Functions of RANKL/RANK/OPG in bone modeling and remodeling

Osteoporosis and cardiovascular disease: a review

BACKGROUND

Osteoporosis and cardiovascular disease are common diseases encountered globally, especially with advancing age. Osteoporosis occurs when there is a loss of bone mineral density leading to increased predisposition to fragility fracture. The conventional perception of osteoporosis is purely as a metabolic bone disease. However, there are mounting reports from recent studies that osteoporosis could be seen as a risk factor for cardiovascular disease just like other traditional risk factors such as hypertension, dyslipidaemia and diabetes. This is a paradigm shift with regards to the outlook of osteoporosis. Osteoporosis and cardiovascular disease have similar risk factors, including diabetes, smoking, excess alcohol, sedentary lifestyle, ageing and dyslipidaemia. This may partly explain the link between osteoporosis and cardiovascular disease. In addition, both osteoporosis and atherosclerosis, which underlies most cardiovascular disease, are both characterized by low grade chronic inflammation. Moreover, the processes involved in the calcification of atheroma are similar to what is seen in bone remodeling. Both processes also involve similar regulators such as osteoprotegerin and related proteins such as osteonectin, osteopontin and type 1 collagen are found in bone matrix and atheromatous plaques.

CONCLUSION

There is emerging evidence that individuals with osteoporosis are also at an increased risk of coronary artery disease and stroke even after controlling for other factors. The traditional risk factors for cardiovascular disease also predispose people to developing osteoporosis, suggesting that the same mechanism may be causing the two. Moreover, a number of anti-osteoporotic drugs have also been largely linked with cardiovascular disease. This calls for a change in the view of osteoporosis as a metabolic disease but as a cardio-metabolic disorder thereby emphasizing the need for intensified preventive strategies for the disease.

Dietary Zinc Glycine Supplementation Improves Tibia Quality of Meat Ducks by Modulating the Intestinal Barrier and Bone Resorption

Leg problems characterized by gait abnormity and bone structure destruction are associated with a high risk of fractures and continuous pain in poultry. Zinc (Zn) acts a pivotal part in normal bone homeostasis and has proven to be highly effective in alleviating leg problems. Therefore, the effects of graded concentration of Zn on bone quality were evaluated in this study. A total of 512 1-d-old male ducks were fed 4 basal diets added 30 mg/kg Zn, 60 mg/kg Zn, 90 mg/kg Zn, and 120 mg/kg Zn as Zn glycine for 35 d. Tibia Zn content, ash percentage, and breaking strength linearly increased with dietary elevated Zn level (P < 0.05). Broken-line analysis revealed that the recommended level of Zn from Zn glycine was 55.13 mg/kg and 64.48 mg/kg based on tibia ash and strength, respectively. To further confirm the role of dietary Zn glycine addition on bone characteristics, data from birds fed either 60 mg/kg Zn as Zn sulfate (ZnSO₄), 30 mg/kg Zn, or 60 mg/kg Zn in the form of Zn glycine indicated that birds given 60 mg/kg Zn from Zn glycine diet exhibited higher tibia ash, strength, and trabecular volume compared to those fed the 30 mg/kg Zn diet (P < 0.05). Dietary 60 mg/kg Zn as Zn glycine addition decreased intestinal permeability, upregulated the mRNA expression of tight junction protein, and increased the abundance of Lactobacillus and Bifidobacterium, which was companied by declined the level of inflammatory cytokines in both the ileum and bone marrow. Regarding bone turnover, the diet with 60 mg/kg Zn from Zn glycine induced osteoprotegerin expression and thus decreased osteoclast number and serum bone resorption biomarker levels including serum tartrate-resistant acid phosphatase activity and C-terminal cross-linked telopeptide of type I collagen level when compared to 30 mg/kg Zn diet (P < 0.05). Except for the upregulation in runt-related transcription factor 2 transcription, the experimental treatments did not apparently change the bone formation biomarker contents in serum. Additionally, Zn glycine displayed a more efficient absorption rate, evidenced by higher serum Zn level, and thus had potentially greater a protective role in the intestine barrier and tibia mass as compared to ZnSO₄. Collectively, the dietary supplementation of 60 mg/kg in the form of Zn glycine could suppress bone resorption mediated by osteoclast and consequently improve tibial quality of meat ducks, in which enhanced intestinal integrity and optimized gut microbiota might be involved.

Diagnostic potential of salivary interleukin-17, RANKL, and OPG to differentiate between periodontal health and disease and discriminate stable and unstable periodontitis: A case-control study

Background and Aims

Limitations of the conventional diagnostic techniques urged researchers to seek novel methods to predict, diagnose, and monitor periodontal disease. Use of the biomarkers available in oral fluids could be a revolutionary surrogate for the manual probing/diagnostic radiograph. Several salivary biomarkers have the potential to accurately discriminate periodontal health and disease. This study aimed to determine the diagnostic sensitivity and specificity of salivary interleukin (IL)-17, receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), RANKL/OPG for differentiating (1) periodontal health from disease and (2) stable and unstable periodontitis.

Methods

Participants with periodontitis (n = 50) and gingivitis (n = 25), both diseases represented the cases, and subjects with healthy periodontium (n = 15) as a control were recruited for this study. Periodontitis cases were further equally subdivided into stable and unstable. Whole unstimulated salivary sample were collected from all participants. Periodontal parameters including bleeding on probing, probing pocket depth, clinical attachment loss, and number of missing teeth were recorded. The protein levels of salivary IL-17, RANKL, and OPG were determined by using enzyme-linked immunosorbent assays technique.

Results

Salivary IL-17, OPG, RANKL, and RANKL/OPG showed high sensitivity and specificity to differentiate periodontal health from gingivitis and periodontitis. Similar pattern was observed in discriminating stable and unstable periodontitis. Salivary IL-17 and RANKL showed a good accuracy to differentiate gingivitis from periodontitis. However, OPG and RANKL/OPG did not exhibit enough sensitivity and specificity to differentiate the latter conditions.

Conclusion

Salivary IL-17, RANKL, OPG, and RANKL/OPG system are potential candidates for differentiating periodontal health and disease and discriminate stable and unstable periodontitis.

Bone disease in patients with cirrhosis of different etiology and severity; are Klotho protein and osteoprotegerin potential biomarkers?

BACKGROUND AND AIMS

Cirrhosis is associated with increased risk for osteoporosis and osteopenia. This study aims to further investigate this relationship by examining if etiology and severity of cirrhosis are independent predictors of bone mineral density (BMD) loss. Furthermore we examined the serum levels of osteoprotegerin (OPG) and Klotho proteins that have been involved in bone metabolism.

METHODS

Seventy-four patients with cirrhosis of different etiology and 25 matched healthy controls were included in this study. Bone mineral densitometry at both lumbar spine and femoral neck was measured. Serum total OPG, Klotho protein and vitamin D levels were also determined. Comparisons were performed according to etiology and severity of cirrhosis.

RESULTS

Decreased bone density was observed in cirrhotic patients compared to healthy controls with T = -1.46 and T = -1.37 in lumbar spine and femoral bone respectively compared to T = -0.396 and T = -0.672 in the control group. In the cirrhotic group, osteopenia was observed in 46% in lumbar spine and 51% in femoral bone whereas osteoporosis was observed in 20% in lumbar spine and 9% in femoral bone. Decreased bone density was confirmed, regardless of cirrhosis etiology or stage of liver function. Patients were found to have higher levels of OPG than the control group (136 pg/ml vs. 67 pg/ml, p < 0.001), but lower levels of Klotho protein (1051 pg/ml vs. 1842 pg/ml, p < 0.001) regardless etiology and severity of cirrhosis. High OPG levels were found to be associated with low femoral bone density.

CONCLUSIONS

BMD is lower in cirrhotic patients regardless etiology and severity of liver disease with osteopenia and osteoporosis be present in 50% and 20%, respectively. Higher levels of OPG and lower levels of Klotho protein were observed in cirrhotic patients regardless etiology and severity in comparison to matched healthy group.

Augmentation of IFN-γ by bone marrow derived immune cells in the presence of severe suppression of IFN-γ in gingivae induced by zoledronic acid and denosumab in Hu-BLT mice model of ONJ

Introduction

The potential mechanisms governing drug induced osteonecrosis of the jaw (ONJ) is not well understood, and is one of the objectives of this study. Thus, we tested the release of IFN-γ within different immune compartments including bone marrow and gingivae upon treatment with zoledronic acid (ZOL) and denosumab which are known to induce ONJ in susceptible individuals.

Methods

We used humanized-BLT mouse model for the in-vivo studies reported in this paper. To determine the effects of zoledronic acid and denosumab on IFN-γ secretion and NK cell-mediated cytotoxicity; peripheral blood, bone marrow, spleen and gingiva were obtained after the injection of ZOL and denosumab in mice.

Results

Percentages of B cells are much higher in wild-type mice whereas the proportions of immune subsets in humans and reconstituted hu-BLT peripheral-blood are similar. Therefore, hu-BLT mice are preferable model to study human disease, in particular, immune-pathologies induced by ZOL and denosumab. Both agents resulted in a severe suppression of IFN-γ in the gingiva, whereas they heightened the release of IFN-γ and NK cell-mediated cytotoxicity by the BM-derived immune cells. ZOL increased the IFN-γ secretion by the spleen and peripheral blood immune cells, whereas denosumab decreased the release IFN-γ by these cells significantly.

Discussion

ZOL and denosumab may likely suppress IFN-γ secretion in gingiva through different mechanisms. In addition, to the suppression of IFN-γ secretion, denosumab mediated effect could in part be due to the decrease in the bone resorptive function of osteoclasts due to the induction of antibody dependent cellular cytotoxicity and lysis of osteoclasts, whereas ZOL is able to mediate cell death of osteoclasts directly. Suppression of IFN-gamma in gingiva is largely responsible for the inhibition of immune cell function, leading to dysregulated osteoblastic and osteoclastic activities. Restoration of IFN-gamma in the local microenvironment may result in establishment of homeostatic balance in the gingiva and prevention of osteonecrosis of jaw.

New Insights into the In Vitro Antioxidant Routes and Osteogenic Properties of Sr/Zn Phytate Compounds

Sr/Zn phytate compounds have been shown interest in biomaterial science, specifically in dental implantology, due to their antimicrobial effects against Streptococcus mutans and their capacity to form bioactive coatings. Phytic acid is a natural chelating compound that shows antioxidant and osteogenic properties that can play an important role in bone remodelling processes affected by oxidative stress environments, such as those produced during infections. The application of non-protein cell-signalling molecules that regulate both bone and ROS homeostasis is a promising strategy for the regeneration of bone tissues affected by oxidative stress processes. In this context, phytic acid (PA) emerged as an excellent option since its antioxidant and osteogenic properties can play an important role in bone remodelling processes. In this study, we explored the antioxidant and osteogenic properties of two metallic PA complexes bearing bioactive cations, i.e., Sr²⁺ (SrPhy) and Zn²⁺ (ZnPhy), highlighting the effect of the divalent cations anchored to phytate moieties and their capability to modulate the PA properties. The in vitro features of the complexes were analyzed and compared with those of their precursor PA. The ferrozine/FeCl₂ method indicated that SrPhy exhibited a more remarkable ferrous ion affinity than ZnPhy, while the antioxidant activity demonstrated by a DPPH assay showed that only ZnPhy reduced the content of free radicals. Likewise, the antioxidant potential was assessed with RAW264.7 cell cultures. An ROS assay indicated again that ZnPhy was the only one to reduce the ROS content (20%), whereas all phytate compounds inhibited lipid peroxidation following the decreasing order of PA > SrPhy > ZnPhy. The in vitro evaluation of the phytate's osteogenic ability was performed using hMSC cells. The results showed tailored properties related to the cation bound in each complex. ZnPhy overexpressed ALP activity at 3 and 14 days, and SrPhy significantly increased calcium deposition after 21 days. This study demonstrated that Sr/Zn phytates maintained the antioxidant and osteogenic properties of PA and can be used in bone regenerative therapies involving oxidative environments, such as infected implant coatings and periodontal tissues.

Time-dependent unloading effects on muscle and bone and involvement of FNDC5/irisin axis

The identification of biomarkers and countermeasures to prevent the adverse effects on the musculoskeletal system caused by the absence of mechanical loading is the main goal of space biomedical research studies. In this study, we analyzed over 4 weeks of unloading, the modulation in the expression of key proteins in Vastus lateralis, Gastrocnemius and cortical bone in parallel with the modulation of irisin serum levels and its precursor FNDC5 in skeletal muscle of hind limb unloaded (HU) mice. Here we report that Atrogin-1 was up-regulated as early as 1- and 2-week of unloading, whereas Murf-1 at 2- and 3-weeks, along with a marked modulation in the expression of myosin heavy chain isoforms during unloading. Since HU mice showed reduced irisin serum levels at 4-weeks, as well as FNDC5 decrease at 3- and 4-weeks, we treated HU mice with recombinant irisin for 4 weeks, showing that unloading-dependent decline of myosin heavy chain isoforms, MyHCIIα and MyHCIIx, and the anti-apoptotic factor Bcl2, were prevented. In parallel, irisin treatment inhibited the increase of the senescence marker p53, and the pro-apoptotic factor Bax. Overall, these results suggest that the myokine irisin could be a possible therapy to counteract the musculoskeletal impairment caused by unloading.

Targeting STING: From antiviral immunity to treat osteoporosis

The cGAS-STING signaling pathway can trigger innate immune responses by detecting dsDNA from outside or within the host. In addition, the cGAS-STING signaling pathway has emerged as a critical mediator of the inflammatory response and a new target for inflammatory diseases. STING activation leads to dimerization and translocation to the endoplasmic reticulum Golgi intermediate compartment or Golgi apparatus catalyzed by TBK1, triggers the production of IRF3 and NF-κB and translocates to the nucleus to induce a subsequent interferon response and pro-inflammatory factor production. Osteoporosis is a degenerative bone metabolic disease accompanied by chronic sterile inflammation. Activating the STING/IFN-β signaling pathway can reduce bone resorption by inhibiting osteoclast differentiation. Conversely, activation of STING/NF-κB leads to the formation of osteoporosis by increasing bone resorption and decreasing bone formation. In addition, activation of STING inhibits the generation of type H vessels with the capacity to osteogenesis, thereby inhibiting bone formation. Here, we outline the mechanism of action of STING and its downstream in osteoporosis and discuss the role of targeting STING in the treatment of osteoporosis, thus providing new ideas for the treatment of osteoporosis.

Reduced bone formation and increased bone resorption drive bone loss in Eimeria infected broilers

Coccidiosis is an economically significant disease in the global poultry industry, but little is known about the mechanisms of bone defects caused by coccidiosis; thus, the study focused on effects of coccidiosis on the bone homeostasis of young broiler chickens. A total of 480 male Cobb500 broilers were randomly allocated into four treatment groups, including an uninfected control consuming diet ad libitum, two infected groups were orally gavaged with two different concentrations of sporulated Eimeria oocysts, and an uninfected pair-fed group fed the same amount of feed as the high Eimeria-infected group consumed. Growth performance and feed intake were recorded, and samples were collected on 6 days post infection. Results indicated that coccidiosis increased systemic oxidative status and elevated immune response in bone marrow, suppressing bone growth rate (P < 0.05) and increasing bone resorption (P < 0.05) which led to lower bone mineral density (P < 0.05) and mineral content (P < 0.05) under Eimeria infection. With the same amount of feed intake, the uninfected pair-fed group showed a distinguished bone formation rate and bone resorption level compared with the Eimeria infected groups. In conclusion, inflammatory immune response and oxidative stress in broilers after Eimeria infection were closely associated with altered bone homeostasis, highlighting the role of inflammation and oxidative stress in broiler bone homeostasis during coccidiosis.

Clostridium butyricum Can Promote Bone Development by Regulating Lymphocyte Function in Layer Pullets

Bone health problems are a serious threat to laying hens; microbiome-based therapies, which are harmless and inexpensive, may be an effective solution for bone health problems. Here, we examined the impacts of supplementation with Clostridium butyricum (CB) on bone and immune homeostasis in pullets. The results of in vivo experiments showed that feeding the pullets CB was beneficial to the development of the tibia and upregulated the levels of the bone formation marker alkaline phosphatase and the marker gene runt-related transcription factor 2 (RUNX2). For the immune system, CB treatment significantly upregulated IL-10 expression and significantly increased the proportion of T regulatory (Treg) cells in the spleen and peripheral blood lymphocytes. In the in vitro test, adding CB culture supernatant or butyrate to the osteoblast culture system showed no significant effects on osteoblast bone formation, while adding lymphocyte culture supernatant significantly promoted bone formation. In addition, culture supernatants supplemented with treated lymphocytes (pretreated with CB culture supernatants) stimulated higher levels of bone formation. In sum, the addition of CB improved bone health by modulating cytokine expression and the ratio of Treg cells in the immune systems of layer pullets. Additionally, in vitro CB could promote the bone formation of laying hen osteoblasts through the mediation of lymphocytes.

Current perspectives of residual ridge resorption: Pathological activation of oral barrier osteoclasts

PURPOSE

Tooth extraction is a last resort treatment for resolving pathological complications of dentition induced by infection and injury. Although the extraction wound generally heals uneventfully, resulting in the formation of an edentulous residual ridge, some patients experience long-term and severe residual ridge reduction. The objective of this review was to provide a contemporary understanding of the molecular and cellular mechanisms that may potentially cause edentulous jawbone resorption.

STUDY SELECTION

Clinical, in vivo, and in vitro studies related to the characterization of and cellular and molecular mechanisms leading to residual ridge resorption.

RESULTS

The alveolar processes of the maxillary and mandibular bones uniquely juxtapose the gingival tissue. The gingival oral mucosa is an active barrier tissue that maintains homeostasis of the internal organs through its unique barrier immunity. Tooth extraction not only generates a bony socket but also injures oral barrier tissue. In response to wounding, the alveolar bone socket initiates regeneration and remodeling through coupled bone formation and osteoclastic resorption. Osteoclasts are also found on the external surface of the alveolar bone, interfacing the oral barrier tissue. Osteoclasts in the oral barrier region are not coupled with osteoblastic bone formation and often remain active long after the completion of wound healing, leading to a net decrease in the alveolar bone structure.

CONCLUSIONS

The novel concept of oral barrier osteoclasts may provide important clues for future clinical strategies to maintain residual ridges for successful prosthodontic and restorative therapies.

Simultaneous neutralization of TGF-β and IL-6 attenuates Staphylococcus aureus-induced arthritic inflammation through differential modulation of splenic and synovial macrophages

Septic arthritis is a joint disease caused by Staphylococcus aureus. Different macrophage populations contribute in various ways to control blood-borne infections and induce inflammatory responses. Macrophage tissue-resident niche is necessary for the suppression of chronic inflammation and may contribute to the pathogenesis of septic arthritis. Thus, to obtain a resolution of the disease and restoration of synovial homeostasis, it needs the activation of macrophages that further regulate the inflammatory consequences. The aim of this study was to find out the mechanism by which neutralization of transforming growth factor-beta (TGF-β) and/or interleukin (IL)-6 after induction of septic arthritis could alter the specific macrophage responses in spleen and synovial joints via different cytokines (osteoprotegerin (OPG), osteopontin (OPN), IL-10, IL-12 and CXCL8) cross-talking, and how the response could be modulated by reactive oxygen species vs antioxidant enzyme activities. Dual neutralization of TGF-β and IL-6 is notably effective in eliciting splenic and synovial tissue-resident macrophage responses. Synovial macrophage-derived IL-10 can elicit protection against septic arthritis via regulating receptor-activated nuclear factor Kappa-B ligand (RANKL)/OPG interaction. They also reduced oxidative stress by increasing the activity of antioxidant enzymes including SOD and catalase. Histopathological analysis revealed that dual neutralization of TGF-β and IL-6 prevented bone destruction and osteoclastic activity in septic arthritis by promoting the differential functional response of the splenic and synovial macrophages. Additionally, the macrophage-derived IL-10 can elicit protection against S. aureus-induced septic arthritis via regulating RANKL/OPG interaction. Further studies on STAT3 and STAT4 are needed for the understanding of such cross-talking in resident macrophages of arthritic mice.

Psoriatic arthritis: review of potential biomarkers predicting response to TNF inhibitors

Psoriatic arthritis (PsA) is a chronic and painful inflammatory immune-mediated disease. It affects up to 40% of people with psoriasis and it is associated with several comorbidities such as obesity, diabetes, metabolic syndrome, and hypertension. PsA is difficult to diagnose because of its diverse symptoms, namely axial and peripheral arthritis, enthesitis, dactylitis, skin changes, and nail dystrophy. Different drugs exist to treat the inflammation and pain. When patients do not respond to conventional drugs, they are treated with biologic drugs. Tumour necrosis factor inhibitors (TNFi's) are commonly given as the first biologic drug; beside being expensive, they also lack efficacy in 50% of patients. A biomarker predicting individual patient's response to TNFi would help treating them earlier with an appropriate biologic drug. This study aimed to review the literature to identify potential biomarkers that should be investigated for their predictive ability. Several such biomarkers were identified, namely transmembrane TNFα (tmTNF), human serum albumin (HSA) and its half-life receptor, the neonatal Fc receptor (FcRn) which is also involved in IgG lifespan; calprotectin, high mobility group protein B1 (HMGB1) and advanced glycation end products (AGEs) whose overexpression lead to excessive production of pro-inflammatory cytokines; lymphotoxin α (LTα) which induces inflammation by binding to TNF receptor (TNFR); and T helper 17 (Th17) cells which induce inflammation by IL-17A secretion.

Particulate beta-tricalcium phosphate and hydroxyapatite doped with silver promote in vitro osteoblast differentiation in MC3T3-E1 cells

BACKGROUND

Calcium phosphates including β-tricalcium phosphate (β-TCP) and hydroxyapatite (HAp) have been widely used for bone regeneration application because of their high osteoconductive activities. In addition, various kinds of inorganic ions enhance differentiation, proliferation, and mineralization of osteoblasts. However, information about the effects of silver-doped β-TCP [β-TCP (Ag)] and HAp [HAp (Ag)] particles on osteogenic differentiation is not available yet.

OBJECTIVE

We focused on the impact of β-TCP (Ag) and HAp (Ag) particles on the osteogenic differentiation of MC3T3-E1 osteoblast precursor cells.

METHODS

MC3T3-E1 osteoblast precursor cells were pre-treated by β-TCP (Ag) or HAp (Ag). And then the medium was changed to differentiation medium. Subsequently, osteoblast differentiation-related markers were determined.

RESULTS

We found that treatment with β-TCP (Ag) or HAp (Ag) particles increased alkaline phosphatase activity in MC3T3-E1 cells. Expression of osteoblast differentiation-related genes also increased after treatment with β-TCP (Ag) or HAp (Ag) particles, a response thought to be regulated by zinc finger-containing transcription factor osterix. The ratio of the receptor activator of nuclear factor kappa-B ligand (RANKL) to osteoprotegerin (OPG) was decreased by β-TCP (Ag) and HAp (Ag) particles.

CONCLUSION

Silver doping of β-TCP and HAp particles is effective for bone regeneration.

Effect of Bifidobacterium on osteoclasts: TNF-α/NF-κB inflammatory signal pathway-mediated mechanism

Osteoporosis is a systemic multifactorial bone disease characterized by low bone quality and density and bone microstructure damage, increasing bone fragility and fracture vulnerability. Increased osteoclast differentiation and activity are important factors contributing to bone loss, which is a common pathological manifestation of bone diseases such as osteoporosis. TNF-a/NF-κB is an inflammatory signaling pathway with a key regulatory role in regulating osteoclast formation, and the classical pathway RANKL/RANK/OPG assists osteoclast formation. Activation of this inflammatory pathway promotes the formation of osteoclasts and accelerates the process of osteoporosis. Recent studies and emerging evidence have consistently demonstrated the potential of probiotics to modulate bone health. Secretions of Bifidobacterium, a genus of probiotic bacteria in the phylum Actinobacteria, such as short-chain fatty acids, equol, and exopolysaccharides, have indicated beneficial effects on bone health. This review discusses the molecular mechanisms of the TNF-a/NF-κB inflammatory pathway in regulating osteoclast formation and describes the secretions produced by Bifidobacterium and their potential effects on bone health through this pathway, opening up new directions for future research.

Bad players in AL amyloidosis in the current era of treatment

INTRODUCTION

Systemic AL amyloidosis (ALA) is a clonal plasma cell (PC) disease characterized by deposition of amyloid fibrils in different organs and tissues. Traditionally, the prognosis of ALA is poor and is primarily defined by cardiac involvement. The modern prognostic models are based on cardiac markers and free light chain difference (dFLC). Cardiac biomarkers have low specificity and are dependent on renal function, volume status, and cardiac diseases other than ALA. New therapies significantly improved the prognosis of the disease. The advancements in technologies - cardiac echocardiography (ECHO) and cardiac MRI (CMR), as well as new biological markers, relying on cardiac injury, inflammation, endothelial damage, and clonal and non-clonal PC markers are promising.

AREAS COVERED

An update on the prognostic significance of cardiac ALA, number of involved organs, response to treatment, including minimal residual disease (MRD), ECHO, MRI, and new biological markers will be discussed. The literature search was done in PubMed and Google Scholar, and the most recent and relevant data are included.

EXPERT OPINION

Prospective multicenter trials, evaluating multiple clinical and laboratory parameters, should be done to improve the risk assessment models in ALA in the modern era of therapy.

Evaluation of an association between RANKL and OPG with bone disease in people with cystic fibrosis

BACKGROUND

As people with Cystic Fibrosis (CF) live longer, extra-pulmonary complications such as CF-related bone disease (CFBD) are becoming increasingly important. The etiology of CFBD is poorly understood but is likely multifactorial. Bones undergo continuous remodeling via pathways including RANK (receptor activator of NF-κB)/sRANKL (soluble ligand)/OPG (osteoprotegerin). We sought to examine the association between sRANKL (stimulant of osteoclastogenesis) and OPG levels (inhibitor of osteoclast formation) and CFBD to investigate their potential utility as biomarkers of bone turnover in people with CF.

METHODS

We evaluated sRANKL and OPG in plasma from people with CF and healthy controls (HC) and compared levels in those with CF to bone mineral density results. We used univariable and multivariable analysis to account for factors that may impact sRANKL and OPG.

RESULTS

We found a higher median [IQR] sRANKL 10,896pg/mL [5,781-24,243] CF; 2,406pg.mL [659.50-5,042] HC; p= 0.0009), lower OPG 56.68pg/mL [36.28-124.70] CF; 583.20pg/mL [421.30-675.10] HC; p < 0.0001), and higher RANKL/OPG in people with CF no BD than in HC (p < 0.0001). Furthermore, we found a higher RANKL/OPG ratio 407.50pg/mL [214.40-602.60] CFBD; 177.70pg/mL [131.50-239.70] CF no BD; p = 0.007) in people with CFBD versus CF without bone disease. This difference persisted after adjusting for variables thought to impact bone health.

CONCLUSIONS

The current screening recommendations of imaging for CFBD may miss important markers of bone turnover such as the RANKL/OPG ratio. These findings support the investigation of therapies that modulate the RANK/RANKL/OPG pathway as potential therapeutic targets for bone disease in CF.

Bone Cells Metabolic Changes Induced by Ageing

Bone is a living organ that exhibits active metabolic processes, presenting constant bone formation and resorption. The bone cells that maintain local homeostasis are osteoblasts, osteoclasts, osteocytes and bone marrow stem cells, their progenitor cells. Osteoblasts are the main cells that govern bone formation, osteoclasts are involved in bone resorption, and osteocytes, the most abundant bone cells, also participate in bone remodeling. All these cells have active metabolic activities, are interconnected and influence each other, having both autocrine and paracrine effects. Ageing is associated with multiple and complex bone metabolic changes, some of which are currently incompletely elucidated. Ageing causes important functional changes in bone metabolism, influencing all resident cells, including the mineralization process of the extracellular matrix. With advancing age, a decrease in bone mass, the appearance of specific changes in the local microarchitecture, a reduction in mineralized components and in load-bearing capacity, as well as the appearance of an abnormal response to different humoral molecules have been observed. The present review points out the most important data regarding the formation, activation, functioning, and interconnection of these bone cells, as well as data on the metabolic changes that occur due to ageing.

Effects of Lactobacillus reuteri MG5346 on Receptor Activator of Nuclear Factor-Kappa B Ligand (RANKL)-Induced Osteoclastogenesis and Ligature-Induced Experimental Periodontitis Rats

Effects of culture supernatants of Lactobacillus reuteri MG5346 (CS-MG5346) on receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclastogenesis were examined. CS-MG5346 treatment up to 400 μg/mL significantly reduced tartrate-resistant acid-phosphatase (TRAP) activity, the phenotype biomarker of osteoclast, without affecting cell viability. CS-MG5346 inhibited the expression of osteoclast specific transcriptional factors (c-fos and nuclear factor-activated T cells c1) and their target genes (TRAP, cathepsin, and matrix metallo-proteinase-9) in a dose-dependent manner (p<0.05). The administration of L. reuteri MG5346 (2×10⁸ CFU/day) for 8 wks significantly improved furcation involvement, but no difference was observed in alveolar bone loss in ligature-induced experimental periodontitis rats. The elevated RANKL/ osteoprotegerin ratio, the biomarker of periodontitis, was significantly lowered in the gingival tissue by administration of L. reuteri MG5346 (p<0.05). L. reuteri MG5346 showed excellent stability in simulated stomach and intestinal fluids and did not have antibiotic resistance. Based on the results, L. reuteri MG5346 has the potential to be a promising probiotic strain for oral health.

The use of bone-modifying agents in multiple myeloma

Multiple myeloma is a hematological neoplasm characterized by abnormal proliferation of plasma cells in the bone marrow and is usually associated with increased bone pain and skeletal-related events such as pathological fracture and/or spinal cord compression. Myeloma bone disease results in changes in the bone-marrow microenvironment evidenced by increased osteoclastic activity and/or decreased osteoblastic activity, which negatively affect quality of life. Treatment of myeloma bone disease includes bisphosphonates or denosumab (bone-modifying agents). These agents do not induce the formation of new bone or repair existing bone damage, but they can decrease bone pain and the risk of pathological fracture. While these agents improve quality of life, it is not known whether they improve overall survival. This review focuses on different classes of bone-modifying agents, their mechanisms of action, time of initiation, duration of therapy, and potential survival benefits.

Influence of Bone Substitutes on Mesenchymal Stromal Cells in an Inflammatory Microenvironment

Bone regeneration is driven by mesenchymal stromal cells (MSCs) via their interactions with immune cells, such as macrophages (MPs). Bone substitutes, e.g., bi-calcium phosphates (BCPs), are commonly used to treat bone defects. However, little research has focused on MSC responses to BCPs in the context of inflammation. The objective of this study was to investigate whether BCPs influence MSC responses and MSC-MP interactions, at the gene and protein levels, in an inflammatory microenvironment. In setup A, human bone marrow MSCs combined with two different BCP granules (BCP 60/40 or BCP 20/80) were cultured with or without cytokine stimulation (IL1β + TNFα) to mimic acute inflammation. In setup B, U937 cell-line-derived MPs were introduced via transwell cocultures to setup A. Monolayer MSCs with and without cytokine stimulation served as controls. After 72 h, the expressions of genes related to osteogenesis, healing, inflammation and remodeling were assessed in the MSCs via quantitative polymerase chain reactions. Additionally, MSC-secreted cytokines related to healing, inflammation and chemotaxis were assessed via multiplex immunoassays. Overall, the results indicate that, under both inflammatory and non-inflammatory conditions, the BCP granules significantly regulated the MSC gene expressions towards a pro-healing genotype but had relatively little effect on the MSC secretory profiles. In the presence of the MPs (coculture), the BCPs positively regulated both the gene expression and cytokine secretion of the MSCs. Overall, similar trends in MSC responses were observed with BCP 60/40 and BCP 20/80. In summary, within the limits of in vitro models, these findings suggest that the presence of BCP granules at a surgical site may not necessarily have a detrimental effect on MSC-mediated wound healing, even in the event of inflammation.

The Use of Polymers to Enhance Post-Orthodontic Tooth Stability

Relapse after orthodontic treatment occurs at a rate of about 70 to 90%, and this phenomenon is an orthodontic issue that has not yet been resolved. Retention devices are one attempt at prevention, but they require a considerable amount of time. Most orthodontists continue to find it challenging to manage orthodontic relapse; therefore, additional research is required. In line with existing knowledge regarding the biological basis of relapse, biomedical engineering approaches to relapse regulation show promise. With so many possible uses in biomedical engineering, polymeric materials have long been at the forefront of the materials world. Orthodontics is an emerging field, and scientists are paying a great deal of attention to polymers because of their potential applications in this area. In recent years, the controlled release of bisphosphonate risedronate using a topically applied gelatin hydrogel has been demonstrated to be effective in reducing relapse. Simvastatin encapsulation in exosomes generated from periodontal ligament stem cells can promote simvastatin solubility and increase the inhibitory action of orthodontic relapse. Moreover, the local injection of epigallocatechin gallate-modified gelatin suppresses osteoclastogenesis and could be developed as a novel treatment method to modify tooth movement and inhibit orthodontic relapse. Furthermore, the intrasulcular administration of hydrogel carbonated hydroxyapatite-incorporated advanced platelet-rich fibrin has been shown to minimize orthodontic relapse. The objective of this review was to provide an overview of the use of polymer materials to reduce post-orthodontic relapse. We assume that bone remodeling is a crucial factor even though the exact process by which orthodontic correction is lost after retention is not fully known. Delivery of a polymer containing elements that altered osteoclast activity inhibited osteoclastogenesis and blocking orthodontic relapse. The most promising polymeric materials and their potential orthodontic uses for the prevention of orthodontic relapse are also discussed.

RANKL neutralisation prevents osteoclast activation in a human in vitro ameloblastoma-bone model

Ameloblastoma is a benign, locally invasive epithelial odontogenic neoplasm of the jaw. Treatment of choice is jaw resection, often resulting in significant morbidity. The aim of this study was to recapitulate ameloblastoma in a completely humanised 3D disease model containing ameloblastoma cells, osteoblasts and activated osteoclasts to investigate the RANKL pathway within the ameloblastoma stromal environment and its response to the RANKL antibody denosumab. In vitro bone was engineered by culturing human osteoblasts (hOB) in a biomimetic, dense collagen type I matrix, resulting in extensive mineral deposits by day 21 forming alizarin red positive bone like nodules throughout the 3D model. Activated TRAP + human osteoclasts were confirmed through the differentiation of human CD14+ monocytes after 10 days within the model. Lastly, the ameloblastoma cell lines AM-1 and AM-3 were incorporated into the 3D model. RANKL release was validated through TACE/ADAM17 activation chemically or through hOB co-culture. Denosumab treatment resulted in decreased osteoclast activation in the presence of hOB and ameloblastoma cells. These findings stress the importance of accurately modelling tumour and stromal populations as a preclinical testing platform.

Metal-phenolic networks acted as a novel bio-filler of a barrier membrane to improve guided bone regeneration via manipulating osteoimmunomodulation

A guided bone tissue regeneration membrane (GBRM) is traditionally viewed as an inert physical barrier to isolate soft tissue from the bone defect area. However, as a "foreign body", the implantation of a GBRM would inevitably modulate immune response and subsequently affect bone dynamics. Herein, we developed strontium ion (Sr²⁺)-based metal-phenolic network complexes (MPNs) as a novel type of bio-filler to manipulate the osteoimmunomodulation of the advanced GBRM. For controllable delivery of Sr²⁺ depending on the difference in affinity between phenolic ligands and Sr²⁺, tannic acid (TA), epigallocatechin gallate (EGCG), and epigallocatechin (EGC) were selected to chelate with Sr²⁺. The formed MPNs were incorporated into PCL nanofibrous membranes by blending electrospinning. Among them, TA/Sr based MPN particles displayed the most sustainable release profile of phenolic ligands and Sr²⁺. Further investigations demonstrated that Sr²⁺ could not only directly promote osteogenic differentiation of BMSCs, but also manipulate an anti-inflammatory osteoimmune microenvironment in a synergistic manner with TA, thus enhancing osteogenesis and inhibiting bone resorption. The rat alveolar bone defect model also confirmed that the TA/Sr nanoparticle modified membrane displayed better bone regeneration performance than the pure PCL membrane via inhibiting bone resorption. This work provides a new platform for controllable delivery of bioactive nutrient elements, and holds great promise for advancing multi-functional biocomposites.

Modulatory Effect of Gut Microbiota on the Gut-Brain, Gut-Bone Axes, and the Impact of Cannabinoids

The gut microbiome is a collection of microorganisms and parasites in the gastrointestinal tract. Many factors can affect this community's composition, such as age, sex, diet, medications, and environmental triggers. The relationship between the human host and the gut microbiota is crucial for the organism's survival and development, whereas the disruption of this relationship can lead to various inflammatory diseases. Cannabidiol (CBD) and tetrahydrocannabinol (THC) are used to treat muscle spasticity associated with multiple sclerosis. It is now clear that these compounds also benefit patients with neuroinflammation. CBD and THC are used in the treatment of inflammation. The gut is a significant source of nutrients, including vitamins B and K, which are gut microbiota products. While these vitamins play a crucial role in brain and bone development and function, the influence of gut microbiota on the gut-brain and gut-bone axes extends further and continues to receive increasing scientific scrutiny. The gut microbiota has been demonstrated to be vital for optimal brain functions and stress suppression. Additionally, several studies have revealed the role of gut microbiota in developing and maintaining skeletal integrity and bone mineral density. It can also influence the development and maintenance of bone matrix. The presence of the gut microbiota can influence the actions of specific T regulatory cells, which can lead to the development of bone formation and proliferation. In addition, its metabolites can prevent bone loss. The gut microbiota can help maintain the bone's equilibrium and prevent the development of metabolic diseases, such as osteoporosis. In this review, the dual functions gut microbiota plays in regulating the gut-bone axis and gut-brain axis and the impact of CBD on these roles are discussed.

Omega-3 fatty acid and menaquinone-7 combination are helpful for aortic calcification prevention, reducing osteoclast area of bone and Fox0 expression of muscle in uremic rats

BACKGROUND

Osteopenia, sarcopenia, and vascular calcification (VC) are prevalent in patients with chronic kidney disease and often coexist. In the absence of proven therapies, it is necessary to develop therapeutic or preventive nutrients supplementation for osteopenia, sarcopenia, and VC. The present study investigated the effect of omega-3 fatty acid (FA) and menaquinone-7 (MK-7) on osteopenia, sarcopenia, and VC in adenine and low-protein diet-induced uremic rats.

METHODS

Thirty-two male Sprague-Dawley rats were fed diets containing 0.75% adenine and 2.5% protein for three weeks. Rats were randomly divided into four groups that were fed diets containing 2.5% protein for four weeks: adenine control (0.9% saline), omega-3 FA (300 mg/kg/day), MK-7 (50 µg/kg/day), and omega-3 FA/MK-7. Von Kossa staining for aortic calcification assessment was performed. Osteoclast surface/bone surface ratio (OcS/BS) of bone and muscle fiber were analyzed using hematoxylin and eosin staining. Osteoprotegerin (OPG) immunohistochemical staining was done in the aorta and bone. Molecules related with sarcopenia were analyzed using western blotting.

RESULTS

Compared to the normal control, OcS/BS and aortic calcification, and OPG staining in the aorta and bone were significantly increased in the adenine controls. OPG staining and aortic calcification progressed the least in the group supplemented with both omega-3 FA/MK-7. In the adenine controls, the regular arrangement of muscle fiber was severely disrupted, and inflammatory cell infiltration was more prominent. These findings were reduced after combined supplementation with omega-3 FA/MK-7. Furthermore, decreased mammalian target of rapamycin and increased Forkhead box protein 1 expression was significantly restored by combined supplementation.

CONCLUSIONS

Combined nutrients supplementation with omega-3 FA and MK-7 may be helpful for aortic VC prevention, reducing osteoclast activation and improving sarcopenia-related molecules in adenine and low-protein diet induced uremic rats.

Advances in Diagnosis and Management of Childhood Osteoporosis

Childhood osteoporosis leads to increased propensity to fracture, and thus is an important cause of morbidity, pain and healthcare utilisation. Osteoporosis in children may be caused by a primary bone defect or secondary to an underlying medical condition and/or its treatment. Primary osteoporosis is rare, but there is an increasing number of children with risk factors for secondary osteoporosis. Therefore it is imperative that all paediatricians are aware of the diagnostic criteria and baseline investigations for childhood osteoporosis to enable timely referral to a specialist in paediatric bone health. This review will discuss the approach to diagnosis, investigation and management of childhood osteoporosis, with particular consideration to advances in molecular diagnosis of primary bone disorders, and current and emerging therapies for fracture reduction.

Topography-mediated immunomodulation in osseointegration; Ally or Enemy

Osteoimmunology is at full display during endosseous implant osseointegration. Bone formation, maintenance and resorption at the implant surface is a result of bidirectional and dynamic reciprocal communication between the bone and immune cells that extends beyond the well-defined osteoblast-osteoclast signaling. Implant surface topography informs adherent progenitor and immune cell function and their cross-talk to modulate the process of bone accrual. Integrating titanium surface engineering with the principles of immunology is utilized to harness the power of immune system to improve osseointegration in healthy and diseased microenvironments. This review summarizes current information regarding immune cell-titanium implant surface interactions and places these events in the context of surface-mediated immunomodulation and bone regeneration. A mechanistic approach is directed in demonstrating the central role of osteoimmunology in the process of osseointegration and exploring how regulation of immune cell function at the implant-bone interface may be used in future control of clinical therapies. The process of peri-implant bone loss is also informed by immunomodulation at the implant surface. How surface topography is exploited to prevent osteoclastogenesis is considered herein with respect to peri-implant inflammation, osteoclastic precursor-surface interactions, and the upstream/downstream effects of surface topography on immune and progenitor cell function.

Rb1 negatively regulates bone formation and remodeling through inhibiting transcriptional regulation of YAP in Glut1 and OPG expression and glucose metabolism in male mice

OBJECTIVE

Bone is a highly dynamic organ that undergoes constant bone formation and remodeling, and glucose as a major nutrient is necessary for bone formation and remodeling. Retinoblastoma (Rb1) is a critical regulator of mesenchymal stem cells (MSCs) fate, but how Rb1 regulates bone formation and remodeling is poorly understood.

METHODS

We generated MSCs- and osteoprogenitors-specific Rb1 knockout mouse models and utilized these models to explore the function and mechanism of Rb1 in regulating bone formation and remodeling in vivo and in vitro primary cell culture.

RESULTS

Rb1 deficiency in MSCs significantly increased bone mass and impaired osteoclastogenesis. Consistently, depletion of Rb1 in osteoprogenitors significantly promoted bone formation. Mechanistically, loss of Rb1 in MSCs elevated YAP nuclear translocation and transcriptional activity of YAP/TEAD1 complex, thereby increasing the transcriptional expression of Glut1 and OPG. Moreover Prx1-Cre; Rb1f/f mice displayed hypoglycemia with increased systemic glucose tolerance instead of increased insulin level. In vitro data revealed that Rb1-mutant MSCs enhanced glucose uptake and lactate and ATP production. Increased osteogenesis caused by increased glucose metabolism and decreased osteoclastogenesis caused by increased expression of OPG eventually resulted in increased bone formation and remodeling.

CONCLUSIONS

Collectively, these findings demonstrated that Rb1 in MSCs inhibits YAP-medicated Glut1 and OPG expression to control glucose metabolism, osteogenesis and osteoclastogenesis during bone formation and remodeling, which provide new insights that controlling Rb1 signaling may be a potential strategy for osteopetrosis.

Histological and Biochemical Analysis after Posterior Mandibular Displacement in Rats

Simple Summary

The lower jaw has a particular contribution to the human appearance, and so it is not uncommon for people to seek treatment in cases of its extreme growth. The orthodontist often selects to place intraoral devices in order to address the problem. This study used healthy young rats to guide their lower jaws backward. Measurements of biochemical molecules in blood that are related to bone metabolism did not reveal any statistically significant differences. However, noteworthy local microscopic alterations of the condyle were evidenced. They involved histological changes in bone structure and the thickness of cartilage. In conclusion, it seems that the procedure under study might not cause any severe organic disturbance in the lab animals under the conditions of the experiment. Only minor histological effects on condylar morphology were observed.

Abstract

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.

Risk association of RANKL and OPG gene polymorphism with breast cancer to bone metastasis in Pashtun population of Khyber Pakhtunkhwa, Pakistan

Introduction

The receptor activator NF-κB ligand (RANKL) and Osteoprotegrin (OPG) single nucleotide polymorphisms (SNPs) have been associated with the risk of breast cancer to bone metastasis. This study was designed to investigate the association of RANKL and OPG gene polymorphisms with breast to bone metastasis in Pashtun population of Khyber Pakhtunkhwa, Pakistan.

Materials and methods

A total of 215 participants were enrolled containing 106 breast cancer patients, 58 breast to bone metastasis and 51 age and gender matched healthy controls. RANKL (rs9533156) and OPG (rs2073618, rs3102735) polymorphisms were genotyped in genomic DNA, using Tetra-ARMS PCR protocol. The results were analyzed among the three groups and P-value less then 0.05 were considered statistically significant.

Results

Our results displayed significant association of OPG (rs3102735) risk allele and corresponding genotypes in breast cancer vs healthy controls, bone metastasis vs healthy controls and breast cancer vs breast to bone metastasis as a disease risk. However, there was no association observed for OPG (rs2073618) risk allele and corresponding genotypes with the diseases risk. Similarly, RANKL (rs9533156) risk allele and corresponding genotypes in breast cancer vs healthy controls, bone metastasis vs healthy controls and breast cancer vs breast to bone metastasis exhibited significant association except for the risk allele carrying genotypes in breast to bone metastasis.

Conclusion

OPG (rs3102735) and RANKL (rs9533156) exhibited significant association with breast to bone metastasis while OPG (rs2073618) didn’t show significant association with breast to bone metastasis in Pashtun population of Pakistan. However, this study unlocks more questions to investigate the exact scenario of genetic predisposition of breast to bone metastasis.

Cytokine-mediated immunomodulation of osteoclastogenesis

Cytokines are an important set of proteins regulating bone homeostasis. In inflammation induced bone resorption, cytokines, such as RANKL, TNF-α, M-CSF, are indispensable for the differentiation and activation of resorption-driving osteoclasts, the process we know as osteoclastogenesis. On the other hand, immune system produces a number of regulatory cytokines, including IL-4, IL-10 and IFNs, and limits excessive activation of osteoclastogenesis and bone loss during inflammation. These unique properties make cytokines powerful targets as rheostat to maintain bone homeostasis and for potential immunotherapies of inflammatory bone diseases. In this review, we summarize recent advances in cytokine-mediated regulation of osteoclastogenesis and provide insights of potential translational impact of bench-side research into clinical treatment of bone disease.

Resistance circuit training combined with hypoxia stimulates bone system of older adults: A randomized trial

PURPOSE

Aging leads to gradual irreversible decline in bone mass. As adherence to pharmacological treatment is poor, hypoxia combined with strength training has been suggested for therapeutic benefit for clinical populations. The present study investigated the effects of normobaric cyclic hypoxic exposure combined with resistance circuit training on bone of older adults.

METHODS

Healthy older adults (n = 50) were randomly assigned to a (1) control group (CON; n = 20), who were instructed to continue with their normal daily activities, (2) a group that performed resistance training in normoxia (RTN; n = 17) and (3) a group that performed resistance training in hypoxia (RTH; n = 13). During 24 weeks, RTH group performed resistance training with elastic bands under normobaric hypoxic conditions (16.1 % FiO2). A session of both exercise groups included nine exercises of several body areas with a structure of 3 sets × 12-15 repetitions per exercise, with a 1-minute rest between sets. Bone mineral density (g·cm-2) was measured using dual-energy X-ray absorptiometry. Bone turnover markers of formation (N-terminal propeptide of type I procollagen; PINP) and resorption (C-terminal telopeptide of type I collagen; bCTX) were analysed with enzyme-linked immunosorbent assay (ELISA) microplate reader.

RESULTS

Values of bCTX and bCTX/PINP significant decreased in RTN (bCTX: 47.79 %; p = 0.002; bCTX/PINP: 61.43 %; p = 0.007) and RTH (bCTX: 59.09 %; p = 0.001; bCTX/PINP: 62.61 %; p = 0.003) groups compared with CON group. Change in bone mineral density was not significantly different between groups. Based on clinically significant change, 23 % of the participants in the RTH group reached this value for femoral neck and trochanter bone mineral density (vs 0 % and 6 % of the RTN group, respectively).

CONCLUSIONS

24-Weeks of normobaric cyclic hypoxic exposure combined with resistance circuit training has potential to generate positive effects on bone in older adults.

TRIAL REGISTRATION NUMBER

NCT04281264 (date of registration: February 24, 2020).

Hypoxia-inducible factor 1α enhances RANKL-induced osteoclast differentiation by upregulating the MAPK pathway

Background

Hypoxia (low-oxygen tension) and excessive osteoclast activation are common conditions in many bone loss diseases, such as osteoporosis, rheumatoid arthritis (RA), and pathologic fractures. Hypoxia-inducible factor 1 alpha (HIF1α) regulates cellular responses to hypoxic conditions. However, it is not yet known how HIF1α directly affects osteoclast differentiation and activation. This study sought to. explore the effects of HIF1α on osteoclast differentiation and it's molecular mechanisms.

Methods

L-mimosine, a prolyl hydroxylase (PHDs) domain inhibitor, was used to stabilize HIF1α in normoxia. In the presence of receptor activator of nuclear factor-kB (NF-kB) ligand (RANKL), RAW264.7 cells were cultured and stimulated by treatment with L-mimosine at several doses to maintain various levels of intracellular HIF1α. The multi-nucleated cells were assessed by a tartrate-resistant acid phosphatase (TRAP) and F-actin ring staining assays. The osteoclast-specific genes, such as Cathepsin K, β3-Integrin, TRAP, c-Fos, nuclear factor of activated T cells, cytoplasmic 1 (NFATc1), and matrix metallo-proteinase 9 (MMP9), were analyzed by real time-polymerase chain reaction (RT-PCR). The expression of relevant proteins was analyzed by Western blot.

Results

L-mimosine increased the content of intracellular HIF1α in a dose-dependent manner, which in turn promoted RANKL-induced osteoclast formation and relevant protein expression by upregulating the mitogen-activated protein kinase (MAPK) pathways.

Conclusions

Our findings suggest that HIF1α directly increases the osteoclast differentiation of RANKL-mediated RAW264.7 cells in vitro by upregulating the MAPK pathways.

How osteogenic is dexamethasone?—effect of the corticosteroid on the osteogenesis, extracellular matrix, and secretion of osteoclastogenic factors of jaw periosteum-derived mesenchymal stem/stromal cells

Dexamethasone (dexa) is commonly used to stimulate osteogenic differentiation of mesenchymal stem/stromal cells (MSCs) in vitro. However, it is paradoxical that glucocorticoids (GCs) such as dexa lead to bone loss and increased fracture risk in patients undergoing glucocorticoid therapy, causing glucocorticoid-induced osteoporosis (GIOP). In a recent publication, we demonstrated that osteogenic differentiation of progenitor cells isolated from jaw periosteal tissue (JPCs) does not depend on dexa, if the medium is supplemented with human platelet lysate (hPL) instead of fetal bovine serum (FBS). This allows the in vitro conditions to be much closer to the natural situation in vivo and enables us to compare osteogenic differentiation with and without dexa. In the present study, we demonstrate that the absence of dexa did not reduce mineralization capacity, but instead slightly improved the osteogenic differentiation of jaw periosteal cells. On the other hand, we show that dexa supplementation strongly alters the gene expression, extracellular matrix (ECM), and cellular communication of jaw periosteal cells. The secretome of periosteal cells previously treated with an osteogenic medium with and without dexa was used to investigate the changes in paracrine secretion caused by dexa. Dexa altered the secretion of several cytokines by jaw periosteal cells and strongly induced osteoclast differentiation of peripheral blood mononuclear cells (PBMCs). This study demonstrates how dexa supplementation can influence the outcome of in vitro studies and highlights a possible role of periosteal cells in the pathogenesis of glucocorticoid-induced osteoporosis. The methods used here can serve as a model for studying bone formation, fracture healing, and various pathological conditions such as (glucocorticoid-induced) osteoporosis, osteoarthritis, bone cancer, and others, in which the interactions of osteoblasts with surrounding cells play a key role.

Effect of Lymphocyte Subsets on Bone Density in Senile Osteoporosis: A Retrospective Study

Background

Several studies have shown that lymphocyte subsets can mediate the occurrence of osteoporosis (OP); however, the predictive ability of lymphocyte subsets in senile OP has not been elucidated.

Purpose

To investigate the ability of lymphocyte subsets to predict senile osteoporosis (OP).

Methods and Materials

This study included 44 patients with senile OP and 44 without OP. Dual-energy X-ray absorptiometry (DEXA) was used to determine bone mineral density (BMD). Flow cytometry was used to analyze the absolute counts of the lymphocyte subsets and cytokine levels. Finally, the correlation between BMD and lymphocyte subset counts in the two groups was analyzed.

Results

There were no significant differences in age, sex, or weight between the OP and non-OP groups. The absolute counts of total T lymphocytes and CD8+ T lymphocytes in the OP group were significantly lower than those in the non-OP group. The levels of IFN-γ or TNF-α in the OP group were significantly higher or lower, respectively, than those in the non-OP group. PCA showed that age, BMI, total T lymphocytes, CD4+ T lymphocytes, CD8+ T lymphocytes, and B lymphocytes were the principal components of senile OP. The linear regression equation showed that BMD of the right femoral neck significantly decreased with a decline in CD8+ T lymphocyte counts.

Conclusion

BMD decreased with a decrease in CD8+ T lymphocytes. The mechanism by which lower lymphocyte subsets lead to lower BMD may be related to abnormal bone metabolism caused by immune aging. Therefore, we considered that CD8+ T lymphocytes could be used to predict the incidence of senile OP.

The Impact of an Adapted Physical Activity Program on Bone Turnover, Physical Performance and Fear of Falling in Osteoporotic Women with Vertebral Fractures: A Quasi-Experimental Pilot Study

Physical activity has been indicated as a potential strategy to counteract osteoporosis (OP). This study of post-menopausal women with osteoporotic vertebral fractures investigated the effect of an adapted physical activity (APA) program on two serum bone turnover biomarkers (Bone Alkaline Phosphatase, B-ALP and C-terminal telopeptide of type 1 collagen, CTX-1), functional capacity (6-Minutes Walking Test, 6MWT), and risk and fear of falls (Tinetti and Falls Efficacy scale). The APA group (n = 12) performed a 1-h group session twice per week for 6 months whereas the control group (n = 9) was asked to maintain their current lifestyle. The exercise program did not affect the serum concentrations of B-ALP and CTX-1 biomarkers measured at the baseline and after 6 months in women of the APA group. Moreover, at the end of intervention no significant differences in serum concentrations for either biomarker was observed between the two study groups. Interestingly, when compared to the control group, women in the APA group showed significant improvement in the functional capacity measures by 6MWT (p = 0.037) and a decrease of the risk and fear of falls as indicated by the Tinetti test (p = 0.043). Based on these findings, exercise could provide new perspectives for the care and management of OP.

Mechanisms of promoting the differentiation and bone resorption function of osteoclasts by Staphylococcus aureus infection

Bone infection is a common and serious complication in the field of orthopedics, which frequently leads to excessive bone destruction and fracture nonunion. Staphylococcus aureus (S. aureus) infection affects bone cell function which, in turn, causes bone destruction. Bone is mainly regulated by osteoblasts and osteoclasts. Osteoclasts are the only cell type with bone resorptive function. Their over-activation is closely associated with excessive bone loss. Understanding how S. aureus changes the functional state of osteoclasts is the key to effective treatment. By reviewing the literature, this paper summarizes several mechanisms of bone destruction caused by S. aureus influencing osteoclasts, thereby stimulating new ideas for the treatment of bone infection.

FTY720 administration results in a M2 associated immunoregulatory effect that positively influences the outcome of alveolar bone repair outcome in mice

The alveolar bone repair process may be influenced by multiple local and systemic factors, which include immune system cells and mediators. Macrophages allegedly play important roles in the repair process, and the transition of an initial inflammatory M1 profile into a pro-reparative M2 profile theoretically contributes to a favorable repair outcome. In this context, considering immunoregulatory molecules as potential targets for improving bone repair, this study evaluated the role of the immunoregulatory molecule FTY720, previously described to favor the development of the M2 phenotype, in the process of alveolar bone healing in C57Bl/6 (WT) mice. Experimental groups submitted to tooth extraction and maintained under control conditions or treated with FTY720 were evaluated by microtomographic (μCT), histomorphometric, immunohistochemical and molecular analysis to characterize healing and host response features at 0, 1, 3, 7 and 14 days. Our results demonstrated that the FTY720 group presented higher bone tissue density, higher bone tissue volume, greater tissue volume fraction, greater number and thickness of trabeculae and a higher number of osteoblasts and osteoclasts than the control group. Accordingly, the bone markers BMP2, BMP7, ALPL, SOST and RANK mRNA expressions increased in the FTY720 treated group. Furthermore, the levels of FIZZ, ARG2 and IL-10 mRNA increased in the FTY720 group together with the presence of CD206⁺ cells, suggesting that the boost of bone formation mediated by FTY720 involves an increased polarization and activity of M2 macrophages in healing sites. Thus, our results demonstrate that FTY720 favored the process of alveolar bone repair, probably trough a strengthened M2 response, associated with an increased expression of markers osteogenic differentiation and activity markers. Immunoregulatory strategies based in the modulation of macrophage polarization profile can comprise effective tools to improve the bone repair process.

Mussaendoside O, a N-triterpene cycloartane saponin, attenuates RANKL-induced osteoclastogenesis and inhibits lipopolysaccharide-induced bone loss

BACKGROUND

Elevated activity of osteoclasts (OCs) is linked to osteolytic bone diseases, such as osteoporosis and rheumatoid arthritis. Developing natural anti-osteoclastogenic compounds with greater efficacy and fewer adverse effects is crucial for preventing or treating osteolytic bone diseases. N-triterpene cycloartane saponins (NTCSs) are rarely found in nature, and their inhibitory effects on OC differentiation in vitro and in vivo have not yet been explored.

PURPOSE

This study was aimed to investigate the effect of mussaendoside O, an NTCS isolated from Mussaenda pubescens, on RANKL-induced OC differentiation and its underlying mechanism in vitro, and lipopolysaccharide (LPS)-induced bone resorption in a mouse model.

METHODS

The content of mussaendoside O in methanol extract of M. pubescens was determined by HPLC. The inhibitory effects of mussaendoside O on RANKL-induced OC formation were assessed using TRAP staining, western blotting, immunofluorescence staining, and real-time qPCR. Meanwhile, the effects of mussaendoside O on LPS-induced inflammatory responses were assessed using a Griess reagent and qPCR. The effects of mussaendoside O on LPS-induced bone resorption in a mouse model were evaluated using micro-CT and immunohistochemical staining.

RESULTS

Mussaendoside O inhibited RANKL-induced TRAP-positive multinucleated OC formation in a concentration-dependent manner without affecting cell viability. However, mussaendoside O did not inhibit LPS-induced mRNA expression of COX-2, iNOS, and TNF-α. Mice orally administrated with mussaendoside O exhibited significant protection from LPS-induced bone resorption and OC formation. At the molecular level, mussaendoside O suppressed RANKL-activated phosphorylation of p38 MAPK and JNK, as well as c-Fos expression. In addition, mussaendoside O suppressed RANKL-induced NFATc1 activation and the expression of its target genes, including OSCAR, DC-STAMP, CtsK, and TRAP.

CONCLUSION

Mussaendoside O attenuates OC differentiation in vitro and LPS-induced bone resorption in a mouse model by inhibiting the RANKL-activated c-Fos/NFATc1 signaling pathways. Therefore, mussaendoside O may be a valuable lead compound for preventing or treating of osteolytic bone diseases.

Long-term stimulation with alternating electric fields modulates the differentiation and mineralization of human pre-osteoblasts

Biophysical stimulation by electric fields can promote bone formation in bone defects of critical size. Even though, long-term effects of alternating electric fields on the differentiation of osteoblasts are not fully understood. Human pre-osteoblasts were stimulated over 31 days to gain more information about these cellular processes. An alternating electric field with 0.7 V_rms and 20 Hz at two distances was applied and viability, mineralization, gene expression, and protein release of differentiation factors were analyzed. The viability was enhanced during the first days of stimulation. A higher electric field resulted in upregulation of typical osteogenic markers like osteoprotegerin, osteopontin, and interleukin-6, but no significant changes in mineralization. Upregulation of the osteogenic markers could be detected with a lower electric field after the first days of stimulation. As a significant increase in the mineralized matrix was identified, an enhanced osteogenesis due to low alternating electric fields can be assumed.

A 92 protein inflammation panel performed on sonicate fluid differentiates periprosthetic joint infection from non-infectious causes of arthroplasty failure

Periprosthetic joint infection (PJI) is a major complication of total joint arthroplasty, typically necessitating surgical intervention and prolonged antimicrobial therapy. Currently, there is no perfect assay for PJI diagnosis. Proteomic profiling of sonicate fluid has the potential to differentiate PJI from non-infectious arthroplasty failure (NIAF) and possibly clinical subsets of PJI and/or NIAF. In this study, 200 sonicate fluid samples, including 90 from subjects with NIAF (23 aseptic loosening, 35 instability, 10 stiffness, five osteolysis, and 17 other) and 110 from subjects with PJI (40 Staphylococcus aureus, 40 Staphylococcus epidermidis, 10 Staphylococcus lugdunensis, 10 Streptococcus agalactiae, and 10 Enterococcus faecalis) were analyzed by proximity extension assay using the 92 protein Inflammation Panel from Olink Proteomics. Thirty-seven of the 92 proteins examined, including CCL20, OSM, EN-RAGE, IL8, and IL6, were differentially expressed in PJI versus NIAF sonicate fluid samples, with none of the 92 proteins differentially expressed between staphylococcal versus non-staphylococcal PJI, nor between the different types of NIAF studied. IL-17A and CCL11 were differentially expressed between PJI caused by different bacterial species, with IL-17A detected at higher levels in S. aureus compared to S. epidermidis and S. lugdunensis PJI, and CCL11 detected at higher levels in S. epidermidis compared to S. aureus and S. agalactiae PJI. Receiver operative characteristic curve analysis identified individual proteins and combinations of proteins that could differentiate PJI from NIAF. Overall, proteomic profiling using this small protein panel was able to differentiate between PJI and NIAF sonicate samples and provide a better understanding of the immune response during arthroplasty failure.

Oat Seedlings Extract Inhibits RANKL-Induced c-Fos/NFATc1 Transcription Factors in the Early Stage of Osteoclast Differentiation

Osteoporosis is a common disease that increases the risk of fractures due to decreased bone density and weakens the bone microstructure. Preventing and diagnosing osteoporosis using the available drugs can be a costly affair with possible side effects. Therefore, natural product-derived therapeutics are promising alternatives. Our study demonstrated that the oat seedlings' extract (OSE) inhibited the receptor activator of the nuclear factor κB ligand (RANKL)-induced osteoclastogenesis from the bone marrow-derived macrophages (BMMs). The OSE treatment significantly attenuated the RANKL-mediated induction of the tartrate-resistant acid phosphatase (TRAP) activity as well as the number of TRAP-positive (TRAP+) multinucleated cells (MNCs) counted through the TRAP staining in a dose-dependent manner. It was also confirmed that the OSE suppressed the formation of the TRAP + MNCs in the early stage of differentiation and not in the middle and late stages. The results of the real-time quantitative polymerase chain reaction (qPCR) and the western blotting showed that the OSE dramatically inhibited the mRNA and protein expressions of the osteoclastogenesis-mediated transcription factors such as the c-Fos and the nuclear factor-activated T cells c1 (NFATc1). In addition, the OSE strongly attenuated the mRNA induction of the c-Fos/NFATc1-dependent molecules such as the TRAP, the osteoclast-associatedimmunoglobulin-like receptor (OSCAR), the dendritic cell-specific transmembrane protein (DC-STAMP), and the cathepsin K. These results suggest that the naturally derived OSE may be useful for preventing bone diseases.

An ankylosing spondylitis risk variant alters osteoclast differentiation

OBJECTIVE

To explore whether the variants in non-MHC proteasome gene is associated with ankylosing spondylitis and explain the role of the variant in the disease.

METHODS

Case-control analysis to identify ankylosing spondylitis predisposition genes; dual-luciferase reporter assay, immunoblot analysis and osteoclastogenesis assays to detect the function of the positive variant. Affected individuals was diagnosed according to the modified New York Criteria by at least two experienced rheumatologists, and rechecked by another rheumatologist.

RESULTS

The study included 1037 AS patients and 1014 no rheumatic and arthritis disease controls. The main age of AS onset is between 16 and 35 years old. HLA-B27-positive subjects comprised 90.0% of patients. A nonsynonymous SNP rs12717 in proteasome gene PSMB1 significantly associated with ankylosing spondylitis. Individuals with CC genotype had a higher onset risk compared with those with GG/GC genotypes (OR = 1.89, p= 0.0047). We also discovered that PSMB1 regulates the receptor activator of nuclear factor-κB (RANK)/RANK ligand (RANKL) signalling pathway and the disease-associated variant PSMB1-Pro11 significantly inhibits RANKL-induced NF-κB pathway in osteoclast differentiation via the degradation of IKK-β compared with PSMB1-Ala11. RANKL induced osteoclast differentiation was significantly lower in primary monocyte osteoclast precursor from individuals with genotype PSMB131C/31C compared with individuals with genotype PSMB131G/31G.

CONCLUSIONS

These results reveal a novel understanding of the bone formation and reabsorbing imbalance in AS. The new bone formation phenotype can be attributed to the inhibition of osteoclast differentiation by a more functional PSMB1 gene.

Traditional Chinese Medicine Rhodiola Sachalinensis Borissova from Baekdu Mountain (RsBBM) for Rheumatoid Arthritis: Therapeutic Effect and Underlying Molecular Mechanisms

The lack of effective rheumatoid arthritis (RA) therapies is a persistent challenge worldwide, prompting researchers to urgently evaluate traditional Chinese medicines (TCMs) as potential clinical RA treatments. The present investigation was conducted to evaluate the therapeutic effects and potential molecular mechanisms of the active components isolated from TCM Rhodiola sachalinensis Borissova from Baekdu Mountain (RsB^BM) using an experimental adjuvant arthritis model induced by injection of rats with Freund’s complete adjuvant. After induction of the adjuvant arthritis rat model, the extract-treated and untreated groups of arthritic rats were evaluated for RsB^BM therapeutic effects based on comparisons of ankle circumferences and ELISA-determined blood serum inflammatory factor levels (TNF-α, IL-1β, and PGE2). In addition, the joint health of rats was evaluated via microscopic examination of hematoxylin-eosin-stained synovial tissues. Furthermore, to explore whether NF-κB and RANK/RANKL/OPG signaling pathways participated in observed therapeutic effects from a molecular mechanistic viewpoint, mRNA and protein levels related to the expression of nuclear factor kappa-B (NF-κB), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-Β ligand (RANKL) were analyzed via quantitative RT-PCR and Western blot analysis, respectively. Treatment of arthritic rats with the extract of RsB^BM was shown to reduce ankle swelling, reduce blood serum levels of inflammatory factors, and alleviate arthritis-associated synovial inflammation and joint damage. Moreover, an RsB^BM 50% ethanol extract treatment inhibited bone destruction by up-regulating OPG-related mRNA and protein expression and down-regulating RANKL-related mRNA and protein expression, while also reducing inflammation by the down-regulating of the NF-κB pathway activity. The results clearly demonstrated that the extract of RsB^BM alleviated adjuvant arthritis-associated joint damage by altering activities of inflammation-associated NF-κB and the RANK/RANKL/OPG signaling pathways. Due to its beneficial effects for alleviating adjuvant arthritis, this RsB^BM 50% ethanol extract should be further evaluated as a promising new therapeutic TCM treatment for RA.

Effects of angiotensin II combined with asparaginase and dexamethasone on the femoral head in mice: A model of steroid-induced femoral head osteonecrosis

Background: To study the pathogenesis of steroid-induced femoral head osteonecrosis, an ideal animal model is very important. As experimental animals, mice are beneficial for studying the pathogenesis of disease. However, there are currently few mouse models of steroid-induced femoral head osteonecrosis, and there are many questions that require further exploration and research.

Purposes: The purpose of this study was to establish a new model of osteonecrosis in mice using angiotensin II (Ang II) combined with asparaginase (ASP) and dexamethasone (DEX) and to study the effects of this drug combination on femoral head osteonecrosis in mice.

Methods: Male BALB/c mice (n = 60) were randomly divided into three groups. Group A (normal control, NC) was treated with physiological saline and given a normal diet. Group B (DEX + ASP, DA) was given free access to food and water (containing 2 mg/L DEX) and subjected to intraperitoneal injection of ASP (1200 IU/kg twice/week for 8 weeks). Group C (DEX + ASP + Ang II, DAA) was treated the same as group B, it was also given free access to food and water (containing 2 mg/L DEX) and subjected to intraperitoneal injection of ASP (1200 IU/kg twice/week for 8 weeks), but in the 4th and 8th weeks, subcutaneous implantation of a capsule osmotic pump (0.28 mg/kg/day Ang II) was performed. The mice were sacrificed in the 4th and 8th weeks, and the model success rate, mouse mortality rate, body weight, blood lipids, coagulation factors, histopathology, and number of local vessels in the femoral head were evaluated.

Results: DAA increased the model success rate [4th week, 30% (DA) vs. 40% (DAA) vs. 0% (NC); 8th week, 40% (DA) vs. 70% (DAA) vs. 0% (NC)]. There was no significant difference in mortality rate between the groups [4th week, 0% (DA) vs. 0% (DAA) vs. 0% (NC); 8th week, 5% (DA) vs. 10% (DAA) vs. 0% (NC)]. DAA affected mouse body weight and significantly affected blood lipids and blood coagulation factors. DAA reduces the number of blood vessels in the femoral head and destroys the local blood supply.

Conclusion: Angiotensin II combined with asparaginase and dexamethasone can obviously promote the necrosis of femoral head and provide a new idea for the model and treatment of osteonecrosis.

Analysis of the femoral neck from rats in the periestropause treated with oxytocin and submitted to strength training

Among the interventions used to prevent osteoporosis in female organisms, strength training (ST) and oxytocin (OT) stand out, as a promising hormone with anabolic action on bone. This study aimed to verify whether the combined action of OT and ST, compared to isolated interventions, potentiates the bone remodeling process of the femoral neck of Wistar rats during periestropause. Forty Wistar rats (18 months) with irregular estrous cycle were randomly distributed into groups: 1-Vehicle (Veh; NaCl 0.15 mol/L ip); 2-Oxytocin (Ot; 134 μg/kg/ip); 3-Strength training (St); 4-Ot + St. The animals of the 1, 2 and 4 groups received two intraperitoneal injections with an interval of 12 h every 30 days, totaling 8 injections at the end of the experimental period (18 to 21 months). The animals in the St and Ot + St groups performed ST on a ladder 3 times a week, maximal voluntary carrying capacity (MVCC) test monthly. After 120 days, the animals were euthanized; the femur was collected for analysis of biomechanical testing, densitometry, bone microtomography, Raman spectroscopy, tissue PCR, and blood for analysis of bone biomarkers, liver damage, and oxidative stress. The main effects in the Ot group were observed in the maximum load and energy in the compression testing (femoral head), and stiffness and energy in the three-points bending testing (femur diaphysis). In addition, the main effects occurred on the bone mineral density (BMD), cortical thickness (Ct.Th), number of pores (Po.N), polar moment of inertia (J), trabecular thickness (Tb.Th), and connectivity density (Conn.Dn), Bone alkaline phosphatase (Alp), Tumor necrosis factor receptor superfamily member 11b (Opg), Tumor necrosis factor ligand superfamily member 11 (Rankl) and Cathepsin K (Ctsk) expression. There was an effect in the tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP). In the St group, the main effect was observed on the energy (compression and the three-points bending), stiffness, aBMD, BMD, cortical bone area (Ct.Ar), Po.N, trabecular bone volume (BV/TV), Tb.Th and in the mineralization ratio (ѵ₁PO₄/proline), Runt-related transcription factor 2 (Runx2), Bone morphogenetic protein 2 (Bmp2), Alp, Osteopontin/secreted phosphoprotein 1 (Opn/Spp1), Opg, Tumor necrosis factor receptor superfamily member 11ª (Rank), Rankl, Ctsk expression. There was an effect in the TRAP and ALP. The interaction in the combination of therapies in the Ot + St group was verified in energy to maximum load (compression and three-points bending testing), stiffness, BMD, Ct.Th, J, Tb.Th and ѵ₁PO₄/proline. In the gene analysis there was interaction in the Runx2, Osterix/Sp7 transcription factor (Osx/Sp7), Bmp2, Alp, Osteocalcin/Bone gamma-carboxyglutamate protein (Ocn/Bglap), Opg, Rankl and Acid phosphatase 5, tartrate resistant (Trap/Acp5) expression. In addition, the combination of OT and ST resulted in a higher maximum load compared to the Veh group, with higher BV/TV than the Ot group, higher Rankl and Ctsk expression than Veh and Ot groups, and lower Po.N and lower activity of TRAP than the other groups. In oxidative stress, total antioxidant capacity (TAC) was lower. These results showed that the combination of interventions is a promising anabolic strategy for the prevention of osteoporosis in the period of periestropause, standing out from the effects of isolated interventions.

A Review of Signaling Transduction Mechanisms in Osteoclastogenesis Regulation by Autophagy, Inflammation, and Immunity

Osteoclastogenesis is an ongoing rigorous course that includes osteoclast precursors fusion and bone resorption executed by degradative enzymes. Osteoclastogenesis is controlled by endogenous signaling and/or regulators or affected by exogenous conditions and can also be controlled both internally and externally. More evidence indicates that autophagy, inflammation, and immunity are closely related to osteoclastogenesis and involve multiple intracellular organelles (e.g., lysosomes and autophagosomes) and certain inflammatory or immunological factors. Based on the literature on osteoclastogenesis induced by different regulatory aspects, emerging basic cross-studies have reported the emerging disquisitive orientation for osteoclast differentiation and function. In this review, we summarize the partial potential therapeutic targets for osteoclast differentiation and function, including the signaling pathways and various cellular processes.

The Therapeutic Relevance of Urolithins, Intestinal Metabolites of Ellagitannin-Rich Food: A Systematic Review of In Vivo Studies

The therapeutic effects of food rich in ellagitannins have been established to stem from its microbial metabolite, urolithin. Over the past decade, there has been a growing trend in urolithin research pertaining to its pharmacological properties. The purpose of this systematic review is to collate and synthesise all available data on urolithin’s therapeutic ability, to highlight its potential as a pharmaceutical agent, and prospective direction on future research. Methods: This systematic review was written based on the PRISMA guideline and was conducted across Ovid via Embase, Ovid MEDLINE, Cochrane Central Register for Controlled Trials, and Web of Science Core Collection. Results: A total of 41 animal studies were included in this systematic review based on the appropriate keyword. The included studies highlighted the neuroprotective, anti-metabolic disorder activity, nephroprotective, myocardial protective, anti-inflammatory, and musculoskeletal protection of urolithin A, B, and its synthetic analogue methylated urolithin A. The Sirt1, AMPK, and PI3K/AKT/mTOR signalling pathways were reported to be involved in the initiation of autophagy and mitochondrial biogenesis by urolithin A. Conclusions: This review methodically discusses the therapeutic prospects of urolithins and provides scientific justification for the potential development of urolithin A as a potent natural mitophagy inducer for anti-ageing purposes.

Blockade of Osteoclast-Mediated Bone Resorption With a RANKL-Inhibitor Enhances Bone Formation in a Rat Spinal Fusion Model

STUDY DESIGN

Rat spine fusion model.

OBJECTIVE

The present study aimed to determine whether administration of osteoprotegerin (OPG) in a rat model of spinal fusion increases bone volume, bone density, and decreases osteoclasts in the fusion mass.

SUMMARY OF BACKGROUND DATA

OPG is a soluble RANK-ligand inhibitor that blocks osteoclast differentiation and activation. This makes it a potential agent to control the remodeling process and enhance bone mass during spinal fusion.

MATERIALS AND METHODS

Forty-eight male Sprague-Dawley rats received a one-level spinal fusion of L4-L5 with bone allograft. Rats were then divided into four groups according to initiation of treatment: (1) saline on day 0 (saline), (2) OPG on day 0 (OPG D0), (3) OPG on day 10 (OPG D10), and (4) OPG on day 21 (OPG D21) postsurgery. After their initial injection, rats received weekly subcutaneous injections of OPG (10 mg/kg) and were euthanized six weeks postsurgery. MicroCT analysis of the fusion site and histological analysis of bone surface for quantification of osteoclast lining was performed.

RESULTS

Increased bone volume in the fusion site and around the spinous process was seen in OPG D0 and OPG D10 when compared with saline. Mean trabecular thickness was greater in all groups receiving OPG compared with saline, with OPG D0 and OPG D10 having significantly greater mean trabecular thickness than OPG D21. All OPG groups had less bone surface lined with osteoclasts when compared with Saline, with OPG D0 and OPG D10 having fewer than OPG D21.

CONCLUSIONS

This study indicates that OPG inhibited osteoclast bone resorption, which led to greater bone at the fusion site. Future studies investigating OPG on its own or in combination with an osteogenic factor to improve spinal fusion outcomes are warranted to further elucidate its potential therapeutic effect.