BACKGROUND:Glucocorticoids are among the most common causes of nontraumatic osteonecrosis of the femoral head among young people. Bone grafting and core decompression are mainly used to treat glucocorticoid-induced osteonecrosis of the femoral head (GIONFH) clinically. However, the results are usually not as satisfactory as expected. Herein, we report a functional hydrogel used to promote bone repair in GIONFH. Compared with traditional therapy, because of the adipogenic differentiation of mesenchymal stem cells in the ONFH region, the inhibition of fat infiltration better promotes bone remodeling. Given that hydrogels can serve as ideal carriers for continuous drug release to improve the efficiency of treatment and application in vivo, we encapsulated lithium-modified bioglass (M-Li) in a methacryloyl gelatin (GelMA) to construct a lithium-loaded bioglass hydrogel (GM/M-Li). METHODS:GM/M-Li hydrogel was synthesized and characterized, and co-cultured with BMSCs, HUVECs, and 3T3-L1 cells, and the lithium concentration was selected after evaluating the biotoxicity and verifying the functions of osteogenesis, angiogenesis, and inhibition of adipogenesis. In addition, New Zealand rabbits were used to establish femoral head necrosis model, and the therapeutic effect was evaluated by establishing bone tunnels through medullary core decompression, and injecting hydrogel into the necrotic bone tissues after removing them. Comparisons between multiple groups were analyzed by one-way or two-way ANOVA. RESULTS:GM/M-Li hydrogel exhibited a suitable compressive modulus of 4 kPa, and satisfactory biocompatibility, supporting cell proliferation in an adequate microenvironment. Additionally, the synthesized lithium-loaded bioglass, featuring a nanoscale size of 217 ± 3.2 nm, possessed high specific surface area, excellent intracellular effects, and efficient carrier properties. The sustained release of Li+ and Si4+ was observed to last over 35 days, significantly enhanced the proliferation and migration of bone marrow mesenchymal stem cells and human umbilical vein endothelial cells and promoted osteogenesis and angiogenesis both in vitro and in vivo. In vivo, micro-CT analysis at 12 weeks revealed that bone mineral density (BMD) of GM/M-Li group was significantly increased by 50 %, while trabecular separation (Tb.Sp) decreased by 20 %, compared to the model group. Histological and immunofluorescence staining were as well confirmed enhanced osteogenesis and angiogenesis. CONCLUSION:Considering the limited therapeutic options for early femoral head necrosis, in order to enhance the efficacy of the treatment and to prevent subchondral osteoradionecrosis collapse of the femoral head, we designed GM/M-Li hydrogels to verify the biocompatibility and the ability of osteogenensis, angiogenesis and fatty infiltration both in vitro and in vivo. In general, GM/M-Li hydrogels provided an appropriate microenvironment for orchestrating ONFH bone regeneration. Therefore, our research presents a promising regenerative platform to improve the ONFH microenvironment and accelerate bone remodeling. TAKE-HOME MESSAGE:This study presented a novel multi-functional regenerative strategy that simultaneously targeted osteogenesis, angiogenesis, and adipogenesis, using lithium-integrated bioactive hydrogel, offering a comprehensive and promising therapeutic platform beyond conventional bone grafts.

Objective:To investigate the analgesic effect of locally injecting a "cocktail" analgesia containing a high-dose compound betamethasone during revision hip arthroplasty, and also to study the usage of opioid drugs. Methods:A retrospective analysis was conducted on the clinical data of 180 patients who underwent revision hip arthroplasty due to aseptic loosening of the hip prosthesis between January 2015 and December 2021. Among them, 95 patients received intraoperative injection of "cocktail" analgesia containing high-dose compound betamethasone (group A), and 85 patients received intraoperative injection of traditional "cocktail" analgesia (group B). There was no significant difference in baseline data such as gender, age, body mass index, presence or absence of diabetes mellitus between the two groups ( P>0.05). The hospital stay, use of opioid drugs within 72 hours, and the incidence of adverse reactions within 72 hours after operation [including nausea and vomiting, insomnia, deep venous thrombosis (DVT), infection, etc.] were recorded and compared between the two groups. The pain relief of patients was evaluated using the static and dynamic visual analogue scale (VAS) scores at 12, 24, 48, and 72 hours after operation. The incidence of complications (including prosthesis re-loosening, hip joint dislocation, hip joint stiffness, limping, chronic pain, etc.) at 2 years after operation was recorded, and the Harris Hip Score (HHS) was used to evaluate the function at 2 years after operation. Results:In group A, the utilization rate of opioid drugs within 72 hours after operation was significantly lower than that in group B ( P<0.05). However, there was no significant difference between the two groups in terms of hospital stay, as well as the incidence of adverse reactions such as nausea and vomiting, insomnia, DVT, and infection within 72 hours after operation ( P>0.05). The VAS scores of both groups decreased with time, and the differences between different time points were significant ( P<0.05). The static and dynamic VAS scores of group A were significantly lower than those of group B at 12, 24, and 48 hours after operation ( P<0.05), but there was no significant difference in static and dynamic VAS scores between the two groups at 72 hours after operation ( P>0.05). All patients in both groups were followed up 2-8 years, with an average of 5.73 years. At 2 years after operation, no significant difference was found between the two groups in the incidence of complications and HHS score ( P>0.05). Conclusion:"Cocktail" analgesia containing a high-dose compound betamethasone for early analgesia after revision hip arthroplasty can effectively reduce postoperative pain and the use of opioid drugs, but will not increase the incidence of infection and DVT after operation.

The demand for systemic treatment of osteoporotic fractures to reduce recurrence is increasing, but current anti-osteoporosis medications exhibit unsatisfactory efficacy due to adverse events and limited effects on fracture healing. Herein, a bone-targeting zeolitic imidazolate framework-8 (ZIF)-based hydrogen sulfide (H2S) delivery system (ZIF-H2S-SDSSD) is designed to simultaneously promote fracture healing and alleviate osteoporosis. With bone-targeting peptide SDSSD grafted on the surface, ZIF-H2S-SDSSD nanoparticles release H2S in bone tissues without affecting the serum H2S level, thereby mitigating potential risks of systematic H2S delivery. Upon cellular uptake, the acidic environment in lysosomes drives the release of H2S from the encapsulated zinc sulfide in conjunction with the degradation of ZIF. The synergistic effects of released Zn2+ and H2S promote macrophage metabolic reprogramming by suppressing succinate accumulation and mitochondrial reactive oxygen species (mtROS) production, and further regulate osteoblast-osteoclast coupling. Overall, this strategy holds great promise in the clinical treatment of osteoporotic fractures and broadens the application of nanomedicine therapy for orthopedic diseases.

In the inflammatory peri-implant microenvironment, excessive polarization of macrophages to the proinflammatory M1 phenotype can trigger the secretion of inflammatory cytokines, which promote bone resorption and impede osteogenesis around implants. The direct consequence of this process is the failure of prosthetic implants due to aseptic loosening. To reverse the inflammatory microenvironment and prevent prosthesis loosening, a mussel adhesion-inspired surface strategy was used for bioengineering of titanium implants with integrin-binding ability. In our design, a mussel-inspired catecholic peptide with tetravalent 3,4-dihydroxy-l-phenylalanine (DOPA) and Arg-Gly-Asp (RGD) sequences was synthesized. The peptide can easily anchor to the surface of medical titanium materials through a mussel adhesive mechanism. We found that peptide-decorated titanium implants could effectively inhibit peri-implant inflammation in a wear particle model and could promote the polarization of macrophages to a pro-healing M2 phenotype by interfering with integrin-α2β1 and integrin-αvβ3. Moreover, the peptide coating increased the adherence of osteoblasts and promoted osteogenesis on titanium implants even under inflammatory conditions. This work suggested that this biomimetic catecholic integrin-binding peptide can provide facile tactics for surface bioengineering of medical prostheses with improved interfacial osteogenesis under inflammatory conditions, which might contribute greatly to the prevention of prosthesis loosening and the improvement of clinical outcomes.

Synovial mesenchymal stem cells (SMSCs) have the potential to attenuate osteoarthritis (OA)-induced injury. The role and mechanism of SMSC-derived exosomes (SMSC-Exos), pivotal paracrine factors of stem cells, in OA-associated injury remain unclear. We aimed to confirm the effect of SMSC-Exos with specific modifications on OA-induced damage and to investigate the potential molecular mechanisms. Exosomes derived from miR-155-5p–overexpressing SMSCs (SMSC-155-5p-Exos) and SMSCs (SMSC-Exos) were isolated and characterized. CCK-8, Transwell, and Western blot analyses were used to detect proliferation, migration, extracellular matrix (ECM) secretion, and apoptosis of osteoarthritic chondrocytes. The therapeutic effect of exosomes in a mouse model of OA was examined using immunohistochemical staining and OARSI scores. SPSS 17.0 and GraphPad software were used for all statistical analyses in this study. The SMSC-Exos enhanced the proliferation and migration and inhibited the apoptosis of osteoarthritic chondrocytes but had no effect on ECM secretion. The miR-155-5p–overexpressing exosomes showed common characteristics of exosomes in vitro and further promoted ECM secretion by targeting Runx2. Thus, the SMSC-155-5p-Exos promoted proliferation and migration, suppressed apoptosis and enhanced ECM secretion of osteoarthritic chondrocytes, and effectively prevented OA in a mouse model. In addition, overexpression of Runx2 partially reversed the effect of the SMSC-155-5p-Exos on osteoarthritic chondrocytes. Given the insufficient effect of the SMSC-Exos on the ECM secretion of osteoarthritic chondrocytes, we modified the SMSM-Exos and demonstrated that the SMSC-155-5p-Exos could prevent OA. Exosomes derived from modified SMSCs may be a new treatment strategy to prevent OA.

Aseptic loosening caused by periprosthetic osteolysis (PPO) is the main reason for the primary artificial joint replacement. Inhibition of inflammatory osteolysis has become the main target of drug therapy for prosthesis loosening. MiR‐106b is a newly discovered miRNA that plays an important role in tumour biology, inflammation and the regulation of bone mass. In this study, we analysed the in vivo effect of miR‐106b on wear debris‐induced PPO. A rat implant loosening model was established. The rats were then administrated a lentivirus‐mediated miR‐106b inhibitor, miR‐106b mimics or an equivalent volume of PBS by tail vein injection. The expression levels of miR‐106b were analysed by real‐time PCR. Morphological changes in the distal femurs were assessed via micro‐CT and histopathological analysis, and cytokine expression levels were examined via immunohistochemical staining and ELISA. The results showed that treatment with the miR‐106b inhibitor markedly suppressed the expression of miR‐106b in distal femur and alleviated titanium particle‐induced osteolysis and bone loss. Moreover, the miR‐106b inhibitor decreased TRAP‐positive cell numbers and suppressed osteoclast formation, in addition to promoting the activity of osteoblasts and increasing bone formation. MiR‐106b inhibition also significantly regulated macrophage polarization and decreased the inflammatory response as compared to the control group. Furthermore, miR‐106b inhibition blocked the activation of the PTEN/PI3K/AKT and NF‐κB signalling pathways. Our findings indicated that miR‐106b inhibition suppresses wear particles‐induced osteolysis and bone destruction and thus may serve as a potential therapy for PPO and aseptic loosening.

Accumulation of advanced glycation end-products (AGEs) increases inflammation and triggers processes involved in the pathogenesis of osteoarthritis (OA). As a major debilitating age-related disease, it is imperative that novel therapies for OA be sought. In the present study, we investigated the effects of the selective dipeptidyl peptidase IV (DPP-4) inhibitor sitagliptin in human primary chondrocytes exposed to insult by AGEs to elucidate the potential role of sitagliptin in the treatment of OA. Our findings show that inhibition of DPP-4 by sitagliptin could reduce oxidative stress, increase cell viability and prevent degradation of type II collagen and aggrecan by matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) induced by AGEs in human primary chondrocytes. Mechanistically, we found that sitagliptin inhibited AGEs-induced nuclear translocation of p65 protein and drastically decreased the luciferase activity of NF-κB. These findings indicate that sitagliptin may have potential as a novel therapeutic option for the treatment and prevention of OA.

Rheumatoid arthritis (RA) is a chronic, inflammatory, synovitis-dominated systemic disease with unknown etiology. RA is characterized by the involvement of multiple affected joints, symmetry, and invasive arthritis of the limbs, which can lead to joint deformity, cartilage destruction, and loss of function. Cannabinoid receptor 2 (CB2) has potent immunomodulatory and anti-inflammatory effects and is predominantly expressed in non-neuronal tissues. In the current study, the role of CB2 in the process of inflammatory bone erosion in RA was examined. The selective agonist or high-affinity ligand of CB2 (4-quinolone-3-carboxamides CB2 agonist, 4Q3C CB2 agonist, 4Q3C) significantly reduced the severity of arthritis, decreased histopathological findings, and markedly reduced bone erosion in collagen-induced arthritis (CIA) mice. In addition, 4Q3C prevented an increase in the nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) ratio and inhibited the formation of osteoclasts in CIA mice. Furthermore, the expression of tumor necrosis factor-alpha, interleukin-1β, cyclooxygenase-2, and inducible nitric oxide synthase was lower in 4Q3C-treated CIA mice than in control CIA mice. Micro-computed tomography corroborated the finding that 4Q3C reduced joint destruction. These data clearly indicate that the CB2-selective agonist, 4Q3C, may have anti-inflammatory and anti-osteoclastogenesis effects in RA and may be considered to be a novel treatment for RA.

Female patients are more likely to have tendon injuries than males, especially those who has a higher concentration of relaxin. Previous studies have demonstrated that relaxin attenuates extracellular matrix (ECM) formation. However, the mechanism of relaxin on tendon repair remains unclear. We hypothesize that relaxin inhibits tendon healing by disrupting collagen synthesis. A patellar tendon window defect model was established using Sprague-Dawley rats. The center of the patellar tendon was removed from the patella distal apex and inserted to the tibia tuberosity in width of 1 mm. Then, the rats were injected with saline (0.2 μg/kg/day) or relaxin (0.2 μg/kg/day) for two and four weeks, which was followed by biomechanical analysis and histological and histochemical examination. Mechanical results indicated that relaxin induces a significant decrease in tear resistance, stiffness, and Young’s modulus compared to those rats without relaxin treatment. In addition, it was shown that relaxin activates relaxin family peptide receptor 1(RXFP1), disturbs the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteases (TIMPs), and reduces the deposition of collagen in injury areas. Relaxin impairs tendon healing in rats. Also, relaxin might lead to tendon injury more commonly for females than males.

Rheumatoid arthritis (RA) is a major debilitating systemic disease characterized by chronic inflammation of the synovium and joint destruction. Despite major advancements in our understanding of RA in recent decades, it remains a disease of unknown etiology. To our knowledge, this is the first study exploring the effects of agonism of the glucagon-like peptide-1 (GLP-1) receptor using lixisenatide, a licensed drug used for the treatment of type II diabetes, on the pathological characteristics of RA in human fibroblast-like synoviocytes. Our findings indicate that lixisenatide inhibited the inflammatory response through downregulation of proinflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8); inhibition of matrix metalloproteinases (MMPs); and blockade of cellular signaling pathways, including the c-Jun N-terminal kinase (JNK), activator protein 1 (AP-1), and nuclear factor κ B (NF-κB) pathways. Furthermore, lixisenatide improved oxidative stress, rescued mitochondrial membrane potential (ΔΨm), and prevented cell death in fibroblast-like synoviocytes. These findings suggest that agonism of the GLP-1 receptor using lixisenatide may serve as a novel therapeutic option for the treatment and prevention of RA.

Rheumatoid arthritis (RA) is a chronic, inflammatory, synovitis-dominated systemic disease with unknown etiology. RA is characterized by the involvement of multiple affected joints, symmetry, and invasive arthritis of the limbs, which can lead to joint deformity, cartilage destruction, and loss of function. Cannabinoid receptor 2 (CB2) has potent immunomodulatory and anti-inflammatory effects and is predominantly expressed in non-neuronal tissues. In the current study, the role of CB2 in the process of inflammatory bone erosion in RA was examined. The selective agonist or high-affinity ligand of CB2 (4-quinolone-3-carboxamides CB2 agonist, 4Q3C CB2 agonist, 4Q3C) significantly reduced the severity of arthritis, decreased histopathological findings, and markedly reduced bone erosion in collagen-induced arthritis (CIA) mice. In addition, 4Q3C prevented an increase in the nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) ratio and inhibited the formation of osteoclasts in CIA mice. Furthermore, the expression of tumor necrosis factor-alpha, interleukin-1β, cyclooxygenase-2, and inducible nitric oxide synthase was lower in 4Q3C-treated CIA mice than in control CIA mice. Micro-computed tomography corroborated the finding that 4Q3C reduced joint destruction. These data clearly indicate that the CB2-selective agonist, 4Q3C, may have anti-inflammatory and anti-osteoclastogenesis effects in RA and may be considered to be a novel treatment for RA.

Bone mass loss around prostheses is a major cause of implant failure, especially in postmenopausal osteoporosis patients. In osteoporosis, excess oxidative stress largely contributed abnormal bone remodeling. Melatonin, which is synthesized from the pineal gland, promotes osteoblast differentiation and bone formation and has effectively been used to combat oxidative stress. Thus, we determined if melatonin can inhibit oxidative stress to promote osteogenesis and improve bone mass around prostheses in osteoporosis. In this study, we observed that received melatonin at 50 mg/kg body weight significantly increased periprosthetic bone mass as well as implant fixation intensity in ovariectomized (OVX) rats. Meanwhile, it decreased the expression of oxidative stress markers (NAPDH oxidase 2 and cytochrome c) and enhanced expressing level of the formation markers of bones (alkaline phosphatase, osteocalcin, and osterix) around prostheses compared to that in the control group. Additionally, melatonin decreased hydrogen peroxide- (H2O2-) induced oxidative stress and restored the osteogenesis potential of MC3T3-E1 cells. Mechanistically, melatonin clearly increased mitochondrial sirtuin 3 (SIRT3) expression and decreased the ratio of acetylated superoxide dismutase 2 (AC-SOD2)/SOD2 compared to the H2O2 group. SIRT3 inhibition counteracted the protective effects of melatonin on oxidative stress and bone formation. Together, the results showed that melatonin ameliorated oxidative stress in mitochondrial via the SIRT3/SOD2 signaling pathway, thereby promoting osteogenesis, improving bone mass around the prostheses, and increasing initial stability. Thus, melatonin might be a suitable candidate to decrease the rate of implant failure and lengthen the lifespan of prostheses after total joint arthroplasty.

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease of unknown etiology characterized by degradation of cartilage and bone, accompanied by unimpeded proliferation of synoviocytes of altered phenotype. In the present study, we investigated the involvement of the glucagon‐like peptide 1 (GLP‐1) receptor on human fibroblast‐like synoviocytes (FLS) in the pathogenesis of RA using the selective GLP‐1 agonist exenatide, a licensed drug used for the treatment of type 2 diabetes. Our results indicate that exenatide may play a role in regulating tumor necrosis factor‐α‐induced mitochondrial dysfunction by increasing mitochondrial membrane potential, oxidative stress by reducing the production of reactive oxygen species, the expression of NADPH oxidase 4, expression of matrix metalloproteinase (MMP)‐3 and MMP‐13, release of proinflammatory cytokines including interleukin‐1β (IL‐1β), IL‐6, monocyte chemoattractant protein‐1, and high‐mobility group protein 1, as well as activation of the p38/nuclear factor of κ light polypeptide gene enhancer in B‐cells inhibitor, α/nuclear factor κB signaling pathway in primary human RA FLS. These positive results indicate that exenatide may have potential as a therapeutic agent for the treatment and prevention of RA. © 2019 IUBMB Life, 9999(9999):1–9, 2019

Excessive osteoclast recruitment and activation is the chief cause of periprosthetic osteolysis and subsequent aseptic loosening, so blocking osteolysis may be useful for protecting against osteoclastic bone resorption. We studied the effect of aspirin on titanium (Ti)‐particle‐induced osteolysis in vivo and in vitro using male C57BL/6J mice randomized to sham (sham surgery), Ti (Ti particles), low‐dose aspirin (Ti/5 mg·kg−1·d−1 aspirin), and high‐dose aspirin (Ti/30 mg·kg−1·d−1 aspirin). After 2 weeks, a three‐dimensional reconstruction evaluation using micro‐computed tomography and histomorphology assessment were performed on murine calvariae. Murine hematopoietic macrophages and RAW264.7 lineage cells were studied to investigate osteoclast formation and function. Aspirin attenuated Ti‐particle‐induced bone erosion and reduced osteoclasts. In vitro, aspirin suppressed osteoclast formation, osteoclastic‐related gene expression, and osteoclastic bone erosion in a dose‐dependent manner. Mechanically, aspirin reduced osteoclast formation by suppressing receptor activator of nuclear factor kappa‐B ligand‐induced activation of extracellular signal‐related kinase, p‐38 mitogen‐activated protein kinase, and c‐Jun N‐terminal kinase. Thus, aspirin may be a promising option for preventing and curing osteoclastic bone destruction, including peri‐implant osteolysis.

Intervertebral disc (IVD) degeneration (IDD) is a major cause of low back pain. The pathogenesis of IDD is associated with the disturbance of reactive oxygen species (ROS) equilibrium, inflammation, and matrix loss. Aspirin is a nonsteroidal anti-inflammatory drug that effectively inhibits inflammation and oxidative stress and has been widely used for the treatment of back pain. Therefore, we hypothesize that aspirin reverses the IDD process via antioxidative and anti-inflammatory effects on the AMPK signaling pathway. In vitro, aspirin diminished cellular oxygen free radicals (ROS, nitric oxide (NO)) and inflammatory cytokines (interleukin- (IL-) 1β and IL-6 and tumor necrosis factor alpha (TNF-α)) induced by lipopolysaccharides (LPS) in nucleus pulposus cells (NPCs). We found that aspirin preserved the extracellular matrix (ECM) content of collagen type II (COL2) and aggrecan while inhibiting the expression of matrix-degenerating enzymes, including matrix metalloproteinase 3 and 13 (MMP-3 and MMP-13) and A disintegrin and metalloproteinase with thrombospondin motifs 4 and 5 (ADAMTS-4, ADAMTS-5). Aspirin significantly promoted the ratios of p-AMPK to AMPK and p-ACC to ACC expression in NPCs. Furthermore, pretreatment with the AMPK inhibitor compound C abrogated the antioxidant effects of aspirin. In vivo, an IDD model was established in Sprague-Dawley rats via percutaneous disc puncture with the 20-gauge needle on levels 8-9 and 9-10 of the coccygeal vertebrae. Imaging assessment showed that after aspirin treatment, improvements in disc height index (DHI) ranged from 1.22-fold to 1.54-fold and nucleus pulposus signal strength improved from 1.26-fold to 1.33-fold. Histological analysis showed that aspirin treatment prevented the loss of COL2 and decreased MMP-3 and MMP-13, inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), IL-1β, and TNF-α expression in the IVD tissues. These results suggest that treatment with aspirin could reverse the IDD process via the AMPK signaling pathway, which provides new insights into the potential clinical applications of aspirin, particularly for IDD treatment.

ABSTRACT Cannabinoid receptor 2 (CB2) has been implicated as an important clinical regulator of inflammation and malignant osteolysis. Here, we observed that CB2 expression was markedly higher in the collagen-induced arthritis (CIA) mice synovium and bone tissues than in the noninflamed synovium and bone tissues. The CB2 selective agonist (JWH133) but not antagonist (SR144528) suppressed CIA in mice without toxic effects, as demonstrated by the decreased synovial hyperplasia, inflammatory responses, cartilage damage, and periarticular and systemic bone destruction. JWH133 treatment decreased the infiltration of pro-inflammatory M1-like macrophages and repolarized macrophages from the M1 to M2 phenotype. Similarly, activation of CB2 increased the expression of anti-inflammatory cytokine interleukin (IL)-10 and reduced the expression of pro-inflammatory cytokines, including tumor necrosis factor-α (TNF-α), IL-1β, and IL-6. In addition, JWH133 treatment attenuated osteoclast formation and osteoclastic bone resorption, and reduced the expression of receptor activators of the nuclear factor-κB (NF-κB) ligand (RANKL), matrix metallopeptidase-9 (MMP-9), tartrate-resistant acid phosphatase (TRAP), cathepsin K (CTSK), and nuclear factor of activated T-cells 1 (NFAT-1) in CIA mice and osteoclast precursors, which were obviously blocked by pretreatment with SR144528. Mechanistically, JWH133 inhibited RANKL-induced NF-κB activation in the osteoclast precursors. We found that JWH133 ameliorates pathologic bone destruction in CIA mice via the inhibition of osteoclastogenesis and modulation of inflammatory responses, thereby highlighting its potential as a treatment for human rheumatoid arthritis. © 2018 American Society for Bone and Mineral Research.

Receptor activator of nuclear factor-kappa B ligand (RANKL)-induced osteoclastogenesis is believed to play a critical role in osteolytic diseases including peri-prosthetic osteolysis (PPO), the primary reason for implant failure and revision surgery. In this study, we observed that protein phosphatase 2A (PP2A), a major serine-threonine phosphatase, was highly expressed in human periprosthetic interface membranes with aseptic loosening and in a murine osteolysis model induced by titanium particle irritation. PP2A inhibition effectively alleviated titanium particle-induced bone destruction at osteolytic sites. In addition, PP2A downregulation significantly decreased osteoclast numbers and RANKL expression, compared with in animals treated with only titanium. Mechanistically, a PP2A selective inhibitor or PP2A siRNA suppressed osteoclastogenesis and alleviated osteoclastic resorption by inhibiting the RANKL-induced nuclear factor-KB and c-Jun N-terminal kinase signaling pathways. Downstream NFATcl and c-Fos expression were also substantially suppressed by PP2A inhibition or knockdown. Our findings support the importance of PP2A during osteoclastogenesis, identifying PP2A as a novel target for treating particle-induced or other osteoclast-mediated bone resorption diseases. Statement of significance Excessive osteoclast activation disrupts bone homeostasis and leads to osteoclast-mediated bone resorption diseases, such as pen-prosthetic osteolysis, regarded as the primary reason for implant failure and revision surgery. Here, we firstly demonstrated protein phosphatase 2A (PP2A), a major serinethreonine phosphatase, was highly expressed in human periprosthetic interface membranes with aseptic loosening and murine osteolysis model. Moreover, PP2A inhibition effectively alleviated titanium particle-induced bone destruction and decreased osteoclast numbers. Meanwhile, a PP2A selective inhibitor or PP2A siRNA suppressed osteoclastogenesis and alleviated osteoclastic resorption by inhibiting the nuclear factor-kappa B and c-Jun N-terminal kinase signaling pathways. Thus, PP2A is involved in osteoclastogenesis and could be a promising target for regulating bone homeostasis and osteolytic responses. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

In the present study, we investigated the effects of the specific DPP-4 inhibitor vildagliptin on degradation of type II collagen and aggrecan, the main components of the articular extracellular matrix, in primary human chondrocytes. The results of our study reveal that vildagliptin reduced degradation of the articular extracellular matrix (ECM) by downregulating IL-1β-induced expression of matrix metalloproteinases-3 (MMP-3), matrix metalloproteinases-13 (MMP-13), a disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4) and a disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS-5). We also found that vildagliptin ameliorated IL-1β-induced activation of the JNK/AP-1 and nuclear factor-κB (NF-κB) pro-inflammatory signaling pathways by downregulating phosphorylation of JNK and nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor α (IκBα), activation of c-Fos/c-Jun, and nuclear translocation of p65. Our findings suggest that vildagliptin may serve as a novel treatment for excessive degradation of the articular ECM in osteoarthritis (OA).

Mesenchymal stem cells (MSCs) hold great potential to treat tissue damage based on their multipotent property, and are also considered as suitable cell resources to create tissue-engineered grafts for tendon repair. However, the clinical application of MSCs is still limited by the lack of efficient methods to induce tenogenic differentiation. In this study, by performing the experiments in transwell system, we found that paracrine factors from tenocytes could induce MSCs to undergo the tenogenic differentiation. We further verified that tenocytes could secrete exosomes and these tenocyte-derived exosomes efficiently initiated the tenogenic differentiation of MSCs. Finally, we revealed that the TGF-β existing in tenocyte-derived exosomes mediated the process, as the inhibition of TGF-β signaling abolished the effects of tenocyte-derived exosomes on MSCs. By investigating the effects of tenocytes on MSCs, we found that tenocytes-derived exosomes can induce tenogenic differentiation of MSCs in a TGF-β dependent manner. These studies provided critical information about the multipotency of MSCs and suggested potential strategies for clinical translation.

Abnormal reduction of extracellular matrix (ECM), including type II collagen and aggrecan, caused by tumor necrosis factor-α (TNF-α) is an important pathological feature of osteoarthritis (OA). Shikimic acid (SA), derived from natural plants, has displayed effective pharmacological properties in diverse diseases. The biological roles of SA in OA have not been reported before. Here, we found that treatment with SA (1 mM, 10 mM) prevented TNF-α-induced degradation of type II collagen and aggrecan ECM in human primary chondrocytes culture in vitro. Importantly, we also reported that SA treatment reduced TNF-α-induced expression of matrix metalloproteinase‑1, ‑3, and ‑13 (MMP‑1, ‑3, and ‑13) and increased expression of tissue inhibitor of metalloproteinase‑1 and ‑2 (TIMP‑1, ‑2). Additionally, SA treatment attenuated TNF-α-induced expression of a disintegrin and metalloprotease‑4 and ‑5 (ADAMTS‑4, ‑5). Mechanistically, we found that SA prevented activation of the nuclear factor-κB (NF‑κB) pathway. Our findings suggest that SA might act as an important therapeutic agent in the treatment of OA.