28 (Disease Activity Score 28)) the BMD of most parts of the skeleton were stabilized. In patients with moderate RA activity, BMD increased significantly in L1–L4 in both groups: RF- and ACCP-positive and -negative , as well as in the total hip – in RF- and ACCP-positive group. The dynamics of the erosion count in RA patients did not depend on the baseline degree of DAS28 activity, no significant changes were detected in the analyzed groups. Conclusions. RF and ACCP positivity in serum in patients with RA and OP treated with denosumab did not have a negative effect on the dynamics of BMD, while the number of erosions increased. The baseline RA activity level did not affect the dynamics of the erosion count and the dynamics of BMD in most subgroups – BMD levels have been increased or stabilized.

Histological and Biochemical Analysis after Posterior Mandibular Displacement in Rats.

The present study aimed to investigate any biochemical and histological changes of the rat condyle and mandible in animals that had sustained mandibular growth restriction. Seventy-two male Wistar rats were divided into two equal groups, experimental and control. Each group consisted of three equal subgroups. The animals were sacrificed 30, 60, and 90 days after the start of the experiment. Blood samples were collected from the eye, and the osteoprotegerin (OPG), Receptor Activator of Nuclear Factor Kappa B Ligand (RANKL), and Macrophage Colony-Stimulating factor (MCSF)concentrations were measured by using enzyme-linked immunosorbent assay (ELISA) kits. A histological analysis was performed on the mandibular condyles. The blood serum values of OPG, RANKL, and MCSF did not exhibit any statistically significant difference between groups or subgroups. However, significant histological changes became evident after a histomorphometric condylar examination was performed. The Bone Surface/Total Surface ratio appeared reduced in the anterior and posterior regions of the condyle. In addition, the Posterior Condylar Cartilage Thickness was measured and determined to be significantly diminished. The present intervention that employed orthodontic/orthopedic devices did not prove to have any significant effect on the circulating proteins under study. Posterior displacement of the mandible may culminate only in local histological alterations in condylar cartilage thickness and its osseous microarchitecture.

Ceritinib (LDK378) prevents bone loss via suppressing Akt and NF-κB-induced osteoclast formation.

Ceritinib is used for the treatment of patients with anaplastic lymphoma kinase (ALK)-rearranged non-small cell lung cancer (NSCLC), who are at the risk of developing bone metastasis. During bone metastasis, tumor cells release factors that induce osteoclast formation, resulting in osteolysis. However, the effect of ceritinib on osteoclast formation remains unclear. Osteoclastogenesis was induced to assess the effect of ceritinib on osteoclast formation and osteoclast-specific gene expression. Western blotting was used to examine the molecular mechanisms underlying the effect of ceritinib on osteoclast differentiation. An in vivo ovariectomized mouse model was established to validate the effect of ceritinib in suppressing osteoclast formation and preventing bone loss. The differentiation of osteoclasts and the expression of osteoclast-specific genes were inhibited upon ceritinib stimulation. Ceritinib suppressed Akt and p65 phosphorylation during the receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis. The administration of ceritinib to ovariectomized mice ameliorated trabecular bone loss by inhibiting osteoclast formation. Ceritinib is beneficial in preventing bone loss by suppressing osteoclastic Akt and nuclear factor κB (NF-κB) signaling.

Roles of osteoprotegerin in endocrine and metabolic disorders through receptor activator of nuclear factor kappa-B ligand/receptor activator of nuclear factor kappa-B signaling.

Endocrine and metabolic diseases show increasing incidence and high treatment costs worldwide. Due to the complexity of their etiology and mechanism, therapeutic strategies are still lacking. Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor superfamily, appears to be a potential candidate for the treatment of these diseases. Studies based on clinical analysis and rodent animal models reveal the roles of OPG in various endocrine and metabolic processes or disorders, such as bone remodeling, vascular calcification, and β-cell proliferation, through the receptor activator of nuclear factor kappa-B ligand (RANKL) and the receptor activator of NF-κB (RANK). Thus, in this review, we mainly focus on relevant diseases, including osteoporosis, cardiovascular disease (CVD), diabetes, and gestational diabetes mellitus (GDM), to summarize the effects of the RANKL/RANK/OPG system in endocrine and metabolic tissues and diseases, thereby providing a comprehensive insight into OPG as a potential drug for endocrine and metabolic diseases.

Substrate stiffness engineered to replicate disease conditions influence senescence and fibrotic responses in primary lung fibroblasts.

In fibrosis remodelling of ECM leads to changes in composition and stiffness. Such changes can have a major impact on cell functions including proliferation, secretory profile and differentiation. Several studies have reported that fibrosis is characterised by increased senescence and accumulating evidence suggests that changes to the ECM including altered composition and increased stiffness may contribute to premature cellular senescence. This study investigated if increased stiffness could modulate markers of senescence and/or fibrosis in primary human lung fibroblasts. Using hydrogels representing stiffnesses that fall within healthy and fibrotic ranges, we cultured primary fibroblasts from non-diseased lung tissue on top of these hydrogels for up to 7days before assessing senescence and fibrosis markers. Fibroblasts cultured on stiffer (±15kPa) hydrogels showed higher Yes-associated protein-1 (YAP) nuclear translocation compared to soft hydrogels. When looking at senescence-associated proteins we also found higher secretion of receptor activator of nuclear factor kappa-B ligand (RANKL) but no change in transforming growth factor-β1 (TGF-β1) or connective tissue growth factor (CTGF) expression and higher decorin protein deposition on stiffer matrices. With respect to genes associated with fibrosis, fibroblasts on stiffer hydrogels compared to soft had higher expression of smooth muscle alpha (α)-2 actin (ACTA2), collagen (COL) 1A1 and fibulin-1 (Fbln1) and higher Fbln1 protein deposition after 7days. Our results show that exposure of lung fibroblasts to fibrotic stiffness activates genes and secreted factors that are part of fibrotic responses and part of the Senescence-associated secretory phenotype (SASP). This overlap may contribute to the creation of a feedback loop whereby fibroblasts create a perpetuating cycle reinforcing progression of a fibrotic response.

Salivary Gene Expression of RANK, RANKL, and OPG in Type 1 Diabetes Mellitus and Periodontal Disease Patients.

The relationship between type 1 diabetes mellitus (T1DM) and periodontal disease may exhibit by the alteration of bone metabolism. However, evidence for this relationship is scarce and inconclusive. Thus, the aims of the present study were to investigate salivary receptor activator of nuclear factor kappa-β (RANK), receptor activator of nuclear factor kappa-β ligand (RANKL), osteoprotegerin (OPG) gene expression and the RANKL:OPG ratio in T1DM and non-T1DM. Secondary objective was to determine the relationships of RANK, RANKL and OPG gene expression to clinical parameters of T1DM and periodontal disease. Twenty patients with T1DM and twenty age-matched non-T1DM were recruited. Clinical periodontal parameters were measured. Total RNA was isolated from non-stimulated saliva, and the relative gene expressions of RANK, RANKL, OPG and RANKL:OPG ratio were determined by quantitative real-time polymerase chain reaction. The T1DM group had significantly higher mean periodontal parameters than the non-T1DM group, while the mean plaque scores of both groups were not significantly different. There was a trend of higher relative gene expression of RANK, RANKL, and the RANKL:OPG ratio and lower expression of OPG in T1DM group but no statistic significant different when compared to non-T1DM. In the T1DM group, RANKL:OPG correlated with the percentage of bleeding sites, whereas RANK, RANKL, and HbA1c levels correlated with pocket depth. Bone metabolisms demonstrating by decreased OPG gene expression and upregulated of RANK, RANKL, RANKL:OPG with higher pocket depth and bleeding in T1DM may play an important role in periodontal destruction in T1DM.

ODP564 Hypercalcemia in the Setting of HTLV-1 Infection and Normal PTHrP Levels

Abstract A 53 year old male with history of HTLV-1 infection associated myelopathy but with unknown mode of transmission, presented with acute on chronic bilateral lower extremity weakness and numbness with no other deficits. Examination revealed decreased strength (grade 1/5) in lower extremities with normal bulk, tone and sensations. Initial blood work revealed hypercalcemia with corrected Calcium of 16.2mg/dl(8.5-11.5), Phosphorus of 2.7mg/dl (2.5- 4.5) and Alkaline Phosphatase of 126mg/dl(20-140). Workup for hypercalcemia revealed Parathyroid hormone (PTH) level of 14pg/ml (10-65), 25 hydroxy vitamin D at 19.6 ng/ml(30-100), 1,25 dihydroxy vitamin D at 6.7pg/ml(19.9-79.3) and TSH of 1.265 microIU/ml(0.5-5). The Parathyroid hormone related protein(PTHrP) level was low at &amp;lt; 2pmol/L while Lactate Dehydrogenase (LDH) was 433U/L(100-220). Urine calcium creatinine ratio was 0.388. Reverse Transcriptase PCR was positive for HTLV-1 but negative for HTLV-2. Smudge cells and atypical lymphocytes were noted on peripheral smear. Imaging revealed generalized lymphadenopathy with splenomegaly but no spinal cord compression. Flow cytometry showed 7.8% atypical helper T cells, positive for CD3, CD4, CD5 and CD45. Clonal T cell receptor gene rearrangements were found, suggesting an underlying T cell neoplasm. Lymph node biopsy confirmed ATLL. He received treatment with fluids, Calcitonin and Denosumab after which serum Calcium levels fell (nadir 7.7mg/dl) and then normalized. He developed another episode of hypercalcemia 5 weeks later which was treated similarly. Discussion Human T cell Lymphotropic Virus-1 (HTLV-1) is a retrovirus causing asymptomatic infections, symptomatic systemic disorders and adult T cell Leukemia and lymphoma(ATLL). HTLV-1 infections, whether in asymptomatic or symptomatic patients, and ATLL are rare but important causes of hypercalcemia and hypercalcemic crises. Individuals with ATLL have the highest incidence of hypercalcemia(50-70%) among all hematologic malignancies. Hypercalcemia is a poor prognostic factor and predicts lower overall survival. It is caused by increased bone resorption, mediated by various factors with the largest role being played by Receptor Activator of Nuclear Factor Kappa B ligand (RANKL), followed by PTHrP, Interleukins, Macrophage Inflammatory Protein 1 alpha and gp 46. RANKL expression is increased upon transactivation by the viral TAX gene product and mediates conversion of osteoclast precursors to mature osteoclasts engaging in bone resorption. PTHrP expression is variable among patients, relating to levels of the TAX gene product that transactivates the PTHrP gene promoter. Thus, a low level, like in our patient, does not rule out HTLV infection as the cause of hypercalcemia. Management of hypercalcemia is in keeping with guidelines for management of other causes of hypercalcemia but may be better responsive to monoclonal antibodies against RANKL than bisphosphonates given the role of the ligand in mediating hypercalcemia in these cases. It can also be used in the setting of poor renal function, which is commonly encountered in hypercalcemic patients. Presentation: No date and time listed

Complete abrogation of key osteoclast markers with a membrane-anchored tissue inhibitor of metalloproteinase : a novel approach in the prevention of osteoclastogenesis.

Tissue inhibitors of metalloproteinases (TIMPs) are the endogenous inhibitors of the zinc-dependent matrix metalloproteinases (MMP) and A disintegrin and metalloproteinases (ADAM) involved in extracellular matrix modulation. The present study aims to develop the TIMPs as biologics for osteoclast-related disorders. We examine the inhibitory effect of a high affinity, glycosyl-phosphatidylinositol-anchored TIMP variant named 'T1PrαTACE' on receptor activator of nuclear factor kappa-Β ligand (RANKL)-induced osteoclast differentiation. Osteoclast progenitor cells transduced with T1PrαTACE failed to form tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts or exhibit bone-resorbing activity following treatment with RANKL. At the messenger RNA level, T1PrαTACE strongly attenuated expression of key osteoclast marker genes that included TRAP, cathepsin K, osteoclast stimulatory transmembrane protein (OC-STAMP), dendritic cell-specific transmembrane protein (DC-STAMP), osteoclast-associated receptor (OSCAR), and ATPase H+-transporting V0 subunit d2 (ATP6V0D2) by blocking autoamplification of nuclear factor of activated T cells 1 (NFATc1), the osteoclastogenic transcription factor. T1PrαTACE selectively extended p44/42 mitogen-activated protein kinase activation, an action that may have interrupted terminal differentiation of osteoclasts. Inhibition studies with broad-spectrum hydroxamate inhibitors confirmed that the anti-resorptive activity of T1PrαTACE was not reliant on its metalloproteinase-inhibitory activity. T1PrαTACE disrupts the RANKL-NFATc1 signalling pathway, which leads to osteoclast dysfunction. As a novel candidate in the prevention of osteoclastogenesis, the TIMP could potentially be developed for the treatment of osteoclast-related disorders such as osteoporosis.Cite this article: Bone Joint Res2022;11(11):763-776.

What's New in Musculoskeletal Basic Science.

What's New in Musculoskeletal Basic Science.

S-Equol enhances osteoblastic bone formation and prevents bone loss through OPG/RANKL via the PI3K/Akt pathway in streptozotocin-induced diabetic rats.

This study aimed to explore whether S-Equol delays diabetes-induced osteoporosis and the molecular mechanisms underlying its therapeutic effects. Thirty-five male Sprague-Dawley rats were randomized into five groups. The diabetic osteoporosis (DOP) group and three S-Equol treatment groups were intraperitoneally injected with streptozotocin (STZ) to develop a DOP model. After the 12-week intervention, bone transformation indicators were detected using an enzyme-linked immunosorbent assay kit; bone mineral density (BMD) and bone microstructure were obtained using dual-energy X-ray absorptiometry and microCT; morphological changes in the bone tissue were investigated using HE staining; bone morphogenetic proteins were detected using immunohistochemical staining. ROS17/2.8 cells were cultured in vitro, and Cell Counting Kit-8 was used to test the protective effects of S-Equol in osteoblastic cells in a high-fat and high-glucose environment. Furthermore, the expression of osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), estrogen receptor β(ERβ), phosphorylated Akt (pAKT)/protein kinase B (AKT), and osteocalcin (OC) in bone tissue and ROS17/2.8 cells was assessed using reverse transcription polymerase chain reaction (RT-PCR) and western blotting. To determine whether ERβ and phosphatidylinositol 3' -kinase (PI3K)/AKT signaling pathways are involved in the process, LY294002 (PI3K signaling pathway inhibitor) and small interfering RNA targeting ERβ mRNA (si-ERβ) were used to verify the function of the ERβ-mediated PI3K/AKT pathway in this process. After the 12-week intervention, S-Equol enhanced BMD, improved bone microarchitecture in DOP rats (P < 0.05), and improved markers of bone metabolism (P < 0.05). In vitro, 10-6 mmol/L S-Equol was selected to significantly protect osteoblasts from high- and high-glucose environments (P < 0.05). Gene expression of OPG, ERβ, pAKT/AKT, and OC was upregulated compared to the DOP group, and RANKL was downregulated compared to the DOP group (P < 0.05) both in bone tissue and osteoblastic cells. The promotion of OPG and pAKT/AKT is mediated by LY294002 and siERβ. S-Equol binds to ERβ to regulate OPG/RANKL via the PI3K/AKT pathway and improve DOP. Our results demonstrate the potential role of S-Equol in the treatment of DOP by targeting ERβ. Thus, S-Equol may have the potential to be an adjuvant drug for treating DOP.

Lithium chloride stimulates bone formation in extraction socket repair in rats.

Previous evidence shows that lithium chloride (LiCl), a suppressor of glycogen synthase kinase-3β (GSK-3β), may enhance bone formation in several medical and dental conditions. Thus, the purpose of the current study was to assess the effects of LiCl on extraction socket repair in rats. Thirty rats were randomly assigned into a control group (administration of water; n = 15) or a LiCl group (administration of 150mg/kg of LiCl; n = 15). LiCl and water were given every other day, starting at 7days before the extraction of upper first molars until the end of each experiment period. Histological sections from five rats per group were obtained at 10, 20, and 30days post-extractions. Histometrical analysis of newly formed bone (NB) and the levels of tartrate-resistant acid phosphatase (TRAP)-stained cells were evaluated at 10, 20, and 30days post-extractions. Immunohistochemical staining for receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), bone sialoprotein (BSP), osteocalcin (OCN), and osteopontin (OPN) was assessed at 10days post-extractions. The LiCl group had a greater proportion of NB than the control group at 20days (P < 0.05). At 30days, the rate of TRAP-stained cells was lower in the LiCl group than in the control group (P < 0.05). At 10days, the LiCl group presented stronger staining for OPG, BSP, OPN, and OCN, when compared to the control group (P < 0.05). Systemic LiCl enhanced extraction socket repair, stimulated an overall increase in bone formation markers, and restricted the levels of TRAP in rats.