Receptor Activator Of Nuclear factor-κB Ligand Research Articles

Hypoparathyroidism: Musculoskeletal Manifestations Related to Parathormone Deficiency.

Hypoparathyroidism is a rare metabolic disorder that can be responsible for musculoskeletal manifestations. We present a systematic review of musculoskeletal manifestations of adult-onset nonsurgical nongenetic hypoparathyroidism. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline using the MEDLINE database, including manuscripts describing musculoskeletal manifestations of adult-onset nonsurgical nongenetic hypoparathyroidism. Musculoskeletal manifestations included myopathy, shoulder disorder, immune-negative non-erosive peripheral arthritis, axial involvement simulating spondylarthritis, and diffuse ligamentous ossifications. An association between hypoparathyroidism and spondyloarthritis or autoimmune diseases is possible. T-cell activation, seen in patients with hypoparathyroidism, may explain the co-occurrence of hypoparathyroidism with other autoimmune diseases. The treatment of these manifestations is based on calcium and active vitamin D supplementation. Parathyroid hormone may have an anabolic effect on muscle atrophy and muscle weakness. Parathyroid hormone can also promote bone formation and bone resorption by stimulating osteoclast differentiation by increasing RANKL (receptor activator for nuclear factor kappa-B ligand) expression. Therefore, hypoparathyroidism can be responsible for an increase in bone mineral density. However, the risk of fractures does not appear to be reduced due to changes in bone microarchitecture and the high risk of falls. Treatment with parathyroid hormone has been shown to improve bone microarchitecture. Our review showed that musculoskeletal manifestations are frequent in patients with hypoparathyroidism, including muscular, axial, peripheral articular, and entheseal manifestations.

Evaluation of Functional Components of Lactobacillus plantarum AR495 on Ovariectomy-Induced Osteoporosis in Mice And RAW264.7 Cells

Osteoporosis is a disease characterized by abnormal bone metabolism, where bone resorption outpaces bone formation. In this study, we investigated the key functional components of Lactobacillus plantarum AR495 in mitigating ovariectomy (OVX)-induced osteoporosis in mice. The results indicated that both Lactobacillus plantarum AR495 and its fermentation broth significantly reduced urinary calcium and deoxypyridinoline (DPD) levels in the mice. These interventions inhibited bone resorption and improved trabecular bone architecture by modulating the nuclear factor κB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) signaling pathway. Additionally, the L. plantarum AR495 and fermentation broth groups inhibited the RANKL/TRAF-6 and TLR4/MYD88 pathways, leading to enhanced bone metabolism, improved intestinal barrier function, and reduced intestinal inflammation. In vitro experiments revealed that AR495 fermentation supernatant fractions larger than 100 kDa and those between 50–100 kDa significantly decreased the activity of the osteoclast marker TRAP, regulated the expression of the TLR4/MYD88 pathway, and inhibited osteoclast formation, thereby alleviating the OVX-induced osteoporosis phenotype. These findings suggest that these components may be primary functional elements of L. plantarum AR495 in the treatment of osteoporosis.

Electrochemical immunoplatform for the determination of multiple salivary biomarkers of oral diseases related to microbiome dysbiosis

Several diseases of the oral cavity are related to compositional and functional shifts in the oral microbiome. The analysis of saliva is an attractive alternative for the diagnosis and prognosis of these diseases. Samples can be obtained by no invasive procedures and processing is relatively simple. However, sensitive and selective analytical methods are needed to make the diagnosis as specific as possible. In this work, four salivary biomarkers of oral diseases: interleukin-6 (IL-6), receptor activator of NF-kB ligand (RANKL), protein arginine deiminase 4 (PAD4) and the corresponding antibody (anti-PAD-4) were selected as targets for their simultaneous determination using an electrochemical immunosensing platform. Sandwich-type amperometric immunoassays were implemented using horseradish peroxidase (HRP)/H2O2/hydroquinone (HQ) for application to the analysis of saliva of six volunteers. The developed method provides excellent sensitivity, selectivity, and wide linear ranges with LOD values of 0.09 pg mL−1 (IL-6), 0.10 pg mL−1 (RANKL); 0.09 ng mL−1(PAD4) and 14.5 ng mL−1 (anti-PAD4) and allows the accurate analysis of saliva without matrix effects, using 25 μL of raw sample. The developed methodology is competitive with commercial ELISA kits available only for a single biomarker determination, while the assay for the four biomarkers can be completed in less than two hours.

CpG Methylation of Receptor Activator NF-κB (RANK) Gene Promoter Region Delineates Senescence-Related Decrease of RANK Gene Expression.

While the rapid decrease in estrogen is well known as the main cause of postmenopausal osteoporosis in women, the precise pathogenesis of senile osteoporosis in the elderly regardless of gender is largely unknown. The age-related epigenetic regulation of receptor activator NF-κB (RANK) gene expression was investigated with the use of a high-passaged mouse osteoclast progenitor cell line, RAW264.7, as an in vitro model of aging. In the RAW264.7 cells after repeated passages, receptor RANK expression was downregulated, resulting in decreased soluble RANK ligand (sRANKL)-induced osteoclastogenesis, expression of tartrate-resistant acid phosphatase-5b (TRAcP) and cathepsin K (CTSK). Methylation-specific PCR and bisulfite mapping revealed hypermethylation of CpG-loci located in the RANK gene promoter in multiple-passaged cells. ICON probe-mediated in situ assessment of methylated-cytosine at the CpG loci revealed an increase in the percentage of methylated RAW264.7 cells in the RANK gene in a passage-dependent manner. Conversely, upon treatment with demethylating agent 5-aza-2-deoxycytidine (5-aza-dC), high-passaged RAW264.7 cells displayed restored expression of the RANK gene, osteoclastogenesis, TRAcP and CTSK. Ex vivo cultures of splenic macrophages from young (10.5 W) and aged (12 M) mice also showed that CpG methylation was predominant in the aged animals, resulting in reduced RANK expression and osteoclastogenesis. Reduced RANK expression by age-related accumulation of DNA methylation, albeit in a limited population of osteoclast precursor cells, might be, at least in part, indicative of low-turnover bone characteristic of senile osteoporosis.

Correlation of OPG/RANKL in patients with thalassemia major at the center of Haemoglobinopathy Lushnje, Albania

Osteoporosis is an important cause of morbidity in hemoglobinopathy patients. It is characterized by low bone mass and disruption of bone architecture, resulting in reduced bone strength and increased risk of fractures. Osteoprotegerin (OPG) and receptor activator of NF-kappa-B ligand (RANKL) have recently been implicated in the pathogenesis of various types of osteoporosis. Our study aimed to determine the correlation between OPG/RANKL and patients affected by thalassemia major at the Center of Hemoglobinopathy in Lushnje. Methods: We measured serum OPG and RANKL levels in 70 patients with Thalassemia major and 67 healthy controls, determining correlations with BMD. Results: Serum OPG levels were significantly lower in thalassemic patients compared to the control group. Serum RANKL levels were higher in β-thalassemia patients compared to controls. 31.1% of our patients with Thalassemia major had osteoporosis and 21.6 % had osteopenia. We found a correlation between OPG-BMD (r=-0.768, p=0.000, and RANKL-BMD (r=0.468; p=0.000). Conclusion: OPG and RANKL in Thalassemia major patients should be considered as the main factors responsible for osteoclast activation.

Effects of Metabolic Dysfunction-Associated Steatotic Liver Disease on Bone Density and Fragility Fractures: Associations and Mechanisms.

Metabolic dysfunction-associated steatotic liver disease (MASLD) has profound adverse effects on bone health and homeostasis. MASLD appears to be associated with changes in bone mineral density (BMD) and fracture rate. However, the data are ambiguous and conflicting. Although several studies have shown that children and adolescents with MASLD have decreased BMD, the data on the prevalence of fragility fractures among children are scarce. In adults, increasing evidence suggests that MASLD decreases BMD and increases the risk of fragility fractures, which appears to be due to deterioration of bone architecture in addition to a decrease in BMD. Effects of MASLD on bone health may also be age- and race-specific. MASLD does not seem to increase fracture risk in children and adolescents but increases the risk of fractures in elderly men, especially those of Asian origin. From a mechanistic perspective, bone remodeling is a continuous process between osteoblasts (bone-forming) and osteoclasts (bone-resorbing), with any imbalance resulting in metabolic bone disease. In individuals with MASLD, loss of anabolic insulin receptor signaling (insulin resistance) in osteoblasts and increased receptor activator of nuclear factor κB (RANK)/RANK ligand signaling in osteoclasts (proinflammatory cytokines) swings the pendulum toward accelerated bone loss. These processes are further complicated by the concomitant presence of obesity, type 2 diabetes mellitus, or sarcopenia in individuals with MASLD. This study reviews the current literature associated with the effects of MASLD on BMD and fragility fractures in children/adolescents and adults. This review also discusses the pathomechanisms that link MASLD with changes in BMD and fragility fractures.

Serum levels of soluble receptor activator for nuclear factor kB ligand play a crucial role in the association of osteoprotegerin with coronary artery disease.

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of nuclear factor kB ligand (RANKL), and is implicated in the pathogenesis of atherosclerosis. The aim of the present study was to examine the hypothesis that serum OPG concentrations are increased in patients with stable coronary artery disease (CAD) at different serum levels of soluble RANKL (sRANKL). The study used a case-control design in which consecutively hospitalized individuals were recruited. Fasting blood samples were taken upon admission for serum testing. Participants with previously diagnosed CAD that was asymptomatic or had controlled symptoms constituted the stable CAD group, whereas patients with negative coronary computed tomography angiography results constituted the control non-CAD group. Exclusion criteria included recent acute coronary syndrome, severe heart failure, CAD-complicating autoimmune, blood or thyroid diseases, cancer, elevated temperature with or without infection, severe liver or kidney dysfunction, abnormal calcium metabolism, recent surgery and trauma history. A total of 118 individuals were included in the study. Smoothed plots generated using the recursive method and multivariate models showed that the incidence of stable CAD increased with serum OPG level up to the turning point of 18 pg/ml. This trend was observed at both high [odds ratio (OR), 1.61; 95% confidence interval (CI), 1.04-2.50; P=0.032) and low sRANKL concentrations (OR, 1.52; 95% CI, 1.06-2.17; P=0.022) after adjustment for cardiovascular risk factors. In conclusion, serum OPG levels ≤18 pg/ml are positively associated with stable CAD, regardless of sRANKL levels. In addition, at the same serum OPG level, higher sRANKL levels are associated with a greater incidence of stable CAD compared with lower sRANKL levels. This study identified the relationship between OPG, sRANKL, and stable CAD, and established the reference range for future clinical use.

A phase Ib study of JMT103, a receptor activator of NF-kB ligand (RANKL) antibody, in patients (pts) with bone metastases from solid tumors.

e15190 Background: JMT103 is a human IgG4 monoclonal antibody against RANKL and blocks the RANK signaling in osteoclasts, thus suppressing bone resorption. This phase Ib study aims to demonstrate the activity of JMT103 in bone metastases patients with solid tumors. Methods: In this randomized, multi-center, open-label, phase Ib study, adult pts with bone metastases from solid tumors were enrolled and randomized at a 1:1:1 ratio to receive JMT103 subcutaneously at 120mg every 4 weeks (Q4W, Cohort 1), 120mg every 8 weeks (Q8W, Cohort 2) and 180mg Q8W (Cohort 3) up to 49 weeks. The primary endpoint was the percent change from baseline to week 13 in creatinine-adjusted urinary N-telopeptide (uNTx/Cr). Secondary endpoints included safety, anti-drug antibodies (ADA) positivity, the percentage of patients who experienced on-study skeletal-related events (SREs), and ≥ 2-point decreases in pain with Brief Pain Inventory – Short Form. Results: At database lock (Mar. 31, 2023), 295 pts were enrolled; 293 were treated with JMT103 and eligible for efficacy and safety evaluation (96 pts in Cohort 1, 97 pts in Cohort 2, and 100 pts in Cohort 3). The median age was 58 years (Interquartile range [IQR] 51, 66), and the primary tumor types were mainly breast (145, 50%) and prostate cancer (44, 15%). At week 13, the median (IQR) percent change in uNTx/Cr was - 80% (- 93%, - 50%) in Cohort 1, - 73% (- 94%, - 34%) in Cohort 2, and - 76% (- 92%, - 40%) in Cohort 3, respectively. The incidence of SREs in the three cohorts was 3%, 6%, and 7%, respectively. Among the 33 pts in Cohort 1, 35 pts in Cohort 2, and 37 pts in Cohort 3 with baseline pain scores ≥ 2, 61% in Cohort 1, 46% in Cohort 2, and 54% in Cohort 3 experienced ≥ 2-point decreases in pain at the first post-treatment visit (Day 15). For ADA analysis, only 1 (1%) pt in Cohort 2 with a negative result at baseline tested positive after treatment. The table shows the overall summary of the safety profile. Most of TRAEs were low in grade and resolved quickly. The most common TRAEs (any grade) were hypocalcemia (68, 23%), hypophosphatemia (67, 23%), and increased aspartate transaminase (35, 12%). Among the 40 cases of grade-5 TEAE, only 1 was reported as a TRAE (pneumonia); the rest were unrelated to JMT103. Conclusions: Our study demonstrated a promising efficacy of JMT103 in reducing bone metabolism biomarker and a good safety profile with low immunogenicity. Clinical trial information: NCT04630522 . [Table: see text]

Place of rank ligand inhibitor in giant cell tumour of bone.

e23511 Background: Giant cell tumour of bone (GCTB) is a locally aggressive and osteolytic tumour.The peak incidence is during the third and fourth decades of life. The majority of tumours occur in the metaepiphyseal (end) region of the long bones. Surgical resection is the preferred treatment option, if possible but it is a tumor which always poses progressive problems. Denosumab is indicated in recurrent or unresectable GCTB. Methods: We report a series of 70 patients treated for GCT at the medical oncology department of the CPMC (Algiers) in collaboration with the orthopedics department of Mustapha University Hospital from January 2020 to December 2023. Results: 70 patients ( 50 women and 20 men). The sex ratio is 0.54 The average age is 22 years (11-54 years). Reason for consultation : - Pathological fracture: n = 10 - Pain: n = 30 - Functional impotence: n = 20 - Tumor mass: n = 5 - Concept of trauma: n = 5 Stage of the disease: -Localized: n = 29 -Recurrence: n = 30, -Recurrence + pulmonary metastases: n = 10, -Sarcomatous transformation: n = 1 Type of treatment: -Radiotherapy, n = 1 -Exercised biopsy: n = 10, -Curettage + cementoplasty: n = 50 -Exeresis with osteosynthesis material: n = 8, -Amputation : n = 1 Medical treatment: Denosumab: n = 45 The number of courses with denosumab was between 6 and 55 cycles. Denosumab was administered neoadjuvantly in 10 patients, in 20 patients with reccurence disease, 15 patients in the metastatic phase - In terms of toxicity, we noted moderate hypocalcemia in 3 patients. -Objective responses: 95% ORR, 5 complete radiological responses and 10 partial responses, 20 stable patients and 9 out of 10 patients who received neoadjuvant denosumab were able to operate.Progression Free Survival was 28 months. Conclusions: GCTs are aggressive tumors with intermediate malignancy that should not be underestimated. The treatment is essentially surgical. Denosumab is indicated for both neoadjuvant and adjuvant use, it allows obtaining a clear clinical and radiological improvement.

Osteogenic mechanism of chlorogenic acid and its application in clinical practice.

Natural polyphenols may have a role in counteracting oxidative stress, which is associated with aging and several bone-related diseases. Chlorogenic acid (CGA) is a naturally occurring polyphenolic compound formed by the esterification of caffeic and quininic acids with osteogenic, antioxidant, and anti-inflammatory properties. This review discusses the potential of CGA to enhance osteogenesis by increasing the osteogenic capacity of mesenchymal stem cells (MSCs), osteoblast survival, proliferation, differentiation, and mineralization, as well as its ability to attenuate osteoclastogenesis by enhancing osteoclast apoptosis and impeding osteoclast regeneration. CGA can be involved in bone remodeling by acting directly on pro-osteoclasts/osteoblasts or indirectly on osteoclasts by activating the nuclear factor kB (RANK)/RANK ligand (RANKL)/acting osteoprotegerin (OPG) system. Finally, we provide perspectives for using CGA to treat bone diseases.

PTHrP participates in the bone destruction of middle ear cholesteatoma via promoting macrophage differentiation into osteoclasts induced by RANKL.

Progressive bone resorption and destruction is one of the most critical clinical features of middle ear cholesteatoma, potentially leading to various intracranial and extracranial complications. However, the mechanisms underlying bone destruction in middle ear cholesteatoma remain unclear. This study aims to explore the role of parathyroid hormone-related protein (PTHrP) in bone destruction associated with middle ear cholesteatoma. A total of 25 cholesteatoma specimens and 13 normal external auditory canal skin specimens were collected from patients with acquired middle ear cholesteatoma. Immunohistochemical staining was used to detect the expressions of PTHrP, receptor activator for nuclear factor-kappa B ligand (RANKL), and osteoprotegerin (OPG) in cholesteatoma and normal tissues. Tartrate-resistant acid phosphatase (TRAP) staining was used to detect the presence of TRAP positive multi-nucleated macrophages in cholesteatoma and normal tissues. Mono-nuclear macrophage RAW264.7 cells were subjected to interventions, divided into a RANKL intervention group and a PTHrP+ RANKL co-intervention group. TRAP staining was used to detect osteoclast formation in the 2 groups. The mRNA expression levels of osteoclast-related genes, including TRAP, cathepsin K (CTSK), and nuclear factor of activated T cell cytoplasmic 1 (NFATc1), were measured using real-time polymerase chain reaction (real-time PCR) after the interventions. Bone resorption function of osteoclasts was assessed using a bone resorption pit analysis. Immunohistochemical staining showed significantly increased expression of PTHrP and RANKL and decreased expression of OPG in cholesteatoma tissues (all P<0.05). PTHrP expression was significantly positively correlated with RANKL, the RANKL/OPG ratio, and negatively correlated with OPG expression (r=0.385, r=0.417, r=-0.316, all P<0.05). Additionally, the expression levels of PTHrP and RANKL were significantly positively correlated with the degree of bone destruction in cholesteatoma (r=0.413, r=0.505, both P<0.05). TRAP staining revealed a large number of TRAP-positive cells, including multi-nucleated osteoclasts with three or more nuclei, in the stroma surrounding the cholesteatoma epithelium. After 5 days of RANKL or PTHrP+RANKL co-intervention, the number of osteoclasts was significantly greater in the PTHrP+RANKL co-intervention group than that in the RANKL group (P<0.05), with increased mRNA expression levels of TRAP, CTSK, and NFATc1 (all P<0.05). Scanning electron microscopy of bone resorption pits showed that the number (P<0.05) and size of bone resorption pits on bone slices were significantly greater in the PTHrP+RANKL co-intervention group compared with the RANKL group. PTHrP may promote the differentiation of macrophages in the surrounding stroma of cholesteatoma into osteoclasts through RANKL induction, contributing to bone destruction in middle ear cholesteatoma.

RANKL, but Not R-Spondins, Is Involved in Vascular Smooth Muscle Cell Calcification through LGR4 Interaction.

Vascular calcification has a global health impact that is closely linked to bone loss. The Receptor Activator of Nuclear Factor Kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system, fundamental for bone metabolism, also plays an important role in vascular calcification. The Leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4), a novel receptor for RANKL, regulates bone remodeling, and it appears to be involved in vascular calcification. Besides RANKL, LGR4 interacts with R-spondins (RSPOs), which are known for their roles in bone but are less understood in vascular calcification. Studies were conducted in rats with chronic renal failure fed normal or high phosphorus diets for 18 weeks, with and without control of circulating parathormone (PTH) levels, resulting in different degrees of aortic calcification. Additionally, vascular smooth muscle cells (VSMCs) were cultured under non-calcifying (1 mM phosphate) and calcifying (3 mM phosphate) media with different concentrations of PTH. To explore the role of RANKL in VSMC calcification, increasing concentrations of soluble RANKL were added to non-calcifying and calcifying media. The effects mediated by RANKL binding to its receptor LGR4 were investigated by silencing the LGR4 receptor in VSMCs. Furthermore, the gene expression of the RANK/RANKL/OPG system and the ligands of LGR4 was assessed in human epigastric arteries obtained from kidney transplant recipients with calcification scores (Kauppila Index). Increased aortic calcium in rats coincided with elevated systolic blood pressure, upregulated Lgr4 and Rankl gene expression, downregulated Opg gene expression, and higher serum RANKL/OPG ratio without changes in Rspos gene expression. Elevated phosphate in vitro increased calcium content and expression of Rankl and Lgr4 while reducing Opg. Elevated PTH in the presence of high phosphate exacerbated the increase in calcium content. No changes in Rspos were observed under the conditions employed. The addition of soluble RANKL to VSMCs induced genotypic differentiation and calcification, partly prevented by LGR4 silencing. In the epigastric arteries of individuals presenting vascular calcification, the gene expression of RANKL was higher. While RSPOs show minimal impact on VSMC calcification, RANKL, interacting with LGR4, drives osteogenic differentiation in VSMCs, unveiling a novel mechanism beyond RANKL-RANK binding.

Unraveling the Intricacies of OPG/RANKL/RANK Biology and Its Implications in Neurological Disorders-A Comprehensive Literature Review.

The OPG/RANKL/RANK framework, along with its specific receptors, plays a crucial role in bone remodeling and the functioning of the central nervous system (CNS) and associated disorders. Recent research and investigations provide evidence that the components of osteoprotegerin (OPG), receptor activator of NF-kB ligand (RANKL), and receptor activator of NF-kB (RANK) are expressed in the CNS. The CNS structure encompasses cells involved in neuroinflammation, including local macrophages, inflammatory cells, and microglia that cross the blood-brain barrier. The OPG/RANKL/RANK trio modulates the neuroinflammatory response based on the molecular context. The levels of OPG/RANKL/RANK components can serve as biomarkers in the blood and cerebrospinal fluid. They act as neuroprotectants following brain injuries and also participate in the regulation of body weight, internal body temperature, brain ischemia, autoimmune encephalopathy, and energy metabolism. Although the OPG/RANKL/RANK system is primarily known for its role in bone remodeling, further exploring deeper into its multifunctional nature can uncover new functions and novel drug targets for diseases not previously associated with OPG/RANKL/RANK signaling.

Gallein increases the fibroblast growth factor 2-elicited osteoprotegerin synthesis in osteoblasts

Gallein is known as an inhibitor of Gβγ subunits, but roles of gallein in bone metabolism have not been reported. Fibroblast growth factor 2 (FGF-2) increases angiogenesis and promotes bone regeneration during the early stages of fracture healing. Osteoprotegerin (OPG) secreted by osteoblasts, binds to the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) as a decoy receptor and prevents RANKL from binding to RANK, resulting in the suppression of bone resorption. Our previous report demonstrated that FGF-2 activates the phosphorylation of p38 mitogen-activated protein kinase (MAPK), stress-activated protein kinase/c-Jun N-terminal kinase (JNK), and p44/p42 MAPK in osteoblast-like MC3T3-E1 cells. Additionally, FGF-2-activated phosphorylation of p38 MAPK and JNK but not p44/p42 MAPK is positively involved in OPG synthesis in these cells. This work aimed to investigate the effects of gallein on the FGF-2-elicited OPG synthesis in osteoblast-like MC3T3-E1 cells and the mechanism. Our findings demonstrated that gallein significantly increased the FGF-2-elicited OPG synthesis in MC3T3-E1 cells. By contrast, fluorescein, gallein-like compound that does not bind Gβγ, did not affect the FGF-2-elicited OPG synthesis. Gallein significantly enhanced the FGF-2-induced OPG mRNA expression levels. Gallein did not affect the FGF-2-activated phosphorylation of p38 MAPK and p44/p42 MAPK, but significantly increased the FGF-2-activated phosphorylation of JNK, while fluorescein did not affect JNK phosphorylation. SP600125, a specific JNK inhibitor, strongly inhibited gallein-induced enhancement of FGF-2-induced OPG synthesis and mRNA expression levels. Our results indicated that gallein increases the FGF-2-induced OPG synthesis due to the JNK activation in the osteoblast.

Iron and bones: effects of iron overload, deficiency and anemia treatments on bone.

Iron is a vital trace element and exerts opposing effects on bone in both iron overload and iron deficiency situations. Remarkably, iron supplementation through intravenous infusion in patients with iron deficiency can also have detrimental effects on bone in special cases. The diverse mechanisms underlying these effects and their manifestations contribute to the complexity of this relationship. Iron overload impacts both bone resorption and formation, accelerating bone resorption while reducing bone formation. These effects primarily result from the direct action of reactive oxygen species (ROS), which influence the proliferation, differentiation, and activity of both osteoclasts and osteoblasts differently. This imbalance favors osteoclasts and inhibits the osteoblasts. Simultaneously, multiple pathways, including bone morphogenic proteins, RANK ligand, and others, contribute to these actions, leading to a reduction in bone mass and an increased susceptibility to fractures. In contrast, iron deficiency induces low bone turnover due to energy and co-factor deficiency, both of which require iron. Anemia increases the risk of fractures in both men and women. This effect occurs at various levels, reducing muscular performance and, on the bone-specific level, decreasing bone mineral density. Crucially, anemia increases the synthesis of the phosphaturic hormone iFGF23, which is subsequently inactivated by cleavage under physiological conditions. Thus, iFGF23 levels and phosphate excretion are not increased. However, in specific cases where anemia has to be managed with intravenous iron treatment, constituents-particularly maltoses-of the iron infusion suppress the cleavage of iFGF23. As a result, patients can experience severe phosphate wasting and, consequently, hypophosphatemic osteomalacia. This condition is often overlooked in clinical practice and is often caused by ferric carboxymaltose. Ending iron infusions or changing the agent, along with phosphate and vitamin D supplementation, can be effective in addressing this issue.

Caffeine induces alveolar bone loss in rats submitted to orthodontic movement via activation of receptor activator of nuclear factor ҡB, receptor activator of nuclear factor ҡB ligand, and osteoprotegerin pathway

Caffeine is a widely consumed substance with several effects on bone metabolism. This study aimed to investigate the effect of caffeine on the bone tissue of rats submitted to orthodontic movement. Twenty-five male Wistar rats underwent orthodontic movement (21 days) of the first permanent maxillary molars on the left side. The experimental group (caffeine; n= 13) and control group (n= 12) received caffeine and water, respectively, by gavage. Microcomputed tomography was performed to analyze orthodontic movement. Histologic analysis of the inflammatory infiltrate and osteoclast count by tartrate-resistant acid phosphatase were conducted. Maxilla tissue was evaluated for receptor activator of nuclear factor ҡB (RANK), RANK ligand (RANKL), and osteoprotegerin by immunohistochemistry. Caffeine exhibited a lower bone volume/tissue volume ratio (78.09% ± 5.83%) than the control (86.84% ± 4.89%; P<0.05). Inflammatory infiltrate was increased in the caffeine group compared with the control group (P<0.05). A higher number of tartrate-resistant acid phosphatase-positive cells was observed in the caffeine (9.67 ± 1.73) than in the control group (2.66 ± 0.76; P<0.01). Immunoexpression of RANK and RANKL in the caffeine group was greater than the control (P<0.05). The use of caffeine thermogenic induces alveolar bone loss in rats submitted to orthodontic movement via activation of RANK, RANKL, and osteoprotegerin signaling pathways.

Epstein-barr virus infections induce aberrant osteoclastogenesis in immune system-humanized NOD/Shi-scid/IL-2RγCnull mice

Epstein-Barr virus (EBV) and other viral infections are possible triggers of autoimmune diseases, such as rheumatoid arthritis (RA). To analyze the causative relationship between EBV infections and RA development, we performed experiment on humanized NOD/Shi-scid/IL-2RγCnull (hu-NOG) mice reconstituted human immune system components and infected with EBV. In EBV-infected hu-NOG mice, breakdown of knee joint bones was found to be accompanied by the accumulation of receptor activator of nuclear factor-κB (NF-κB) (RANK) ligand (RANKL), a key factor in osteoclastogenesis, human CD19 and EBV-encoded small RNA (EBER)-bearing cells. Accumulation of these cells expanded in the bone marrow adjacent to the bone breakage, showing a histological feature like to that in bone marrow edema. On the other hand, human RANK/human matrix metalloprotease-9 (MMP-9) positive, osteoclast-like cells were found at broken bone portion of EBV-infected mouse knee joint. In addition, human macrophage-colony stimulating factor (M-CSF), an essential factor in development of osteoclasts, evidently expressed in spleen and bone marrow of EBV-infected humanized mice. Furthermore, RANKL and M-CSF were identified at certain period of EBV-transformed B lymphoblastoid cells (BLBCs) derived from umbilical cord blood lymphocytes. Co-culturing bone marrow cells of hu-NOG mice with EBV-transformed BLBCs resulted in the induction of a multinucleated cell population positive for tartrate-resistant acid phosphatase and human MMP-9 which indicating human osteoclast-like cells. These findings suggest that EBV-infected BLBCs induce human aberrant osteoclastogenesis, which cause erosive arthritis in the joints.

Oligomeric proanthocyanidins ameliorates osteoclastogenesis through reducing OPG/RANKL ratio in chicken's embryos

Skeletal disorders can seriously threaten the health and the performance of poultry, such as tibial dyschondroplasia (TD) and osteoporosis (OP). Oligomeric proanthocyanidins (OPC) are naturally occurring polyphenolic flavonoid compounds that can be used as potential substances to improve the bone health and the growth performance of poultry. Eighty 7-day-old green-eggshell yellow feather layer chickens were randomly divided into 4 groups: basal diet and basal diet supplementation with 25, 50, and 100 mg/kg OPC. The results have indicated that the growth performance and bone parameters of chickens were significantly improved supplementation with OPC in vivo, including the bone volume (BV), the bone mineral density (BMD) and the activities of antioxidative enzymes, but ratio of osteoprotegerin (OPG)/receptor activator of NF-κB (RANK) ligand (RANKL) was decreased. Furthermore, primary bone marrow mesenchymal stem cells (BMSCs) and bone marrow monocytes/macrophages (BMMs) were successfully isolated from femur and tibia of chickens, and co-cultured to differentiate into osteoclasts in vitro. The osteogenic differentiation derived from BMSCs was promoted treatment with high concentrations of OPC (10, 20, and 40 µmol/L) groups in vitro, but emerging the inhibition of osteoclastogenesis by increasing the ratio of OPG/RANKL. In contrary, the osteogenic differentiation was also promoted treatment with low concentrations of OPC (2.5, 5, and 10 µmol/L) groups, but osteoclastogenesis was enhanced by decreasing the ratio of OPG/RANKL in vitro. In addition, OPG inhibits the differentiation and activity of osteoclasts by increasing the autophagy in vitro. Dietary supplementation of OPC can improve the growth performance of bone and alter the balance of osteoblasts and osteoclasts, thereby improving the bone health of chickens.

Association of Peri-Implant Keratinized Mucosa Width and Mucosal Thickness with Early Bone Loss: A Cross-Sectional Study.

Objective: The objective of this study was to evaluate the effects of keratinized mucosa width (KMW) and mucosal thickness (MT) around dental implants on marginal bone loss (MBL). The evaluation was performed one year after loading by comparing clinical, radiographic, and biochemical parameters. Methods: The study included 87 implants in 87 patients undergoing regular follow-ups without hard or soft tissue augmentation one year after loading. Clinical measurements included plaque index (PI), gingival index (GI), bleeding on probing (BoP), probing depth (PD), KMW, and MT. MBL was assessed with periapical radiography. The peri-implant crevicular fluid (PICF) was analyzed for tumor necrosis factor-alpha (TNF-α), receptor activator of nuclear factor-kB ligand (RANKL), osteoprotegerin (OPG), and microRNA-27a. Results: The MBL of implants with thin MT (<2 mm) was higher than that of implants with thick MT (≥2 mm) (p < 0.05). A significant negative correlation (r: -0.217) was established between MT and MBL. No significant association was found between KMW and MBL (p > 0.05). No significant associations was found between KMW and MT with TNF-α, RANKL, OPG and RANKL/OPG (p > 0.05), with the exception of increased microRNA-27a levels in implants with KMW ≥ 2 mm (p < 0.05). Conclusions: Implants with a thick MT had a lower MBL. There may be an association between adequate KMW and high miRNA-27a levels. The relationship between MBL and miRNA-27a remains unclear.

Derivation of functional thymic epithelial organoid lines from adult murine thymus

Thymic epithelial cells (TECs) orchestrate Tcell development by imposing positive and negative selection on thymocytes. Current studies on TEC biology are hampered by the absence of long-term exvivo culture platforms, while the cells driving TEC self-renewal remain to be identified. Here, we generate long-term (>2 years) expandable 3D TEC organoids from the adult mouse thymus. For further analysis, we generated single anddouble FoxN1-P2A-Clover, Aire-P2A-tdTomato, and Cldn4-P2A-tdTomato reporter lines by CRISPR knockin. Single-cell analyses of expanding clonal organoids reveal cells with bipotent stem/progenitor phenotypes. These clonal organoids can be induced to express Foxn1 and to generate functional cortical- and Aire-expressing medullary-like TECs upon RANK ligand+ retinoic acid treatment. TEC organoids support Tcell development from immature thymocytes invitro as well as invivo upon transplantation into athymic nude mice. This organoid-based platform allows invitro study of TEC biology and offers a potential strategy for exvivo Tcell development.