Titanium Particle-induced Osteolysis Research Articles

NOD2 negatively regulated titanium particle-induced osteolysis in mice.

For patients undergoing total joint replacement (TJR), one of the complications, aseptic loosening, could cause serious consequences, such as revision surgery. In early research, pattern recognition receptors (PRRs) were reported to play vital roles in recognizing wear particles from the prosthesis and initiating an inflammation response. In this research, we aimed to clarify the role of nucleotide-binding and oligomerization domain containing protein 2 (NOD2), one of the PRRs, in macrophage-induced aseptic loosening in vivo and in vitro. High expressions of NOD2 and TNFα were observed from twenty patients who underwent primary or revision total hip replacements (THR). The effect of NOD2 on the activation of inflammation pathways was observed in RAW264.7 cells and CRISPR-Cas9 NOD2-knockout mice. The expressions of NOD2, the NF-κB pathway, the MAPK pathway and proinflammatory cytokine TNF-α in macrophages stimulated by wear particles were up-regulated. Otherwise, inhibition of NOD2 further up-regulated the expressions of NOD2, the NF-κB pathway, the MAPK pathway and TNF-α. Knockdown of the NOD2 gene enhanced the cranial osteolysis induced by titanium particles in a mouse model. In conclusion, our study demonstrated that NOD2 plays a negative role in osteolysis induced by titanium particles in vitro and in vivo.

Mechanism and Prevention of Titanium Particle-Induced Inflammation and Osteolysis.

The worldwide number of dental implants and orthopedic prostheses is steadily increasing. Orthopedic implant loosening, in the absence of infection, is mostly attributable to the generation of wear debris. Dental peri-implantitis is characterized by a multifactorial etiology and is the main cause of implant failure. It consists of a peri-implant inflammatory lesion that often results in loss of supporting bone. Disease management includes cleaning the surrounding flora by hand instruments, ultrasonic tips, lasers, or chemical agents. We recently published a paper indicating that US scaling of titanium (Ti) implants releases particles that provoke an inflammatory response and osteolysis. Here we show that a strong inflammatory response occurs; however, very few of the titanium particles are phagocytosed by the macrophages. We then measured a dramatic Ti particle-induced stimulation of IL1β, IL6, and TNFα secretion by these macrophages using multiplex immunoassay. The particle-induced expression profile, examined by FACS, also indicated an M1 macrophage polarization. To assess how the secreted cytokines contributed to the paracrine exacerbation of the inflammatory response and to osteoclastogenesis, we treated macrophage/preosteoclast cultures with neutralizing antibodies against IL1β, IL6, or TNFα. We found that anti-TNFα antibodies attenuated the overall expression of both the inflammatory cytokines and osteoclastogenesis. On the other hand, anti-IL1β antibodies affected osteoclastogenesis but not the paracrine expression of inflammatory cytokines, whereas anti-IL6 antibodies did the opposite. We then tested these neutralizing antibodies in vivo using our mouse calvarial model of Ti particle-induced osteolysis and microCT analysis. Here, all neutralizing antibodies, administered by intraperitoneal injection, completely abrogated the particle-induced osteolysis. This suggests that blockage of paracrine inflammatory stimulation and osteoclastogenesis are similarly effective in preventing bone resorption induced by Ti particles. Blocking both the inflammation and osteoclastogenesis by anti-TNFα antibodies, incorporated locally into a slow-release membrane, also significantly prevented osteolysis. The osteolytic inflammatory response, fueled by ultrasonic scaling of Ti implants, results from an inflammatory positive feedback loop and osteoclastogenic stimulation. Our findings suggest that blocking IL1β, IL6, and/or TNFα systemically or locally around titanium implants is a promising therapeutic approach for the clinical management of peri-implant bone loss.

Jatrorrhizine Hydrochloride Suppresses RANKL-Induced Osteoclastogenesis and Protects against Wear Particle-Induced Osteolysis.

Wear particle-induced aseptic prosthetic loosening is a major complication associated with total joint arthroplasty (TJA). A growing body of evidence suggests that receptor activator of nuclear factor κ-B ligand (RANKL)-stimulated osteoclastogenesis and bone resorption are responsible for peri-implant loosening. Thus, agents which attenuate excessive osteoclast differentiation and function have been considered to offer therapeutic potential for prolonging the life of TJA implants. Jatrorrhizine hydrochloride (JH), a major protoberberine alkaloid isolated from the traditional Chinese herb Coptis chinensis, has been reported to have antimicrobial, antitumor, and antihypercholesterolemic and neuroprotective activities. However, its effects on osteoclast biology remain unknown. Here, we found that JH inhibited RANKL-induced osteoclast formation and bone resorption in vitro and exerted protection against titanium (Ti) particle-induced osteolysis in vivo. Biochemical analysis demonstrated that JH suppressed RANKL-induced activation of MAPKs (p38 and ERK) which down-regulated the production of NFATc1 and NFATc1-regulated osteoclastic marker genes, such as TRAP, CTR and CTSK. Collectively, our findings suggest that JH may be a promising anti-osteoclastogenesis agent for treating periprosthetic osteolysis or other osteoclast-related osteolytic diseases.

Arctigenin inhibits RANKL-induced osteoclastogenesis and hydroxyapatite resorption in vitro and prevents titanium particle-induced bone loss in vivo.

Wear particle-induced bone resorption leads to prosthesis loosening, which is a major complication associated with total joint arthroplasty. Although the exact mechanism remains unclear, wear particle-induced extensive osteoclastogenesis plays a critical role in this process. Thus, a potential treatment of prosthetic loosening is focused on suppressing extensive osteoclast formation and bone resorption, which prevents wear particle-induced osteolysis. Arctigenin isolated from Arctium lappa has numerous beneficial pharmacologic effects, including anti-inflammatory, antiviral, and anticancer activities. Here, we explored the potential impact of arctigenin on titanium (Ti) particle-induced osteolysis in vivo. Our data showed that arctigenin significantly suppressed Ti particle-induced osteolysis and prevented bone destruction compared with Ti group. In addition, the number of osteoclasts reduced after treatment with arctigenin in vivo, indicating osteoclastogenesis might be inhibited by arctigenin. Next, bone marrow-derived macrophages were used to examine osteoclast differentiation, bone resorption, and activation of osteoclast-related signaling pathways. The results showed that arctigenin inhibited RANKL-induced osteoclastogenesis without any cytotoxicity and suppressed osteoclastic marker genes expression and hydroxyapatite resorption activity in a dose-dependent manner. Additionally, arctigenin suppressed receptor activator of nuclear factor κΒ (NF-κB) ligand-induced NF-κB activation, concomitant with retarded IκBɑ degradation and inhibition of p65 nuclear translocation, leading to impaired osteoclastogenesis. Collectively, our results suggest that arctigenin is a promising candidate for the treatment of osteoclast-related osteolytic diseases caused by excessive osteoclast formation.

Stevioside Prevents Wear Particle-Induced Osteolysis by Inhibiting Osteoclastogenesis and Inflammatory Response via the Suppression of TAK1 Activation.

Aseptic loosening and periprosthetic osteolysis are the leading causes of total joint arthroplasty failure, which occurs as a result of chronic inflammatory response and enhanced osteoclast activity. Here we showed that stevioside, a natural compound isolated from Stevia rebaudiana, exhibited preventative effects on titanium particle-induced osteolysis in a mouse calvarial model. Further histological assessment and real-time PCR analysis indicated that stevioside prevented titanium particle-induced osteolysis by inhibiting osteoclast formation and inflammatory cytokine expression in vivo. In vitro, we found that stevioside could suppress RANKL-induced osteoclastogenesis and titanium particle-induced inflammatory response in a dose-dependent manner. Mechanistically, stevioside achieved these effects by disrupting the phosphorylation of TAK1 and subsequent activation of NF-κB/MAPKs signaling pathways. Collectively, our data suggest that stevioside effectively suppresses osteoclastogenesis and inflammatory response both in vitro and in vivo, and it might be a potential therapy for particle-induced osteolysis and other osteolytic diseases.

Gö6983 attenuates titanium particle-induced osteolysis and RANKL mediated osteoclastogenesis through the suppression of NFκB/JNK/p38 pathways

Osteoclast activation by wear particles has caused major difficulties for surgeons. Wear particles are the main causes of aseptic prosthetic loosening. Gö6983, a protein kinase C inhibitor, inhibits five subtypes of protein kinase C family members. Here, we found that Gö6983 had an obviously inhibitory effect on wear-particles-induced osteolysis in vivo. In vitro, Gö6983 inhibited RANKL-stimulated osteoclast formation and function by inhibiting the RANKL-stimulated nuclear factor-κB/JNK/p38 signaling pathway. We also observed that Go6983 had no effect on the differentiation of osteoblasts and osteoblast-associated genes expression. According to our data, Gö6983 has potential therapeutic effects for aseptic prosthetic loosening caused by osteoclast activation.

Flavopiridol Protects Bone Tissue by Attenuating RANKL Induced Osteoclast Formation.

Bone resorption and homeostasis is carried out by osteoclasts, whose differentiation and activity are regulated by the RANK/RANKL axis. Our previous studies using a mouse model of joint injury show that joint trauma induces local inflammation followed by bone remodeling. The transcription factor cyclin-dependent kinase 9 (CDK9) is the major regulator of inflammation, as CDK9 inhibitor flavopiridol effectively suppress injury-induced inflammatory response. The objective of this study was to investigate the underlying mechanism through which flavopiridol regulates bone resorption. The effects of CDK9 inhibition, by the specific-inhibitor flavopiridol, on bone resorption were determined in vivo using two distinct and clinically relevant bone remodeling models. The first model involved titanium particle-induced acute osteolysis, and the second model was ovariectomy-induced chronic osteoporosis. The effects and mechanism of CDK9 inhibition on osteoclastogenesis were examined using in vitro culture of bone marrow macrophages (BMMs). Our results indicated that flavopiridol potently suppressed bone resorption in both in vivo bone-remodeling models. In addition, CDK9 inhibition suppressed in vitro osteoclastogenesis of BMM and reduced their expression of osteoclast-specific genes. Finally, we determined that flavopiridol suppressed RANKL signaling pathway via inhibition of p65 phosphorylation and nuclear translocation of NF-κB. Summary, CDK9 is a potential therapeutic target to prevent osteolysis and osteoporosis by flavopiridol treatment.

Icariin attenuates titanium particle-induced inhibition of osteogenic differentiation and matrix mineralization via miR-21-5p.

Inhibition of bone regeneration by wear debris is the main cause of peri-prosthetic osteolysis. Here, we investigated the effect of icariin on cell proliferation, apoptosis, osteogenic differentiation and matrix mineralization of osteoblasts in an in vitro model of titanium (Ti) particle-induced osteolysis. In the present study, MC3T3-E1 cells were pretreated with 10-8 M icariin for 4 h and then incubated with Ti particles (0.1 mg/mL). The results showed that Ti particles inhibited cell proliferation and promoted cell apoptosis of MC3T3-E1 cells, whereas icariin pretreatment blocked the effect of Ti particles. In addition, we found that icariin stimulation alone increased ALP activity, accelerated matrix mineralization and upregulated the levels of bone morphogenetic protein 2 (BMP2), Runt-related transcription factor 2 (Runx2), osteocalcin (OCN) and miR-21-5p; whereas, Ti particles alone exerted the opposite effects. Icariin partly reversed the effect of Ti particles on cell differentiation and mineralization. Twenty hours after transfection with antagomiR-21-5p or antagomiR-NC, the cells were pretreated with icariin for 4 h and then incubated with Ti particles. Further studies showed that partial knockdown of miR-21-5p abolished the promotion effect of icariin on osteoblast differentiation and matrix mineralization in Ti particle-stimulated MC3T3-E1 cells. In conclusion, miR-21-5p may be a potential pro-osteogenesis regulator and icariin may protect against Ti particle-induced inhibition of osteogenic differentiation and mineralization through upregulation of miR-21-5p.

Emodin attenuates titanium particle-induced osteolysis and RANKL-mediated osteoclastogenesis through the suppression of IKK phosphorylation

Aseptic loosening due to wear particles is a serious challenge for orthopedic surgeons, sabotaging the long-term success of total joint arthroplasty. The existing treatments for aseptic loosening are still far from satisfactory, necessitating more aggressive drug exploration. Here, we examined the effect of emodin on titanium particle-induced osteolysis and further investigated its underlying mechanism in vivo and in vitro. Thirty-two C57BL/6 mice were randomly assigned into four groups: the Sham group (sham operation with vehicle injection), Vehicle group (titanium particle treatment with vehicle injections), Low group (titanium particle treatment with injections of 10 mg/kg/day emodin) and High group (titanium particle treatment with injections of 50 mg/kg/day emodin). Micro-CT scanning and histological analysis revealed that after emodin injections, the inflammatory response and bone destruction were markedly ameliorated. TRAP staining showed that osteoclast numbers were also dramatically reduced. Throughout the in vitro culture period, emodin significantly decreased the bone resorption area, number of osteoclasts and formation of F-actin rings. Mechanistic studies suggested that reduced NF-κB signaling might be mediating the inhibitory effects of emodin. Collectively, our findings suggest that emodin, a natural product extracted from Rheum palmatum, may be developed as a promising candidate for the treatment of wear particle-induced osteolysis and subsequent aseptic loosening.

Strontium ranelate reduces the progression of titanium particle-induced osteolysis by increasing the ratio of osteoprotegerin to receptor activator of nuclear factor-κB ligand invivo.

The present study aimed to investigate the effects of strontium ranelate (SR), an anti‑osteoporotic drug, on osteolysis in an experimental mouse model of aseptic loosening. A total of 45 female C57BL/6J mice each received implantation of one titanium alloy pin into the tibia, followed by intraarticular injection of titanium particles. One week following surgery, mice were randomly divided into three groups: Control group (no additional treatment), SR625 group (treated with SR at a dose of 625mg/kg/day), and SR1800 group (treated with SR at a dose of 1,800mg/kg/day). SR was administered via oral gavage once every day for 12weeks. Micro‑computed tomography scanning and hematoxylin/eosin staining were used to assess osteolysis around the prosthesis. Immunohistochemistry and reverse transcription-quantitative polymerase chain reaction analysis were used to measure the expression of receptor activator of nuclear factor‑κB ligand (RANKL) and osteoprotegerin (OPG). Compared with the control, the SR625 and SR1800 groups exhibited a significantly increased pulling force of the titanium alloy pin. Bone volume and the bone surface/volume ratio in the periprosthetic tissue were significantly increased in the SR‑treated groups. Significant differences were observed between the SR1800 group and control group with respect to trabecular thickness and trabecular number. Mechanistically, SR downregulated the expression of RANKL and upregulated the expression of OPG in the periprosthetic tissue. In addition, SR was observed to inhibit wear particle‑associated osteolysis in a dose‑dependent manner. In conclusion, the present data illustrated that SR inhibited titanium particle‑induced osteolysis invivo.

The effect of anti-osteoporosis treatment on titanium particle-induced osteolysis in osteoporotic mouse calvarial model

The effect of anti-osteoporosis treatment on titanium particle-induced osteolysis in osteoporotic mouse calvarial model

Inhibitory effects of melatonin on titanium particle-induced inflammatory bone resorption and osteoclastogenesis via suppression of NF-κB signaling.

Wear debris-induced chronic inflammation, osteoclastic activation and osteoblastic inhibition have been identified as critical factors of peri-implant bone loss. We previously demonstrated that melatonin, a bioactive indolamine secreted mainly by the pineal gland, activates Wnt/β-catenin signaling pathway and enhances bone regeneration at osteolytic site in vivo. In the current study, we further demonstrated that melatonin significantly suppresses wear debris-induced bone resorption and inflammatory cytokine expression in vivo. In addition, melatonin inhibits receptor activator of nuclear factor kappa-B ligand induced osteoclast formation and osteoclastic bone resorption in vitro. Meanwhile, we found that melatonin mediates its anti-inflammation and anti-bone resorption effects by abrogating nuclear factor kappa-B activation. These results further support the protective effects of melatonin on wear debris-induced peri-implant bone loss, and strongly suggest that melatonin could be considered as a potential candidate for the prevention and treatment of wear debris-induced osteolysis and subsequent aseptic loosening.

Melatonin attenuates titanium particle-induced osteolysis via activation of Wnt/β-catenin signaling pathway.

Peri-prosthetic osteolysis, initiated by wear debris-induced inhibition of bone regeneration and extensive bone resorption, is the leading cause for implant failure and reason for revision surgery. In the current study, we demonstrated for the first time that melatonin can induce bone regeneration and reduce bone resorption at osteolytic sites caused by titanium-particle stimulation. These effects might be mediated by activating Wnt/β-catenin signaling pathway and enhancing osteogenic differentiation. Meanwhile, the ability of melatonin to modulate the balance between receptor activator of nuclear factor kappa-B ligand and osteoprotegerin mediated by Wnt/β-catenin signaling pathway, thereby suppressing osteoclastogenesis, may be implicated in the protective effects of melatonin on titanium-particle-induced bone resorption. These results suggested that melatonin can be considered as a promising therapeutic agent for the prevention and treatment of peri-prosthetic osteolysis.

Theaflavin-3,3'-digallate represses osteoclastogenesis and prevents wear debris-induced osteolysis via suppression of ERK pathway.

Total joint arthroplasty is widely accepted for the treatment of end-stage joint diseases. However, it is reported that aseptic loosening, initiated by peri-implant osteolysis, is the major reason for prosthesis failure. Although the pathophysiology of PIO remains unclear, increasing evidence indicates that osteoclasts are excessively activated at the implant site by wear debris from materials. Here, we demonstrated that theaflavin-3,3'-digallate, a natural active compound derived from black tea, inhibited osteoclast formation and osteoclastic bone resorption mainly via suppressing the ERK pathway. Moreover, the findings of this study have confirmed for the first time that theaflavin-3,3'-digallate has a protective effect on particle-induced osteolysis in a mouse calvarial model, thus preventing bone loss. These results indicate that theaflavin-3,3'-digallate may be a suitable therapeutic agent to treat wear debris-induced peri-implant osteolysis.

Scutellarin inhibits RANKL-mediated osteoclastogenesis and titanium particle-induced osteolysis via suppression of NF-κB and MAPK signaling pathway

Aseptic prosthetic loosening is a major complication after hip joint replacement. Wear particle-induced periprosthetic osteolysis plays a key role in aseptic prosthetic loosening. Attempting to modulate receptor activator of nuclear factor-κB (RANKL) mediated signaling pathways is a promising strategy to prevent aseptic prosthetic loosening. In the present study, we determined the effect of scutellarin (SCU) on titanium (Ti) particle-induced osteolysis in a mouse calvarial model and RANKL-mediated osteoclastogenesis. We determined that SCU, the major effective constituent of breviscapine isolated from a Chinese herb, has potential effects on preventing Ti particle-caused osteolysis in calvarial model of mouse. In vitro, SCU could suppress RANKL-mediated osteoclastogenesis, the function of osteoclast bone resorption, and the expression levels of osteoclast-specific genes (tartrate-resistant acid phosphatase (TRAP), cathepsin K, c-Fos, NFATc1). Further investigation indicated that SCU could inhibit RANKL-mediated MAPK and NF-κB signaling pathway, including JNK1/2, p38, ERK1/2, and IκBα phosphorylation. Taken together, these results indicate that SCU could inhibit osteoclastogenesis and prevent Ti particle-induced osteolysis by suppressing RANKL-mediated MAPK and NF-κB signaling pathway. These results suggest that SCU is a promising therapeutic agent for preventing wear particle-induced periprosthetic osteolysis.

Adenovirus-mediated siRNA targeting CXCR2 attenuates titanium particle-induced osteolysis by suppressing osteoclast formation.

BackgroundWear particle-induced peri-implant loosening is the most common complication affecting long-term outcomes in patients who undergo total joint arthroplasty. Wear particles and by-products from joint replacements may cause chronic local inflammation and foreign body reactions, which can in turn lead to osteolysis. Thus, inhibiting the formation and activity of osteoclasts may improve the functionality and long-term success of total joint arthroplasty. The aim of this study was to interfere with CXC chemokine receptor type 2 (CXCR2) to explore its role in wear particle-induced osteolysis.Material/MethodsMorphological and biochemical assays were used to assess osteoclastogenesis in vivo and in vitro. CXCR2 was upregulated in osteoclast formation.ResultsLocal injection with adenovirus-mediated siRNA targeting CXCR2 inhibited titanium-induced osteolysis in a mouse calvarial model in vivo. Furthermore, siCXCR2 suppressed osteoclast formation both directly by acting on osteoclasts themselves and indirectly by altering RANKL and OPG expression in osteoblasts in vitro.ConclusionsCXCR2 plays a critical role in particle-induced osteolysis, and siCXCR2 may be a novel treatment for aseptic loosening.

Inhibitive effect of icariin on titanium particle-induced inflammatory osteolysis

Objective To determine the therapeutic effect of icariin in the treatment of titanium particle-induced inflammatory osteolysis and examine the relationship between icariin and receptor activator of NF-κB ligand (RANKL)/ osteoprotegerin (OPG). Methods Eighty-four male C57BL/J6 mice were divided into four groups (21 animals for each) according to the random number table: black group, control group (titanium particles only), low-dosage icariin group (0. 1 mg·g-1·d-1, L group), and high-dosage icariin group (0. 3 mg·g-1·d-1, H group). The animal model of titanium particle-induced calvaria osteolysis was used in this study. After 2 weeks mice calvariae were harvested for micro-CT, histological and molecular analysis. Results As assessed by the micro-CT, icariin reduced particle-induced osteolysis: bone mineral density and bone volume fraction in L group was (89.44±18.51)mg/cm2 and (48.32±9.54)% and was (144.85±19.49)mg/ cm2 and (65.67±6.80)% in H group as compared to (61.23±13.41)mg/cm2 and (27.83±7.51)% in control group (P<0.05). HE staining demonstrated diminished inflammation after treatment with icariin while intensive macrophage infiltration into the calvariae in control group. Histomorphometric results demonstrated the area of eroded bone surface (EBS) was reduced to (0.07±0.01)mm2 and (0.04±0.01)mm2 respectively in L and H groups compared to (0.14±0.03)mm2 in control group (P<0.05). Tartrate resistant acid phosphatase (TRAP) staining revealed multiple TRAP-positive cells accumulated along the EBS in control group, whereas the number of TRAP-positive cells was reduced by icariin. Immunohistological examination showed titanium particle up-regulated expressions of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6. In contrast, low expressions were noted after icariin treatment. RT-PCR showed titanium particle stimulation could enhance mRNA expressions of calcitonin receptor (CTR), TRAP, cathepsin-K (Cath-K) and nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) in the clavariae tissues. However, the mRNA levels of these genes were markedly reduced after icariin treatment. ELISA results showed levels of RANKL and OPG were (23.02±4.39)pg/ml and (1 360.52±514.08)pg/ml in control group, but secretion of RANKL was reduced together with an increase in OPG by icariin[L group: (16.87±4.75), (1 890.54±550.94)pg/ml; H group: (12.80±5.77), (2 001.67±325.01)pg/ml, P<0.05]. Conclusion Icariin can effectively inhibit titanium particle-induced inflammatory osteolysis by suppressing osteoclast activity and attenuating osteolysis. Key words: Arthroplasty, replacement; Osteolysis; Osteoclasts; Titanium

Lycorine suppresses RANKL-induced osteoclastogenesis in vitro and prevents ovariectomy-induced osteoporosis and titanium particle-induced osteolysis in vivo.

Osteoclasts play an important role in diseases involving bone loss. In this study, we assessed the effect of a plant-derived natural alkaloid (lycorine, or LY) on osteoclastogenesis in vitro and in vivo. Our in vitro study showed that receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis could be inhibited by LY; this effect was due to inhibition of mitogen-activated protein kinase (MAPK) signalling via MAP kinase kinases (MKKs). The MAPK agonist anisomycin could partially rescue the inhibitory effect of LY. Furthermore, LY also played a protective role in both a murine ovariectomy (OVX)-induced osteoporosis model and a titanium particle-induced osteolysis model. These results confirmed that LY was effective in preventing osteoclast-related diseases in vivo. In conclusion, our results show that LY is effective in suppressing osteoclastogenesis and therefore could be used to treat OVX-induced osteoporosis and wear particle-induced osteolysis.

Icariin protects against titanium particle-induced osteolysis and inflammatory response in a mouse calvarial model

Periprosthetic osteolysis and subsequent aseptic loosening are common in implant failure, a complication with revision surgery being the only established treatment. Wear particle-induced inflammation and extensive osteoclastogenesis play critical roles in periprosthetic osteolysis. A recent approach in limiting osteolysis is therefore focused on inhibiting osteoclastic bone resorption. This study aimed to investigate the potential impact of icariin, the major ingredient of Epimedium, on titanium particle-induced osteolysis in a mouse calvarial model. Eighty-four male C57BL/J6 mice were divided randomly into four groups. Mice in the sham group underwent sham surgery only, whereas animals in the vehicle, low- and high-concentration icariin groups received titanium particles. Mice in the low- and high-concentration icariin groups were gavage-fed with icariin at 0.1 or 0.3 mg/g/day, respectively, until sacrifice. Mice in the sham and vehicle groups received phosphate-buffered saline daily. After 2 weeks, mouse calvariae were collected for micro-computed tomography, histomorphometry and molecular analysis. Icariin significantly reduced particle-induced bone resorption compared with the vehicle group. Icariin also prevented an increase in receptor activator of nuclear factor kappa B ligand/osteoprotegerin ratio and subsequently suppressed osteoclast formation in titanium particle-charged calvariae. In addition, immunohistochemical analysis and enzyme-linked immunosorbent assay showed icariin significantly reduced expression and secretion of tumor necrosis factor-α, interleukin-1β and interleukin-6 in the calvariae of titanium-stimulated mice. Collectively, these results suggest that icariin represents a potential treatment for titanium particle-induced osteolysis and could be developed as a new therapeutic candidate for the prevention and treatment of aseptic loosening.

Inhibitory effects of ursolic acid on osteoclastogenesis and titanium particle-induced osteolysis are mediated primarily via suppression of NF-κB signaling

Ursolic acid (UA), a pentacyclic triterpenoid found in a variety of plants, has attracted considerable attention because of its important biological and pharmacological activities. However, its effect on osteoclasts and mechanism of action require further investigation. In this study, we evaluated the effects of UA on osteoclastogenesis and osteoclast-mediated osteolysis in vitro and in vivo, and explored its possible mechanism of action. The results indicated that UA could inhibit receptor activator of nuclear factor-κB ligand (RANKL)-mediated osteoclastogenesis and the bone resorptive function of osteoclasts in a concentration-dependent manner in vitro. Further, UA effectively inhibited the mRNA and protein expression of NFATc1, primarily via the suppression of nuclear factor-κB (NF-κB) signaling, and partly through the suppression of c-Jun N-terminal kinase (JNK) signaling. Additionally, UA treatment downregulated the expression of NFATc1-regulated osteoclast marker genes. Likewise, UA induced dose-dependent attenuation of titanium (Ti) particle-induced mouse calvarial bone loss, and decreased the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts. In conclusion, these results demonstrate that UA protects against wear particle-induced osteolysis by suppressing osteoclast formation and function. These effects are associated with the inhibition of the NF-κB- and JNK-related signaling pathways.