The IRF1/GBP5 axis promotes osteoarthritis progression by activating chondrocyte pyroptosis.

Background: Osteoarthritis (OA) is a chronic degenerative joint disease that primarily affects middle-aged and elderly individuals. The decline in chondrocyte function plays a crucial role in the development of OA. Inflammasome-mediated chondrocyte pyroptosis is implicated in matrix degradation and cartilage degeneration in OA patients. Guanylate binding protein 5 (GBP5), a member of the GTPase family induced by Interferon-γ (IFN-γ), significantly influences cellular inflammatory responses, including intracellular inflammasome activation and cytokine release. However, the role of GBP5 in chondrocyte pyroptosis and OA progression remains unclear. Methods: In this study, we used tumor necrosis factor-α (TNF-α) to induce inflammation and created an OA mouse model with surgically-induced destabilization of the medial meniscus (DMM). We isolated and cultured primary chondrocytes from the knee joints of suckling C57 mice. TNF-α-stimulated primary chondrocytes served as an in vitro model for OA and underwent RNA sequencing. Chondrocytes were transfected with GBP5-overexpression plasmids and small interfering RNA and were subsequently treated with TNF-α. We assessed the expression of cartilage matrix components (COL2A1 and aggrecan), catabolic factors (MMP9 and MMP13), and NLRP3 inflammasome pathway genes (NLRP3, Caspase1, GSDMD, Pro-IL-1ß, and Pro-Caspase1) using RT-qPCR and Western blotting. We analyzed the expression of GBP5, NLRP3, and Caspase1 in the cartilage of DMM-induced post-traumatic OA mice and human OA patients. Immunohistochemistry (IHC) was used to detect the expression of GBP5, NLRP3 and GSDMD in cartilage specimens from OA patients and mouse DMM models. Chondrocyte pyroptosis was assessed using flow cytometry, and the levels of interleukin-1ß (IL-1ß) and interleukin-18 (IL-18) were measured with ELISA. We conducted double luciferase reporter gene and chromatin immunoprecipitation (ChIP) assays to confirm the relationship between IRF1 and GBP5. Results: GBP5 expression increased in TNF-α-induced chondrocytes, as revealed by RNA sequencing. GBP5 inhibited COL2A1 and aggrecan expression while promoting the expression of MMP9, MMP13, NLRP3, Caspase1, GSDMD, Pro-IL-1ß, and Pro-Caspase1. GBP5 expression also increased in the cartilage of DMM-induced post-traumatic OA mice and human OA patients. Knockout of GBP5 reduced chondrocyte injury in OA mice. GBP5 promoted chondrocyte pyroptosis and the production of IL-1ß and IL-18. Additionally, we found that IRF1 bound to the promoter region of GBP5, enhancing its expression. After co-transfected with ad-IRF1 and siGBP5, the expression of pyroptosis-related genes was significantly decreased compared with ad-IRF1 group. Conclusions: The IRF1/GBP5 axis enhances extracellular matrix (ECM) degradation and promotes pyroptosis during OA development, through the NLRP3 inflammasome signaling pathway. The translational potential of this article: This study underscores the significance of the IRF1/GBP5 axis in NLRP3 inflammasome-mediated chondrocyte pyroptosis and osteoarthritic chondrocyte injury. Modulating IRF1 and GBP5 expression could serve as a novel therapeutic target for OA.

Osteoclast-derived exosomal miR-212-3p suppressed the anabolism and accelerated the catabolism of chondrocytes in osteoarthritis by targeting TGF-ß1/Smad2 signaling.

Osteoarthritis (OA) is a common aging-related disease affecting entire joint structures, encompassing articular cartilage and subchondral bone. Although senescence and dysfunction of chondrocytes are considered crucial factors in the occurrence of OA, the exact pathogenesis remains to be investigated. In our study, chondrocytes were incubated with a conditioned medium obtained from osteoclasts at different differentiation stages, suggesting that osteoclasts and osteoclast precursors suppressed anabolism and promoted the catabolism of chondrocytes in vitro. In contrast, the function of osteoclasts was more significant than osteoclast precursors. Further blocking of osteoclast exosome secretion by using GW4869 abolished the effect of osteoclasts on chondrocytes. Functionally, exosomal transfer of osteoclast-derived miR-212-3p inhibited Smad2 to mediate chondrocyte dysfunction, thus accelerating cartilage matrix degradation in OA via TGF-ß1/Smad2 signaling. The mechanism was also confirmed within the articular cartilage in OA patients and surgery-induced OA mice. Our study provides new information on intercellular interactions in the bone microenvironment within articular cartilage and subchondral bone during OA progression. The miR-212-3p/Smad2 axis is a potential target for the prevention and therapy of OA.

Replenishing decoy extracellular vesicles inhibits phenotype remodeling of tissue-resident cells in inflammation-driven arthritis.

The interleukin 6 (IL6) signaling pathway plays pleiotropic roles in regulating the inflammatory milieu that contributes to arthritis development. Here, we show that activation of IL6 trans-signaling induces phenotypic transitions in tissue-resident cells toward an inflammatory state. The establishment of arthritis increases the serum number of extracellular vesicles (EVs), while these EVs express more IL6 signal transducer (IL6ST, also known as gp130) on their surface. Transferring these EVs can block IL6 trans-signaling in vitro by acting as decoys that trap hyper IL6 and prevent inflammatory amplification in recipient arthritic mice. By genetically fusing EV-sorting domains with extracellular domains of receptors, we engineered EVs that harbor a higher quantity of signaling-incompetent decoy receptors. These exogenous decoy EVs exhibit significant potential in eliciting efficient anti-inflammatory effects in vivo. Our findings suggest an inherent resistance of decoy EVs against inflammation, highlighting the therapeutic potential of efficient decoy EVs in treating inflammatory diseases.

Antagonizing exosomal miR-18a-5p derived from prostate cancer cells ameliorates metastasis-induced osteoblastic lesions by targeting Hist1h2bc and activating Wnt/ß-catenin pathway.

More than 50% of prostate cancer (PCa) patients have bone metastasis with osteoblastic lesions. MiR-18a-5p is associated with the development and metastasis of PCa, but it remains unclear whether it is involved in osteoblastic lesions. We first found that miR-18a-5p was highly expressed in the bone microenvironment of patients with PCa bone metastases. To address how miR-18a-5p affects PCa osteoblastic lesions, antagonizing miR-18a-5p in PCa cells or pre-osteoblasts inhibited osteoblast differentiation in vitro. Moreover, injection of PCa cells with miR-18a-5p inhibition improved bone biomechanical properties and bone mineral mass in vivo. Furthermore, miR-18a-5p was transferred to osteoblasts by exosomes derived from PCa cells and targeted the Hist1h2bc gene, resulting in Ctnnb1 up-regulation in the Wnt/ß-catenin signaling pathway. Translationally, antagomir-18a-5p significantly improved bone biomechanical properties and alleviated sclerotic lesions from osteoblastic metastases in BALB/c nude mice. These data suggest that inhibition of exosome-delivered miR-18a-5p ameliorates PCa-induced osteoblastic lesions.

Advanced application of stimuli-responsive drug delivery system for inflammatory arthritis treatment.

Inflammatory arthritis is a major cause of disability in the elderly. This condition causes joint pain, loss of function, and deterioration of quality of life, mainly due to osteoarthritis (OA) and rheumatoid arthritis (RA). Currently, available treatment options for inflammatory arthritis include anti-inflammatory medications administered via oral, topical, or intra-articular routes, surgery, and physical rehabilitation. Novel alternative approaches to managing inflammatory arthritis, so far, remain the grand challenge owing to catastrophic financial burden and insignificant therapeutic benefit. In the view of non-targeted systemic cytotoxicity and limited bioavailability of drug therapies, a major concern is to establish stimuli-responsive drug delivery systems using nanomaterials with on-off switching potential for biomedical applications. This review summarizes the advanced applications of triggerable nanomaterials dependent on various internal stimuli (including reduction-oxidation (redox), pH, and enzymes) and external stimuli (including temperature, ultrasound (US), magnetic, photo, voltage, and mechanical friction). The review also explores the progress and challenges with the use of stimuli-responsive nanomaterials to manage inflammatory arthritis based on pathological changes, including cartilage degeneration, synovitis, and subchondral bone destruction. Exposure to appropriate stimuli induced by such histopathological alterations can trigger the release of therapeutic medications, imperative in the joint-targeted treatment of inflammatory arthritis.

Angelicin Alleviates Post-Trauma Osteoarthritis Progression by Regulating Macrophage Polarization via STAT3 Signaling Pathway.

Post-trauma osteoarthritis (PTOA) is the most common articular disease characterized by degeneration and destruction of articular cartilage (Bultink and Lems, Curr. Rheumatol Rep., 2013, 15, 328). Inflammatory response of local joint tissue induced by trauma is the most critical factor accelerating osteoarthritis (OA) progression (Sharma et al., 2019; Osteoarthritis. Cartilage, 28, 658-668). M1/M2 macrophages polarization and repolarization participates in local inflammation, which plays a major role in the progression of OA (Zhang et al., 2018; Ann. Rheum. Dis., 77, 1524-1534). The regulating effect of macrophage polarization has been reported as a potential therapy to alleviate OA progression. Synovitis induced by polarized macrophages could profoundly affect the chondrocyte and cartilage matrix (Zhang et al., 2018; Ann. Rheum. Dis., 77, 1524-1534). Generally, anti-inflammatory medications widely used in clinical practice have serious side effects. Therefore, we focus on exploring a new therapeutic strategy with fewer side effects to alleviate the synovitis. Angelicin (ANG) is traditional medicine used in various folk medicine. Previous studies have revealed that angelicin has an inhibitory effect on inflammation (Wei et al., 2016; Inflammation, 39, 1876-1882), tumor growth (Li et al., 2016; Oncology reports, 36, 3,504-3,512; Wang et al., 2017; Molecular Medicine Reports, 16, 5441-5449), DNA damage (Li et al., 2019; Exp. Ther. Med., 18, 1899-1906), and virus proliferation (Li et al., 2018; Front. Cell. Infect. Microbiol., 8, 178). But its specific effects on influencing the process of OA were rarely reported. In this study, the molecular mechanism of angelicin in vivo and in vitro was clearly investigated. Results showed that angelicin could regulate the M1/M2 ratio and function and alleviate the development of PTOA in the meanwhile. Bone marrow monocytes were isolated and induced by macrophage colony-stimulating factor (M-CSF), lipopolysaccharide (LPS) and interferon (IFN)-γ for M1 polarization and interleukin (IL)-4/IL-13 for M2 polarization. Subsequently, repolarization intervention was performed. The results indicate that angelicin can repolarize M1 toward M2 macrophages by upregulating the expression of CD9. Besides, angelicin can also protect and maintain M2 polarization in the presence of LPS/IFN-γ, and subsequently downregulate the expression of inflammatory mediators such as IL-1ß and TNF-α. Mechanistically, angelicin can activate the p-STAT3/STAT3 pathway by conducting CD9/gp130 to repolarize toward M2 macrophages. These results suggest angelicin can alleviate the progression of OA by regulating M1/M2 polarization via the STAT3/p-STAT3 pathway. Therefore, angelicin may have a promising application and potential therapeutic value in OA clinical treatment.

Bone-targeted pH-responsive cerium nanoparticles for anabolic therapy in osteoporosis.

Antiresorptive drugs are widely used for treatment of osteoporosis and cancer bone metastasis, which function mainly through an overall inhibition of osteoclast. However, not all osteoclasts are "bone eaters"; preosteoclasts (pOCs) play anabolic roles in bone formation and angiogenesis through coupling with osteoblasts and secreting platelet derived growth factor-BB (PDGF-BB). In this study, a bone-targeted pH-responsive nanomaterial was designed for selectively eliminating mature osteoclasts (mOCs) without affecting pOCs. Biocompatible cerium nano-system (CNS) was guided to the acidic extracellular microenvironment created by mOCs and gained oxidative enzymatic activity. Oxidative CNS decreased the viability of mOCs through accumulating intracellular reactive oxygen species and enhancing calcium oscillation. Non-acid secreting anabolic pOCs were thus preserved and kept producing PDGF-BB, which lead to mesenchymal stem cell osteogenesis and endothelial progenitor cell angiogenesis via PI3K-Akt activated focal adhesion kinase. In treating osteoporotic ovariectomized mice, CNS showed better protective effects compare with the current first line antiresorptive drug due to the better anabolic effects marked by higher level of bone formation and vascularization. We provided a novel anabolic therapeutic strategy in treating bone disorders with excessive bone resorption.

Small extracellular vesicles deliver osteolytic effectors and mediate cancer-induced osteolysis in bone metastatic niche.

Extracellular vesicles (EVs) play critical roles in regulating bone metastatic microenvironment through mediating intercellular crosstalks. However, little is known about the contribution of EVs derived from cancer cells to the vicious cycle of bone metastasis. Here, we report a direct regulatory mode between tumour cells and osteoclasts in metastatic niche of prostate cancer via vesicular miRNAs transfer. Combined analysis of miRNAs profiles both in tumour-derived small EVs (sEVs) and osteoclasts identified miR-152-3p as a potential osteolytic molecule. sEVs were enriched in miR-152-3p, which targets osteoclastogenic regulator MAFB. Blocking miR-152-3p in sEVs upregulated the expression of MAFB and impaired osteoclastogenesis in vitro. In vivo experiments of xenograft mouse model found that blocking of miR-152-3p in sEVs significantly slowed down the loss of trabecular architecture, while systemic inhibition of miR-152-3p using antagomir-152-3p reduced the osteolytic lesions of cortical bone while preserving basic trabecular architecture. Our findings suggest that miR-152-3p carried by prostate cancer-derived sEVs deliver osteolytic signals from tumour cells to osteoclasts, facilitating osteolytic progression in bone metastasis.

Therapeutic efficacy and cardioprotection of nucleolin-targeted doxorubicin-loaded ultrasound nanobubbles in treating triple-negative breast cancer.

Targeted lipid nanobubbles as theranostic ultrasound molecular probes with both targeted contrast-enhanced ultrasound molecular imaging and synergistic treatment capabilities are expected to overcome severe challenges in the diagnosis and treatment of refractory triple-negative breast cancer (TNBC). In this study, AS1411 aptamer-functionalised nucleolin-targeted doxorubicin-loaded lipid nanobubbles (AS1411-DOX-NBs) were constructed, and their physicochemical properties as well as anti-tumour and cardioprotective efficacies were systematically tested and evaluated. The results showed that AS1411-DOX-NBs can carry and maintain the physicochemical and pharmacodynamic properties of doxorubicin (DOX) and show stronger tumour cell-killing abilityin vitroby increasing the active uptake of drugs. AS1411-DOX-NBs also significantly inhibited the growth of TNBC xenografts while maintaining the weight and health of the mice. Echocardiography and pathological examination further confirmed that AS1411-DOX-NBs effectively caused tumour tissue apoptosis and necrosis while reducing DOX-induced cardiotoxicity. The AS1411-DOX-NBs constructed in this study enable both targeted contrast-enhanced ultrasound molecular imaging and synergistic therapeutic efficacy and can be used as safe and efficient theranostic ultrasound molecular probes for the diagnosis and treatment of TNBC.

Laminin alpha 4 promotes bone regeneration by facilitating cell adhesion and vascularization.

Selective cell retention (SCR) has been widely used as a bone tissue engineering technique for the real-time fabrication of bone grafts. The greater the number of mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs) retained in the scaffold, the better the osteoinductive and angiogenic properties of the scaffold's microenvironment. Improved bioscaffold properties in turn lead to improved bone graft survival, bone regeneration, and angiogenesis. Laminin plays a key role in cell-matrix adhesion, cell proliferation, and differentiation. We designed a collagen-binding domain (CBD) containing the core functional amino acid sequences of laminin α4 (CBD-LN peptide) to supplement the functional surface of a collagen-based decalcified bone matrix (DBM) scaffold. This scaffold promoted MSCs and EPCs early cell adhesion through up-regulating the expression of integrin α5ß1 and integrin αvß3 respectively, thus accelerated the following cell spreading, proliferation, and differentiation. Interestingly, it promoted the retention of MSCs (CD90+/CD105+ cells) and EPCs (CD31+ cells) in the scaffold following the use of clinical SCR technology. Furthermore, the DBM/CBD-LN scaffold induced the formation of type H vessels through the activation of the HIF-1α signaling pathway. The DBM/CBD-LN scaffold displayed rapid bone formation and angiogenesis in vivo, suggesting that it might be used as a new biomaterial in bone tissue engineering. STATEMENT OF SIGNIFICANCE: Selective cell retention technology (SCR) has been utilized in clinical settings to manufacture bioactive bone grafts. Specifically, demineralized bone matrix (DBM) is a widely-used SCR clinical biomaterial but it displays poor adhesion performance and angiogenic activity. In this work, we designed a collagen-binding domain (CBD) containing the core functional amino acid sequences of laminin α4 to supplement the functional surface of a collagen-based DBM scaffold. This bioscaffold promoted SCR-mediated MSCs and EPCs early cell adhesion, thus accelerated the following cell spreading, proliferation, and differentiation. Our results indicate this bioscaffold greatly induced osteogenesis and angiogenesis in vivo. In general, this bioscaffold has a good prospect for SCR application and may provide highly bioactive bone implant in clinical environment.

A selected small molecule prevents inflammatory osteolysis through restraining osteoclastogenesis by modulating PTEN activity.

BACKGROUND: Inflammatory osteolysis is a severe infectious bone disorder that occurs during orthopaedic surgery and is caused by disruptions in the dynamic balance of bone matrix homeostasis, which makes this condition a burden on surgical procedures. Developing novel therapeutic drugs about inhibiting excessive osteoclastogenesis acts as an efficient approach to preventing inflammatory bone destruction. METHODS: To study this, we explored the potential effects and mechanisms of compound 17 on inflammatory osteolysis in vitro. Meanwhile, a lipopolysaccharide (LPS)-induced calvarial osteolysis mouse model was used to evaluate the protective effect of compound 17 on inflammatory bone destruction in vivo. RESULTS: In our study, we found that compound 17 could inhibit osteoclast (OC) differentiation and bone resorption during RANKL and LPS stimulation in a time- and dose-dependent manner, while compounds 5 and 13 did not have the same effects. Mechanistically, compound 17 promoted phosphatase and tensin homologue (PTEN) activity by reducing PTEN ubiquitination, thereby restraining the RANKL-induced NF-κB pathway, resulting in the inhibition of the expression of osteoclastogenesis-related genes and the formation of the NLRP3 inflammasome. Additionally, we also investigated whether compound 17 could negatively modulate macrophage polarization and repolarization due to its anti-inflammatory effects. Moreover, compound 17 also plays an important role in osteoblast differentiation and mineralization. In vivo experiments showed that compound 17 could effectively protect mice from LPS-induced inflammatory bone destruction by inhibiting osteoclastogenesis and inflammation. CONCLUSIONS: Taken together, these results show that compound 17 might play protective role in inflammatory bone destruction through inhibiting osteoclastogenesis and inflammation. These findings imply a possible role of compound 17 in inflammatory osteolysis-related diseases.

[Effect of demineralized bone matrix modified by laminin α4 chain functional peptide on H-type angiogenesis and osteogenesis to promote bone defect repair].

OBJECTIVE: Based on the cell-extracellular matrix adhesion theory in selective cell retention (SCR) technology, demineralized bone matrix (DBM) modified by simplified polypeptide surface was designed to promote both bone regeneration and angiogenesis. METHODS: Functional peptide of α4 chains of laminin protein (LNα4), cyclic RGDfK (cRGD), and collagen-binding domain (CBD) peptides were selected. CBD-LNα4-cRGD peptide was synthesized in solid phase and modified on DBM to construct DBM/CBD-LNα4-cRGD scaffold (DBM/LN). Firstly, scanning electron microscope and laser scanning confocal microscope were used to examine the characteristics and stability of the modified scaffold. Then, the adhesion, proliferation, and tube formation properties of CBD-LNα4-cRGD peptide on endothelial progenitor cells (EPCs) were detected, respectively. Western blot method was used to verify the molecular mechanism affecting EPCs. Finally, 24 10-week-old male C57 mice were used to establish a 2-mm-length defect of femoral bone model. DBM/LN and DBM scaffolds after SCR treatment were used to repair bone defects in DBM/LN group ( n=12) and DBM group ( n=12), respectively. At 8 weeks after operation, the angiogenesis and bone regeneration ability of DBM/LN scaffolds were evaluated by X-ray film, Micro-CT, angiography, histology, and immunofluorescence staining [CD31, endomucin (Emcn), Ki67]. RESULTS: Material related tests showed that the surface of DBM/LN scaffold was rougher than DBM scaffold, but the pore diameter did not change significantly ( t=0.218, P=0.835). After SCR treatment, DBM/LN scaffold was still stable and effective. Compared with DBM scaffold, DBM/LN scaffold could adhere to more EPCs after the surface modification of CBD-LNα4-cRGD ( P<0.05), and the proliferation rate and tube formation ability increased. Western blot analysis showed that the relative expressions of VEGF, phosphorylated FAK (p-FAK), and phosphorylated ERK1/2 (p-ERK1/2) proteins were higher in DBM/LN than in DBM ( P<0.05). In the femoral bone defect model of mice, it was found that mice implanted with DBM/LN scaffold had stronger angiogenesis and bone regeneration capacity ( P<0.05), and the number of CD31 hiEmcn hi cells increased significantly ( P<0.05). CONCLUSION: DBM/LN scaffold can promote the adhesion of EPCs. Importantly, it can significantly promote the generation of H-type vessels and realize the effective coupling between angiogenesis and bone regeneration in bone defect repair.

KEAP1 Mutations Drive Tumorigenesis by Suppressing SOX9 Ubiquitination and Degradation.

The transcription factor SOX9 is frequently amplified in diverse advanced-stage human tumors. Its stability has been shown to be tightly controlled by ubiquitination-dependent proteasome degradation. However, the exact underlying molecular mechanisms remain unclear. This work reports that SOX9 protein abundance is regulated by the Cullin 3-based ubiquitin ligase KEAP1 via proteasome-mediated degradation. Loss-of-function mutations in KEAP1 compromise polyubiquitination-mediated SOX9 degradation, leading to increased protein levels, which facilitate tumorigenesis. Moreover, the loss of critical ubiquitination residues in SOX9, by either a SOX9 (ΔK2) truncation or K249R mutation, leads to elevated protein stability. Furthermore, it is shown that the KEAP1/SOX9 interaction is modulated by CKIγ-mediated phosphorylation. Importantly, it is demonstrated that DNA damage drugs, topoisomerase inhibitors, can trigger CKI activation to restore the KEAP1/SOX9 interaction and its consequent degradation. Collectively, herein the findings uncover a novel molecular mechanism through which SOX9 protein stability is negatively regulated by KEAP1 to control tumorigenesis. Thus, these results suggest that mitigating SOX9 resistance to KEAP1-mediated degradation can represent a novel therapeutic strategy for cancers with KEAP1 mutations.

Construction of Nucleolin-Targeted Lipid Nanobubbles and Contrast-Enhanced Ultrasound Molecular Imaging in Triple-Negative Breast Cancer.

PURPOSE: To construct aptamer AS1411-functionalized targeted lipid nanobubbles that could simultaneously target abnormally highly expressed nucleolin (NCL) on tumor tissue and neovasculature. Additionally, the study of their contrast-enhanced ultrasound molecular imaging capabilities in vitro and in vivo to explore new methods and approaches for the early and accurate diagnosis of triple-negative breast cancer (TNBC). METHODS: First, the targeted lipid-nucleic acid molecules were constructed by an amide reaction. Then, the targeted lipid nanobubbles (AS1411-NBs) and nontargeted lipid nanobubbles (NBs) were prepared by membrane hydration, mechanical vibration and centrifugal floatation. The physicochemical characteristics and contrast-enhanced ultrasound imaging capabilities of AS1411-NBs and NBs were compared and analyzed in vitro and in vivo. RESULTS: There were no significant differences between the AS1411-NBs and NBs in their concentration, average particle size or ultrasound imaging capabilities in vitro (P > 0.05). However, AS1411-NBs could simultaneously target NCL in tumor tissue and neovasculature to effectively prolong the duration of contrast-enhanced ultrasound imaging compared to NBs in vivo. The area under the time-intensity curve was significantly different between AS1411-NBs and NBs (P < 0.001), and the drug loading capacity of the AS1411-NBs was also significantly higher than that of the NBs (P < 0.05). CONCLUSIONS: Aptamer AS1411-functionalized targeted lipid nanobubbles could significantly prolong the duration of contrast-enhanced ultrasound imaging to achieve dual-targeted ultrasound molecular imaging of tumor tissue and neovasculature. AS1411-NBs also have higher drug loading and targeted drug delivery capabilities compared with NBs, which can provide new methods and approaches for the early accurate diagnosis and effective treatment of TNBC.

Epothilone B prevents lipopolysaccharide-induced inflammatory osteolysis through suppressing osteoclastogenesis via STAT3 signaling pathway.

Inflammatory osteolysis is a common osteolytic specificity that occurs during infectious orthopaedic surgery and is characterized by an imbalance in bone homeostasis due to excessive osteoclast bone resorption activity. Epothilone B (Epo B) induced α-tubulin polymerization and enhanced microtubule stability, which also played an essential role in anti-inflammatory effect on the regulation of many diseases. However, its effects on skeletal system have rarely been investigated. Our study demonstrated that Epo B inhibited osteoclastogenesis in vitro and prevented inflammatory osteolysis in vivo. Further analysis showed that Epo B also markedly induced mature osteoclasts apoptosis during osteoclastogenesis. Mechanistically, Epo B directly suppressed osteoclastogenesis by the inhibitory regulation of the phosphorylation and activation of PI3K/Akt/STAT3 signaling directly, and the suppressive regulation of the CD9/gp130/STAT3 signaling pathway indirectly. The negative regulatory effect on STAT3 signaling further restrained the translocation of NF-κB p65 and NFATc1 from the cytosol to the nuclei during RANKL stimulation. Additionally, the expression of osteoclast specific genes was also significantly attenuated during osteoclast fusion and differentiation. Taken together, these findings illustrated that Epo B protected against LPS-induced bone destruction through inhibiting osteoclastogenesis via regulating the STAT3 dependent signaling pathway.

Dendritic cells-derived interferon-λ1 ameliorated inflammatory bone destruction through inhibiting osteoclastogenesis.

Bone infection contributing to inflammatory osteolysis is common in orthopedic surgery. The dynamic balance between bone formation and bone resorption is destroyed due to excessive osteoclast fusion and differentiation, which results in severe bone matrix loss. Many therapeutic approaches that restrain osteoclast formation and function act as efficient ways to prevent inflammatory bone erosion. We have demonstrated for the first time that dendritic cells-derived interferon-λ1 (IFN-λ1) inhibited inflammatory bone destruction in vivo and explored its underlying mechanisms on osteoclast formation in vitro. We found that IFN-λ1 was highly expressed in infectious bone tissue compared with that of non-infectious bone tissue. Additionally, dendritic cells marker genes such as CD80, CD86, and CD1a were higher expressed in infectious bone tissue than that of non-infectious bone tissue. Dendritic cells that were pretreated with LPS showed high expression of IFN-λ1. Moreover, conditioned medium of LPS-pretreated dendritic cells significantly inhibited osteoclast differentiation, as determined by TRAP staining assay. This suppressive effect was reversed by adding an IFN-λ1 monoclonal antibody. It was also investigated whether exogenous IFN-λ1 restrained osteoclastogenesis, bone resorption, F-actin ring formation, osteoclast-specific gene expression, release of pro-inflammatory cytokines, and translocation of p65 and NFATc1 by preventing the NF-κB signaling pathway and NLRP3 inflammasome formation, as well as by inducing the JAK-STAT signaling pathways in vitro. In vivo study indicated that IFN-λ1 prevents lipopolysaccharide (LPS)-induced inflammatory bone destruction by inhibiting excessive osteoclast fusion and bone resorption activity. In conclusion, our findings confirmed that dendritic cells-derived IFN-λ1 could attenuate osteoclast formation and bone resorptive activity in vitro and in vivo. These novel findings pave the way for the use of exogenous IFN-λ1 as a potential therapeutic treatment for excessive osteoclast-related diseases, such as inflammatory osteolysis, by regulating osteoclastogenesis to maintain the dynamic balance between bone formation and bone resorption.

Tumour dormancy in inflammatory microenvironment: A promising therapeutic strategy for cancer-related bone metastasis.

Cancer metastasis is a unique feature of malignant tumours. Even bone can become a common colonization site due to the tendency of solid tumours, including breast cancer (BCa) and prostate cancer (PCa), to metastasize to bone. Currently, a previous concept in tumour metabolism called tumour dormancy may be a promising target for antitumour treatment. When disseminated tumour cells (DTCs) metastasize to the bone microenvironment, they form a flexible regulatory network called the "bone-tumour-inflammation network". In this network, bone turnover as well as metabolism, tumour progression, angiogenesis and inflammatory responses are highly unified and coordinated, and a slight shift in this balance can result in the disruption of the microenvironment, uncontrolled inflammatory responses and excessive tumour growth. The purpose of this review is to highlight the regulatory effect of the "bone-tumour-inflammation network" in tumour dormancy. Osteoblast-secreted factors, bone turnover and macrophages are emphasized and occupy in the main part of the review. In addition, the prospective clinical application of tumour dormancy is also discussed, which shows the direction of future research.

Modification of PLGA Scaffold by MSC-Derived Extracellular Matrix Combats Macrophage Inflammation to Initiate Bone Regeneration via TGF-ß-Induced Protein.

The immunologic response toward chronic inflammation or bone regeneration via the accumulation of M1 or M2 macrophages after injury could determine the fate of biomaterial. Human umbilical cord mesenchymal stem cells (hUCMSCs) have a pivotal immunomodulatory property on directing macrophage behaviors. Herein, for the first time, 3D-printed poly(lactide-co-glycolide) (PLGA) scaffolds modified with hUCMSC-derived extracellular matrix (PLGA-ECM) are prepared by a facile tissue engineering technique with physical decellularization and 2.44 ± 0.29 mg cm-3 proteins immobilized on the PLGA-ECM contain multiple soluble cytokines with a sustainable release profile. The PLGA-ECM not only attenuates the foreign body response, but also improves bone regeneration by increasing the accumulation of M2 macrophages in an improved heterotopic transplantation model of SCID mice. Furthermore, the PLGA-ECM scaffolds with the knockdown of transforming growth factor-ß-induced protein (TGFßI/ßig-H3) demonstrate that M2 macrophage accumulation improved by the PLGA-ECM could be attributed to increasing the migration of M2 macrophages and the repolarization of M1 macrophages to M2 phenotype, which are mediated by multiple integrin signaling pathways involving in integrin ß7, integrin α9, and integrin ß1 in a TGFßI-dependent manner. This study presents an effective surface modification strategy of polymeric scaffolds to initiate tissue regeneration and combat inflammatory response by increasing M2 macrophage accumulation.

P2X7 receptor acts as an efficient drug target in regulating bone metabolism system.

Skeletal system is a highly dynamic system going through continuous resorption and reconstruction to maintain homeostasis, which is influenced by numerous factors. Once the balance is disrupted, various kinds of bone diseases may occur such as osteoporosis. It has been well known that ATP (adenosine triphosphate), an important signaling molecule, is important in maintaining the dynamic balance of bone matrix. ATP mainly functions through P2X receptors, a kind of ATP receptors expressed by various kinds of bone cells to regulate the whole network of skeleton system. Among P2X receptors, P2X7 plays a crucial role in bone since P2X7 is widely expressed by bone cells and the mutation of P2X7 receptor is associated with kinds of bone diseases. It's acknowledged that P2X7 acts as a potential therapeutic target for clinical treatment of bone-related diseases but further investigations are needed for the practical application. However, since P2X7 has a complicated effect in many aspects, the exact role of P2X7 in skeleton system is ambiguous. This review discusses the function of P2X7 in bone and other cells and their general effect on skeleton system, especially focusing on the possible clinical application for bone diseases.