Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon (RAP). Despite its therapeutic effects, the surgical risk and unclear mechanism hamper the clinical application. Numerous evidences support macrophages as the key immune cells during bone remodeling. Our study discovered that the monocyte-derived macrophages primarily exhibited a pro-inflammatory phenotype that dominated bone remodeling in corticotomy by CX3CR1^CreERT2; R26^GFP lineage tracing system. Fluorescence staining, flow cytometry analysis, and western blot determined the significantly enhanced expression of binding immunoglobulin protein (BiP) and emphasized the activation of sensor activating transcription factor 6 (ATF6) in macrophages. Then, we verified that macrophage specific ATF6 deletion (ATF6^f/f; CX3CR1^CreERT2 mice) decreased the proportion of pro-inflammatory macrophages and therefore blocked the acceleration effect of corticotomy. In contrast, macrophage ATF6 overexpression exaggerated the acceleration of orthodontic tooth movement. In vitro experiments also proved that higher proportion of pro-inflammatory macrophages was positively correlated with higher expression of ATF6. At the mechanism level, RNA-seq and CUT&Tag analysis demonstrated that ATF6 modulated the macrophage-orchestrated inflammation through interacting with Tnfα promotor and augmenting its transcription. Additionally, molecular docking simulation and dual-luciferase reporter system indicated the possible binding sites outside of the traditional endoplasmic reticulum-stress response element (ERSE). Taken together, ATF6 may aggravate orthodontic bone remodeling by promoting Tnfα transcription in macrophages, suggesting that ATF6 may represent a promising therapeutic target for non-invasive accelerated orthodontics.
Animals ; Mice ; Macrophages/metabolism* ; Tumor Necrosis Factor-alpha/genetics* ; Tooth Movement Techniques/methods* ; Activating Transcription Factor 6/metabolism* ; Bone Remodeling ; Flow Cytometry ; Blotting, Western

OBJECTIVE: This study aimed to investigate possible serum 25-hydroxyvitamin D [25(OH)D] cutoffs for the associations between 25(OH)D and Bone turnover markers (BTMs), and how GC gene variation influences such cutoffs in Chinese women of childbearing age. METHODS: In total, 1,505 non-pregnant or non-lactating women (18-45 years) were recruited from the 2015 Chinese Adult Chronic Disease and Nutrition Surveillance. Serum 25(OH)D, osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP), β-CrossLaps of type 1 collagen containing cross-linked C-telopeptide (β-CTX), and single nucleotide polymorphisms were determined. Locally weighted regression and smoothing scatterplot and segmented regression were performed to estimate the 25(OH)D thresholds. RESULTS: The median serum 25(OH)D was 16.63 (11.96-22.55) ng/mL and the prevalence of low serum 25(OH)D (< 12 ng/mL) was 25.2%. Women with the lowest 25(OH)D had the highest β-CTX. After adjustment for the confounders, 25(OH)D cutoffs for OC [14.04 (12.84-15.23) ng/mL], β-CTX [13.94 (12.49-15.39) ng/mL], and P1NP [13.87 (12.37-15.37) ng/mL] in the whole population, cutoffs for OC [12.30 (10.68-13.91) ng/mL], β-CTX [12.23 (10.22-14.23) ng/mL], and P1NP [11.85 (10.40-13.31) ng/mL] in women with the GC rs2282679 G allele, and cutoffs for OC [12.75 (11.81-13.68) ng/mL], β-CTX [13.05 (11.78-14.32) ng/mL], and P1NP [12.81 (11.57-14.06) ng/mL] in women with the GC rs2282679 T allele, were observed. Below these cutoffs, BTMs were negatively associated with 25(OH)D, while above these cutoffs, BTMs plateaued. CONCLUSION In Chinese women of childbearing age, there were thresholds effect of serum 25(OH)D concentrations on BTMs. The results indicated that serum 25(OH)D concentrations < 13.87 ng/mL in this population had adverse influences on maintaining bone remodeling. BTMs were suppressed at a relatively lower serum 25(OH)D in women with the GC rs2282679 G allele compared with those with the T allele.
Humans ; Female ; Vitamin D/blood* ; Adult ; Middle Aged ; Polymorphism, Single Nucleotide ; Adolescent ; Young Adult ; China ; Biomarkers/blood* ; Bone Remodeling/genetics* ; Vitamin D-Binding Protein/genetics* ; Procollagen/blood* ; Osteocalcin/blood* ; Peptide Fragments/blood* ; East Asian People

OBJECTIVES: This study explores the differences in fluid flow within alveolar cancellous bone at various sites under orthodontic forces and elucidates the relationship between fluid shear stress and bone remodeling. These fin-dings lay the groundwork for understanding the biomechanical mechanisms of orthodontic tooth movement. METHODS: Stress relaxation tests were performed on human alveolar bone samples to determine material parameters by using the Prony series. An inverse model of alveolar bone was then developed for numerical simulations of fluid-structure interactions to calculate fluid flow within cancellous bone. Meanwhile, a rat model of tooth movement was established to investigate variations in bone remodeling speeds across different regions. RESULTS: The microstructural distribution of cancellous alveolar bone was similar in humans and rats. The bone volume fraction and trabecular thickness gradually decreased from root cervical region to root apical region, while the trabecular space gradually increased. Under the influence of orthodontic forces, fluid shear stress within cancellous bone showed spatial variability across different levels, with the highest shear stress occurring at the root apical region, ranging from 0 to 0.936 6 Pa. Additionally, the rat model of tooth movement indicated that bone remodeling occurred more rapidly at the root apical region. CONCLUSIONS Fluid stimulation has a remarkable effect on al-veolar bone remodeling, causing changes in the structure of alveolar bone and ultimately regulating the speed of structu-ral remodeling.
Bone Remodeling ; Animals ; Tooth Movement Techniques ; Rats ; Alveolar Process/physiology* ; Stress, Mechanical ; Humans ; Biomechanical Phenomena ; Cancellous Bone/physiology* ; Shear Strength

Pyroptosis, an inflammatory caspase-dependent programmed cell death, plays a vital role in maintaining tissue homeostasis and activating inflammatory responses. Orthodontic tooth movement (OTM) is an aseptic force-induced inflammatory bone remodeling process mediated by the activation of periodontal ligament (PDL) progenitor cells. However, whether and how force induces PDL progenitor cell pyroptosis, thereby influencing OTM and alveolar bone remodeling remains unknown. In this study, we found that mechanical force induced the expression of pyroptosis-related markers in rat OTM and alveolar bone remodeling process. Blocking or enhancing pyroptosis level could suppress or promote OTM and alveolar bone remodeling respectively. Using Caspase-1^-/- mice, we further demonstrated that the functional role of the force-induced pyroptosis in PDL progenitor cells depended on Caspase-1. Moreover, mechanical force could also induce pyroptosis in human ex-vivo force-treated PDL progenitor cells and in compressive force-loaded PDL progenitor cells in vitro, which influenced osteoclastogenesis. Mechanistically, transient receptor potential subfamily V member 4 signaling was involved in force-induced Caspase-1-dependent pyroptosis in PDL progenitor cells. Overall, this study suggested a novel mechanism contributing to the modulation of osteoclastogenesis and alveolar bone remodeling under mechanical stimuli, indicating a promising approach to accelerate OTM by targeting Caspase-1.
Animals ; Humans ; Mice ; Rats ; Bone Remodeling/physiology* ; Caspase 1 ; Periodontal Ligament ; Pyroptosis ; Tooth Movement Techniques

Bone formation and deposition are initiated by sensory nerve infiltration in adaptive bone remodeling. Here, we focused on the role of Semaphorin 3A (Sema3A), expressed by sensory nerves, in mechanical loads-induced bone formation and nerve withdrawal using orthodontic tooth movement (OTM) model. Firstly, bone formation was activated after the 3rd day of OTM, coinciding with a decrease in sensory nerves and an increase in pain threshold. Sema3A, rather than nerve growth factor (NGF), highly expressed in both trigeminal ganglion and the axons of periodontal ligament following the 3rd day of OTM. Moreover, in vitro mechanical loads upregulated Sema3A in neurons instead of in human periodontal ligament cells (hPDLCs) within 24 hours. Furthermore, exogenous Sema3A restored the suppressed alveolar bone formation and the osteogenic differentiation of hPDLCs induced by mechanical overload. Mechanistically, Sema3A prevented overstretching of F-actin induced by mechanical overload through ROCK2 pathway, maintaining mitochondrial dynamics as mitochondrial fusion. Therefore, Sema3A exhibits dual therapeutic effects in mechanical loads-induced bone formation, both as a pain-sensitive analgesic and a positive regulator for bone formation.
Humans ; Bone Remodeling ; Cell Differentiation ; Osteogenesis ; Semaphorin-3A/pharmacology* ; Trigeminal Ganglion/metabolism*

OBJECTIVE: To evaluate the effect of denosumab on bone mineral density around proximal femoral prosthesis after total hip arthroplasty(THA) in the postmenopausal osteoporotic patients. METHODS: Fifty-four consecutive patients underwent unilateral primary THA were included in this retrospective study. Twenty-five patients received denosumab for osteoporosis as the treatment group, and the twenty-nine without denosumab were the control group. At 1 week, 3month, 6 months, and 12 months after THA, bone turnover markers and proximal femoral periprosthetic bone mineral density (BMD) were measured. RESULTS: At 3, 6 and 12 months after operation, the level of TRACP-5b in the control group was significantly higher than that in the treatment group (P<0.05);the level of bone-specific alkaline phosphatase (BALP) between two groups showed significant difference in 12 months after operation (control group was higher than treatment group, P<0.05). The BMD of Gruen 1 and Gruen 7 decreased at 3, 6 and 12 months after operation compared with 1 week after operation. Comparing the treatment group and the control group, the differences of the the decrease of BMD in Gruen 1 and Gruen 7 were no significant at 3 months after surgery. In Gruen 1, Gruen 7 at 6 months after operation and Gruen 1, Gruen 7 at 12 months after operation, the decrease of BMD in the control group was significantly higher than that in the treatment group(P<0.05). It is suggested that desudumab could inhibit the loss of BMD after 6 months, and continuously show a protective effect on bone mass at 12 months after operation. CONCLUSION After THA in postmenopausal patients with osteoporotic femoral neck fracture, Desuzumab can reduce the loss of BMD around the proximal femoral prosthesis and effectively inhibit bone resorption.
Humans ; Arthroplasty, Replacement, Hip ; Bone Density ; Denosumab/therapeutic use* ; Retrospective Studies ; Postmenopause ; Absorptiometry, Photon ; Bone Remodeling ; Follow-Up Studies ; Hip Prosthesis

OBJECTIVE: To determine whether resveratrol (Res) can correct osteoporosis induced in a rat model of male hypogonadism. METHODS: Thirty-two rats were randomly divided into 4 groups, 8 in each group; 1) a control sham group: underwent a similar surgical procedure for induction of orchiectomy (ORCD) without ligation of any arteries or veins or removal of the testis and epididymis; 2) a control + Res-treated group (Con+Res): underwent sham surgery similar to the control, but was then treated with Res, as described below; 3) an ORCD-induced group: bilateral ORCD surgery as described above, and 4) a ORCD+Res-treated group: bilateral ORCD surgery followed by Res treatment. Res treatment began 4 weeks after ORCD and continued for 12 weeks. After 12 weeks, bone mineral density (BMD) and bone mineral content (BMC) were measured in the tibia and femur of each rat's right hind leg. Blood levels of bone turnover indicators such as deoxypyridinoline (Dpd), N-telopeptide of type I collagen (NTX I), alkaline phosphatase (ALP), and osteocalcin (OC), as well as receptor activator of nuclear factor kappa B (RANK) and osteoprotegerin (OPG) were assessed. RESULTS: ORCD significantly decreased BMD (P<0.01) and significantly increased bone resorption, manifested by increased RANK. In addition, it inhibited serum levels of OPG and OC. Res treatment after ORCD effectively increased serum levels of bone formation markers such as OPG and OC, compared with testisectomized rats (P<0.05). CONCLUSION Res could ameliorate bone loss induced by male hypogonadism, possible via restoration of the normal balance between RANK and OPG.
Rats ; Male ; Animals ; Bone Density ; Resveratrol/pharmacology* ; Osteoporosis ; Osteoprotegerin/pharmacology* ; Bone Remodeling ; Hypogonadism ; RANK Ligand/pharmacology*

The morbidity rate of medication-related osteonecrosis of the jaws (MRONJ) increased rapidly in recent years. Thusfar, the mechanism of MRONJ has no consensus. The possible mechanisms may include bone remodeling inhibition theory, angiogenesis inhibition theory, oral microorganism infection theory, immunosuppression theory, cytotoxicity-targeted oral epithelial cells, microcrack formation of maxillary or mandibular bone, and single nucleotide polymorphism. However, the efficacy of prevention and treatment based on a single mechanism is not ideal. Routine oral examination before MRONJ-related drug treatment, treatment of related dental diseases, and regular oral follow-up during drug treatment are of great significance for the prevention of MRONJ. During the treatment of MRONJ, the stage of MRONJ must be determined accurately, treatment must be standardized in accordance with the guidelines, and personalized adjustments must be made considering the specific conditions of patients. This review aimed to combine the latest research and guidelines for MRONJ and the experiences on the treatment of MRONJ in the Maxillofacial Surgery Department of West China Hospital of Stomatology, Sichuan University, and discuss the strategies to improve the clinical process.
Bisphosphonate-Associated Osteonecrosis of the Jaw/prevention & control* ; Bone Density Conservation Agents ; Bone Remodeling ; China ; Humans ; Jaw

The occurrence and development of pulmonary arterial hypertension (PAH) is closely related to the genetic mutation of bone morphogenetic protein receptor type II (BMPRII) encoding gene and the inflammatory response mediated by nuclear factor κB (NF-κB) pathway. This paper was aimed to investigate the effect of NF-κB pathway inhibitors on lipopolysaccharide (LPS)-induced pulmonary artery endothelial cell injury. Human pulmonary artery endothelial cells were treated with 1 μg/mL of LPS. The expression levels of BMPRII and interleukin-8 (IL-8) were detected by Western blot and qPCR. The rat PAH model was established by intraperitoneal (i.p.) injection of monocrotaline (MCT). The expression levels of BMPRII and IL-8 in pulmonary artery endothelial cells were detected by immunofluorescence staining. Cardiac hemodynamic changes and pulmonary vascular remodeling were detected in the MCT-PAH model rats. The results showed that LPS caused down-regulation of BMPRII expression and up-regulation of IL-8 expression in human pulmonary artery endothelial cells. NF-κB inhibitor BAY11-7082 (10 μmol/L) reversed the effect of LPS. In the pulmonary artery endothelial cells of MCT-PAH model, BMPRII expression was down-regulated, IL-8 expression was up-regulated, weight ratio of right ventricle to left ventricle plus septum [RV/(LV+S)] and right ventricular systolic pressure (RVSP) were significantly increased, cardiac output (CO) and tricuspid annular plane systolic excursion (TAPSE) were significantly reduced, and pulmonary vessel wall was significantly thickened. BAY11-7082 (5 mg/kg, i.p., 21 consecutive days) reversed the above changes in the MCT-PAH model rats. These results suggest that LPS down-regulates the expression level of BMPRII through NF-κB signaling pathway, promoting the occurrence and development of PAH. Therefore, the NF-κB pathway can be used as a potential therapeutic target for PAH.
Animals ; Bone Morphogenetic Protein Receptors, Type II ; Down-Regulation ; Endothelial Cells/metabolism* ; Humans ; Hypertension, Pulmonary/drug therapy* ; Lipopolysaccharides ; NF-kappa B/metabolism* ; Rats ; Rats, Sprague-Dawley ; Vascular Remodeling

In order to evaluate the biomechanical stability of titanium alloy screw with different structural parameters under bone remodeling, some three-dimensional finite element models were established and the bone remodeling process after implanting the screw was simulated. Three-dimensional finite element models consist of bone and screw with different lengths and diameters. Bone remodeling process was simulated by user-defined subroutine. It is found that the stress on the bone is concentrated on the groove and root of the internal thread. The screw stress is mainly on the beginning of the thread, and the whole stress decreases along the long axis of the screw. The stress distribution trend of bone and screw did not change significantly during the bone remodeling. The maximum equivalent stress value was different, the maximum equivalent stress on the screw and cancellous bone increased while the maximum equivalent stress value on the cortical bone decreased.
Biomechanical Phenomena ; Bone Remodeling ; Bone Screws ; Finite Element Analysis ; Stress, Mechanical ; Titanium