TGFβ reprograms TNF stimulation of macrophages towards a non-canonical pathway driving inflammatory osteoclastogenesis

Inflammatory gene regulation by Cdc42 in airway epithelial cells

Cytokine release from airway epithelial cells is a key immunological process that coordinates an immune response in the lungs. We propose that the Rho GTPase, Cdc42, regulates both transcription and trafficking of cytokines, ultimately affecting the essential process of cytokine release and subsequent inflammation in the lungs. Here, we examined the pro-inflammatory transcriptional profile that occurs in bronchial epithelial cells (BEAS-2B) in response to TNF-α using RNA-Seq and differential gene expression analysis. To interrogate the role of Cdc42 in inflammatory gene expression, we used a pharmacological inhibitor of Cdc42, ML141, and determined changes in the transcriptomic profile induced by Cdc42 inhibition. Our results indicated that Cdc42 inhibition with ML141 resulted in a unique inflammatory phenotype concomitant with increased gene expression of ER stress genes, Golgi membrane and vesicle transport genes. To further interrogate the inflammatory pathways regulated by Cdc42, we made BEAS-2B knockdown strains for the signaling targets TRIB3, DUSP5, SESN2 and BMP4, which showed high differential expression in response to Cdc42 inhibition. Depletion of DUSP5 and TRIB3 reduced the pro-inflammatory response triggered by Cdc42 inhibition as shown by a reduction in cytokine transcript levels. Depletion of SESN2 and BMP4 did not affect cytokine transcript level, however, Golgi fragmentation was reduced. These results provide further evidence that in airway epithelial cells, Cdc42 is part of a signaling network that controls inflammatory gene expression and secretion by regulating Golgi integrity. Summary sentence:We define the Cdc42-regulated gene networks for inflammatory signaling in airway epithelial cells which includes regulation of ER stress response and vesicle trafficking pathways.

CD11B + CD36 + cells are bone anabolic macrophages that limit age-associated bone loss

Disruptions in the bone remodeling cycle that occur with increasing age lead to degeneration of the skeleton and increased risk of fragility fractures. Our understanding of how the bone remodeling process within cortical bone is controlled and altered with age in males and females is limited. Here, we generated bone marrow chimeric mice to understand the impacts of age and sex on the bone remodeling process. We demonstrate that transplantation of aged male or female bone marrow into young lethally irradiated male hosts unexpectedly enhances cortical bone mass without an impacting cancellous bone. Our single cell RNA-sequencing data show that mice reconstituted with aged bone marrow exhibited subsets of cells marked by CD11B/CD36 expression that demonstrate enhanced production of anabolic cytokines as compared to young counterparts, and that these myeloid subsets exist under conditions of normal physiology in aged mice. Importantly, CD11B + CD36 + cells do not differentiate into osteoclasts in vitro, and CD36 does not mark TRAP+ cells in vivo. Instead, CD36 + cells localize to resorption sites, including within cortical bone defects, suggesting their involvement in cortical bone remodeling and healing. CD11B + CD36 + cells also express elevated levels of bone anabolic WNT ligands, especially Wnt6. In functional assays, we demonstrate that soluble factors produced by CD11B + CD36 + cells enhance osteoblast progenitor commitment, mineralization, and activation of WNT signaling in vitro. Moreover, CD11B/CD36 exquisitely mark a subset of anabolic myeloid cells within human bone marrow. In conclusion, our studies identified a novel population of aged macrophages that limit cortical bone loss.

The balance between helper T 17 and regulatory T cells in osteoimmunology and relevant research progress on bone tissue engineering

BACKGROUND

Bone regeneration is a well-regulated dynamic process, of which the prominent role of the immune system on bone homeostasis is more and more revealed by recent research. Before fully activation of the bone remodeling cells, the immune system needs to clean up the microenvironment in facilitating the bone repair initiation. Furthermore, this microenvironment must be maintained properly by various mechanisms over the entire bone regeneration process.

OBJECTIVE

This review aims to summarize the role of the T-helper 17/Regulatory T cell (Th17/Treg) balance in bone cell remodeling and discuss the relevant progress in bone tissue engineering.

RESULTS

The role of the immune response in the early stages of bone regeneration is crucial, especially the impact of the Th17/Treg balance on osteoclasts, mesenchymal stem cells (MSCs), and osteoblasts activity. By virtue of these knowledge advancements, innovative approaches in bone tissue engineering, such as nano-structures, hydrogel, and exosomes, are designed to influence the Th17/Treg balance and thereby augment bone repair and regeneration.

CONCLUSION

Targeting the Th17/Treg balance is a promising innovative strategy for developing new treatments to enhance bone regeneration, thus offering potential breakthroughs in bone injury clinics.

Preventing periprosthetic osteolysis in aging populations through lymphatic activation and stem cell-associated secretory phenotype inhibition

With increases in life expectancy, the number of patients requiring joint replacement therapy and experiencing periprosthetic osteolysis, the most common complication leading to implant failure, is growing or underestimated. In this study, we found that osteolysis progression and osteoclast differentiation in the surface of the skull bone of adult mice were accompanied by significant expansion of lymphatic vessels within bones. Using recombinant VEGF-C protein to activate VEGFR3 and promote proliferation of lymphatic vessels in bone, we counteracted excessive differentiation of osteoclasts and osteolysis caused by titanium alloy particles or inflammatory cytokines LPS/TNF-α. However, this effect was not observed in aged mice because adipogenically differentiated mesenchymal stem cells (MSCs) inhibited the response of lymphatic endothelial cells to agonist proteins. The addition of the JAK inhibitor ruxolitinib restored the response of lymphatic vessels to external stimuli in aged mice to protect against osteolysis progression. These findings suggest that inhibiting SASP secretion by adipogenically differentiated MSCs while activating lymphatic vessels in bone offers a new method to prevent periprosthetic osteolysis during joint replacement follow-up.

Hecogenin alleviates LPS-induced osteolysis via regulating pyroptosis and ROS involved Nrf2 activation

Reactive oxidative species (ROS) generation triggers pyroptosis and induces development of inflammatory osteolysis. Hecogenin (HG) has anti-inflammatory and antioxidative property, but its effects on inflammatory osteolysis remains unclear. In our study, we investigated the mechanism of HG on pyroptosis and its effect on inflammatory osteolysis in vitro and in vivo. The impact of HG on osteoclastogenesis was evaluated using cytotoxicity, TRAcP staining and bone resorption assays. The RNA-sequencing was employed to identify potential signaling pathways, and then RT-qPCR, western blot, immunofluorescence, and ELISA were used to verify. To determine the protective effect of HG in vivo, Lipopolysaccharide (LPS)-induced animal models were utilized, along with micro-CT and histological examination. HG suppressed RANKL-induced osteoclast differentiation, bone resorption, NFATc1 activity and downstream factors. RNA-sequencing results showed that HG inhibited osteoclastogenesis by modulating the inflammatory response and macrophage polarization. Furthermore, HG inhibited the NF-κB pathway, and deactivated the NLRP3 inflammasome. HG activated the expression of nuclear factor E2-related factor 2 (Nrf2) to eliminate ROS generation. Importantly, the inhibitory effect of HG on NLRP3 inflammasome could be reversed by treatment with the Nrf2 inhibitor ML385. In vivo, HG prevented the mice against LPS-induced osteolysis by suppressing osteoclastogenesis and inflammatory factors. In conclusion, HG could activate Nrf2 to eliminate ROS generation, inactivate NLRP3 inflammasome and inhibit pyroptosis, thereby suppressing osteoclastogenesis in vitro and alleviating inflammatory osteolysis in vivo, which indicating that HG might be a promising candidate to treat inflammatory osteolysis.

An adaptive biodegradable zinc alloy with bidirectional regulation of bone homeostasis for treating fractures and aged bone defects

Healing of fractures or bone defects is significantly hindered by overactivated osteoclasts and inhibited osteogenesis in patients with abnormal bone metabolism. Current clinical approaches using titanium alloys or stainless steel provide mechanical support but have no biological effects on bone regeneration. Therefore, designing and fabricating degradable metal materials with sufficient mechanical strength and bidirectional regulation of both osteoblasts and osteoclasts is a substantial challenge. Here, this study first reported an adaptive biodegradable Zn-0.8 Mg alloy with bidirectional regulation of bone homeostasis, which promotes osteogenic differentiation by activating the Pi3k/Akt pathway and inhibits osteoclast differentiation by inhibiting the GRB2/ERK pathway. The anti-osteolytic ability of the Zn-0.8 Mg alloy was verified in a mouse calvarial osteolysis model and its suitability for internal fracture fixation with high-strength screws was confirmed in the rabbit femoral condyle fracture model. Furthermore, in an aged postmenopausal rat femoral condyle defect model, 3D printed Zn-0.8 Mg scaffolds promoted excellent bone regeneration through adaptive structures with good mechanical properties and bidirectionally regulated bone metabolism, enabling personalized bone defect repair. These findings demonstrate the substantial potential of the Zn-0.8 Mg alloy for treating fractures or bone defects in patients with aberrant bone metabolism.

The miR-29-3p family suppresses inflammatory osteolysis

Osteoclasts are the cells primarily responsible for inflammation-induced bone loss, as is particularly seen in rheumatoid arthritis. Increasing evidence suggests that osteoclasts formed under homeostatic versus inflammatory conditions may differ in phenotype. While microRNA-29-3p family members (miR-29a-3p, miR-29b-3p, miR-29c-3p) promote the function of RANKL-induced osteoclasts, the role of miR-29-3p during inflammatory TNF-α-induced osteoclastogenesis is unknown. We used bulk RNA-seq, histology, qRT-PCR, reporter assays, and western blot analysis to examine bone marrow monocytic cell cultures and tissue from male mice in which the function of miR-29-3p family members was decreased by expression of a miR-29-3p tough decoy (TuD) competitive inhibitor in the myeloid lineage (LysM-cre). We found that RANKL-treated monocytic cells expressing the miR-29-3p TuD developed a hypercytokinemia/proinflammatory gene expression profile in vitro, which is associated with macrophages. These data support the concept that miR-29-3p suppresses macrophage lineage commitment and may have anti-inflammatory effects. In correlation, when miR-29-3p activity was decreased, TNF-α-induced osteoclast formation was accentuated in an in vivo model of localized osteolysis and in a cell-autonomous manner in vitro. Further, miR-29-3p targets mouse TNF receptor 1 (TNFR1/Tnfrsf1a), an evolutionarily conserved regulatory mechanism, which likely contributes to the increased TNF-α signaling sensitivity observed in the miR-29-3p decoy cells. Whereas our previous studies demonstrated that the miR-29-3p family promotes RANKL-induced bone resorption, the present work shows that miR-29-3p dampens TNF-α-induced osteoclastogenesis, indicating that miR-29-3p has pleiotropic effects in bone homeostasis and inflammatory osteolysis. Our data supports the concept that the knockdown of miR-29-3p activity could prime myeloid cells to respond to an inflammatory challenge and potentially shift lineage commitment toward macrophage, making the miR-29-3p family a potential therapeutic target for modulating inflammatory response.

Ctdnep1 phosphatase is required for negative regulation of RANKL-induced osteoclast differentiation in RAW264.7 cells

Osteoclasts are multinucleated cells with bone resorption activity. Excessive osteoclast activity has been implicated in osteoporosis, rheumatoid arthritis, and bone destruction due to bone metastases from cancer, making osteoclasts essential target cells in bone and joint diseases. C-terminal domain nuclear envelope phosphatase 1 (Ctdnep1, formerly Dullard) is a negative regulator of transforming growth factor (TGF)-β superfamily signaling and regulates endochondral ossification in mesenchymal cells during skeletal development. In this study, we investigated the role of Ctdnep1 in the Receptor activator of nuclear factor-kappa B ligand (RANKL)-induced RAW264.7 osteoclast differentiation. Expression of Ctdnep1 did not change during osteoclast differentiation; Ctdnep1 protein localized to the cytoplasm before and after osteoclast differentiation. Small interfering RNA-mediated knockdown of Ctdnep1 increased tartrate-resistant acid phosphatase-positive multinucleated osteoclasts and the expression of osteoclast marker genes, including Acp5, Ctsk, and Nfatc1. Interestingly, the knockdown of Ctdnep1 increased the protein level of Nfatc1 in cells unstimulated with RANKL. Knockdown of Ctdnep1 also enhanced calcium-resorbing activity. Mechanistically, the knockdown of Ctdnep1 increased the phosphorylation of RANKL signaling components. These results suggest that Ctdnep1 negatively regulates osteoclast differentiation by suppressing the RANKL signaling pathway.

Reciprocal suppression between TGFβ signaling and TNF stimulation finetunes the macrophage inflammatory response

Inflammation plays a crucial role in the development of various disease conditions or is closely associated with them. Inflammatory cytokines like TNF often engage in interactions with other cytokines and growth factors, including TGFβ, to orchestrate inflammatory process. Basal/endogenous TGFβ signaling is a universal presence, yet the precise way TNF communicates with TGFβ signaling to regulate inflammation and influence inflammatory levels in macrophages has remained elusive. To address this question, this study utilized genetic approaches and a combination of molecular and cellular methods, including conditional TGFβ receptor knockout mice, human cells, RNAseq, ATACseq and Cut & Run-seq. The results reveal that the TGFβ signaling functions as a vital homeostatic pathway, curtailing uncontrolled inflammation in macrophages in response to TNF. Conversely, TNF employs two previously unrecognized mechanisms to suppress the TGFβ signaling. These mechanisms encompass epigenetic inhibition and RBP-J-mediated inhibition of the TGFβ signaling pathway by TNF. These mechanisms empower TNF to diminish the antagonistic influence exerted by the TGFβ signaling pathway, ultimately enhancing TNF's capacity to induce heightened levels of inflammation. This reciprocal suppression dynamic between TNF and the TGFβ signaling pathway holds unique physiopathological significance, as it serves as a crucial "braking" mechanism. The balance between TNF levels and the activity of the endogenous TGFβ signaling pathway plays a pivotal role in determining the overall extent of inflammation. The potential for therapeutically augmenting the TGFβ signaling pathway presents an intriguing avenue for countering the impact of TNF and, consequently, developing innovative strategies for inflammation control.

Mesenchymal Stem Cells-Involved Strategies for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of the joints and bone destruction. Because of systemic administration and poor targeting, traditional anti-rheumatic drugs have unsatisfactory treatment efficacy and strong side effects, including myelosuppression, liver or kidney function damage, and malignant tumors. Consequently, mesenchymal stem cells (MSCs)-involved therapy is proposed for RA therapy as a benefit of their immunosuppressive and tissue-repairing effects. This review summarizes the progress of MSCs-involved RA therapy through suppressing inflammation and promoting tissue regeneration and predicts their potential clinical application.

The bone nonunion microenvironment: A place where osteogenesis struggles with osteoclastic capacity

Bone nonunion is a common and serious orthopedic disorder, the occurrence of which is associated with a disruption of the dynamic balance between osteoblasts and osteoclasts during bone repair. However, the critical molecular mechanisms affecting this homeostasis are not well understood, and it is essential to investigate the specific components of this mechanism and to restore the balance between osteoblasts and osteoclasts to promote bone repair. First, we defined this complex local environmental factor as the "bone nonunion microenvironment" and identified the importance of the "struggle" between osteoblasts and osteoclasts, which is the most essential element in determining the process of repair. On this basis, we also explored the cellular factors that influence osteogenesis and the molecular signals that influence the balance between osteoclast and osteoblasts, which are important for restoring homeostasis. Further, we explored other factors involved in osteogenesis, such as the biomechanical environment, the nutritional environment, the acid-base environment, and the temperature environment, which are important players in osteogenesis. In conclusion, we found that the balance between osteoblasts and osteoclasts is the essence of bone healing, which is based on the "bone nonunion microenvironment". Therefore, investigating the role of the bone nonunion microenvironment in the system of osteoblast-osteoclast "struggle" provides an important basis for further understanding of the mechanism of nonunion and the development of new therapeutic approaches.

Malat1 fine-tunes bone homeostasis by orchestrating cellular crosstalk and the β-catenin-OPG/Jagged1 pathway

The IncRNA Malat1 was initially believed to be dispensable for physiology due to the lack of observable phenotypes in Malat1 knockout (KO) mice. However, our study challenges this conclusion. We found that both Malat1 KO and conditional KO mice in the osteoblast lineage exhibit significant osteoporosis. Mechanistically, Malat1 acts as an intrinsic regulator in osteoblasts to promote osteogenesis. Interestingly, Malat1 does not directly affect osteoclastogenesis but inhibits osteoclastogenesis in a non-autonomous manner in vivo via integrating crosstalk between multiple cell types, including osteoblasts, osteoclasts and chondrocytes. Our findings substantiate the existence of a novel remodeling network in which Malat1 serves as a central regulator by binding to β-catenin and functioning through the β-catenin-OPG/Jagged1 pathway in osteoblasts and chondrocytes. In pathological conditions, Malat1 significantly promotes bone regeneration in fracture healing. Bone homeostasis and regeneration are crucial to well-being. Our discoveries establish a previous unrecognized paradigm model of Malat1 function in the skeletal system, providing novel mechanistic insights into how a lncRNA integrates cellular crosstalk and molecular networks to fine tune tissue homeostasis, remodeling and repair.

Vascular endothelial cells-derived exosomes synergize with curcumin to prevent osteoporosis development

Osteoporosis has gradually become a major public health problem. Further elucidation of the pathophysiological mechanisms that induce osteoporosis and identification of more effective therapeutic targets will have important clinical significance. Experiments in vitro on bone marrow stem cells (BMSCs) subjected to osteogenic and adipogenic differentiation and in vivo on surgical bilateral ovariectomy (OVX) mouse models revealed that exosomes of vascular endothelial cells (EC-EXOs) can promote osteogenic differentiation of BMSCs and inhibit BMSC adipogenic differentiation through miR-3p-975_4191. Both miR-3p-975_4191 and curcumin can target tumor necrosis factor (TNF) and act synergistically to regulate BMSCs fate differentiation and delay the progression of osteoporosis. Our findings suggest that EC-EXOs may exert a synergistic effect with curcumin in reversing the progression of osteoporosis by targeting TNF via miR-3p-975_4191. Our study may provide therapeutic options and potential therapeutic targets for osteoporosis and thus has important clinical implications.

Exercise and osteoimmunology in bone remodeling

Bones can form the scaffolding of the body, support the organism, coordinate somatic movements, and control mineral homeostasis and hematopoiesis. The immune system plays immune supervisory, defensive, and regulatory roles in the organism, which mainly consists of immune organs (spleen, bone marrow, tonsils, lymph nodes, etc.), immune cells (granulocytes, platelets, lymphocytes, etc.), and immune molecules (immune factors, interferons, interleukins, tumor necrosis factors, etc.). Bone and the immune system have long been considered two distinct fields of study, and the bone marrow, as a shared microenvironment between the bone and the immune system, closely links the two. Osteoimmunology organically combines bone and the immune system, elucidates the role of the immune system in bone, and creatively emphasizes its interdisciplinary characteristics and the function of immune cells and factors in maintaining bone homeostasis, providing new perspectives for skeletal-related field research. In recent years, bone immunology has gradually become a hot spot in the study of bone-related diseases. As a new branch of immunology, bone immunology emphasizes that the immune system can directly or indirectly affect bones through the RANKL/RANK/OPG signaling pathway, IL family, TNF-α, TGF-β, and IFN-γ. These effects are of great significance for understanding inflammatory bone loss caused by various autoimmune or infectious diseases. In addition, as an external environment that plays an important role in immunity and bone, this study pays attention to the role of exercise-mediated bone immunity in bone reconstruction.

The abortive SARS-CoV-2 infection of osteoclast precursors promotes their differentiation into osteoclasts

The Coronavirus Disease 2019 (COVID-19) pandemic has resulted in the loss of millions of lives, although a majority of those infected have managed to survive. Consequently, a set of outcomes, identified as long COVID, is now emerging. While the primary target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the respiratory system, the impact of COVID-19 extends to various body parts, including the bone. This study aims to investigate the effects of acute SARS-CoV-2 infection on osteoclastogenesis, utilizing both ancestral and Omicron viral strains. Monocyte-derived macrophages, which serve as precursors to osteoclasts, were exposed to both viral variants. However, the infection proved abortive, even though ACE2 receptor expression increased postinfection, with no significant impact on cellular viability and redox balance. Both SARS-CoV-2 strains heightened osteoclast formation in a dose-dependent manner, as well as CD51/61 expression and bone resorptive ability. Notably, SARS-CoV-2 induced early pro-inflammatory M1 macrophage polarization, shifting toward an M2-like profile. Osteoclastogenesis-related genes (RANK, NFATc1, DC-STAMP, MMP9) were upregulated, and surprisingly, SARS-CoV-2 variants promoted RANKL-independent osteoclast formation. This thorough investigation illuminates the intricate interplay between SARS-CoV-2 and osteoclast precursors, suggesting potential implications for bone homeostasis and opening new avenues for therapeutic exploration in COVID-19.

Fibromodulin facilitates the osteogenic effect of Masquelet's induced membrane by inhibiting the TGF-β/SMAD signaling pathway

Masquelet's induced membrane (IM) technique is a promising treatment strategy for the repair of substantial bone defects. The formation of an IM around polymethylmethacrylate bone cement plays a crucial role in this technique. Several studies have indicated that IMs have bioactivity because they contain abundant blood vessels, a variety of cells, and biological factors. The bioactivity of an IM increases during the initial stages of formation, thereby facilitating bone regeneration and remodeling. Nevertheless, the precise mechanisms underlying the enhancement of IM bioactivity and the promotion of bone regeneration necessitate further investigation. In this study, we successfully developed a Masquelet IM model of critical femur defects in rats. By employing proteomics analysis and biological detection techniques, we identified fibromodulin (FMOD) as a pivotal factor contributing to angiogenesis and the enhanced bioactivity of the IM. A significant increase in angiogenesis and the expression of bioactive factors in the IM was also observed with the upregulation of FMOD expression. Furthermore, this effect is mediated through the inhibition of the transforming growth factor beta (TGF-β)/SMAD signaling pathway. We also demonstrated that administering recombinant human FMOD enhanced osteogenesis in rat bone marrow mesenchymal stem cells and angiogenesis in human umbilical vein endothelial cells in vitro. Furthermore, the negative regulatory effect of the TGF-β signaling pathway was verified. In conclusion, this study provides a novel theoretical basis for the application of IMs in bone-defect reconstruction and explores possible new mechanisms that may play an important role in promoting the bioactivity and osteogenic potential of IMs.

In Vitro Insights into the Role of 7,8-Epoxy-11-Sinulariolide Acetate Isolated from Soft Coral Sinularia siaesensis in the Potential Attenuation of Inflammation and Osteoclastogenesis

The balance between bone-resorbing osteoclasts and bone-forming osteoblasts is essential for the process of bone remodeling. Excessive osteoclast differentiation plays a pivotal role in the pathogenesis of bone diseases such as rheumatoid arthritis and osteoporosis. In the present study, we examined whether 7,8-epoxy-11-sinulariolide acetate (Esa), a marine natural product present in soft coral Sinularia siaesensis, attenuates inflammation and osteoclastogenesis in vitro. The results indicated that Esa significantly inhibited lipopolysaccharide (LPS)-induced inflammation model of RAW264.7 cells and suppressed receptor activator for nuclear factor-κB ligand (RANKL)-triggered osteoclastogenesis. Esa significantly down-regulated the protein expression of iNOS, COX-2, and TNF-α by inhibiting the NF-κB/MAPK/PI3K pathways and reducing the release of reactive oxygen species (ROS) in RAW264.7 macrophages. Besides, Esa treatment significantly inhibited osteoclast differentiation and suppressed the expression of osteoclast-specific markers such as NFATC1, MMP-9, and CTSK proteins. These findings suggest that Esa may be a potential agent for the maintenance of bone homeostasis associated with inflammation.

Epithelial-Mesenchymal Transition in Acute Leukemias

Epithelial-mesenchymal transition (EMT) is a metabolic process that confers phenotypic flexibility to cells and the ability to adapt to new functions. This transition is critical during embryogenesis and is required for the differentiation of many tissues and organs. EMT can also be induced in advanced-stage cancers, leading to further malignant behavior and chemotherapy resistance, resulting in an unfavorable prognosis for patients. Although EMT was long considered and studied only in solid tumors, it has been shown to be involved in the pathogenesis of hematological malignancies, including acute leukemias. Indeed, there is increasing evidence that EMT promotes the progression of acute leukemias, leading to the emergence of a more aggressive phenotype of the disease, and also causes chemotherapy resistance. The current literature suggests that the levels and activities of EMT inducers and markers can be used to predict prognosis, and that targeting EMT in addition to conventional therapies may increase treatment success in acute leukemias.

Systemic and Local Administration of a Dual-siRNA Complex Efficiently Inhibits Tumor Growth and Bone Invasion in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) accounts for nearly 90% of oral and oropharyngeal cancer cases and is characterized by high mortality and poor prognosis. RNA-based gene therapies have been developed as an emerging option for cancer treatment, but it has not been widely explored in OSCC. In this work, we developed an efficient siRNA cationic micelle DOTAP-mPEG-PCL (DMP) by self-assembling the cationic lipid DOTAP and monomethoxy poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) polymer. We tested the characteristics and transformation efficiency of this micelle and combined DMP with siRNA targeting STAT3 and TGF-β to evaluate the antitumor effect and bone invasion interfering in vitro and in vivo. The average size of the DMP was 28.27 ± 1.62 nm with an average zeta potential of 54.60 ± 0.29 mV. The DMP/siRNA complex showed high delivery efficiency, with rates of 97.47 ± 0.42% for HSC-3. In vitro, the DMP/siSTAT3 complex exhibited an obvious cell growth inhibition effect detected by MTT assay (an average cell viability of 25.1%) and clonogenic assay (an average inhibition rate of 51.9%). Besides, the supernatant from HSC-3 transfected by DMP/siTGF-β complexes was found to interfere with osteoclast differentiation in vitro. Irrespective of local or systemic administration, DMP/siSTAT3+siTGF-β showed antitumor effects and bone invasion inhibition in the OSCC mice mandibular invasion model according to tumor volume assays and Micro-CT scanning. The complex constructed by DMP cationic micelles and siSTAT3+siTGF-β represents a potential RNA-based gene therapy delivery system for OSCC.

Network Pharmacology and Experimental Validation Explore the Pharmacological Mechanisms of Herb Pair for Treating Rheumatoid Arthritis

OBJECTIVE

This study aimed to elucidate the multitarget mechanism of the Mori Ramulus - Taxilli Herba (MT) herb pair in treating rheumatoid arthritis (RA).

METHODS

The targets of the herb pair and RA were predicted from databases and screened through cross-analysis. The core targets were obtained using protein-protein interaction (PPI) network analysis. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed. Finally, animal experiments were conducted to validate the anti-RA effect and mechanism of this herb pair.

RESULTS

This approach successfully identified 9 active compounds of MT that interacted with 6 core targets (AKT1, TNF, IL6, TP53, VEGFA, and IL1β). Pathway and functional enrichment analyses revealed that MT had significant effects on the TNF and IL-17 signaling pathways. The consistency of interactions between active components and targets in these pathways was confirmed through molecular docking. Moreover, the potential therapeutic effect of MT was verified in vivo, demonstrating its ability to effectively relieve inflammation by regulating these targeted genes and pathways.

CONCLUSION

The present work suggests that the therapeutic effect of MT herb pair on RA may be attributed to its ability to regulate the TNF signaling pathway and IL-17 signaling pathway.

Zuogui pill disrupt the malignant cycle in breast cancer bone metastasis through the Piezo1-Notch-1-GPX4 pathway and active molecules fishing

BACKGROUND

Breast cancer bone metastasis is closely associated with the bone microenvironment. Zuogui Pill (ZGP), a clinically approved formulation in China, effectively regulates the bone microenvironment for the prevention and treatment of osteoporosis.

PURPOSE

Few reports have utilized the ZGP for bone metastasis models. This study investigated the intervention and bone-protective properties of ZGP against breast cancer bone metastasis, explored the potential mechanism, and screened for its active compositions by molecules fishing.

METHODS

To investigate the intervention efficacy of ZGP and its protein-level mechanism of action, the mouse bone metastasis model and in vitro cell co-culture model were constructed. Affinity ultrafiltration, molecular docking, cellular thermal shift assay and physical scale detection were used to investigate the affinity components of the RANKL protein in ZGP.

RESULTS

The administration of ZGP combined with zoledronic acid inhibited the development of tumors and secondary lung metastasis in mice. This translated to a prolonged survival period and enhanced quality of life. ZGP could disrupt the malignant cycle by modulating the Piezo1-Notch-1-GPX4 signaling pathway in the "bone-cancer" communication in the cell co-culture model. Furthermore, 25 chemical components of ZGP were identified, with 10 active compounds exhibiting significant affinity for the RANKL protein.

CONCLUSION

The findings of this work highlighted ZGP's potential for intervening in the progression of breast cancer bone metastasis. Thus, this investigation served as an experimental foundation for expanding the application scope of ZGP and for advancing drug development efforts in bone metastasis treatment.

A case of concentrated growth factor gel to fill the defect after large jaw cyst enucleation

Management of large jaw cyst is challenging since high risks including pathologic fracture, limited opening, and insufficient bone healing occur after enucleation. The current case of concentrated growth factor (CGF) gel to fill defect after enucleation of large jaw cyst is rare. A 12-year-old boy with pain and swelling for 4 months in the left mandible region made a medical consultation at our hospital. Computerized tomography scan indicated that cystic lesion was found in the left mandible region. In this case, we present a patient with large jaw cyst (31 mm × 44 mm × 53 mm) who received enucleation followed by CGF gel filling the defect. The patient was discharged after 13 days without discomfort symptoms. The lesion size was reduced significantly at 1-month re-examination. No abnormality was detected in maxillofacial region at 1-year re-examination. Application of CGF gel is one of the possible options for filling defect after jaw cyst enucleation.

Inflammatory Processes Affecting Bone Health and Repair

PURPOSE OF REVIEW

The purpose of this article is to review the current understanding of inflammatory processes on bone, including direct impacts of inflammatory factors on bone cells, the effect of senescence on inflamed bone, and the critical role of inflammation in bone pain and healing.

RECENT FINDINGS

Advances in osteoimmunology have provided new perspectives on inflammatory bone loss in recent years. Characterization of so-called inflammatory osteoclasts has revealed insights into physiological and pathological bone loss. The identification of inflammation-associated senescent markers in bone cells indicates that therapies that reduce senescent cell burden may reverse bone loss caused by inflammatory processes. Finally, novel studies have refined the role of inflammation in bone healing, including cross talk between nerves and bone cells. Except for the initial stages of fracture healing, inflammation has predominately negative effects on bone and increases fracture risk. Eliminating senescent cells, priming the osteo-immune axis in bone cells, and alleviating pro-inflammatory cytokine burden may ameliorate the negative effects of inflammation on bone.

Jagged1 Acts as an RBP-J Target and Feedback Suppresses TNF-Mediated Inflammatory Osteoclastogenesis

TNF plays a crucial role in inflammation and bone resorption in various inflammatory diseases, including rheumatoid arthritis (RA). However, its direct ability to drive macrophages to differentiate into osteoclasts is limited. Although RBP-J is recognized as a key inhibitor of TNF-mediated osteoclastogenesis, the precise mechanisms that restrain TNF-induced differentiation of macrophages into osteoclasts are not fully elucidated. In this study, we identified that the Notch ligand Jagged1 is a previously unrecognized RBP-J target. The expression of Jagged1 is significantly induced by TNF mainly through RBP-J. The TNF-induced Jagged1 in turn functions as a feedback inhibitory regulator of TNF-mediated osteoclastogenesis. This feedback inhibition of osteoclastogenesis by Jagged1 does not exist in RANKL-induced mouse osteoclast differentiation, as RANKL does not induce Jagged1 expression. The Jagged1 level in peripheral blood monocytes/osteoclast precursors is decreased in RA compared with the nonerosive inflammatory disease systemic lupus erythematosus, suggesting a mechanism that contributes to increased osteoclast formation in RA. Moreover, recombinant Jagged1 suppresses human inflammatory osteoclastogenesis. Our findings identify Jagged1 as an RBP-J direct target that links TNF and Notch signaling pathways and restrains TNF-mediated osteoclastogenesis. Given that Jagged1 has no effect on TNF-induced expression of inflammatory genes, its use may present a new complementary therapeutic approach to mitigate inflammatory bone loss with little impact on the immune response in disease conditions.

Preosteoclast plays a pathogenic role in syndesmophyte formation of ankylosing spondylitis through the secreted PDGFB - GRB2/ERK/RUNX2 pathway

OBJECTIVES

Ankylosing spondylitis (AS) is a chronic inflammatory disease that mainly affects the sacroiliac joint and spine. However, the real mechanisms of immune cells acting on syndesmophyte formation in AS are not well identified. We aimed to find the key AS-associated cytokine and assess its pathogenic role in AS.

METHODS

A protein array with 1000 cytokines was performed in five AS patients with the first diagnosis and five age- and gender-matched healthy controls to discover the differentially expressed cytokines. The candidate differentially expressed cytokines were further quantified by multiplex protein quantitation (3 AS-associated cytokines and 3 PDGF-pathway cytokines) and ELISA (PDGFB) in independent samples (a total of 140 AS patients vs 140 healthy controls). The effects of PDGFB, the candidate cytokine, were examined by using adipose-derived stem cells (ADSCs) and human fetal osteoblast cell line (hFOB1.19) as in vitro mesenchymal cell and preosteoblast models, respectively. Furthermore, whole-transcriptome sequencing and enrichment of phosphorylated peptides were performed by using cell models to explore the underlying mechanisms of PDGFB. The xCELLigence system was applied to examine the proliferation, chemotaxis, and migration abilities of PDGFB-stimulated or PDGFB-unstimulated cells.

RESULTS

The PDGF pathway was observed to have abnormal expression in the protein array, and PDGFB expression was further found to be up-regulated in 140 Chinese AS patients. Importantly, PDGFB expression was significantly correlated with BASFI (Pearson coefficient/p value = 0.62/6.70E - 8) and with the variance of the mSASSS score (mSASSS 2 years - baseline, Pearson coefficient/p value = 0.76/8.75E - 10). In AS patients, preosteoclasts secreted more PDGFB than the healthy controls (p value = 1.16E - 2), which could promote ADSCs osteogenesis and enhance collagen synthesis (COLI and COLIII) of osteoblasts (hFOB 1.19). In addition, PDGFB promoted the proliferation, chemotaxis, and migration of ADSCs. Mechanismly, in ADSCs, PDGFB stimulated ERK phosphorylation by upregulating GRB2 expression and then increased the expression of RUNX2 to promote osteoblastogenesis of ADSCs.

CONCLUSION

PDGFB stimulates the GRB2/ERK/RUNX2 pathway in ADSCs, promotes osteoblastogenesis of ADSCs, and enhances the extracellular matrix of osteoblasts, which may contribute to pathological bone formation in AS.

Innate immune memory in inflammatory arthritis

The concept of immunological memory was demonstrated in antiquity when protection against re-exposure to pathogens was observed during the plague of Athens. Immunological memory has been linked with the adaptive features of T and B cells; however, in the past decade, evidence has demonstrated that innate immune cells can exhibit memory, a phenomenon called 'innate immune memory' or 'trained immunity'. Innate immune memory is currently being defined and is transforming our understanding of chronic inflammation and autoimmunity. In this Review, we provide an up-to-date overview of the memory-like features of innate immune cells in inflammatory arthritis and the crosstalk between chronic inflammatory milieu and cell reprogramming. Aberrant pro-inflammatory signalling, including cytokines, regulates the metabolic and epigenetic reprogramming of haematopoietic progenitors, leading to exacerbated inflammatory responses and osteoclast differentiation, in turn leading to bone destruction. Moreover, imprinted memory on mature cells including terminally differentiated osteoclasts alters responsiveness to therapies and modifies disease outcomes, commonly manifested by persistent inflammatory flares and relapse following medication withdrawal.

Protective effects of curcumin against osteoporosis and its molecular mechanisms: a recent review in preclinical trials

Osteoporosis (OP) is one of the most common metabolic skeletal disorders and is commonly seen in the elderly population and postmenopausal women. It is mainly associated with progressive loss of bone mineral density, persistent deterioration of bone microarchitecture, and increased fracture risk. To date, drug therapy is the primary method used to prevent and treat osteoporosis. However, long-term drug therapy inevitably leads to drug resistance and specific side effects. Therefore, researchers are constantly searching for new monomer compounds from natural plants. As a candidate for the treatment of osteoporosis, curcumin (CUR) is a natural phenolic compound with various pharmacological and biological activities, including antioxidant, anti-apoptotic, and anti-inflammatory. This compound has gained research attention for maintaining bone health in various osteoporosis models. We reviewed preclinical and clinical studies of curcumin in preventing and alleviating osteoporosis. These results suggest that if subjected to rigorous pharmacological and clinical trials, naturally-derived curcumin could be used as a complementary and alternative medicine for the treatment of osteoporosis by targeting osteoporosis-related mechanistic pathways. This review summarizes the mechanisms of action and potential therapeutic applications of curcumin in the prevention and mitigation of osteoporosis and provides reference for further research and development of curcumin.

Possible correlated signaling pathways with chronic urate nephropathy: A review

Hyperuricemia nephropathy, also known as gouty nephropathy, refers to renal damage induced by hyperuricemia caused by excessive production of serum uric acid or low excretion of uric acid. the persistence of symptoms will lead to changes in renal tubular phenotype and accelerate the progress of renal fibrosis. The existence and progressive aggravation of symptoms will bring a heavy burden to patients, their families and society, affect their quality of life and reduce their well-being. With the increase of reports on hyperuricemia nephropathy, the importance of related signal pathways in the pathogenesis of hyperuricemia nephropathy is becoming more and more obvious, but most studies are limited to the upper and lower mediating relationship between 1 or 2 signal pathways. The research on the comprehensiveness of signal pathways and the breadth of crosstalk between signal pathways is limited. By synthesizing the research results of signal pathways related to hyperuricemia nephropathy in recent years, this paper will explore the specific mechanism of hyperuricemia nephropathy, and provide new ideas and methods for the treatment of hyperuricemia nephropathy based on a variety of signal pathway crosstalk and personal prospects.

SPARC: a potential target for functional nanomaterials and drugs

Secreted protein acidic and rich in cysteine (SPARC), also termed osteonectin or BM-40, is a matricellular protein which regulates cell adhesion, extracellular matrix production, growth factor activity, and cell cycle. Although SPARC does not perform a structural function, it, however, modulates interactions between cells and the surrounding extracellular matrix due to its anti-proliferative and anti-adhesion properties. The overexpression of SPARC at sites, including injury, regeneration, obesity, cancer, and inflammation, reveals its application as a prospective target and therapeutic indicator in the treatment and assessment of disease. This article comprehensively summarizes the mechanism of SPARC overexpression in inflammation and tumors as well as the latest research progress of functional nanomaterials in the therapy of rheumatoid arthritis and tumors by manipulating SPARC as a new target. This article provides ideas for using functional nanomaterials to treat inflammatory diseases through the SPARC target. The purpose of this article is to provide a reference for ongoing disease research based on SPARC-targeted therapy.

New insights into inflammatory osteoclast precursors as therapeutic targets for rheumatoid arthritis and periodontitis

Rheumatoid arthritis (RA) and periodontitis are chronic inflammatory diseases leading to increased bone resorption. Preventing this inflammatory bone resorption is a major health challenge. Both diseases share immunopathogenic similarities and a common inflammatory environment. The autoimmune response or periodontal infection stimulates certain immune actors, leading in both cases to chronic inflammation that perpetuates bone resorption. Moreover, RA and periodontitis have a strong epidemiological association that could be explained by periodontal microbial dysbiosis. This dysbiosis is believed to be involved in the initiation of RA via three mechanisms. (i) The dissemination of periodontal pathogens triggers systemic inflammation. (ii) Periodontal pathogens can induce the generation of citrullinated neoepitopes, leading to the generation of anti-citrullinated peptide autoantibodies. (iii) Intracellular danger-associated molecular patterns accelerate local and systemic inflammation. Therefore, periodontal dysbiosis could promote or sustain bone resorption in distant inflamed joints. Interestingly, in inflammatory conditions, the existence of osteoclasts distinct from "classical osteoclasts" has recently been reported. They have proinflammatory origins and functions. Several populations of osteoclast precursors have been described in RA, such as classical monocytes, a dendritic cell subtype, and arthritis-associated osteoclastogenic macrophages. The aim of this review is to synthesize knowledge on osteoclasts and their precursors in inflammatory conditions, especially in RA and periodontitis. Special attention will be given to recent data related to RA that could be of potential value in periodontitis due to the immunopathogenic similarities between the two diseases. Improving our understanding of these pathogenic mechanisms should lead to the identification of new therapeutic targets involved in the pathological inflammatory bone resorption associated with these diseases.

Cytokine-mediated immunomodulation of osteoclastogenesis

Cytokines are an important set of proteins regulating bone homeostasis. In inflammation induced bone resorption, cytokines, such as RANKL, TNF-α, M-CSF, are indispensable for the differentiation and activation of resorption-driving osteoclasts, the process we know as osteoclastogenesis. On the other hand, immune system produces a number of regulatory cytokines, including IL-4, IL-10 and IFNs, and limits excessive activation of osteoclastogenesis and bone loss during inflammation. These unique properties make cytokines powerful targets as rheostat to maintain bone homeostasis and for potential immunotherapies of inflammatory bone diseases. In this review, we summarize recent advances in cytokine-mediated regulation of osteoclastogenesis and provide insights of potential translational impact of bench-side research into clinical treatment of bone disease.

IRF8: Mechanism of Action and Health Implications

Interferon regulatory factor 8 (IRF8) is a transcription factor of the IRF protein family. IRF8 was originally identified as an essentialfactor for myeloid cell lineage commitment and differentiation. Deletion of Irf8 leads to massive accumulation of CD11b⁺Gr1⁺ immature myeloid cells (IMCs), particularly the CD11b⁺Ly6C^hi/+Ly6G⁻ polymorphonuclear myeloid-derived suppressor cell-like cells (PMN-MDSCs). Under pathological conditions such as cancer, Irf8 is silenced by its promoter DNA hypermethylation, resulting in accumulation of PMN-MDSCs and CD11b⁺ Ly6G⁺Ly6C^lo monocytic MDSCs (M-MDSCs) in mice. IRF8 is often silenced in MDSCs in human cancer patients. MDSCs are heterogeneous populations of immune suppressive cells that suppress T and NK cell activity to promote tumor immune evasion and produce growth factors to exert direct tumor-promoting activity. Emerging experimental data reveals that IRF8 is also expressed in non-hematopoietic cells. Epithelial cell-expressed IRF8 regulates apoptosis and represses Osteopontin (OPN). Human tumor cells may use the IRF8 promoter DNA methylation as a mechanism to repress IRF8 expression to advance cancer through acquiring apoptosis resistance and OPN up-regulation. Elevated OPN engages CD44 to suppress T cell activation and promote tumor cell stemness to advance cancer. IRF8 thus is a transcription factor that regulates both the immune and non-immune components in human health and diseases.