Tartrate-resistant Acid Phosphatase Research Articles

Markers of Bone Mineral Metabolism in Thyroid Disorders

Abstract Background and Aim: Thyroid hormones are essential for normal skeletal development and bone metabolism. Despite various studies, the effect of thyroid hormone on bone metabolism has not been clearly understood. We studied the bone formation markers (procollagen type 1 N-propeptide [P1NP] and osteocalcin [OC]) and bone resorption markers (C-terminal cross-linking telopeptide of type 1 collagen [CTX] and tartrate-resistant acid phosphatase [TRAP]) in patients with thyroid disorders and the effect of treatment on them. Furthermore, a study correlating these markers with thyroid-stimulating hormone (TSH) levels was done. Materials and Methods: This cross-sectional study recruited 60 cases (40 – hypothyroid and 20 – hyperthyroid) and 20 controls based on inclusion and exclusion criteria. To evaluate the effect of treatment, cases were further subdivided based on the duration of treatment received into 0-month (newly diagnosed), 1–6-month, and >6-month treatment subgroups. Both the cases and control underwent a thorough history, clinical examination, and detailed investigation based on a predesigned proforma. Results: In hyperthyroidism with 0-month treatment subgroup, both formation (OC, P1NP) and resorption (CTX) markers were significantly increased compared to control (P < 0.05), which became insignificant on treatment (1–6 months) with antithyroid medication despite low TSH value. Contrarily, in hypothyroidism, a statistically significant (P < 0.05) lower mean value of markers (OC, P1NP, and CTX) was observed only in the subgroup with levothyroxine supplementation. In hyperthyroidism, both the formation (OC and P1NP) and resorption markers (CTX and TRAP) showed a strong negative (P < 0.001) correlation with TSH, the strength of correlation decreased, and became insignificant on treatment. In hypothyroidism, only P1NP and CTX showed an overall significant positive (P < 0.05) correlation with TSH. Conclusion: Hyperthyroidism has high bone turnover markers, which showed early reversibility of markers on treatment with antithyroid medication despite low TSH, whereas in hypothyroidism, significantly lower mean value of markers is seen only in the subgroup with levothyroxine supplementation, probably owing to the suppressive effect of TSH. P1NP and CTX showed high sensitivity in both hypothyroidism and hyperthyroidism. The pattern of correlation between TSH and bone metabolism markers in hyperthyroidism suggests a direct negative effect of TSH on bone turnover, whereas in hypothyroidism, it either suggests TSH showing a positive correlation at a very high level which becomes negative as the TSH value decreases or TSH is not a dominant hormone regulating bone metabolism in hypothyroidism.

Inhibition of tartrate-resistant acid phosphatase 5 can prevent cardiac fibrosis after myocardial infarction

BackgroundMyocardial infarction (MI) leads to enhanced activity of cardiac fibroblasts (CFs) and abnormal deposition of extracellular matrix proteins, resulting in cardiac fibrosis. Tartrate-resistant acid phosphatase 5 (ACP5) has been shown to promote cell proliferation and phenotypic transition. However, it remains unclear whether ACP5 is involved in the development of cardiac fibrosis after MI. The present study aimed to investigate the role of ACP5 in post-MI fibrosis and its potential underlying mechanisms.MethodsClinical blood samples were collected to detect ACP5 concentration. Myocardial fibrosis was induced by ligation of the left anterior descending coronary artery. The ACP5 inhibitor, AubipyOMe, was administered by intraperitoneal injection. Cardiac function and morphological changes were observed on Day 28 after injury. Cardiac CFs from neonatal mice were extracted to elucidate the underlying mechanism in vitro. The expression of ACP5 was silenced by small interfering RNA (siRNA) and overexpressed by adeno-associated viruses to evaluate its effect on CF activation.ResultsThe expression of ACP5 was increased in patients with MI, mice with MI, and mice with Ang II-induced fibrosis in vitro. AubipyOMe inhibited cardiac fibrosis and improved cardiac function in mice after MI. ACP5 inhibition reduced cell proliferation, migration, and phenotypic changes in CFs in vitro, while adenovirus-mediated ACP5 overexpression had the opposite effect. Mechanistically, the classical profibrotic pathway of glycogen synthase kinase-3β (GSK3β)/β-catenin was changed with ACP5 modulation, which indicated that ACP5 had a positive regulatory effect. Furthermore, the inhibitory effect of ACP5 deficiency on the GSK3β/β-catenin pathway was counteracted by an ERK activator, which indicated that ACP5 regulated GSK3β activity through ERK-mediated phosphorylation, thereby affecting β-catenin degradation.ConclusionACP5 may influence the proliferation, migration, and phenotypic transition of CFs, leading to the development of myocardial fibrosis after MI through modulating the ERK/GSK3β/β-catenin signaling pathway.

Thick Skin on the Dorsal Spine in Osteoproliferative Disease: Ossification of the Posterior Longitudinal Ligament and Diffuse Idiopathic Skeletal Hyperostosis.

Background Although the correlation between reduced skin thickness and reduced bone density has been investigated, no study has evaluated skin thickness and osteoproliferative diseases, including ossification of the posterior longitudinal ligament (OPLL) and diffuse idiopathic skeletal hyperostosis (DISH). Methodology This retrospective cohort study consisted of 99 consecutive patients aged ≥60 years treated for spinal surgery at our hospital between January 2022 and March 2023. Skin thickness was measured at the dorsal side of the cervical, thoracic, and lumbar vertebrae on the sagittal cross-section image of whole-spine CT. Based on the median value, skin thickness was categorized into two groups based on a median thickness of 4 mm. Bone mineral density (BMD) was assessed. The sum of the vertebral body and intervertebral bridging osteophytes of the anterior longitudinal and posterior longitudinal ligament were defined as the OALL index and OPLL index. Serum levels of bone metabolism-related markers, such as tartrate-resistant acid phosphatase type 5b, procollagen I N-propeptide, 25-hydroxyvitamin D, and periostin, were measured. To assess the association between skin thickness and imaging findings, we calculated the adjusted odds ratios, adjusting for age, sex, and body mass index (BMI) and using univariate and multivariate logistic regression analyses. Results No significant differences were found in skin thickness in the three dorsal regions of the cervical, thoracic, and lumbar spine (median = 3.3 mm versus 3.5 mm versus 3.4 mm, p = 0.357) and bone metabolism-related markers. Adjusting for age, sex, and BMI, cervical, thoracic, and lumbar skin thicknesses were related to DISH, the OPLL index, and the OPLL and OPLL index, respectively. Conclusions Skin thickness did not correlate with BMD but with the amount of spinal ossification. A correlation was found between skin thickness and vertebral and intervertebral ossification; vertebral osteophytes, OPLL, and DISH may be more common in thicker skin.

The efficacy and safety of Gukang Capsule for primary osteoporosis: a systematic review and meta-analysis of randomized clinical trial.

Background: Gukang Capsule has been used as a complementary and alternative medicine (CAM) for the treatment of primary osteoporosis (POP) in China. The primary aim of this study was to assess the clinical effectiveness and safety of Gukang Capsule in POP patients. Methods: A systematic search was conducted across multiple academic databases including PubMed, Web of science, Cochrane Library, China National Knowledge Infrastructure, Chongqing VIP Information, and Wanfang database to identify randomized controlled trials investigating the Gukang Capsule in the treatment of POP. The screening process, data extraction, and assessment of methodological quality were conducted independently by two reviewers. Statistical analysis was performed using the Rev Man 5.3 software. Subgroup analysis was carried out through the combination of OPF. Subgroup analysis was performed according to whether OPF were combined. Stata 12.0 was used for sensitivity and bias analysis. Results: Nineteen studies were assessed that included 1804 participants. It was found that compared with the control group, the total effective rate (RR = 1.26, 95% CI, 1.20, 1.33), the Medical Outcomes Study Short-form 36 [RR = 1.26, 95% CI(1.20, 1.33)], the bone mineral density (BMD) of lumbar vertebra (SMD = 0.77, 95% CI, 0.48, 1.07), the BMD of femoral neck [SMD = 0.84, 95% CI(0.53, 1.14)], and the BMD of Ward's triangle (SMD = 0.64, 95% CI, 0.44, 0.85) of the Gukang Capsule experimental group were higher. Compared with the control group, the fracture healing time (SMD = -2.14, 95% CI, -2.45, -1.84), the bone specific alkaline phosphatase (BALP) levels in serum (SMD = -2.00, 95% CI, -2.83, -1.17), the tartrate resistant acid phosphatase 5b (TRACP-5b) levels in serum (SMD = -2.58, 95% CI, -3.87, -1.29) of the Gukang Capsule experimental group were lower. The bone glaprotein (BGP) levels in serum (SMD = -0.22, 95% CI, -1.86, 1.43) and the adverse events (RR = 0.80, 95% CI, 0.40, 1.63) of the experimental group and the control group have no difference. Conclusion: Gukang Capsule, as a CAM for the management of POP, exhibits the potential to enhance BMD and quality of life, expedite the healing time of OPF, diminish levels of BALP and TRACP-5b, and improve the total effective rate without increasing the adverse events. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023477774, PROSPERO CRD42023477774.

Physiological occlusal force attenuates replacement root resorption of replanted teeth: an experimental animal study

BackgroundTooth avulsion represents the most severe form of dental trauma, necessitating tooth replantation as the primary treatment. However, the risk of replacement root resorption (RRR) poses a significant threat to tooth retention following replantation. This study preliminarily aimed to investigate the effect of physiological occlusal force on RRR after the replantation of avulsed teeth and to explore the potential underlying mechanisms.MethodsThirty-six 4-week-old male Sprague-Dawley rats underwent extraction and immediate replantation of their left maxillary molars. The rats were randomly divided into two major groups: the occluded (n = 18) group, where the opposite mandibular teeth were preserved; non-occluded (n = 18) group, where the opposite mandibular teeth were extracted. Within each major group, there were three subgroups corresponding to 7 days, 14 days, and 2 months, resulting in a total of six subgroups, (n = 6 per subgroup). The right maxillary first molars served as the normal control. Various periodontal characteristics were assessed using haematoxylin-eosin (H&E), tartrate-resistant acid phosphatase (TRAP) staining, and micro-computed tomography (micro-CT).ResultsHistological staining revealed that under occlusal force, the early stage (day 7) after tooth replantation mainly manifested as root surface resorption, especially in the non-occluded group, which gradually diminished over time. Cementum and periodontal ligament (PDL) repair was observed on day 14. Micro-CT analysis indicated a significant decrease in PDL width in the non-occluded group two months after replantation, consistent with the histological findings, signifying severe RRR in the non-occluded group.ConclusionsThis study provides preliminary evidence that physiological occlusal force may attenuate osteoclastogenesis during the early stage of tooth replantation, thereby reducing the occurrence of RRR and promoting periodontal healing.

Effect and mechanism of Gusong Qianggu Decoction on reducing bone loss in ovariectomized mice by targeting endoplasmic reticulum stress-induced apoptosis of osteocytes

This study aims to investigate the role and mechanism of Gusong Qianggu Decoction(GSQG) in attenuating bone loss in ovariectomized mice by targeting the endoplasmic reticulum stress(ERS)-induced apoptosis of osteocytes. After the modeling of osteoporosis in mice with bilateral ovary removal(OVX), 60 mice were randomized by the random number method into six groups: sham,model, low-, medium-, and high-dose GSQG(GSQG-L, GSQG-M, and GSQG-H, respectively), and estradiol(E_2), with 10 mice in each group. The mice in each group were administrated with corresponding drugs by gavage one month after surgery and the administration lasted for 3 months. Enzyme-linked immunosorbent assay(ELISA) was employed to determine the serum levels of osteocalcin(OCN), procollagen type Ⅰ N-terminal propeptide(PINP), carboxy-terminal cross-linked telopeptide of type Ⅰ collagen(CTX),and anti-tartarte acid phosphatase 5b(TRAcP-5b). Micro-CT was employed to observe the changes in bone microstructure of the distal femur. Hematoxylin-eosin(HE) staining was employed to observe the morphology of the bone tissue. RT-qPCR was conducted to determine the m RNA levels of tibial stem osteogenesis-associated genes [type Ⅰ collagen(Col-Ⅰ), alkaline phosphatase(ALP), Runtrelated transcription factor-2(Runx2), bone sialoprotein(BSP), and OCN] and bone-breaking related genes [tartrate-resistant acid phosphatase(TRAP), nuclear factor-activated T cell 1(NFATc1), and cathepsin K(CATK)]. TUNEL staining and immunohistochemistry were employed to detect the apoptosis of osteoblasts. Western blot was employed to measure the expression of ERS-related proteins glucose-regulated protein 78( Grp78), protein kinase RNA-like endoplasmic reticulum kinase( PERK), phosphorylated PERK(p-PERK),eukaryotic translation initiation factor 2 alpha(eIF2α), phosphorylated e IF2α(p-eIF2α), inositol-requiring enzyme 1 alpha(IRE1α), phosphorylated IRE1α(p-IRE1α), and activating transcription factor 6(ATF6) in the proximal tibial bone tissue. The results showed that GSQG significantly recovered the levels of OCN, PINP, TRAc P-5b, and CTX in the serum of ovariectomized mice, and Micro-CT showed that GSQG improved the bone microstructure of distal femur in a dose-dependent manner. Compared with the model group, GSQG widened and increased the bone trabeculae, restored the reticular structure with neat arrangement and enlarged interstitial gaps, and reduced the number of TUNEL-positive cells(P<0. 05, P<0. 01). Furthermore, GSQG down-regulated the expression levels of cysteine aspartate protease-3( caspase-3) and factor Bcl-2-associated X protein( Bax)(P< 0. 05,P<0. 01) and up-regulated the expression level of Bcl-2(P<0. 05, P<0. 01). The GSQG groups showed up-regulated m RNA levels of Col-Ⅰ, ALP, Runx2, BSP, and OCN(P< 0. 01) and down-regulated m RNA levels of TRAP, NFATc1, and CATK(P< 0. 05,P<0. 01). In addition, GSQG, especially GSQG-H, down-regulated the protein levels of Grp78, p-PERK, p-eIF2, p-IRE1α, and ATF6(P< 0. 05, P< 0. 01). In conclusion, GSQG can inhibit the apoptosis of osteocytes by inhibiting the Grp78/PERK/e IF2α/IRE1α/ATF6 signaling pathway in the proximal tibia tissue, thus reducing bone loss in ovariectomized mice.

Novel artificial tricalcium phosphate and magnesium composite graft facilitates angiogenesis in bone healing

BackgroundBone grafting is the standard treatment for critical bone defects, but autologous grafts have limitations like donor site morbidity and limited availability, while commercial artificial grafts may have poor integration with surrounding bone tissue, leading to delayed healing. Magnesium deficiency negatively impacts angiogenesis and bone repair. Therefore, incorporating magnesium into a synthetic biomaterial could provide an excellent bone substitute. This study aims to evaluate the morphological, mechanical, and biological properties of a calcium phosphate cement (CPC) sponge composed of tetracalcium phosphate (TTCP) and monocalcium phosphate monohydrate (MCPM), which could serve as an excellent bone substitute by incorporating magnesium. MethodsThis study aims to develop biomedical materials composed mainly of TTCP and MCPM powder, magnesium powder, and collagen. The materials were prepared using a wet-stirred mill and freeze-dryer methods. The particle size, composition, and microstructure of the materials were investigated. Finally, the biological properties of these materials, including 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) assay for biocompatibility, effects on bone cell differentiation by alkaline phosphatase (ALP) activity assay and tartrate-resistant acid phosphatase (TRAP) activity assay, and endothelial cell tube formation assay for angiogenesis, were evaluated as well. ResultsThe data showed that the sub-micron CPC powder, composed of TTCP/MCPM in a 3.5:1 ratio, had a setting time shorter than 15 minutes and a compressive strength of 4.39±0.96 MPa. This reveals that the sub-micron CPC powder had an adequate setting time and mechanical strength. We found that the sub-micron CPC sponge containing magnesium had better biocompatibility, including increased proliferation and osteogenic induction effects without cytotoxicity. The CPC sponge containing magnesium also promoted angiogenesis. ConclusionIn summary, we introduced a novel CPC sponge, which had a similar property to human bone promoted the biological functions of bone cells, and could serve as a promising material used in bone regeneration for critical bone defects.

Unveiling osteoprotective potential of biologically active naringenin in rats with dexamethasone-induced osteoporosis

ObjectiveTo investigate the protective effects of naringenin (NRG) against dexamethasone (DEX)-induced osteoporosis (OP) in rats. MethodsMolecular docking of NRG was done with AutoDock Vina 1.2.0 software. Forty-eight female Wistar rats were randomly divided into six groups (n = 8 each): normal control (NC), DEX (7 mg/kg, i.m.), NRG-low (NRG-L; 25 mg/kg, i.g.), NRG-medium (NRG-M; 50 mg/kg, i.g.), NRG-high (NRG-H; 100 mg/kg, i.g.), and alendronate (ALN; 0.25 mg/d, i.g.) groups. OP was induced by administering DEX once a week for five weeks in all groups except NC group. Begining in the third week after the initial DEX administration, the rats in NRG-L, NRG-M, NRG-H, and ALN groups received the corresponding treatments daily for three weeks, while NC and DEX groups received no additional treatment. Serum samples were collected at the end of the experiment for biochemical, bone turnover, antioxidant, lipid profile, and inflammatory cytokine analyses. Femur bones underwent physical parameter testing and histopathological examination. ResultsThe molecular docking results illustrated that NRG docked with calcitonin (CT), low-density lipoprotein (LDL), bone morphogenetic protein (BMP), vascular endothelial growth factor (VEGF) receptor, forkhead transcription factors, and osteoprogenitor cells showed good binding energy. In rats administered with 25, 50, and 100 mg/kg NRG, there was a significant enhancement in serum biochemical indices, characterized by a reduction in tartrate-resistant acid phosphatase (TRAP), parathyroid hormone (PTH), and an elevation in osteocalcin (OC) and CT levels (P < 0.05, P < 0.01, and P < 0.001, respectively). Despite no significant changes in thickness, weight, and length (P > 0.05), there was a marked increase in bone mineral density (BMD) (P < 0.01, P < 0.001, and P < 0.001, respectively). Antioxidant enzyme markers showed significant upregulation, with higher glutathione, superoxide dismutase, and catalase, and a concurrent decrease in malondialdehyde (MDA) (P < 0.05, P < 0.01, and P < 0.001, respectively). The lipid profile also improved significantly, with lower cholesterol (CH), triglycerides (TG), and low-density lipoprotein (LDL) levels, and an increase in high-density lipoprotein (HDL) level (P < 0.05, P < 0.01, and P < 0.001, respectively). Inflammatory cytokine levels were reduced, as evidenced by decreases in tumor necrosis factor (TNF), interleukin (IL)-6, and IL-1β (P < 0.05, P < 0.01, and P < 0.001, respectively). Furthermore, histological alterations revealed obvious improvements, and the body weight of rats treated with NRG showed an increase compared with DEX group. ConclusionThese findings imply that NRG exhibited a protective effect against DEX-induced OP in rats as it promotes the bone formation process by increasing the number of bone turnover markers including OC and CT, and restoring of antioxidant status, lipid metabolism, and inflammatory markers.

Mechanism study on fig exosome-like nanoparticles inhibiting the progression of bone metastasis in breast cancer.

e12562 Background: Breast cancer has overtaken lung cancer as the most common cancer worldwide. Breast cancer bone metastases can lead to death. How to inhibit the progression of bone metastasis of breast cancer is the key to improve the quality of life of breast cancer patients. In recent years, there have been increasing studies on the therapeutic significance of plant-derived extracellular vesicles (PDEVs), which play an important role in anti-tumor and anti-inflammatory. It is a new potential anti-tumor therapy. According to the Chinese medicine classics, figs have anti-cancer effect, but the main active ingredients are not clear yet. Methods: The exosomes were extracted by differential ultracentrifugation. The breast cancer cells (MDA-MB-231, MCF-7, 4T1, E0771) were treated with 0.1 ug/ml and 0.5 ug/ml fig exosome-like nanoparticles (FELNs) for 48 hours. The proliferation rate was measured by BrdU kit and verified by RT-qPCR. The total RNA from MDA-MB-231 cells treated by FELNs was sequenced to screen the differential genes. Key genes were differentially expressed in MDA-MB-231 and MCF-7 cells and further verified. Animal models of breast cancer in situ and bone metastasis were constructed in mice. FELNs were injected intraperitoneally twice a week, live imaging of small animals was performed on the 14th and 21st day to observe the tumor size and progression of breast cancer, and tibia samples were collected for Trap staining. The bone marrow macrophages of mice were extracted and treated by FELNs. The polarization was detected by RT-qPCR. After the removal of the proteins and nucleic acids in FELNs by protease, DNase and RNase, FELNs intervened in breast cancer cells and macrophages to determine the effective components of the FELNs. Results: After breast cancer cells were treated with FELNs, the proliferation rate was significantly decreased, especially MDA-MB-231 (from 70.3% to 17.7%) and MCF-7 (from 7.32% to 1.63%), and the RNA level of proliferation-related gene were significantly down-regulated. The key gene RN7SL1 was screened by sequencing. Overexpression of RN7SL1 significantly promoted the proliferation of MDA-MB-231 and MCF-7 cells, while the level of proliferation-related gene RNA was significantly up-regulated. FELNs significantly inhibited the tumor size and bone metastasis of breast cancer, and the tibial osteolysis was significantly abated by the treatment of FELNs in tibial Trap staining. After the intervention of FELNs in mouse macrophages, the polarization of M1 macrophages was significantly promoted. The proliferation rate of breast cancer cells increased and the polarization of M1 macrophages disappeared by treatment with protein-free FELNs. Conclusions: The protein components in FELNs inhibit the proliferation of breast cancer cells through RN7SL1, thereby inhibiting the progression of breast cancer bone metastasis.

Elucidating the mechano-molecular dynamics of TRAP activity using CRISPR/Cas9 mediated fluorescent reporter mice

Osteoclasts are essential for bone remodeling by adapting their resorptive activity in response to their mechanical in vivo environment. However, the molecular mechanisms underlying this process remain unclear. Here, we demonstrated the role of tartrate-resistant acid phosphatase (TRAP, Acp5), a key enzyme secreted by osteoclasts, in bone remodeling and mechanosensitivity. Using CRISPR/Cas9 reporter mice, we demonstrated bone cell reporter (BCRIbsp/Acp5) mice feature fluorescent TRAP-deficient osteoclasts and examined their activity during mechanically driven trabecular bone remodeling. Although BCRIbsp/Acp5 mice exhibited trabecular bone impairments and reduced resorption capacity in vitro, RNA sequencing revealed unchanged levels of key osteoclast-associated genes such as Ctsk, Mmp9, and Calcr. These findings, in conjunction with serum carboxy-terminal collagen crosslinks (CTX) and in vivo mechanical loading outcomes collectively indicated an unaltered bone resorption capacity of osteoclasts in vivo. Furthermore, we demonstrated similar mechanoregulation during trabecular bone remodeling in BCRIbsp/Acp5 and wild-type (WT) mice. Hence, this study provides valuable insights into the dynamics of TRAP activity in the context of bone remodeling and mechanosensation.

Effect of Acridine Orange and Zoledronic Acid on Bone Metastasis in Renal Cell Carcinoma.

The increasing incidence of renal cell carcinoma (RCC) and its associated bone metastasis pose challenges in surgical interventions, warranting the exploration of novel therapeutic approaches. Therefore, this study aimed to assess the impact of hematogenously administering acridine orange (AO) alone and in combination with zoledronic acid (ZA) on bone metastasis in RCC. RENCA cells (1.0×106 cells/10 μl) were directly injected into the right femur of male BALB/c mice. The mice were categorized into four groups based on the applied therapeutic intervention and were euthanized after five weeks. Micro-computed tomography was performed to quantify the extent of periosteal reaction, indicative of bone metastasis, along the entire length of the femur. Tumor weight and volume were measured at euthanization. Hematoxylin and eosin staining was used to examine the extent of tumor development in the bone. Apoptotic cell, osteoclast, and vascular endothelial growth factor (VEGF)-positive cell counts were assessed using TdT-mediated dUTP-biotin nick end labeling, tartrate-resistant acid phosphatase staining, and VEGF staining, respectively. The periosteal reaction was significantly reduced in the intervention groups compared to the control group (p<0.05). The apoptotic cell numbers in the intervention groups surpassed that in the control group (p<0.05), whereas those of osteoclasts and VEGF-positive cells in the intervention groups were lower than those in the control group (p<0.05). AO hinders bone metastasis progression in RCC, and combination therapy with ZA may be more effective than AO administration alone.

Bone turnover prediction in patients with chronic kidney disease (CKD) undergoing hemodialysis using shortened dynamic 18F-NaF PET/CT Ki–Patlak

This study investigated whether Ki–Patlak derived from a shortened scan time for dynamic 18F-NaF PET/CT in chronic kidney disease (CKD) patients undergoing hemodialysis can provide predictive accuracy comparable to that obtained from a longer scan. Twenty-seven patients on chronic hemodialysis, involving a total of 42 scans between December 2021 and August 2023 were recruited. Dynamic 18F-NaF PET/CT scans, lasting 60–90 min, were immediately acquired post-injection, covering the mid-twelfth thoracic vertebra to the pelvis region. Ki–Patlak analysis was performed on bone time–activity curves at 15, 30, 45, 60, and 90 min in the lumbar spine (L1–L4) and both anterior iliac crests. Spearman’s rank correlation (rs) and interclass correlation coefficient were used to assess the correlation and agreement of Ki–Patlak between shortened and standard scan times. Bone-specific alkaline phosphatase (BsAP) and tartrate-resistant acid phosphatase isoform 5b (TRAP5b) were tested for their correlation with individual Ki–Patlak. Strong correlations and good agreement were observed between Ki–Patlak values from shortened 30-min scans and longer 60–90-min scans in both lumbar spine (rs = 0.858, p < 0.001) and anterior iliac crest regions (rs = 0.850, p < 0.001). The correlation between BsAP and Ki–Patlak in the anterior iliac crests was weak and statistically insignificant. This finding suggests that a proposed shortened dynamic 18F-NaF PET/CT scan is effective in assessing bone metabolic flux in CKD patients undergoing hemodialysis, offering a non-invasive alternative approach for bone turnover prediction.

Cedrol alleviates postmenopausal osteoporosis in rats through inhibiting the activation of the NF-κB signaling pathway.

Pharmacological studies have shown that Cedrol (CE) exhibits extensive biological activities, including anti-inflammatory and analgesic. Moreover, it can inhibit the NF-κB pathway and the expression of various associated proteins. This study aimed to investigate the role of CE in postmenopausal osteoporosis. The results showed that intragastric administration of CE (10 and 20mg/kg) significantly improved the bone microstructure damage and increased bone mineral density, trabecular bone volume, and bone trabecular thickness in ovariectomized (OVX) rats (p < 0.05). CE treatment additionally made a well-organized arrangement of bone trabeculae and improved its thickness and density. Compared with the OVX group, the levels of tartrate-resistant acid phosphatase from 5b and C-terminal telopeptide of type I collagen were significantly reduced by 42.75% and 49.27% in the OVX + CE rats (p < 0.05). TRAP staining visually showed that the number of osteoclasts in the femur tissue of CE-treated rats was less than that of the OVX group. The expressions of nuclear factor of activated T-cells, cytoplasmic 1, acid phosphatase 5, and cathepsin K in OVX + CE rats were significantly decreased by 51.61%, 46.07%, and 50.34% compared to the OVX group (p < 0.01). In addition, CE intervention effectively reduced the phosphorylation levels of P65 and IκBα and inhibited the NF-κB signaling pathway. Meanwhile, CE diminished the number of multinucleated osteoclasts induced by receptor activator for nuclear factor-κB ligand and hindered cell fusion as well as nuclear translocation of osteoclast precursor cells P65. In conclusion, CE inhibits osteoclastogenesis by suppressing the activation of the NF-κB signaling pathway, thereby alleviating postmenopausal osteoporosis.

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

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

GCTRP3 inhibits oophorectomy‑induced osteoporosis by activating the AMPK/SIRT1/Nrf2 signaling pathway in mice.

C1q/tumor necrosis factor‑related protein 3 (CTRP3) expression is markedly reduced in the serum of patients with osteoporosis. The present study aimed to investigate whether CTRP3 reduces bone loss in oophorectomy (OVX)‑induced mice via the AMP‑activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/nuclear factor E2‑related factor 2 (Nrf2) signaling pathway. Female C57BL/6J mice and MC3T3‑E1 cells were used to construct in vivo and in vitro models of osteoporosis, respectively. The left femurs of mice were examined using micro‑computed tomography scans and bone‑related quantitative morphological evaluation was performed. Pathological changes and the number of osteoclasts in the left femurs of mice were detected using hematoxylin and eosin, and tartrate‑resistant acid phosphatase (TRAP) staining. Runt‑related transcription factor‑2 (RUNX2) expression in the left femurs was detected using immunofluorescence analysis, and the serum levels of bone resorption markers (C‑telopeptide of type I collagen and TRAP) and bone formation markers [osteocalcin (OCN) and procollagen type 1 N‑terminal propeptide] were detected. In addition, osteoblast differentiation and calcium deposits were examined in MC3T3‑E1 cells using alkaline phosphatase (ALP) and Alizarin red staining, respectively. Moreover, RUNX2, ALP and OCN expression levels were detected using reverse transcription‑quantitative PCR, and the expression levels of proteins associated with the AMPK/SIRT1/Nrf2 signaling pathway were detected using western blot analysis. The results revealed that globular CTRP3 (gCTRP3) alleviated bone loss and promoted bone formation in OVX‑induced mice. gCTRP3 also facilitated the osteogenic differentiation of MC3T3‑E1 cells through the AMPK/SIRT1/Nrf2 signaling pathway. The addition of an AMPK inhibitor (Compound C), SIRT1 inhibitor (EX527) or Nrf2 inhibitor (ML385) reduced the osteogenic differentiation of MC3T3‑E1 cells via inhibition of gCTRP3. In conclusion, gCTRP3 inhibits OVX‑induced osteoporosis by activating the AMPK/SIRT1/Nrf2 signaling pathway.

TGF-β Signaling in Cranial Neural Crest Affects Late-Stage Mandibular Bone Resorption and Length.

Malocclusions are common craniofacial malformations which cause quality of life and health problems if left untreated. Unfortunately, the current treatment for severe skeletal malocclusion is invasive surgery. Developing improved therapeutic options requires a deeper understanding of the cellular mechanisms responsible for determining jaw bone length. We have recently shown that neural crest mesenchyme (NCM) can alter jaw length by controlling recruitment and function of mesoderm-derived osteoclasts. Transforming growth factor beta (TGF-β) signaling is critical to craniofacial development by directing bone resorption and formation, and heterozygous mutations in TGF-β type I receptor (TGFBR1) are associated with micrognathia in humans. To identify what role TGF-β signaling in NCM plays in controlling osteoclasts during mandibular development, mandibles of mouse embryos deficient in the gene encoding Tgfbr1 specifically in NCM were analyzed. Our lab and others have demonstrated that Tgfbr1fl/fl;Wnt1-Cre mice display significantly shorter mandibles with no condylar, coronoid, or angular processes. We hypothesize that TGF-β signaling in NCM can also direct later bone remodeling and further regulate late embryonic jaw bone length. Interestingly, analysis of mandibular bone through micro-computed tomography and Masson's trichrome revealed no significant difference in bone quality between the Tgfbr1fl/fl;Wnt1-Cre mice and controls, as measured by bone perimeter/bone area, trabecular rod-like diameter, number and separation, and gene expression of Collagen type 1 alpha 1 (Col1α1) and Matrix metalloproteinase 13 (Mmp13). Though there was not a difference in localization of bone resorption within the mandible indicated by TRAP staining, Tgfbr1fl/fl;Wnt1-Cre mice had approximately three-fold less osteoclast number and perimeter than controls. Gene expression of receptor activator of nuclear factor kappa-β (Rank) and Mmp9, markers of osteoclasts and their activity, also showed a three-fold decrease in Tgfbr1fl/fl;Wnt1-Cre mandibles. Evaluation of osteoblast-to-osteoclast signaling revealed no significant difference between Tgfbr1fl/fl;Wnt1-Cre mandibles and controls, leaving the specific mechanism unresolved. Finally, pharmacological inhibition of Tgfbr1 signaling during the initiation of bone mineralization and resorption significantly shortened jaw length in embryos. We conclude that TGF-β signaling in NCM decreases mesoderm-derived osteoclast number, that TGF-β signaling in NCM impacts jaw length late in development, and that this osteoblast-to-osteoclast communication may be occurring through an undescribed mechanism.

#2223 Glycosylated hemoglobin levels and bone phenotype in patients with end-stage kidney disease

Abstract Background and Aims Diabetes mellitus is common as both cause and comorbidity of patients with chronic kidney disease (CKD). Both diabetes and CKD are states of increased fracture risk compared to healthy controls, with multiple potential contributing mechanisms. In type 2 diabetes, hyperglycemia contributes to the accumulation of advanced glycation end-products and osteocyte dysfunction, and it may play a pathogenic role in bone fragility. In this study, we wanted to examine the association between glycemic status and bone phenotype in patients with end-stage kidney disease (ESKD). Method This is a cross-sectional cohort study of 626 patients with CKD G5-5D referred for kidney transplantation between April 2006 and December 2013. Patients with type 1 diabetes were excluded. Patients were divided into quartiles based on HbA1c. Laboratory parameters of bone mineral metabolism (including biointact parathyroid hormone (PTH), fibroblast growth factor-23 (FGF23), and sclerostin), and bone turnover markers (bone alkaline phosphatase (BALP), trimeric pro-collagen type 1 N-terminal pro-peptide (intact P1NP), and tartrate-resistant acid phosphatase 5b (TRAP5b)) were measured. Bone mineral density (BMD) assessed by dual-energy X-ray absorptiometry (DEXA) (n = 537), bone histomorphometry (n = 180), and bone trabecular score (TBS) (n = 192) were available for subsets of patients. Results The median HbA1c were 4.8% in Q1, 5.1% in Q2, 5.4% in Q3, and 5.9% in Q4. Age and BMI differed across quartiles, with the highest age and BMI in Q4. Differences in bone turnover markers were found, with decreasing bone formation (BALP and intact P1NP) and decreasing bone resorption (TRAP5b) with ascending quartiles (Fig. 1). No differences across quartiles were found for FGF23, or circulating levels of sclerostin; however a weak, positive correlation between HbA1c and sclerostin was noted (rho = 0.08, p = 0.047). Overall, BMD at lumbar spine, femoral neck, and total hip increased across quartiles, the highest values in Q4 (Table 1). There were no differen in bone histomorphometry or TBS based on glycemic status. Conclusion Chronic hyperglycemia associates with suppressed bone turnover and higher BMD in patients with ESKD, even in non-diabetics. Potential mechanisms linking glucose metabolism to bone quantity and quality requires further investigation.

#1443 Bone and mineral metabolism in patients with nephropathic cystinosis as a function of age and eGFR

Abstract Background and Aims Cystinosis-associated metabolic bone disease (CMBD) is a major challenge in the treatment of patients with infantile nephropathic cystinosis (NC). Study data are limited due to small case numbers, lack of adults or patients on renal replacement therapy and/or inadequate assessment of bone health. Method We investigated markers for CMBD in all age groups (1-44 years; 61% children) and CKD stages 1-5D/T in the largest NC cohort to date with 103 German and Austrian NC patients. Skeletal comorbidity and concentrations of fibroblast growth factor 23 (FGF23), the osteoblast marker bone-specific alkaline phosphatase (BAP), the bone remodeling inhibitor sclerostin, the osteoclast marker tartrate-resistant acid phosphatase 5b (TRAP5b), the soluble receptor activator of nuclear factor kappa B ligand (sRANKL), osteoprotegerin (OPG) and the sRANKL/OPG ratio as surrogates for the regulation of osteoclastogenesis by osteoblasts were determined by ELISA, converted into age- and sex-specific z-scores and compared as a function of eGFR. Multivariable regression analyses were used to identify specific influencing factors associated with biochemical and clinical findings in pre-transplant NC patients. Results Skeletal complications occurred in two-thirds of patients, with the risk being five times higher in adults than in children. Pediatric and adult NC patients with CKD stages 1-4 showed hypophosphatemia and hypocalcemia associated with suppressed FGF23 and PTH levels and elevated BAP concentrations. This was associated with age, eGFR and treatment with phosphate and active vitamin D, suggesting more vigorous treatment of Fanconi syndrome in pre-transplant patients. As indicated by the increased TRAP5b and decreased sRANKL/OPG ratio, osteoclast activity was increased despite counterregulation by osteoblasts, which in conjunction with increased sclerostin activity may have contributed to the progressive bone loss and skeletal comorbidity in our patient cohort. Conclusion Bone health in NC progressively deteriorates with age, largely due to persistent rickets/osteomalacia associated with inadequate treatment of Fanconi syndrome and increased osteoclast activity despite osteoblast counterregulation via OPG/RANKL. Our data suggest that a primary osteoclast defect in NC promotes increased bone resorption, limiting maximal bone mass and leading to progressive bone loss and increased skeletal comorbidity.

#3127 Bedside cycling modulated the bone-resorption markers in patients with end-stage renal disease

Abstract Background and Aims Exercise provided multifactorial benefits in improving the health of the CKD patients. The exercise itself improved the bone remodeling. For CKD patients, chronic kidney disease mineral bone disorder (CKD-MBD) is an important complication and the treatment for renal osteodystrophy is unsatisfactory. The aim of study is to validate the role of bedside cycling in bone remodeling markers for patients with end-stage renal disease (ESRD). Method Participants were grouped into 4 groups: health control, chronic kidney disease (GFR 15∼60 ml/min) and ESRD (GFR&amp;lt;15 ml/min with maintenance dialysis). For ESRD patients, 12-week bedside cycling ((30 minutes per session; 3 times per week) were given for subjects. The pre-and post-exercise bone remodeling markers and clinical outcome were compared in ESRD with and without exercise in ESRD subjects. Results Bone formation markers (Bone specific alkaline phosphatase (15.57 ± 1.59 pg/dL) and Procollagen type 1 amino-terminal propeptide (1269.12 ± 116.34 pg/dL) were higher in ESRD patients with correlation with indoxyl sulfate and intact parathyroid hormone concentration(p &amp;lt; 0.05) respectively. In ESRD patients, the post-exercise concentration of Tartrate-resistant acid phosphatase 5b (3.64 ± 0.25 pg/dL to 4.23 ± 0.31 pg/mL, p = 0.003) and N-terminal telopeptide-1 (113.67 ± 20.53 pg/mL to 260.61 ± 30.9 pg/mL, p = 0.001)increased after 12 weeks of bed-side cycling. The hospitalization and mortality were similar between ESRD with or without exercise. Conclusion The bone formation marker concentration increased along with the severity of CKD. Bedside cycling increased the concentration of the bone resorption markers in ESRD patients.

#2708 Impact of dialysis modality on bone phenotype

Abstract Background and Aims Literature data suggest that low bone turnover is the prevailing bone phenotype in patients treated with peritoneal dialysis (PD) and point to high sclerostin as the central culprit. Lack of adequate controls, diagnostic heterogeneity, and a changing mineral metabolism landscape and armamentarium call for a cautious interpretation and confirmation in contemporary patients. Method Laboratory parameters of mineral metabolism (biointact parathyroid hormone (PTH), fibroblast growth factor 23 [FGF23] and sclerostin), bone turnover markers (bone alkaline phosphatase [BALP], intact procollagen type I N-terminal propeptide [PINP], tartrate-resistant acid phosphatase 5b [TRAP5b]) and bone mineral density (BMD) were assessed in 636 non-diabetic kidney transplant candidates of whom 447 were treated with hemodialysis (HD) and 189 with PD. A bone biopsy was performed in 204 patients (n = 134 HD; n = 70 PD), with bone sclerostin expression assessed in a subset (n = 52). Results Patients treated with PD had lower levels of PINP (79.6 vs 99.5 ug/L; p &amp;lt; 0.01) and BALP (20.2 vs 23.7 ug/L; p = 0.04) compared to those treated with HD. Histomorphometric parameters of bone formation were numerically lower in patients treated with PD, but significance was not reached. Bone mineralization was impaired in HD patients (osteoid width: 7.90 vs 6.75 µM; p = 0.01; osteoid maturation: 9 vs 6 days; p = 0.03), while frank osteomalacia was rare in both modalities (6.0%, both groups). BMD was higher in patients treated with PD compared to HD at skeletal sites rich in cortical bone (Z-score midshaft radius −0.4 ± 1.3 vs −0.9 ± 1.7; p = 0.04). PTH levels were comparable (150 vs 144 pg/mL, PD vs HD), while patients treated with PD showed higher serum phosphate (4.9 ± 1.3 vs 4.5 ± 1.6 mg/dl; p &amp;lt; 0.01) and FGF23 levels (3852 pg/ml vs 2361 pg/ml; p = 0.01). Circulating (1.82 ng/mL, both groups) and bone tissue expression (205 ± 126 vs 206 ± 112 positive osteocytes per mm2) of sclerostin did not differ between groups. Conclusion Patients treated with PD present a lower bone turnover, better mineralization, and higher cortical BMD than counterparts treated HD. Overall, differences are marginal and most probably clinically irrelevant. We speculate that inferior phosphate control may be in the causal pathway.