RANKL Levels Research Articles

The effects of photobiomodulation and/or azithromycin treatment on bone resorption biomarkers in gingival crevicular fluid from patients with stage III-IV grade C periodontitis.

This study aims to investigate the impact of photobiomodulation (PBM) and/or azithromycin (AZM) therapy in combination with full-mouth subgingival instrumentation (FSI) on receptor activator of nuclear factor κB ligand (RANKL) and osteoprotegerin (OPG) levels and RANKL/OPG ratios in gingival crevicular fluid (GCF) on patients with stage III-IV grade C periodontitis. The study was conducted on 77 stage III-IV grade C periodontitis patients and 20 periodontally healthy controls. Patients with stage III-IV grade C periodontitis were categorized into four treatment groups: 1) only FSI (FSI) group; 2) FSI&#43;AZM (AZM) group; 3)FSI&#43;PBM (PBM) group and 4) FSI&#43;PBM&#43;AZM (AZM&#43;PBM) group. Clinical periodontalparameters and RANKL and OPG levels and RANKL/OPG ratios in GCF were measured at thebaseline and month 3rd of the therapy. Compared with the periodontally healthy controls,all the baseline clinical parameters were higher in the Stage III-IV grade C periodontitis groups (P< 0.05); however, there were no statistically significant differences between the Stage III-IV gradeC periodontitis groups (P>0.05). In month 3rd, the lowest values in all clinical parameters weregenerally observed in the antibiotics groups whereas the highest values were observed in the FSIgroup. Furthermore, the highest RANKL and OPG values in antibiotic groups and the highestRANKL/OPG ratio in PBM group were observed in the third months. RANKL/OPG ratios did notchange in the FSI and antibiotics groups after the treatment, but it increased significantly in thePBM group. While PBM treatment combined with FSI increases the RANKL levels,AZM increases OPG levels. Also, PBM&#43;AZM treatment shows additional clinical andimmunological beneficial efficacy.

Foxe1 mutant zebrafish show indications of a hypothyroid phenotype and increased sensitivity to ethanol for craniofacial malformations.

FOXE1 mutations in humans are associated with cleft palate and hypothyroidism. We previously developed a foxe1 mutant zebrafish demonstrating mineralization defects in larvae. In the present study, we investigate the thyroid status and skeletal phenotype of adult foxe1 mutants. Mutant fish have increased expression of tshβ in the pituitary, and of hepatic dio1 and dio2. In plasma, we found higher Mg levels. Together these findings are indicative of hypothyroidism. We further observed mineralization defects in scales due to enhanced osteoclast activity as measured by increased expression levels of tracp, ctsk, and rankl. Gene-environment interactions in the etiology of FOXE1-related craniofacial abnormalities remain elusive, which prompts the need for models to investigate genotype-phenotype associations. We here investigated whether ethanol exposure increases the risk of developing craniofacial malformations in foxe1 mutant larvae that we compared to wild types. We found in ethanol-exposed mutants an increased incidence of developmental malformations and marked changes in gene expression patterns of cartilage markers (sox9a), apoptotic markers (casp3b), retinoic acid metabolism (cyp26c1), and tissue hypoxia markers (hifaa, hifab). Taken together, this study shows that the foxe1 mutant zebrafish recapitulates phenotypes associated with FOXE1 mutations in human patients and a clear foxe1-ethanol interaction.

Interactions of the Osteokines, Glucose/Insulin System and Vascular Risk Networks in Patients With Newly Diagnosed Type 2 Diabetes (VNDS 15).

Bone as an endocrine organ regulates metabolic processes independently of mineral metabolism through the production/release of proteins collectively named 'osteokines'. Relevant connections were reported between the insulin/glucose system, calcification of the atherosclerotic plaque, and several osteokines. We aimed to test the hypothesis that the osteokine network could be involved in beta-cell function, insulin sensitivity, and vascular damage in a cohort of people with newly diagnosed type 2 diabetes (T2D). In 794 drug-naive, GADA-negative, newly-diagnosed T2D patients (mean±SD age: 59±9.8years; BMI: 29.3±5.3kg/m2; HbA1c: 6.6±1.3%) we assessed: plasma concentration of osteocalcin (OCN), osteopontin (OPN),RANKL, and its putative decoy receptor osteoprotegerin (OPG); insulin sensitivity (SI) by hyperinsulinemic euglycemic clamp; beta cell function (BCF), estimated by OGTT minimal modelling and expressed as derivative (DC) and proportional (PC) control. Echo-doppler of carotid and lower limb arteries were also performed in 708 and 701 subjects, respectively. OCN, RANKL and OPG were significantly associated with PC (p<0.02); OCN was positively related to DC (p=0.018). OPG was associated with lower IS (p<0.001). Finally, the higher RANKL levels, the greater was the severity of atherosclerosis in common carotid artery (p<0.001). Increased OPG and OPN concentrations were related to subclinical atherosclerosis in peripheral arteries of lower limbs (p=0.023 and p=0.047, respectively). These data suggest that, in patients with newly diagnosed T2D, the osteokine network crosstalks with the glucose/insulin system and may play a role in modulating the atherosclerotic process.

Beneficial effects of IVIG treatment on experimental-induced osteoporosis.

Estrogen (E2) plays a significant role in postmenopausal osteoporosis, and its deficiency is related to chronic low-grade inflammation. Intravenous immunoglobulin (IVIG) is composed of immunoglobulins derived from the plasma of healthy donors. Numerous anti-inflammatory pathways are responsible for IVIG's anti-inflammatory action The aim of this study is to investigate the effects of IVIG on experimental-induced osteoporosis. Forty adult female Wistar rats were included in the study. Thirty rats underwent bilateral dorsal ovariectomy. Rats were grouped as Group 1 (n = 10, ovariectomy and saline); Group 2 (n = 10, ovariectomy and E2); Group 3 (n = 10, ovariectomy and IVIG), and Control group (n = 10, no oophorectomy). Histopathological examination of bone tissue, and biochemical analysis for beta-catenin, plasma Tumor Necrosis Factor-α, IL-6, receptor activator of nuclear-κB ligand (RANKL), and osteoprotegerin (OPG) levels were made. The IVIG group had increased trabecular number, area, and thickness with increased bone mineral density as well as decreased trabecular separation compared with the saline group. IVIG group had lower serum RANKL and higher serum OPG levels when compared with the saline group. The bone marrow beta-catenin level was significantly higher in the control and ovariectomy + IVIG groups. IVIG has beneficial effects on experimentally induced osteoporosis with a possible action on inflammation and RANKL-β-catenin pathway.

Role of Pulsed Electromagnetic Field on Alveolar Bone Remodeling during Orthodontic Retention Phase in Rat Models.

Alveolar bone remodeling during the retention phase is essential for successful orthodontic treatment. Pulsed electromagnetic field (PEMF) therapy is an adjunctive therapy for bone-related diseases that induces osteogenesis and prevents bone loss. This study aimed to examine the role of PEMF exposure during the retention phase of orthodontic treatment in alveolar bone remodeling. A total of 36 male Wistar rats were divided into control, PEMF 7, and PEMF 14 groups; a 50 g force nickel-titanium closed-coil spring was inserted to create mesial movement in the first molar for 21 d. Furthermore, the spring was removed, and the interdental space was filled with glass ionomer cement. Concurrently, rats were exposed to a PEMF at 15 Hz with a maximum intensity of 2.0 mT 2 h daily, for 7 and 14 days. Afterwards, the cements were removed and the rats were euthanized on days 1, 3, 7, and 14 to evaluate the expression of Wnt5a mRNA and the levels of RANKL, OPG, ALP, and Runx2 on the tension side. The data were analyzed with ANOVA and post hoc tests, with p < 0.05 declared statistically significant. PEMF exposure significantly upregulated Wnt5a mRNA expression, OPG and ALP levels, and Runx2 expression, and decreased RANKL levels in the PEMF 7 and 14 groups compared to the control group (p < 0.05). This study showed that PEMF exposure promotes alveolar bone remodeling during the orthodontic retention phase on the tension side by increasing alveolar bone formation and inhibiting resorption.

Effects of Three Retrograde Filling Materials on Production of Inflammatory Cytokines and Resorbing Mediators

: Root-end filling materials are typically used following endodontic surgeries, and due to their different chemical compositions, they have varying effects on the survival and differentiation of tissues around the root apex. The purpose of this in vitro study was to evaluate the effects of three retrograde filling materials—ProRoot MTA, Super ethoxy benzoic acid (EBA), and Geristore—on the production of pro-inflammatory and resorptive cytokines (RANK, RANK-L, OPG, IL-1β, and TNF-α). After mixing and setting, the experimental materials were exposed to UV rays and then applied to the prepared cells. This study used osteoblast (MG-63) and THP-1 monocyte cell lines, as well as peripheral blood monocytes (PBM). The evaluation times for RANK-L and OPG were 24 and 48 hours, while IL-1β and tumor necrosis factor (TNF-α) were evaluated at 24 hours. The RANK levels were measured using flow cytometry, and monocyte survival was assessed at different times using the MTT assay. The results were analyzed using Minitab statistical software, which indicated that the type of material significantly affected cytokine production. Exposure of monocytes to EBA resulted in a decrease in TNF-α and IL-1β secretion compared to the other groups. However, in the THP-1 cell line, there was no significant difference in the release of pro-inflammatory cytokines between the groups. Conversely, Geristore induced the highest level of RANK-L and the lowest level of OPG in cultures with the MG-63 cell line. According to the MTT assay, the viability order of the materials from early to late was Geristore &lt; EBA &lt; MTA.

Cathepsin K Expression is Upregulated Following Micropulse Vibration Stimulation of Osteoclasts Cultured in Vitro

Aim: To evaluate osteoclast inhibition following micropulse vibration and the effects of micropulse vibration on the expression of IL-1β, TNF-α, and RANKL in osteoblasts and osteoclasts and that of cathepsin K (CatK) in osteoclasts cultivated in vitro. Materials and methods: Primary murine osteoblasts and osteoclasts were cultured in vitro and stimulated with an AcceleDent Aura device for 20 min per day for 0 to 96 hours, with microvibrations of 0.25 N/30 Hz. Subsequently, the levels of IL-1β, TNF-α, and RANKL in the supernatants of the culture medium of both types of cells were measured by enzyme-linked immunosorbent assays (ELISAs). In addition, the level of CatK in osteoclasts was evaluated by flow cytometry. Results: Microvibrations significantly upregulated IL-1β and TNF-α expression and downregulated RANKL expression in osteoblasts compared with the corresponding expression in the control group. Compared to those in the control group, osteoclasts treated with microvibrations showed significant downregulation of IL-1β, TNF-α, and RANKL expression. CatK levels in stimulated osteoclasts were increased compared to those in the control group. Conclusion: The type of microvibration applied in this study inhibits osteoclastogenesis and upregulates the expression of CatK, an enzyme that induces bone matrix degradation in osteoclasts cultured in vitro, which stimulates bone formation by osteoblasts and accelerates bone mineralization.

Aging Influences Fracture Healing on the Cellular Level and Alters Systemic RANKL and OPG Concentrations in a Murine Model.

Clinical complications frequently follow polytrauma and bleeding fractures, increasing the risk of delayed fracture healing and nonunions, especially in aged patients. Therefore, this study examines age's impact on fracture repair with and without severe bleeding in mice. Young (17-26 weeks) and aged (64-72 weeks) male C57BL/6J mice (n=72 in total, n=6 per group) are allocated into 3 groups: the fracture group (Fx) undergoes femur osteotomy stabilized via external fixator, the combined trauma group (THFx) additionally receives pressure-controlled trauma hemorrhage (TH) and Sham animals are implanted with catheter and fixator without blood loss or osteotomy. Femoral bones are evaluated histologically 24h and 3 weeks post-trauma, while RANKL/OPG and β-CTx are measured systemically via ELISA after 3 weeks. Aging results in less mineralized bone and fewer osteoclasts within the fracture of aged mice in contrast to young groups after three weeks. Systemically, aged animals exhibit increased RANKL and OPG levels after fracture compared to their young counterparts. The RANKL/OPG ratio rises in aged Fx animals compared to young mice, with a similar trend in THFx groups. In conclusion, age has an effect during the later course of fracture healing on the cellular and systemic levels.

Investigation of bone remodeling in gingival crevicular fluid in patients treated with rapid maxillary expansion during pubertal period

Purpose: We aimed to evaluate bone remodeling following 3-month and 6-month retention periods of rapid maxillary expansion (RME) in gingival crevicular fluid (GCF). Materials and Methods: 23 pubertal participants (15 girls- 8 boys, 12-15 years) with maxillary transversal deficiency were enrolled in the study. Following banded-type RME appliance was introduced into the mouth, RME protocol was initiated by turning the Hyrax screw twice daily (morning/evening) with ¼ activation. GCF samples were taken from right maxillary first molars at four different time points (T0: before the appliance was deployed, T1: following active phase, T2: at the end of the 3-month retention period, T3: at the end of the 6-month retention period) using paper strips. Probing depth, gingival index, plaque index, and bleeding percentage at probing were recorded. BALP, OPG, RANKL, and TNF-α levels were measured in GCF samples using ELISA kits. Results: Our study revealed that GCF's BALP and OPG levels remained unchanged over time in tension and pressure regions, and there were no statistically significant differences among regions at each time point (p&gt;0.05). RANKL level was statistically significantly increased in the buccal region (the pressure region) at time T1 (p=0.042). The palatinal region's TNF-α level was statistically significantly higher than the buccal region at T0, T2, and T3 time points (p=0.005, p=0.042, and p=0.006, respectively). Our study showed no correlation between 3-month and 6-month retention periods and biomarkers indicating RME's bone metabolic activities. Conclusions: Further studies with different retention periods and larger sample sizes are suggested.

Effect of RANKL on Lower Depressive Symptoms In Hemodialysis Patients.

Depression and osteoporosis are common diseases in dialysis patients. In addition, patients with osteoporosis are more susceptible to depression. Contrary to previous anti-osteoporosis agents, denosumab and romosozumab could be used in dialysis patients and have similar action mechanisms for blocking RANKL. RANKL causes bone resorption after binding RANKL, but binding with OPG leads to suppress of bone resorption. In recent mice study, inhibition of RANKL with denosumab improved depressive-like phenotype. Besides, it was found that OPG was associated with depression. Therefore, this study aimed to investigate the association of depressive symptoms with RANKL and OPG in hemodialysis patients. We conducted a cross-sectional study with a total of 172 hemodialysis patients. The participants were measured for plasma RANKL, OPG, MMP-2, and MMP-9 levels. Logistic regression analysis was performed to evaluate the effect of RANKL and OPG on the presence of depressive symptoms. The depressive symptoms were observed in 90 (52.3%) subjects. RANKL tertile 3 had negative association with BDI score (β - 4.527, 95% CI - 8.310 to - 0.743) in univariate analysis, and this association persisted even after multivariate adjustments (β - 5.603, 95% CI - 9.715 to -1.491) in linear regression. In logistic regression between RANKL tertiles and depressive symptoms, RANKL tertile 3 had significantly lower unadjusted OR (0.40, 95% CI 0.19-0.86), and multivariate-adjusted OR (0.31, 95% CI 0.12-0.82) for depressive symptoms. OPG was not significantly associated with depressive symptoms. Higher plasma RANKL concentrations were significantly associated with lower depressive symptoms in HD patients.Trial registration WHO registry, No. KCT0003281, date: January 12, 2017.

Interleukin-18 binding protein regulates mast cell activation and mast cell induced osteoclastogenesis of rheumatoid arthritis.

Mast cell activation induces pathological responses, including increased osteoclastogenesis in rheumatoid arthritis (RA). Interleukin (IL)-18 binding protein (IL-18BP) has anti-inflammatory effects. In this study, we evaluated the effect of IL-18BP on mast cell activation and mast cell induced osteoclastogenesis. Mast cells were activated by IL-33 (100 ng/mL) and cultured with IL-18BP (10, 50, and 100 ng/mL). The proliferation, apoptosis, and necroptosis of mast cells were measured using flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of mast cell enzymes, matrix metalloproteinase (MMP), soluble RANKL (sRANKL), and pro-inflammatory cytokines in the culture media. Monocytes from patients with RA patients (n=5) were cultured with activated mast cells with various concentrations of IL-18BP. TRAP+ multinucleated osteoclasts, bone resorption area, and osteoclast differentiation-related genes were measured. Proliferation of tryptase+chymase+c-kit+FcεR1+ mast cells was suppressed following incubation with IL-18BP (10, 50, and 100 ng/mL). RNA expression levels of tryptase and chymase were reduced by 100 ng/mL IL-18BP. Additionally, the levels of MMP-3/9, IL-17A, IL-6, TNF-α, and sRANKL were significantly inhibited by 100 ng/mL IL-18BP. Annexin V+ and annexin V-PI+ mast cells were reduced following incubation with 100 ng/mL IL-18BP. The addition of IL-33 significantly stimulated mast cell and increased TRAP+ multinucleated cells and bone resorption area, and these effects were suppressed by IL-18BP. The osteoclast-related genes (TRAP, ATP6v0d2, RANK, and cathepsin K) expression were suppressed by IL-18BP. IL-18BP suppressed mast cell activation and mast cell induced osteoclastogenesis. This suggests a potential anti-arthritic role for IL-18BP in patients with RA.

Fu-zi decoction attenuate rheumatoid arthritis in vivo and in vitro by modulating RANK/RANKL signaling pathway.

Fu-zi decoction (FZD) has a long history of application for treating Rheumatoid arthritis (RA) as a classic formulation. However, its underlying mechanisms have not been fully elucidated. This study aimed to decipher the potential mechanism of FZD in treating RA, with a specific focus on receptor activator of nuclear factor κB/receptor activator of nuclear factor κB ligand (RANK/RANKL) signaling pathway. The impact of FZD on RA was investigated in collagen-induced arthritis rats (CIA), and the underlying mechanism was investigated in an osteoclast differentiation cell model. In vivo, the antiarthritic effect of FZD at various doses (2.3, 4.6, 9.2g/kg/day) was evaluated by arthritis index score, paw volume, toe thickness and histopathological examination of inflamed joints. Additionally, the ankle joint tissues were determined with micro-CT and safranin O fast green staining to evaluate synovial hyperplasia and articular cartilage damage. In vitro, osteoclast differentiation and maturation were evaluated by TRAP staining in RANKL-induced bone marrow mononuclear cells. The levels of pro- and anti-inflammatory cytokines as well as RANKL and OPG were evaluated by ELISA kits. In addition, Western blotting was used to investigate the effect of FZD on RANK/RANKL pathway activation both in vivo and in vitro. FZD significantly diminished the arthritis index score, paw volume, toe thickness and weigh loss in CIA rats, alleviated the pathological joint alterations. Consistent with in vivo results, FZD markedly inhibited RANKL-induced osteoclast differentiation by decreasing osteoclast numbers in a dose-dependent manner. Moreover, FZD decreased the levels of pro-inflammatory cytokines IL-6, IL-1β and TNF-α, while increasing anti-inflammatory cytokine IL-10 level both in serum and culture supernatants. Treatment with FZD significantly reduced serum RANKL levels, increased OPG levels, and decreased the RANKL/OPG ratio. In both in vivo and in vitro settings, FZD downregulated the protein expressions of RANK, RANKL, and c-Fos, while elevating OPG levels, further decreasing the RANKL/OPG ratio. In conclusion, FZD exerts a therapeutic effect in CIA rats by inhibiting RANK/RANKL-mediated osteoclast differentiation, which suggested that FZD is a promising treatment for RA.

Genetic Variants of the Receptor Activator Nuclear of κB Ligand Gene Increase the Risk of Rheumatoid Arthritis in a Mexican Mestizo Population: A Case-Control Study.

To assess the association of rs9533155 (-693C>G) and rs9533156 (-643T>C) genetic variants with RA risk. A case-control study was carried out. A total of 94 patients with RA (RA group) and 134 subjects without any rheumatologic disease (control group) were included. Genetic DNA was extracted from peripheral white blood cells (leukocytes). Genetic variant rs9533155 (-693C>G) was screened by an approach based on Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP), while rs9533156 (-643T>C) was screened using quantitative polymerase chain reaction (qPCR) with TaqMan probes. RANKL serum levels were measured by ELISA. For rs9533155 (-693C>G), the polymorphic homozygous genotype frequencies (CC) were higher in the RA group (p = 0.006). Individuals carrying the risk genotype presented higher levels of serum RANKL. Carriers of the polymorphic homozygous genotype in the dominant model (CC vs. CG + GG) had an increased risk of developing RA (OR: 1.8, 95% CI 1.04 to 3.1). No association between rs9533156 (-643T>C) and the haplotypes with RA risk was observed. The rs9533155 (-693C>G) genetic variant exhibits a potential role in RA risk. The studied population had no association with the rs9533156 (-643T>C) genetic variant.

Effectiveness of desertliving cistanche in managing hyperlipidemic osteoporosis in ovariectomized rats through the PI3K/AKT signaling pathway

BackgroundTo aim of this study is to assess the mechanism through which Desertliving Cistanche modulates the PI3K/AKT signaling pathway in the treatment of hyperlipidemic osteoporosis in ovariectomized rats.MethodsWe randomly assigned specific-pathogen-free (SPF) rats into five groups (n = 10 per group). The normal control group received a standard diet, while the model group, atorvastatin group, diethylstilbestrol group, and treatment group were fed a high-fat diet. Four weeks later, bilateral ovariectomies were conducted, followed by drug interventions. After six weeks of treatment, relevant indicators were compared and analyzed.ResultsCompared to the normal control group, rats in the model group exhibited blurred trabecular morphology, disorganized osteocytes, significantly elevated levels of bone-specific alkaline phosphatase (BALP), bone Gla-protein (BGP), total cholesterol (TC), tumor necrosis factor-α (TNF-α), and receptor activator of NF-κB ligand (RANKL). Also, the model group revealed significantly reduced levels of ultimate load, fracture load, estradiol (E2), bone mineral density (BMD), osteoprotegerin (OPG), and phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) in femoral tissue. The atorvastatin group presented with higher TC and TNF-α levels compared to the normal control group. Conversely, the treatment group demonstrated enhanced trabecular morphology, denser structure, smaller bone marrow cavities, and reduced BALP, BGP, TC, TNF-α, and RANKL levels. Furthermore, the treatment group exhibited higher levels of E2, BMD, OPG, and PI3K and Akt in bone tissue compared to the model group. The treatment group also had lower TC and TNF-α levels than the atorvastatin group. Biomechanical analysis indicated that after administration of Desertliving Cistanche, the treatment group had reduced body mass, increased ultimate and fracture load of the femur, denser bone structure, smaller bone marrow cavities, and altered periosteal arrangement compared to the model group.ConclusionOur study revealed that Desertliving Cistanche demonstrated significant efficacy in preventing and treating postmenopausal hyperlipidemic osteoporosis in rats.

Role of OPG/RANKL/RANK/TLR4 signaling pathway in sepsis-associated acute kidney injury

BackgroundSepsis-associated acute kidney injury (SA-AKI) has high mortality rates. The osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of nuclear factor-κB (RANK)/Toll-like receptor 4 (TLR4) pathway and its potential role in SA-AKI pathogenesis remain to be fully understood. Herein, we addressed this issue using mouse models.MethodsAn SA-AKI mouse model was established using the cecal ligation and puncture method (CLP). Mice were grouped into sham, CLP model, CLP + recombinant RANKL, and CLP + anti-RANKL groups. Serum creatinine (Scr) and blood urea nitrogen (BUN) levels were measured to assess kidney function. ELISA was used to detect serum IL-1β, TNF-α, and IL-6 levels. Real-time quantitative PCR and Western blot were used to detect the mRNA and protein expression levels of OPG, RANKL, RANK, and TLR4 in kidney tissues. HE staining was performed to evaluate the pathological changes.ResultsThe CLP model group showed higher levels of Scr and BUN, indicating impaired kidney function in SA-AKI, compared to the sham group. Treatment with recombinant RANKL in the CLP + recombinant RANKL group reduced Scr and BUN levels, while anti-RANKL treatment in the CLP + anti-RANKL group elevated their levels. Moreover, the CLP model group had significantly increased IL-1β, TNF-α, and IL-6 than the sham group, indicating elevated inflammation in SA-AKI. The CLP + recombinant RANKL group demonstrated decreased cytokine levels, whereas the CLP + anti-RANKL group showed an increase. Additionally, the histopathological evaluation revealed distinct kidney tissue damage in the CLP model group. Recombinant RANKL treatment reduced this damage, while anti-RANKL treatment exacerbated it. Mechanically, the mRNA and protein expression of RANKL were significantly decreased, while those of OPG, RANK, and TLR4 were significantly increased in the CLP model group and the CLP + anti-RANKL group. Interestingly, treatment with recombinant RANKL reversed these changes, as evidenced by significantly increased RANKL but decreased OPG, RANK, and TLR4.ConclusionThe OPG/RANKL/RANK/TLR4 pathway is involved in SA-AKI pathogenesis. Recombinant RANKL treatment attenuates the inflammatory response and kidney tissue damage in SA-AKI, possibly via regulating this pathway. This pathway shows promise as a therapeutic target for SA-AKI.

Biological alterations associated with the orthodontic treatment with conventional appliances and aligners: A systematic review of clinical and preclinical evidence

Background&objectivesMechanical forces applied during an orthodontic tooth movement (OTM) propel several biochemical and molecular responses in the periodontal ligament and alveolar bone. Here, we compile the existing clinical and preclinical evidence on these biological changes, aiming to provide a comprehensive discussion on the influence of the mechanical parameters of the OTM in the biological profile of the periodontium. Material and methodsThis systematic integrative review was conducted according to PICOS strategy and PRISMA guidelines. A bibliographic search was performed in three electronic databases (PubMed, Scopus, and Web of Science) to find research articles published until 2023 and written in English. This search resulted in a total of 2279 publications, which were independently assessed by two evaluators using appropriate tools. ResultsForty-six studies were selected for this review. These revealed that compression, and stretching of the periodontal ligament fibers and cells are observed in the initial phase of the OTM. Specifically, on the tension side, high levels of IL-1β, OPG, and TIMPs are identified. On the compression side, an increase of RANKL, RANK, and MMPs levels predominate. ConclusionThis paper describes the release profile of common biomarkers according to the orthodontic protocol, suggesting the most appropriate parameters to keep the teeth and their supporting structures healthy. Overall, this manuscript provides a better understanding of the OTM-associated biological phenomena, also highlighting the importance of early evaluation of oral health, and thus it contributes as a fundamental basis for the development of more effective and safe orthodontic treatments with conventional appliances and aligners.

Influence of immunodeficiency on spring-assisted cranioplasty: A study in mice

BackgroundSpring-assisted cranioplasty has been widely used in craniomaxillofacial surgery in recent years, but the molecular mechanisms that regulate the process of spring-assisted distraction osteogenesis are still unclear. The study aimed to investigate the influence of immunodeficiency on spring-assisted distraction osteogenesis. MethodsThe experimental group consisted of Thirty-six 6-week-old male scid-beige mice and the control group consisted of Thirty-six wild-type mice. All mice conducted spring-assisted cranioplasty with a distraction force of 10 g. The sagittal suture tissue of mice was obtained at 6 time points: Immediately after surgery, 1, 3, 7, 14, and 28 days after surgery. The width of the sagittal suture was measured and osteogenesis was observed through HE staining and Masson staining. The expression levels of OPG, RANKL, and IL-6 were detected through immunohistochemistry and RT-PCR. ResultsThe control group had the widest sagittal suture gap on the 3rd postoperative day, and then the gap narrowed to exceed the preoperative level. The experimental group had the widest sagittal suture gap on the 7th postoperative day, and then the gap narrowed and reached the preoperative level. Histological staining showed that the experimental group showed slower growth of skull tissue. Immunohistochemistry showed that the percentage of positive cells for OPG, RANKL, and IL-6 in the experimental group increased and decreased later than that of the control group, and the magnitude of change was smaller. RT-PCR showed that the mRNA expression levels of OPG, RANKL, and IL-6 in the experimental group exhibited a smaller increase, lower peak levels, and a delayed time to reach peak expression. These differences were statistically significant (P<0.05). ConclusionsDuring the process of spring-assisted cranioplasty, immunodeficient mice had lagging bone reconstruction responses and poor osteogenic ability. Immunologic factors, especially lymphocytes, may play an important regulatory role in the distraction osteogenesis process.

Characterization of a spontaneous osteopetrosis model using RANKL-dysfunctional mice

Tumor necrosis factor superfamily member 11 (TNFSF11), or receptor activator of nuclear factor-κB ligand (RANKL), is a crucial osteoclast-stimulating factor binding to RANK on osteoclast membranes. Mouse models are powerful tools for understanding the genetic mechanisms of related diseases. Here, we examined the utility of Tnfsf11 mutation in mice for understanding the mechanisms of bone remodeling and dysmorphology. The Tnfsf11gum mouse, discovered in 2011 at Jackson Laboratory, was used to study the genetic landscape associated with TNFSF11 inactivation in bone marrow tissues. Tnfsf11gum/+ and Tnfsf11+/+ mice were subjected to Micro-CT observation, ELISA analysis, histological evaluation, and massively-parallel mRNA sequencing (RNA-Seq) analysis. Tnfsf11gum/+ mice exhibited severe osteopetrotic changes in the bone marrow cavity, along with significantly lower serum RANKL levels and a reduced number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts in the bone marrow compared to those in Tnfsf11+/+ mice. However, tooth eruption between Tnfsf11gum/+ and Tnfsf11+/+ mice did not differ. Furthermore, genes involved in osteoblast proliferation and differentiation, including Gli1, Slc35b2, Lrrc17, and Junb were differentially expressed. Heterozygous mutation of TNFSF11 was also associated with a slightly increased expression of genes involved in osteoclast proliferation and differentiation, including Tcirg1, Junb, Anxa2, and Atp6ap1. Overall, we demonstrate that single gene mutations in Tnfsf11 cause bone resorption instability without significantly altering the genes related to osteoblast and osteoclast activity in the bone marrow cavity, thus establishing an optimal resource as an experimental animal model for bone resorption in bone biology research.

Inflammation and tissue remodeling mediator expression during gingivitis: A comparison between experimental, naturally occurring gingivitis, and periodontal health.

The aim of this study is to evaluate the immune regulation and tissue remodeling responses during experimental gingivitis (EG) and naturally occurring gingivitis (NG) to provide a comprehensive analysis of host responses. Gingival crevicular fluid (GCF) was obtained from 2 human studies conducted in university settings. The EG study enrolling 26 volunteers provided controls for the baseline (Day 0) from healthy disease-free participants, while Day 21 (the end of EG induction of the same group) was used to represent EG. Twenty-six NG participants age-matched with those of the EG group were recruited. GCF samples were analyzed for 39 mediators of inflammatory/immune responses and tissue remodeling using commercially available bead-based multiplex immunoassays. The differences in GI and mediator expression among groups were determined at a 95% confidence level (p ≤ 0.05) by a 2-way analysis of variance (ANOVA) with a post-hoc Tukey's test. Our findings showed that EG had a greater gingival index than NG and was healthy (p<0.01 of all comparisons). Furthermore, EG showed significantly higher levels of MPO (p<0.001), CCL3 (p<0.05), and IL-1B (p<0.001) than NG. In contrast, NG had increased levels of MIF (p<0.05), Fractalkine (p<0.001), angiogenin (p<0.05), C3a (p<0.001), BMP-2 (p<0.001), OPN (p<0.05), RANKL (p<0.001), and MMP-13 (p<0.001) than EG. Consistent with the findings from chronic (NG) versus acute (EG) inflammatory lesions, these data reveal that NG displays greater immune regulation, angiogenesis, and bone remodeling compared to EG.

Cortactin controls bone homeostasis through regulating the differentiation of osteoblasts and osteoclasts.

Cortactin (CTTN), a cytoskeletal protein and substrate of Src kinase, is implicated in tumor aggressiveness. However, its role in bone cell differentiation remains unknown. The current study revealed that CTTN was upregulated during osteoblast and adipocyte differentiation. Functional experiments demonstrated that CTTN promoted the in vitro differentiation of mesenchymal stem/progenitor cells into osteogenic and adipogenic lineages. Mechanistically, CTTN was able to stabilize the protein level of mechanistic target of rapamycin kinase (mTOR), leading to the activation of mTOR signaling. In-depth investigation revealed that CTTN could bind with casitas B lineage lymphoma-c (c-CBL) and counteract the function of c-CBL, a known E3 ubiquitin ligase responsible for the proteasomal degradation of mTOR. Silencing c-Cbl alleviated the impaired differentiation of osteoblasts and adipocytes caused by CTTN siRNA, while silencing mTOR mitigated the stimulation of osteoblast and adipocyte differentiation induced by CTTN overexpression. Notably, transplantation of CTTN-silenced bone marrow stromal cells (BMSCs) into the marrow of mice led to a reduction in trabecular bone mass, accompanied by a decrease in osteoblasts and an increase in osteoclasts. Furthermore, CTTN-silenced BMSCs expressed higher levels of receptor activator of nuclear factor κB ligand (RANKL) than control BMSCs did and promoted osteoclast differentiation when cocultured with bone marrow-derived osteoclast precursor cells. This study provides evidence that CTTN favors osteoblast differentiation by counteracting the c-CBL-induced degradation of mTOR and inhibits osteoclast differentiation by downregulating the expression of RANKL. It also suggests that maintaining an appropriate level of CTTN expression may be advantageous for maintaining bone homeostasis.