Multimodality Treatment of Deep-seated Cerebral Arteriovenous Malformations: The Experiences of One Center.

OBJECTIVE: Treatment of deep-seated cerebral arteriovenous malformations (AVMs) remains challenging for neurosurgeons or neuroradiologists. This study aims to review the experiences of one center in using multimodality treatment for deep-seated AVMs. METHODS: The AVM database of Xuanwu Hospital, Capital Medical University was searched, and 96 patients who were diagnosed with a deep-seated cerebral AVM between 2010 and 2020 were identified. The following information was collected and analyzed: patients' clinical features, treatment modality used, posttreatment complications, AVM obliteration rate, rebleeding rate, and functional outcome during follow-up. The patients' posttreatment modified Rankin scale (mRS) scores were split into two groups: good outcome (mRS score ≤ 2) and poor outcome (mRS score ≥ 3). Univariate and multivariate logistic regression analyses were applied to test the predictors of clinical outcomes and AVM obliteration. RESULTS: Eighty-eight out of 96 patients (91.7%) presented with initial hemorrhaging. The pretreatment mRS score was ≤ 2 in 80 patients (88.3%) patients and ≥ 3 in 16 patients (16.7%). Limb weakness was present in 42 patients (43.8%). In this sample, 210 hemorrhages occurred during 2056 person-years before diagnosis, yielding an annual hemorrhage rate of 10.2% per person-year. Angiographic obliteration was achieved in 29 patients (30.2%). At the last follow-up, 80 patients (83.3%) had good clinical outcomes, whereas 16 (16.7%) had a deterioration in their clinical presentation following treatment. Multivariate analyses indicated that pretreatment limb weaknesses and a high Spetzler-Martin grade predicted poor clinical outcomes (P = 0.003 and 0.008, respectively). Fewer feeding arteries were a predictor for AVM obliteration (P = 0.034). CONCLUSION: Good outcomes can be achieved through multimodal treatment of deep-seated AVMs. A single supplying artery is a predictor of AVM obliteration. Pretreatment limb weaknesses and high Spetzler-Martin grades predict poor clinical outcomes.

Local administration of high-dose diabetes medicine exendin-4 inhibits orthodontic tooth movement in mice.

OBJECTIVES: To investigate the effects of exendin-4 on orthodontic tooth movement distance, root resorption, and expression levels of osteoclast-related cytokines in a mouse model. MATERIALS AND METHODS: A 10-g NiTi coil spring was placed between the anterior alveolar bone and upper left first molar of 8-week-old male C57BL/6 mice. Twenty microliters of exendin-4 solution (containing 0.2 µg, 4 µg, or 20 µg exendin-4) or phosphate-buffered saline (PBS) were injected on the buccal side of the upper left first molar at 2-day intervals (4 mice per group). Mice were sacrificed on day 12; silicone impressions were taken to record tooth movement distance. The left maxillae of the PBS and 20 µg exendin-4 groups were also excised for histological analysis and quantitative reverse transcription polymerase chain reaction analysis. RESULTS: Orthodontic tooth movement distance was smaller in the 20 µg exendin-4 group than in the PBS group (P < .01). Compared with the PBS group, the 20 µg exendin-4 group showed lower osteoclast number (P < .05), odontoclast number (P < .05), and root resorption surface percentage (P < .05). Relative to maxillae with PBS injections, maxillae with 20 µg exendin-4 injections had lower receptor activator of nuclear factor kappa-B ligand (RANKL) mRNA expression (P < .05), TNF-α mRNA expression (P < .05), and RANKL/osteoprotegerin (OPG) ratio (P < .01). There were no differences in the expression of OPG mRNA. CONCLUSIONS: Exendin-4 inhibits orthodontic tooth movement. Therefore, additional attention is needed for orthodontic patients who receive exendin-4 for diabetes treatment. GLP-1 receptor may be a treatment target for patients with severe root resorption.

Effect of a DPP-4 Inhibitor on Orthodontic Tooth Movement and Associated Root Resorption.

OBJECTIVES: Dipeptidyl peptidase-4 (DPP-4) inhibitors are used as a treatment for type 2 diabetes mellitus and have also recently been applied to enhance bone quality and density, and increase the expression of bone markers. This study aimed to investigate the effect of a DPP-4 inhibitor on orthodontic tooth movement (OTM) and related root resorption in a mouse model. MATERIALS AND METHODS: Mice were randomly divided into three groups: those undergoing OTM with the addition of a DPP-4 inhibitor (30 µg), those undergoing OTM and receiving phosphate-buffered saline (PBS), and those without force loading (control group). OTM was achieved by means of a nickel-titanium closed coil spring that moved the first molar in a mesial direction for 12 days. The distance of OTM was measured using silicone impression. Maxillae were removed for histological analysis or real-time PCR analysis. RESULTS: The distance of OTM and the number of osteoclasts were significantly decreased after administration of the DPP-4 inhibitor, which also significantly suppressed the number of odontoclasts and root resorption after OTM. Furthermore, the mRNA expression of tumour necrosis factor-α (TNF-α) and the receptor activator of nuclear factor kappa-B ligand (RANKL) were decreased in DPP-4 inhibitor-treated mice compared with those receiving PBS and control animals. CONCLUSION: The DPP-4 inhibitor inhibited tooth movement and associated root resorption by blocking the formation of osteoclasts and odontoclasts, respectively. It also appeared to inhibit osteoclastogenesis and odontoclastogenesis by suppressing the expression of TNF-α and/or RANKL.

Anti-c-fms Antibody Prevents Osteoclast Formation and Bone Resorption in Co-Culture of Osteoblasts and Osteoclast Precursors In Vitro and in Ovariectomized Mice.

Osteoporosis morphology is characterized by bone resorption and decreases in micro-architecture parameters. Anti-osteoporosis therapy targets osteoclasts because bone resorption is a unique function of osteoclasts. Anti-c-fms antibodies against the receptor for macrophage colony-stimulating factor (M-CSF) inhibit osteoclast formation and bone resorption in vitro and in vivo. However, the effect of anti-c-fms antibodies on bone resorption in ovariectomized (OVX) mice is unknown. In this study, we evaluated the effect of anti-c-fms antibodies on osteoclast formation and bone resorption in osteoblast-osteoclast precursor co-culture in vitro and in OVX mice. Osteoblast and osteoclast precursor co-cultures treated with anti-c-fms antibodies showed significantly inhibited osteoclast formation, while cultures without anti-c-fms antibody treatment showed osteoclast formation. However, anti-c-fms antibodies did not change the receptor activator of nuclear factor kappa-B ligand (RANKL) or osteoprotegrin (OPG) expression during osteoblast and osteoclast differentiation in vitro. These results indicate that anti-c-fms antibodies directly affected osteoclast formation from osteoclast precursors in co-culture. OVX mice were treated with intraperitoneal injections of anti-c-fms antibody. The trabecular bone structure of the femur was assessed by micro-computer tomography. The anti-c-fms antibody inhibited osteoclast formation and bone loss compared with PBS-treated OVX mice. These results indicate potential for the therapeutic application of anti-c-fms antibodies for postmenopausal osteoporosis.

Osteocyte-Related Cytokines Regulate Osteoclast Formation and Bone Resorption.

The process of bone remodeling is the result of the regulated balance between bone cell populations, namely bone-forming osteoblasts, bone-resorbing osteoclasts, and the osteocyte, the mechanosensory cell type. Osteoclasts derived from the hematopoietic stem cell lineage are the principal cells involved in bone resorption. In osteolytic diseases such as rheumatoid arthritis, periodontitis, and osteoporosis, the balance is lost and changes in favor of bone resorption. Therefore, it is vital to elucidate the mechanisms of osteoclast formation and bone resorption. It has been reported that osteocytes express Receptor activator of nuclear factor κΒ ligand (RANKL), an essential factor for osteoclast formation. RANKL secreted by osteocytes is the most important factor for physiologically supported osteoclast formation in the developing skeleton and in pathological bone resorption such as experimental periodontal bone loss. TNF-α directly enhances RANKL expression in osteocytes and promotes osteoclast formation. Moreover, TNF-α enhances sclerostin expression in osteocytes, which also increases osteoclast formation. These findings suggest that osteocyte-related cytokines act directly to enhance osteoclast formation and bone resorption. In this review, we outline the most recent knowledge concerning bone resorption-related cytokines and discuss the osteocyte as the master regulator of bone resorption and effector in osteoclast formation.

TNF-α stimulates the expression of RANK during orthodontic tooth movement.

OBJECTIVE: This study aimed to evaluate the effects of tumor necrosis factor (TNF)-α on receptor activator of nuclear factor-κB (RANK) expression in osteoclast precursors in vitro and during orthodontic tooth movement (OTM) in vivo. DESIGN: We assessed whether TNF-α influenced RANK expression levels in osteoclast precursors in vitro by real-time PCR and western blotting. For in vivo experiments, TNF-α was subcutaneously injected into mouse calvariae daily for 5 days. Mice were sacrificed and RANK expression was evaluated by real-time PCR and immunohistochemistry. For OTM, a nickel-titanium closed-coil spring was fixed between the upper incisors and upper-left first molar to move the first molar in the mesial direction in wild-type (WT) and TNFR1/TNFR2-deficient (TNFRsKO) mice. After OTM, the number of RANK-positive cells on the compression side was evaluated by immunohistochemistry. RESULTS: RANK levels were enhanced in TNF-α-treated osteoclast precursors in vitro. RANK mRNA expression levels and the number of RANK-positive cells were higher in TNF-α-injected mice than in phosphate-buffered saline-injected mice. RANK-positive cells increased on the compression side of the alveolar bone in WT mice because of the mechanical loading. In addition, the number of RANK-positive cells on the compression side was significantly higher in WT mice than in TNFRsKO mice after OTM. CONCLUSION: These results suggest that TNF-α induces RANK expression in vitro and at baseline in vivo, as well as on the compression side during OTM.

IL-33 Inhibits TNF-α-Induced Osteoclastogenesis and Bone Resorption.

Interleukin (IL)-33 is a member of the IL-1 family, which acts as an alarmin. Several studies suggested that IL-33 inhibited osteoclastogenesis and bone resorption. Tumor necrosis factor-α (TNF-α) is considered a direct inducer of osteoclastogenesis. However, there has been no report regarding the effect of IL-33 on TNF-α-induced osteoclastogenesis and bone resorption. The objective of this study is to investigate the role of IL-33 on TNF-α-induced osteoclastogenesis and bone resorption. In an in vitro analysis of osteoclastogenesis, osteoclast precursors, which were derived from bone marrow cells, were treated with or without IL-33 in the presence of TNF-α. Tartrate-resistant acid phosphatase (TRAP) staining solution was used to assess osteoclast formation. In an in vivo analysis of mouse calvariae, TNF-α with or without IL-33 was subcutaneously administrated into the supracalvarial region of mice daily for 5 days. Histological sections were stained for TRAP, and osteoclast numbers were determined. Using micro-CT reconstruction images, the ratio of bone destruction area on the calvariae was evaluated. The number of TRAP-positive cells induced by TNF-α was significantly decreased with IL-33 in vitro and in vivo. Bone resorption was also reduced. IL-33 inhibited IκB phosphorylation and NF-κB nuclear translocation. These results suggest that IL-33 inhibited TNF-α-induced osteoclastogenesis and bone resorption.

TNF-α is responsible for the contribution of stromal cells to osteoclast and odontoclast formation during orthodontic tooth movement.

Compressive force during orthodontic tooth movement induces osteoclast formation in vivo. TNF-α plays an important role in mouse osteoclast formation and bone resorption induced by compressive force during orthodontic tooth movement. Stromal cells, macrophages and T cells take part in TNF-α-induced osteoclast formation in vitro. Root resorption caused by odontoclasts is a major clinical problem during orthodontic tooth movement. In this study, we determined the cell type targeted by TNF-α during compressive-force-induced osteoclast and odontoclast formation to elucidate the mechanism of bone and root resorption in vivo. An orthodontic tooth movement mouse model was prepared with a nickel-titanium closed coil spring inserted between the maxillary incisors and the first molar. Using TNF receptor 1- and 2-deficient (KO) mice, we found that osteoclast and odontoclast formation was mediated by TNF-α in orthodontic tooth movement. We generated four types of chimeric mice: wild-type (WT) bone marrow cells transplanted into lethally irradiated WT mice (WT>WT), KO bone marrow cells transplanted into lethally irradiated WT mice (KO>WT), WT bone marrow cells transplanted into lethally irradiated KO mice (WT>KO), and KO marrow cells transplanted into lethally irradiated KO mice (KO>KO). Using anti-CD4 and anti-CD8 antibodies, T cells were eliminated from these mice. We subjected these chimeric mice to orthodontic tooth movement. Orthodontic tooth movement was evaluated and tartrate-resistant acid phosphatase-positive cells along the alveolar bone (osteoclasts) and along the tooth root (odontoclasts) were counted after 12 days of tooth movement. The amount of orthodontic tooth movement, and the number of osteoclasts and odontoclasts on the compression side were significantly lower in WT>KO and KO>KO mice than in WT>WT and KO>WT mice. According to these results, we concluded that TNF-α-responsive stromal cells are important for osteoclast and odontoclast formation during orthodontic tooth movement.

Effect of TNF-α-Induced Sclerostin on Osteocytes during Orthodontic Tooth Movement.

Osteocytes are abundant cells in bone, which contribute to bone maintenance. Osteocytes express receptor activator of nuclear factor kappa-B ligand (RANKL) and regulate osteoclast formation. Orthodontic tooth movement (OTM) occurs by osteoclast resorption of alveolar bone. Osteocyte-derived RANKL is critical in bone resorption during OTM. Additionally, tumor necrosis factor-α (TNF-α) is important in osteoclastogenesis during OTM. Sclerostin has been reported to enhance RANKL expression in the MLO-Y4 osteocyte-like cell line. This study investigated the effect of TNF-α on sclerostin expression in osteocytes during OTM. In vitro analysis of primary osteocytes, which were isolated from DMP1-Topaz mice by sorting the Topaz variant of GFP-positive cells, revealed that SOST mRNA expression was increased when osteocytes were cultured with TNF-α and that RANKL mRNA expression was increased when osteocytes were cultured with sclerostin. Moreover, the number of TRAP-positive cells was increased in osteocytes and osteoclast precursors cocultured with sclerostin. In vivo analysis of mouse calvariae that had been subcutaneously injected with phosphate-buffered saline (PBS) or TNF-α revealed that the number of TRAP-positive cells and the percentage of sclerostin-positive osteocytes were higher in the TNF-α group than in the PBS group. Furthermore, the level of SOST mRNA was increased by TNF-α. As an OTM model, a Ni-Ti closed-coil spring connecting the upper incisors and upper-left first molar was placed to move the first molar to the mesial direction in wild-type (WT) mice and TNF receptor 1- and 2-deficient (TNFRsKO) mice. After 6 days of OTM, the percentage of sclerostin-positive osteocytes on the compression side of the first molar in TNFRsKO mice was lower than that in WT mice. In this study, TNF-α increased sclerostin expression in osteocytes, and sclerostin enhanced RANKL expression in osteocytes. Thus, TNF-α may play an important role in sclerostin expression in osteocytes and enhance osteoclast formation during OTM.

Establishment of an orthodontic retention mouse model and the effect of anti-c-Fms antibody on orthodontic relapse.

Orthodontic relapse after orthodontic treatment is a major clinical issue in the dental field. However, the biological mechanism of orthodontic relapse is still unclear. This study aimed to establish a mouse model of orthodontic retention to examine how retention affects the rate and the amount of orthodontic relapse. We also sought to examine the role of osteoclastogenesis in relapse using an antibody to block the activity of M-CSF, an essential factor of osteoclast formation. Mice were treated with a nickel-titanium closed-coil spring that was fixed between the upper incisors and the upper-left first molar to move the first molar in a mesial direction over 12 days. Mice were randomly divided into three groups: group 1, no retention (G1); group 2, retention for 2 weeks (G2); and group 3, retention for 4 weeks (G3). In G2 and G3, a light-cured resin was placed in the space between the first and second molars as a model of retention. Orthodontic relapse was assessed by measuring changes in the dimensions of the gap created between the first and second molars. To assess the activity and role of osteoclasts, mice in G3 were injected with anti-c-Fms antibody or PBS, and assessed for changes in relapse distance and rate. Overall, we found that a longer retention period was associated with a slower rate of relapse and a shorter overall amount of relapse. In addition, inhibiting osteoclast formation using the anti-c-Fms antibody also reduced orthodontic relapse. These results suggest that M-CSF and/or its receptor could be potential therapeutic targets in the prevention and treatment of orthodontic relapse.

Effect of Anti-c-fms Antibody on Osteoclast Formation and Proliferation of Osteoclast Precursor In Vitro.

Bone remodeling is a complex process and it involves periods of deposition and resorption. Bone resorption is a process by which bone is broken down by osteoclasts in response to different stimuli. Osteoclast precursors differentiate into multinuclear osteoclasts in response to macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor Kappa-B ligand (RANKL). Under pathologic conditions, the cytokine profile is different and involves a mixture of inflammatory cytokines. Tumor necrosis factor alpha (TNF-α) is one of the most important cytokines as it is found in large amounts in areas involved with inflammatory osteolysis. The purpose of this protocol is to provide a method by which murine bone marrow is isolated to generate osteoclasts through induction with M-CSF and either RANKL or TNF-α which will be subsequently inhibited by increasing doses of anti-c-fms antibody, the receptor for M-CSF. This experiment highlights the therapeutic value of anti-c-fms antibody in diseases of inflammatory bone resorption.

Docosahexaenoic Acid Inhibits Inflammation-Induced Osteoclast Formation and Bone Resorption in vivo Through GPR120 by Inhibiting TNF-α Production in Macrophages and Directly Inhibiting Osteoclast Formation.

Docosahexaenoic acid (DHA) is an n-3 fatty acid that is an important structural component of the cell membrane. DHA exerts potent anti-inflammatory effects through G protein-coupled receptor 120 (GPR120), which is a functional receptor for n-3 fatty acids. DHA also regulates osteoclast formation and function. However, no studies have investigated the effect of DHA on inflammation-induced osteoclast formation in vivo. In the present study, we investigated whether DHA influences osteoclast formation, bone resorption and the expression of osteoclast-associated cytokines during lipopolysaccharide (LPS)-induced inflammation in vivo, and then we elucidated the underlying mechanisms by using in vitro experiments. In vitro experiments revealed both receptor activator of NF-kB ligand (RANKL)- and tumor necrosis factor-α (TNF-α)-induced osteoclast formation was inhibited by DHA. Supracalvarial administration of LPS with or without DHA was carried out for 5 days and then the number of osteoclasts, ratio of bone resorption pits and the level of type I collagen C-terminal cross-linked telopeptide were measured. All measurements were significantly lower in LPS+DHA-co-administered mice than LPS-administered mice. However, this DHA-induced inhibition was not observed in LPS-, DHA-, and selective GPR120 antagonist AH7614-co-administered mice. Furthermore, the expression of RANKL and TNF-α mRNAs was lower in the LPS+DHA-co-administered group than in the LPS-administered group in vivo. TNF-α mRNA levels were decreased in macrophages co-treated with LPS+DHA compared with cells treated with LPS in vitro. In contrast, RANKL mRNA expression levels from osteoblasts co-treated with DHA and LPS in vitro were equal to that in cells treated with LPS alone. Finally, the inhibitory effects of DHA on osteoclast formation in vitro were not observed by using osteoclast precursors from GPR120-deficient mice, and inhibition of LPS-induced osteoclast formation and bone resorption by DHA in vivo was not observed in GPR120-deficient mice. These results suggest that DHA inhibits LPS-induced osteoclast formation and bone resorption in vivo via GPR120 by inhibiting LPS-induced TNF-α production in macrophages along with direct inhibition of osteoclast formation.

TNF-α Directly Enhances Osteocyte RANKL Expression and Promotes Osteoclast Formation.

Osteoimmunology peeks into the interaction of bone and the immune system, which has largely proved to be a multiplex reaction. Osteocytes have been shown to regulate bone resorption through the expression of RANKL in physiologic and pathologic conditions. TNF-α, a product of the immune system, is an important cytokine regulating bone resorption in inflammatory conditions either directly or by increasing RANKL and M-CSF expressions by osteoblasts and stromal cells. The effect of TNF-α on a wide range of cell types has been documented; however, the direct effect of TNF-α on osteocytes has not been established yet. In this study, primary osteocytes were isolated by cell sorting from neonatal calvaria of Dmp1-Topaz mice, which express the green fluorescent protein under the influence of dentin matrix protein 1 promoter. The results show that osteocytes have a significantly higher RANKL mRNA expression when cultured with TNF-α. A co-culture system of osteocytes and TNF receptors I and II deficient osteoclast precursors treated with TNF-α show a significant increase in TRAP-positive cells while cultures without TNF-α failed to show TRAP-positive cells. Additionally, in vivo experiments of TNF-α injected to mouse calvaria show an increase in TRAP-positive cell number in the suture mesenchyme and an increase in the percentage of RANKL-positive osteocytes compared to PBS-injected calvaria. Osteocytes cultured with TNF-α show up-regulation of MAPKs phosphorylation measured by western blot, and adding MAPKs inhibitors to osteocytes cultured with TNF-α significantly decreases RANKL mRNA expression compared to osteocytes cultured with TNF-α alone. We also found that TNF-α activates the NF-κB pathway in osteocytes measured as a function of p65 subunit nuclear translocation. TNF-α directly affects osteocyte RANKL expression and increases osteoclastogenesis; our results demonstrate that osteocytes guard an important role in inflammatory bone resorption mediated by TNF-α.

DPP-4 inhibitor impedes lipopolysaccharide-induced osteoclast formation and bone resorption in vivo.

OBJECTIVES: Dipeptidyl peptidase 4 (DPP-4) inhibition is a new therapeutic strategy for type 2 diabetic patients. DPP-4 has been reported to enhance inflammation. However, the effect of DPP-4 inhibition on inflammation remains unknown. Lipopolysaccharide (LPS) is a strong inducer of inflammation and osteoclast formation. In this study, we investigated in vivo effects of DPP-4 inhibition on LPS-induced osteoclast formation and bone resorption, as well as in vitro effects of DPP-4 inhibition on RANKL-induced osteoclastogenesis and TNF-α-induced osteoclastogenesis. METHODS: LPS with or without a DPP-4 inhibitor was subcutaneously injected into mouse calvaria for 5 days. Histological sections of calvaria were stained for tartrate-resistant acid phosphatase, and osteoclast numbers were determined. The ratio of calvaria bone resorption was evaluated via microfocal computed tomography reconstruction images. RESULTS: Osteoclast number and bone resorption were significantly lower in mice that underwent LPS and DPP-4 inhibitor co-administration than in those that underwent LPS administration alone. Moreover, RANKL, TNF-α, and M-CSF expression was reduced in the LPS and DPP-4 inhibitor co-administration group. In vitro, there were no direct effects of DPP-4 inhibitor or DPP-4 on RANKL- and TNF-α-induced osteoclastogenesis, or on LPS-induced RANKL expression in stromal cells. Nevertheless, macrophages from LPS and DPP-4 inhibitor co-administered mice exhibited lower TNF-α expression than macrophages from LPS-only mice. Notably, TNF-α expression was not reduced in LPS and DPP-4 inhibitor co-treated macrophages in vitro, compared with macrophages treated with LPS alone.

The Glucagon-Like Peptide-1 Receptor Agonist Exendin-4 Inhibits Lipopolysaccharide-Induced Osteoclast Formation and Bone Resorption via Inhibition of TNF-α Expression in Macrophages.

Glucagon-like peptide-1 (GLP-1) receptor agonists are an effective treatment approach for type 2 diabetes. Recently, anti-inflammatory effects of GLP-1 receptor agonists have also been reported. Lipopolysaccharide (LPS) induces inflammation and osteoclast formation. In this study, we investigated the effect of exendin-4, a widely used GLP-1 receptor agonist, in LPS-induced osteoclast formation and bone resorption. LPS with or without exendin-4 was administered on mouse calvariae by daily subcutaneous injection. The number of osteoclasts, the ratio of bone resorption pits, and the level of C-terminal cross-linked telopeptide of type I collagen (CTX) were significantly lower in LPS- and exendin-4-coadministered mice than in mice administered with LPS alone. RANKL and TNF-α mRNA expression levels were lower in the exendin-4- and LPS-coadministered group than in the LPS-administered group. Our in vitro results showed no direct effects of exendin-4 on RANKL-induced osteoclast formation, TNF-α-induced osteoclast formation, or LPS-induced RANKL expression in stromal cells. Conversely, TNF-α mRNA expression was inhibited in the exendin-4- and LPS-cotreated macrophages compared with cells treated with LPS alone. These results indicate that the GLP-1 receptor agonist exendin-4 may inhibit LPS-induced osteoclast formation and bone resorption by inhibiting LPS-induced TNF-α production in macrophages.

C-X-C Motif Chemokine 12 Enhances Lipopolysaccharide-Induced Osteoclastogenesis and Bone Resorption In Vivo.

C-X-C motif chemokine 12 (CXCL12) belongs to the family of CXC chemokines. Lipopolysaccharide (LPS) induces inflammation-induced osteoclastogenesis and bone resorption, and in recent years, stimulatory effects of CXCL12 on bone resorption have also been reported. In the present study, we investigated the effects of CXCL12 on LPS-induced osteoclastogenesis and bone resorption. LPS was administered with or without CXCL12 onto mouse calvariae by daily subcutaneous injection. Numbers of osteoclasts and bone resorption were significantly elevated in mice co-administered LPS and CXCL12 compared with mice administered LPS alone. Moreover, receptor activator of NF-kB ligand (RANKL) and tumor necrosis factor-α (TNF-α) mRNA levels were higher in mice co-administered LPS and CXCL12 compared with mice administered LPS alone. These in vitro results confirmed a direct stimulatory effect of CXCL12 on RANKL- and TNF-α-induced osteoclastogenesis. Furthermore, TNF-α and RANKL mRNA levels were elevated in macrophages and osteoblasts, respectively, co-treated in vitro with CXCL12 and LPS, in comparison with cells treated with LPS alone. Our results suggest that CXCL12 enhances LPS-induced osteoclastogenesis and bone resorption in vivo through a combination of increasing LPS-induced TNF-α production by macrophages, increasing RANKL production by osteoblasts, and direct enhancement of osteoclastogenesis.

pH-sensitive chitosan-derived nanoparticles as doxorubicin carriers for effective anti-tumor activity: preparation and in vitro evaluation.

pH-sensitive self-aggregated nanoparticles (SNPs), based on amphiphilic deoxycholic acid (DOCA) modified carboxymethyl chitosan (DCMC), were prepared for delivery of the anticancer drug doxorubicin (DOX). DCMCs with different degrees of substitution (DS) of DOCA were initially synthesized and characterized. Based on self-aggregation, DCMC formed nanoparticles with size ranging from 87 to 174 nm. The critical aggregation concentration (CAC) decreased on increasing the DS of DOCA. Moreover, the DCMC SNPs showed an acidic pH-induced aggregation and deformation behavior. The DOX-loaded SNPs ([D]NP) exhibited a sustained drug release manner, which could be accelerated by an acidic pH, but delayed by a higher DS of DOCA. Antitumor efficacy results showed that [D]NP could suppress both sensitive and resistant MCF-7 cells effectively in a dose- and time-dependent manner. The enhanced cellular uptake and greater retention of [D]NP in drug-resistant cells, as evidenced by confocal microscopy and flow cytometry, contributed to a superior efficacy of [D]NP over free DOX. These results suggest the potential of DCMC SNPs as carriers for the hydrophobic drug DOX for effective cancer therapy against drug-resistant tumors.