Effect of endocannabinoid system on senile osteoporosis / 中华骨科杂志

Osteoporosis is a common disease of old age that affects millions of people worldwide. Besides, it has been a chronic disease difficult to treat in the elderly, so it is of great significance to develop new drugs for the treatment of senile osteoporosis. The endocannabinoid system contains cannabinoid ligands, endocannabinoid receptors, and enzymes required for the synthesis and degradation of endocannabinoids, which play an important role in bone metabolism. Preclinical studies using endocannabinoid system-based therapies in animal models and in vitro have shown that endocannabinoid systems can prevent senile osteoporosis and highlight their therapeutic potential for senile osteoporosis. In this paper, PubMed, ScienceDirect, CNKY, and Wanfang databases were searched for articles related to the endocannabinoid system and osteoporosis. This paper analyzed the pathogenesis of senile osteoporosis (such as calcium, active vitamin D3 deficiency or insufficiency, sex hormone deficiency, cell function decline and secondary to chronic diseases, etc.), and reviewed the various components of the endocannabinoid system and their application in osteoporosis by regulating bone homeostasis in recent years, providing a new direction for the clinical treatment of senile osteoporosis.

Effects of Zuogui Pill on osteoclast activity and expression of miR-133b-3p/RhoA in postmenopausal osteoporosis rats / 国际中医中药杂志

Objective:To study the effects of Zuogui Pills on the expressions of miR-133b-3p and RhoA in osteoclasts of postmenopausal osteoporosis rats; To discuss its potential mechanism.Methods:SD female rats were randomly divided into normal group, model group, sham-operation group, and Zuogui Pills group using a random number table method, with 6 rats in each group. The model group and Zuogui Pills group were treated with oophorectomy to construct a rat model of osteoporosis. Zuogui Pills group was orally administered with Zuogui Pills decoction at a concentration of 10 g/kg for 12 consecutive weeks. Colorimetric method was used to measure the serum calcium and phosphorus levels of rats, and ELISA method was used to detect ALP levels. Bone density meter was used to measure the bone density of the femurs of rats in each group. The osteoclast of each group were cultured, and the expressions of RANKL and RUNX2 protein were detected by Western blot. MiRNA sequencing and differential expression analysis were performed on bone tissues of rats. Osteoclasts were treated with miR-133b-3p mimic and its negative control. The cell proliferation activity of osteoclasts was detected by cell counting kit-8 (CCK-8). The osteoclast differentiation activity was detected by the tartrate-resistant acid phosphatase staining. The dual-luciferase reporter assay was used to detect the relationship between miR-133b-3p and RhoA. The "rescue" experiment of miR-133b-3p mimic and RhoA co-expression were used to study the molecular regulatory mechanism of Zuogui Pills on osteoclast activity.Results:Compared with the model group, the bone mineral density of Zuogui Pills group significantly increased ( P<0.05, P<0.01), the levels of calcium and phosphorus in serum increased, the level of alkaline phosphatase ALP decreased ( P<0.05), the expression of RANKL protein decreased, and the expression of RUNX2 protein increased. Sequencing results showed that rno-miR-133b-3p was down-regulated in osteoclasts of postmenopausa osteoporosis rats treated with Zuogui Pills with the maximum difference ( P<0.01). Q-PCR results showed that the expression of miR-133b-3p in osteoclasts of Zuogui Pills group was significantly lower than that of the model group. The upregulation of miR-133b-3p could significantly promote the cell proliferation and differentiation of osteoclasts. RhoA overexpression could reverse the excessive proliferation and differentiation of osteoclasts caused by miR-133b-3p overexpression. Conclusions:RhoA is the target gene regulated by miR-133b-3p. Zuogui Pills can inhibit the activity of osteoclasts by regulating miR-133b-3p/RhoA axis, relieving the symptoms of osteoporosis.

Research progress on an autophagy-mediating AMPK pathway involving bone metabolism-related cells that regulate bone homeostasis in periodontitis / 口腔疾病防治

@#Osteoclasts are the only cells responsible for bone resorption in the body, and osteoblasts are the main cells responsible for bone regeneration in the body. Under physiological conditions, these cells maintain a dynamic balance to maintain bone homeostasis. It was widely believed that the imbalance of bone metabolism is mainly affected by the expression of related inflammatory factors. However, with the gradual expansion of related studies in recent years, autophagy has been shown to be closely related to the differentiation, apoptosis and functions of osteoclasts and osteoblasts. AMP-activated protein kinase (AMPK) is an important regulator of energy metabolism in vivo and is involved in the regulation of autophagy and bone homeostasis in bone metabolism-related cells. Periodontitis is a chronic infectious disease, and its typical symptoms are alveolar bone resorption. At present, controlling the level of periodontal inflammation and alveolar bone resorption more effectively in clinical practice remains a challenge. The detection of AMPK and autophagy levels in bone metabolism-related cells shows certain prospects for the clinical prevention and treatment of periodontitis in the future. Therefore, this article reviews the regulation of periodontal inflammation levels and bone homeostasis through cell autophagy related to AMPK-mediated bone metabolism.

Regulatory function and mechanism of autophagy on osteoclast / 中国骨伤

Osteoclast (OC) is multinucleated, bone-resorbing cells originated from monocyte/macrophage lineage of cells, excessive production and abnormal activation of which could lead to many bone metabolic diseases, such as osteoporosis, osteoarthritis, etc. Autophagy, as a highly conserved catabolic process in eukaryotic cells, which plays an important role in maintaining cell homeostasis, stress damage repair, proliferation and differentiation. Recent studies have found that autophagy was also involved in the regulation of osteoclast generation and bone resorption. On the one hand, autophagy could be induced and activated by various factors in osteocalsts, such as nutrient deficiency, hypoxia, receptor activator of nuclear factor(NF)-κB ligand(RANKL), inflammatory factors, wear particles, microgravity environment, etc, different inducible factors, such as RANKL, inflammatory factors, wear particles, could interact with each other and work together. On the other hand, activated autophagy is involved in regulating various stages of osteoclast differentiation and maturation, autophagy could promote proliferation of osteoclasts, inhibiting apoptosis, and promoting differentiation, migration and bone resorption of osteoclast. The classical autophagy signaling pathway mediated by mammalian target of rapamycin complex 1(mTORC1) is currently a focus of research, and it could be regulated by upstream signalings such as phosphatidylinositol 3 kinase(PI-3K)/protein kinase B (PKB), AMP-activated protein kinase(AMPK). However, the paper found that mTORC1-mediated autophagy may play a bidirectional role in regulating differentiation and function of osteoclasts, and its underlying mechanism needs to be further ciarified. Integrin αvβ3 and Rab protein families are important targets for autophagy to play a role in osteoclast migration and bone resorption, respectively. In view of important role of osteoclast in the occurrence of various bone diseases, it is of great significance to elucidate the role of autophagy on osteoclast and its mechanism for the treatment of various bone diseases. The autophagy pathway could be used as a new therapeutic target for the treatment of clinical bone diseases such as osteoporosis.

Experimental study of subcutaneous adipose-derived stem cells inhibiting orthodontic root resorption / 中国修复重建外科杂志

OBJECTIVE@#To investigate the effect of human subcutaneous adipose-derived stem cells (hADSCs) local transplantation on orthodontically induced root resorption (OIRR) and provide theoretical and experimental basis for the clinical application of hADSCs to inhibit OIRR.@*METHODS@#Forty 8-week-old male Sprague Dawley rats were randomly divided into experimental group and control group, with 20 rats in each group, to establish the first molar mesial orthodontic tooth movement (OTM) model of rat right maxillary. The rats in the experimental group were injected with 25 μL of cell suspension containing 2.5×10 5 hADSCs on the 1st, 4th, 8th, and 12th day of modeling, while the rats in the control group were injected with 25 μL of PBS. The rat maxillary models were obtained before and after 7 and 14 days of force application, and 10 rats in each group were killed and sampled after 7 and 14 days of force application. The OTM distance was measured by stereomicroscope, the root morphology of the pressure side was observed by scanning electron microscope and the root resorption area ratio was measured. The root resorption and periodontal tissue remodeling of the pressure side were observed by HE staining and the root resorption index was calculated. The number of cementoclast and osteoclast in the periodontal tissue on the pressure side was counted by tartrate resistant acid phosphatase staining.@*RESULTS@#The TOM distance of both groups increased with the extension of the force application time, and there was no significant difference ( P<0.05). There was no significant difference in OTM distance between the experimental group and the control group after 7 and 14 days of force application ( P>0.05). Scanning electron microscope observation showed that small and shallow scattered resorption lacunae were observed on the root surface of the experimental group and the control group after 7 days of force application, and there was no significant difference in the root resorption area ratio between the two groups ( P>0.05); after 14 days of application, the root resorption lacunae deepened and became larger in both groups, and the root resorption area ratio in the experimental group was significantly lower than that in the control group ( P<0.05). The range and depth of root absorption in the experimental group were smaller and shallower than those in the control group, and the root absorption index in the experimental group was significantly lower than that in the control group after 14 days of force application ( P<0.05). The number of cementoclast in the experimental group was significantly lower than that in the control group after 7 and 14 days of force application ( P<0.05); the number of osteoclasts in the experimental group was significantly lower than that in the control group after 14 days of force application ( P<0.05).@*CONCLUSION@#Local transplantation of hADSCs may reduce the area and depth of root resorption by reducing the number of cementoclasts and osteoclasts during OTM in rats, thereby inhibiting orthodontic-derived root resorption.

Investigação de marcadores moleculares sanguíneos durante a infecção pelo vírus Chikungunya / Investigation of blood molecular markers during Chikungunya virus infection

A febre Chikungunya (CHIKF) é uma infecção viral causada pelo vírus Chikungunya (CHIKV). Os sintomas agudos incluem febre alta de início súbito, erupção cutânea, poliartrite e poliartralgia. Embora a infecção geralmente seja resolvida em menos de duas semanas, muitos pacientes experenciam recorrente dor e inflamação nas articulações, que podem persistir por anos. Esse estudo buscou marcadores moleculares no sangue de infectados pelo CHIKV que estejam associados a dor articular e cronicidade da CHIKF. O sequenciamento de receptores de células B (BCR) e T (TCR) demonstrou que a infecção por CHIKV diminui a diversidade desses receptores. Essa diversidade é ainda menor, durante a fase aguda da infecção, naqueles pacientes que irão desenvolver cronicidade. A menor diversidade de BCR em infectados está associada a um aumento na expressão de genes envolvidos na diferenciação e ativação de osteoclastos pela sinalização RANK/RANKL. Em adição, a cronicidade pode estar relacionada um aumento na expressão do gene ZBTB7A cuja expressão confere maior resistência a apoptose em precursores de osteoclastos naqueles pacientes que vão se tornar crônicos. Caso o envolvimento dos osteoclastos durante a patogênese de CHIKF seja confirmado, os pacientes poderão se beneficiar de abordagens terapêuticas já existentes como alternativas adicionais ao tratamento de CHIKF

Chikungunya fever (CHIKF) is a viral infection caused by the Chikungunya virus (CHIKV). Acute symptoms include sudden-onset high fever, rash, polyarthritis, and polyarthralgia. Although the infection usually resolves within two weeks, many patients experience recurrent joint pain and inflammation, which can persist for years. This study sought molecular markers in the blood of CHIKV-infected individuals that are associated with joint pain and chronicity of CHIKF. Sequencing of B (BCR) and T (TCR) cell receptors demonstrated that CHIKV infection decreases the diversity of these receptors. The diversity is even lower, during the acute phase of the infection, in those patients who will develop chronicity. The lower diversity of BCR in infected individuals is associated with an increase in the expression of genes involved in the differentiation and activation of osteoclasts by RANK/RANKL signaling. In addition, chronicity may be related to an increase in the expression of the ZBTB7A gene whose expression confers greater resistance to apoptosis in osteoclast precursors in those patients who will become chronic. If osteoclast role during CHIKF pathogenesis is confirmed, patients may benefit from existing therapeutic approaches as additional alternatives to CHIKF treatment

Channa Striata and Hyperbaric Oxygen Therapy Combination for Pressure Areas in Orthodontic Treatment

ABSTRACT Objective: To study the effect of using a combination of Channa Striata gel and hyperbaric oxygen therapy on pressure areas during orthodontic treatment. Material and Methods: The study was conducted using the ARRIVE Essential 10 guidelines. In this study, 35 3-4 months male guinea pigs (Cavia Cobaya) weighing 300-400 grams were used and divided into 5 groups (n=7). Decalcification was performed to dissolve the dental calcium and jawbone to cut the tissue properly. The decalcification was performed for 30 days. Then preparations were made with HE (Hematoxylin Eosin), observed using a microscope, and counted the number of osteoclasts and macrophages on a light microscope with 400 times magnification. The results of the preparations were analyzed using the SPSS program. Results: The Kruskal-Wallis test of macrophage cells and the ANOVA test of osteoclast cells showed significant results between all groups (p<0.05). Conclusion: The effect of hyperbaric oxygen therapy 2,4 ATA administered on days 8-14 and Channa Striata extract gel administered on days 3-14 can increase the number of macrophages in the periodontal ligament and osteoclasts in the alveolar bone in the pressure area during orthodontic tooth movement.

Effects of polydopamine-coated porous titanium alloy scaffolds loaded with zoledronic acid-gelatin nanoparticles for topical sustained drug release on osteoclasts: an in vitro study / 中华创伤骨科杂志

Objective:To analyze the effects of a novel type of polydopamine (PDA)-coated porous titanium alloy scaffolds loaded with zoledronic acid-gelatin nanoparticles (ZOL-GNPs) for topical sustained drug release on osteoclasts in vitro. Methods:After porous titanium alloy scaffolds were fabricated using electron beam melting technique and ZOL-GNPs with different ZOL concentrations (0, 1, 10, 50, 100, 500 μmol/L) were prepared by desolvation method, PDA-coated porous titanium alloy scaffolds loaded with ZOL-GNPs were constructed by combining the two. The characteristics of the scaffolds were analyzed. The biomechanics of 3 different scaffolds (bare porous titanium alloy scaffolds, PDA-coated porous titanium alloy scaffolds, and PDA-coated porous titanium alloy scaffolds loaded with ZOL-GNPs) were investigated. Drug release detection was carried out by high performance liquid chromatography on the 1st, 4th, 7th, 14th, 21st, and 28th days respectively. The osteoclasts were inoculated into the novel scaffolds with different ZOL concentrations. The expression of osteoclast-related genes was detected by real-time quantitative (RT)-polymerase chain reaction (PCR); the expression of osteoclast-related proteins was detected by Western-blot.Results:The PDA-coated porous titanium alloy scaffolds loaded with ZOL-GNPs were successfully constructed. Electron microscope scanning showed that the GNPs were well spheroidized, smooth in surface, and uniformly dispersed, with a particle size of (243.6±63.4) nm. The ZOL-GNPs were uniformly compounded on the surface and in the pores of the scaffolds, and the spheres were regular in shape with no adhesion. The biomechanical experiments showed that the elastic moduli of the porous titanium alloy scaffolds under 3 different conditions were (1.81±0.12) GPa, (1.80±0.23) GPa and (1.81±0.15) GPa, showing no significant difference ( P> 0.05). The drug release percentage in the porous titanium alloy scaffolds was obviously high on the first day, and increased gradually and slowly in the subsequent 27 days. In the scaffolds with a low concentration ZOL, more osteoclasts adhered and proliferated; in the 50 μmol/L scaffolds, spheroid cells appeared; the spheroid cells increased and even apoptosis occurred with an increase in the ZOL concentration. RT-PCR showed that the expression of Ctsk gene and TRAP gene increased with the increased ZOL concentration, peaked in the 50 μmol/L scaffolds, and then decreased with the increased concentration, showing statistically significant differences ( P < 0.05). Western-blot showed that the expression pattern of Ctsk and TRAP was similar to that of their related genes. Conclusions:The novel PDA-coated porous titanium alloy scaffolds loaded with ZOL-GNPs demonstrate good mechanical properties and an anti-osteoporosis effect via their topical sustained drug release. The scaffolds with a ZOL concentration of 50 μmol/L may exert the best effect on inhibition of osteoclasts.

Correlation between proteoglycan and alveolar bone resorption in a mouse periodontitis model / 口腔疾病防治

Objective@#To analyze changes in proteoglycan and its correlation with alveolar bone resorption in periodontitis. @*Methods @#Twelve eight-week-old C57BL/6J male mice were selected, and the periodontitis model was established by ligating the right maxillary second molar with 6-0 silk thread. The nonligated part of the left maxilla was used as the control. The mice were killed 14 days after the operation. Micro-CT was used to assess alveolar bone resorption. HE staining was used to observe the alveolar bone profile, and TRAP staining was conducted to examine the positive rate of osteoclasts. The expression of proteoglycan-related genes, such as aggrecan (ACAN), biglycan (BGN), versican (VCAN), decorin (DCN), osteoclast-related genes, such as cathepsin K (CTSK), matrix metalloprotein-9 (MMP-9), and receptor activator of nuclear factor kappa-B ligand (RANKL), and inflammation-related genes, such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), was detected by real-time quantitative PCR. Additionally, the correlation of the expression of proteoglycans with osteoclast-related genes and inflammation-related genes was evaluated by Pearson correlation analysis.@* Results@#The resorption of alveolar bone on the periodontitis side increased. TRAP staining showed that the number of osteoclasts was substantially increased in the maxilla with periodontitis. Real-time quantitative PCR demonstrated that compared with the control side, the expression of proteoglycan-related genes, such as ACAN, BGN, and DCN, was decreased, whereas the expression of the VCAN gene was significantly increased in the periodontitis side. Meanwhile, the expression of osteoclast-related genes, such as CTSK, MMP-9, and RANKL, and inflammation-related genes, such as IL-1β, IL-6, and TNF-α, was markedly increased in the periodontitis side (P<0.05). Pearson correlation analysis indicated a negative correlation between the expression of proteoglycans and the mRNA levels of osteoclast-related genes and inflammation-related genes (P<0.05). @*Conclusion @#The expression of proteoglycan was closely related to alveolar bone resorption in a periodontitis model.

Multi-functional osteoclasts in matrix-based tissue engineering bone / 中华创伤杂志(英文版)

The repair of bone defects, especially for the large segment of bone defects, has always been an urgent problem in orthopedic clinic and attracted researchers' attention. Nowadays, the application of tissue engineering bone in the repair of bone defects has become the research hotspot. With the rapid development of tissue engineering, the novel and functional scaffold materials for bone repair have emerged. In this review, we have summarized the multi-functional roles of osteoclasts in bone remodeling. The development of matrix-based tissue engineering bone has laid a theoretical foundation for further investigation about the novel bone regeneration materials which could perform high bioactivity. From the point of view on preserving pre-osteoclasts and targeting mature osteoclasts, this review introduced the novel matrix-based tissue engineering bone based on osteoclasts in the field of bone tissue engineering, which provides a potential direction for the development of novel scaffold materials for the treatment of bone defects.

Research progress on interaction between osteoblasts and osteoclasts / 中国药理学通报

Osteoclasts and osteoblasts play an important role in bone remodeling, and their dysfunction can lead to a series of bone diseases, such as osteoporosis and osteoselerosis.Reeent studies have found that the active substances secreted by osteo¬blasts can regulate the recruitment, attachment, proliferation and differentiation of osteoclasts, thus affecting bone resorption.'Hie active substances derived from osteoclasts can also regulate the formation, survival, differentiation and mineralization of os¬ teoblasts and affect bone fonnation.In this paper, the active substances produced by osteoblasts and osteoclasts at present are summarized, and their functions are analyzed, so as to provide new ideas for dnjgs regulation of the dynamic balance between osteoblasts and osteoclasts.

Bioactive glass-ceramic for bone tissue engineering: an in vitro and in vivo study focusing on osteoclasts

Abstract: Despite the crucial role of osteoclasts in the physiological process of bone repair, most bone tissue engineering strategies have focused on osteoblast-biomaterial interactions. Although Biosilicate® with two crystalline phases (BioS-2P) exhibits osteogenic properties and significant bone formation, its effects on osteoclasts are unknown. This study aimed to investigate the in vitro and in vivo effects of BioS-2P on osteoclast differentiation and activity. RAW 264.7 cells were cultured in osteoclastogenic medium (OCM) or OCM conditioned with BioS-2P (OCM-BioS-2P), and the cell morphology, viability, and osteoclast differentiation were evaluated. BioS-2P scaffolds were implanted into rat calvarial defects, and the bone tissue was evaluated using tartrate-resistant acid phosphatase (TRAP) staining and RT-polymerase chain reaction (PCR) after 2 and 4 weeks to determine the gene expressions of osteoclast markers and compare them with those of the bone grown in empty defects (Control). OCM-BioS-2P favored osteoclast viability and activity, as evidenced by an increase in the TRAP-positive cells and matrix resorption. The bone tissue grown on BioS-2P scaffolds exhibited higher expression of the osteoclast marker genes (Ctsk, Mmp 9, Rank) after 2 and 4 weeks and the RankL/Opg ratio after 2 weeks. Trap gene expression was lower at 2 weeks, and a higher number of TRAP-stained areas were observed in the newly formed bone on BioS-2P scaffolds at both 2 and 4 weeks compared to the Controls. These results enhanced our understanding of the role of bioactive glass-ceramics in bone repair, and highlighted their role in the modulation of osteoclastic activities and promotion of interactions between bone tissues and biomaterials.

The Role of Signal Transducer and Activator of Transcription 3 in Bone Homeostasis and Load-Driven Bone Remodeling / 医用生物力学

Bone homeostasis is a relative balance between bone formation and resorption. Signal transducer and activator of transcription 3 (STAT3), which is closely related to bone homeostasis, takes part in multiple intracellular and extracellular signal pathways. STAT3 participates in the process of osteoblast differentiation regulated by several factors. It can also maintain bone homeostasis by regulating the recruitment, differentiation and activation of osteoclasts. In addition, STAT3 is involved in the interaction between osteoblasts and osteoclasts. Patients with STAT3 mutations can have several inherited bone metabolism diseases. Furthermore, STAT3 plays a critical role in load-driven bone remodeling. Mechanical stimulation promotes osteoblast differentiation and bone formation through activating or enhancing STAT3 expression during bone remodeling process. This review summarizes the participation of STAT3 in maintaining bone homeostasis together with its possible mechanisms and discusses the connection between STAT3 and mechanical stimulation in bone remodeling, so as to provide a potential pharmacological target for the treatment of bone diseases.

Effect of mechano-growth factor on osteoclast activity and its mechanism / 中华创伤杂志

Objective:To investigate the effect of mechano-growth factor（MGF）on osteoclast activity and its mechanism.Methods:The RAW264.7 precursor osteoclast cell line was cultured with 25 ng/ml macrophage-colony stimulating factor（M-CSF）and 30 ng/ml receptor activator of NF-κB ligand（RANKL），and identified by tartrate resistant acid phosphatase（TRAP）staining after 7 days of culture. Western blot anslysis was used to determine the effect of 45 ng/ml MGF on the phosphoinositide-3-kinase/protein kinase B（PI3K/AKT）signaling pathway in separated osteoclasts，including levels of AKT，phosphorylation（p）-AKT，lactation mammalian target of rapamycin（mTOR），p-mTOR and TRAP at 0，4，8 and 12 hours. Real-time fluorescence quantitative PCR was used to expressions of TRAP in osteoclasts at 0，4，8 and 12 hours. The PI3K/Akt phosphorylation inhibitor LY294002（20 μmol/L）combined with MGF（45 ng/ml）was used to act on osteoclasts，and expression levels of Akt，p-Akt，mTOR，p-mTOR and TRAP were detected by Western blot at 0，4，8 and 12 hours.Results:After culturing RAW264.7 cells with M-CSF and RANKL for 7 days，a large number of osteoclasts with positive TRAP staining can be obtained. Western blot analysis showed expression levels of Akt and mTOR did not change significantly over time（ P>0.05），expression levels of p-Akt and p-mTOR increased continuously from（2.18±0.34）pg/ml and（0.83±0.10）pg/ml at 0 hour to（3.86±0.36）pg/ml and（1.56±0.19）pg/ml at 12 hours（ P<0.05），and expression level of TRAP decreased significantly over time，from（5.66±0.47）pg/ml at 0 hour to（3.76±0.38）pg/ml at 12 hours（ P<0.05）. Real-time fluorescence quantitative PCR analysis of expression of TRAP in osteoclasts showed that MGF inhibited the expression of TRAP in osteoclasts，which decreased from 1.02±0.06 at 0 hour to 0.53±0.11 at 12 hours（ P<0.05）. After acting LY294002 combined with MGF on osteoclasts，Western blot analysis showed expression levels of Akt and mTOR did not change significantly over time（ P>0.05），expression levels of p-AKT and p-mTOR decreased significantly from（3.28±0.18）pg/ml and（3.29±0.22）pg/ml at 0 hour to（2.06±0.34）pg/ml and（2.04±0.20）pg/ml at 12 hours（ P<0.05），and expression level of TRAP had no significant difference over time（ P>0.05）. Conclusions:MGF inhibits osteoclast activity by inhibiting the expression of TRAP in osteoclasts through PI3K/Akt signaling pathway. LY294002 inhibits the expression of PI3K/Akt signaling pathway in osteoclasts，further verifying the mechanism of MGF inhibiting osteoclast activity，and this finding puts forward new ideas for clinical prevention and treatment of osteoporosis.

Humulus lupulus L. Extract Prevents Ovariectomy-Induced Osteoporosis in Mice and Regulates Activities of Osteoblasts and Osteoclasts / 中国结合医学杂志

OBJECTIVE@#To systematically evaluate the protective effects of Humulus lupulus L. extract (HLE) on osteoporosis mice.@*METHODS@#In vivo experiment, a total of 35 12-week-old female ICR mice were equally divided into 5 groups: the sham control group (sham); the ovariectomy with vehicle group (OVX); the OVX with estradiol valerate [EV, 0.2 mg/(kg•d)] the OVX with low- or high-dose HLE groups [HLE, 1 g/(kg•d) and 3 g/(kg•d)], 7 in each group. Treatment began 1 week after the ovariectomized surgery and lasted for 12 weeks. Bone mass and trabecular bone mircoarchitecture were evaluated by micro computed tomography, and bone turnover markers in serum were evaluated using enzyme-linked immunosorbent assay (ELISA) kits. In vitro experiment, osteoblasts and osteoclasts were treated with HLE at doses of 0, 4, 20 and 100 µg/mL. Biomarkers for bone formation in osteoblasts and bone resorption in osteoclasts were analyzed.@*RESULTS@#Compared with the OVX group, HLE exerted bone protective effects by the increase of estradiol (P<0.05), the improvement of cancellous bone structure, bone mineral density (P<0.01) and the reduction of serum alkaline phosphatase (ALP), tartrate resistant acid phosphatase (TRAP), bone gla-protein, c-terminal telopeptides of type I collagen (CTX-I) and deoxypyridinoline levels (P<0.01 for all). In vitro experiment, compared with the control group, HLE at 20 µg/mL promoted the cell proliferation (P<0.01), and increased the expression of bone morphogenetic protein-2 and osteopontin levels in osteoblasts (both P<0.05). HLE at 100 µg/mL increased the osteoblastic ALP activities, and HLE at all dose enhanced the extracellular matrix mineralization (both P<0.01). Furthermore, compared with the control group, HLE at 20 µg/mL and 100 µg/mL inhibited osteoclastic TRAP activity (P<0.01), and reduced the expression of matrix metalloproteinase-9 and cathepsin K (both P<0.05).@*CONCLUSION@#HLE may protect against bone loss, and have potentials in the treatment of osteoporosis.

Recombinant human insulin-like growth factor-1 promotes osteoclast formation and accelerates orthodontic tooth movement in rats

Abstract Background: IGF-1 may be an important factor in bone remodeling, but its mechanism of action on osteoclasts during orthodontic tooth movement is complex and unclear. Methodology: The closed-coil spring was placed between the left maxillary first molar and upper incisors with a force of 50 g to establish an orthodontic movement model. Eighty SD rats were randomized to receive phosphate buffer saline or 400 ng rhIGF-1 in the lateral buccal mucosa of the left maxillary first molar every two days. Tissue sections were stained for tartrate-resistant acidic phosphatase (TRAP), the number of TRAP-positive cells was estimated and tooth movement measured. Results: The rhIGF-1 group exhibited evidential bone resorption and lacuna appeared on the alveolar bone compared to the control group. Moreover, the number of osteoclasts in compression side of the periodontal ligament in the rhIGF-1 group peaked at day 4 (11.37±0.95 compared to 5.28±0.47 in the control group) after the orthodontic force was applied and was significantly higher than that of the control group (p<0.01). Furthermore, the distance of tooth movement in the rhIGF-1 group was significantly larger than that of the control group from day 4 to day 14 (p<0.01), suggesting that rhIGF-1 accelerated orthodontic tooth movement. Conclusion: Our study has showed that rhIGF-1 could stimulate the formation of osteoclasts in the periodontal ligament, and accelerate bone remodeling and orthodontic tooth movement.

Relationship between lactic acid concentration and osteoclast differentiation of mouse monocytes / 中国组织工程研究

BACKGROUND: Preliminary study found that polylactic acid composite material could accelerate the bone construction rate, and the underlying mechanism still needs to be studied further. OBJECTIVE: To investigate the effect of lactic acid at different concentrations on osteoclast differentiation of mononuclear cells in mice. METHODS: Mouse RAW264.7 cells were cultured in DMEM with 0 (control group), 5, 10 and 20 mmol/L lactic acid, respectively, under the induction of 50 µg/L RANKL for 5 days. The effect of lactic acid concentration on the cell proliferation rate was analyzed by cell counting kit-8 assay. Tartrate resistant acid phosphatase positive polykaryotic cells were stained and counted with tartrate resistant acid phosphatase staining kit. mRNA expression levels of acid phosphatase 5, nuclear factor of activated T-cells 1 and RANK were detected by RT-PCR. Protein expression levels of cathepsin K and nuclear factor of activated T-cells 1 were detected by western blot assay. RESULTS AND CONCLUSION: (1) 5 mmol/L lactic acid produced the highest proliferation rate of raw264.7 cells, whereas the 20 mmol/L lactic acid produced lowest cell proliferation rate. Compared with the control group, the proliferation rate of raw264.7 cells by 10 mmol/L lactic acid was insignificant. (2) Tartrate resistant acid phosphatase staining showed the highest positive rate and mRNA expression levels of acid phosphatase 5, nuclear factor of activated T-cells 1 and RANK under the condition of 10 mmol/L lactic acid. (3) With the increase of lactic acid concentration, the expression level of cathepsin K increased, while the expression level of nuclear factor of activated T-cells 1 was on a decline. (4) Under the current experimental conditions, with the increase of lactic acid concentration, the ability of lactic acid to promote the osteoclast differentiation of mouse RAW264.7 cells is firstly increased and then decreased, and 10 mmol/L lactic acid was the optimal concentration to promote the osteoclast differentiation of mouse RAW264.7 cells. Lactic acid can affect the osteoclastic differentiation of mouse raw264.7 cells by nuclear factor of activated T-cells 1 in nuclear factor-KB signaling pathway.

Effect of Porphyromonas gingivalis lipopolysaccharide on innate immune responses in bone-marrow derived macrophages and osteoclasts / 中华口腔医学杂志

Objective@#To analyze the immune responses of bone-marrow derived macrophages and osteoclasts to lipopolysaccharide from Porphyromonas gingivalis (Pg-LPS) so as to provide reference for host immunomodulatory therapy of periodontitis.@*Methods@#Bone marrow mononuclear cells from C57BL/6 mice were obtained and induced into bone marrow macrophages (BMM) and osteoclasts (OC) by conditioned medium. The BMMs and OCs were divided into blank control group and Pg-LPS treated experimental group. Pg-LPS (10 μg/ml) was used to stimulate BMM and OC. The mRNA and protein expression of TLR-2 and TLR-4 and secretion of inflammatory cytokines were detected, respectively. Furthermore, the effect of Pg-LPS on the differentiation of BMM into OC was evaluated.@*Results@#Mouse bone marrow mononuclear cells were successfully induced into BMM and mature OC. In the presence of Pg-LPS, the gene level of TLR-2 in BMM was significantly up-regulated by (41.41±13.07) folds (P<0.01), while the level of TLR-4 mRNA was not significantly changed. TLR-2 mRNA and TLR-4 mRNA levels in OC increased by (2.24±0.23) times (P<0.05) and (4.83±1.07) times (P<0.01), respectively. Flow cytometry results showed that TLR-2 protein expression in BMM was robustly enhanced (P<0.01), as mean fluorescence intensities (MFI) were (39.85±5.27) in blank group and (221.57±13.13) in experimental group, respectively. The MFI of TLR-2 in OC also increased as (83.31±2.69) in blank group and (108.65±6.32) in experimental group, respectively (P<0.01). However, no significant TLR-4 expressions were observed in both BMM and OC (P>0.05). Moreover, the productions of tumor necrosis factor-α and interleukin-6 in response to LPS in BMM and OC remarkably increased (P<0.01). Lower cytokine expression was observed in OC than that in BMM (P<0.01). In addition, Pg-LPS obviously inhibited the number and size of OC formation, with a reduction in area percentage of approximately 47%.@*Conclusions@#Pg-LPS generated a robust immune inflammatory response to BMM, while OC had a relatively weaker immune response to the Pg-LPS. Pg-LPS might inhibite the differentiation of BMM into OC.

Effect of low level laser on osteoclasts and collagen fiber remodeling during the process of tooth retention after tooth movement in rats / 口腔疾病防治

Objective@#To investigate the effect of low level laser on osteoclast and collagen fiber remodeling during the process of tooth retention after tooth movement in rats and to provide the experimental basis for clinical application.@*Methods @# In total, 20 eight-week-old Wistar rats were selected to establish a mesial movement model of the maxillary first molar and then randomly divided into four groups after the appliance was removed. In total, 5 rats were included in each group, including baseline group (without force as blank control), control group (without any intervention after removing the force appliance), retention group (teeth were wrapped with orthodontic ligature wires that were screwed into hemp flower as fixed retention to maintain the space between the first molar and incisor after appliances were removed) and retention and low energy laser irradiation group (teeth were wrapped with the orthodontic ligature wires that were screwed into hemp flower as fixed retention and low energy laser irradiation was applied on days 0, 3, 6, 9 and 12 after appliance removal). Two weeks later, all the rats were sacrificed and the first molar tissue blocks of each group were collected. The distribution of osteoclasts and collagen fiber were studied by HE staining, TRAP staining and Masson staining to illustrate the process of alveolar bone and collagen fiber remodeling.@*Results @# Two weeks after appliances were removed, collagen fibers were deposited on both sides of the root in the baseline group, but no osteoclasts were observed in the distal side of the root. In the control group, collagen fibers on the two sides of the root were not obvious and osteoclasts were active on the distal side. In the retention group, collagen fibers were obvious on the two sides of the root and the osteoclasts on the distal side were less active than the control group. Regarding the retention and low energy laser irradiation group, collagen fibers were significantly obvious and osteoclasts were not seen. The difference was statistically significant between the retention and low energy laser irradiation group and the other three groups (P＜0.05). @*Conclusion@#These results suggest that fixed retention with simultaneous low level laser can effectively promote the synthesis of collagen fibers and inhibit the activity of osteoclasts during the process of tooth retention after movement, thus reducing the possibility of molar recurrence.

Expression of sclerostin in alveolar bone remodeling of ovariectomized rats / 口腔疾病防治

Objective@# To investigate the expression and distribution of sclerostin in the alveolar bone of rat in the absence of estrogen, and to provide evidence for the analysis of the histological correlation between sclerostin and alveolar bone remodeling in rats. @*Methods @#The experimental subjects of this study were 32 8-week-old female Wistar rats. Among them, 16 rats were ovariectomized (OVX), and 16 rats were subjected to a sham operation (Sham). These rats were sacrificed 1, 2, 3, and 4 weeks after the operation, and the mandibles were removed and embedded. The mesial and distal sections of the rat,s mandibular first molars were selected and stained with anti-tartrate phosphatase (TRAP), sclerostin immunostaining, multiple immunostainings, RANKL and TRAP double staining, and silver-plated multiple staining. @*Results @#As the postoperative time in rats increased, the TRAP-positive osteoclasts counts in the OVX group in the interalveolar septum of mandibular first molar increased significantly, and statistical difference was noted between the groups (P ＜ 0.05). The OVX 2w, 3w, and 4w groups exhibited more TRAP-positive osteoclasts compared with the Sham group at the corresponding time point, and the results were statistically different (P ＜ 0.05). Sclerostin immunostaining revealed that the proportion of positive bone cells in the mesial side of the periodontal ligament area of mandibular first molar in the OVX group gradually decreased. Statistical differences were noted between the OVX 3w group and the OVX 4w group as well as the OVX 1w group and, the OVX 2w group (P ＜ 0.05). In the comparison between the area near the periodontal ligament and the central area of the alveolar bone septum of the mandibular first molar in the same group, the positive expression ratio of sclerostin in the OVX 3w and OVX 4w groups in the area near the periodontal ligament was reduced compared with that in the central area of the alveolar bone septum. The results were statistically significant (P ＜ 0.05). A larger number of osteoblasts was noted around the osteoclasts in the OVX 4w group compared with the Sham 4w group based on ALP/ TRAP /sclerostin multiple staining, whereas less sclerostin-positive osteoblasts were noted in the OVX 4w group. Sclerostin/TRAP/silver plating staining showed that the bone tubules around the sclerostin positive bone cells mostly exhibited a parallel and neat arrangement, and the bone tubules around sclerostin negative bone cells were more irregular and disorderly arranged in the OVX 4w group@*Conclusion@#Sclerostin protein is involved in alveolar bone remodeling in estrogen-deficient rats.