Macrophage-Osteoclast Associations: Origin, Polarization, and Subgroups

Single-cell RNA sequencing reveals B cell dynamics and osteoclast activation in Talaromycosis-related bone destruction

OBJECTIVE

To explore the changes in bone destruction caused by Talaromycosis and its potential mechanisms.

METHODS

We assessed bone destruction and its severity using Micro CT, hematoxylin and eosin staining, tartrate-resistant acid phosphatase staining, F-actin staining, and Western blotting. We evaluated the biomechanical properties and pain perception in mice through biomechanical testing and the von Frey test. Single-cell RNA sequencing was used to analyze B cell composition in mouse tibial bone marrow, with findings verified by flow cytometry and qRT-PCR. Inflammatory cytokine levels, reactive oxygen species (ROS), and mitochondrial membrane potential were measured via enzyme-linked immunosorbent assay, immunofluorescence, and flow cytometry. Key proteins in the MAPK signaling pathway were also evaluated using Western blot.

RESULTS

Talaromyces marneffei (TM) infection led to increased osteoclast activity and significant bone destruction, accompanied by a reduction in weight gain, increased pain, and diminished bone biomechanical properties in mice. Post-infection, an increase in the number of B cells, particularly Naïve-B, ProB, and mature B cells, was observed, potentially linked to oxidative phosphorylation processes. TM infection elevated inflammatory cytokines production, ROS production and decreased mitochondrial membrane potential in vivo and in vitro. Furthermore, TM infection enhanced osteoclast differentiation through the activation of MAPK signaling pathways, including p38, ERK, and JNK.

CONCLUSION

TM infection induces B cell maturation and promotes bone destruction in the tibia of mice. This effect may be associated with mitochondrial apoptosis and ROS production during oxidative phosphorylation, potentially through MAPK pathway activation.

M2 macrophage-derived exosome facilitates aerobic glycolysis and osteogenic differentiation of hPDLSCs by regulating TRIM26-induced PKM ubiquitination

BACKGROUND

Our previous findings revealed that exosomes derived from M2-polarized macrophages enhance the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs), and identified key microRNAs (miRNAs) using high-throughput miRNA sequencing. Therefore, the present study aimed to elucidate the role and underlying molecular mechanism by which exosomes derived from M2 macrophages mediate the osteogenic differentiation of hPDLSCs.

METHODS

Following lentiviral-mediated modulation of miR-6879-5p in both hPDLSCs and M2 macrophage-derived exosomes, RT-qPCR, western blotting, and Alizarin Red staining were applied to assess alterations in osteogenic markers, including ALP, OCN, Collagen I, and RUNX2, as well as mineralized nodule formation in hPDLSCs. Immunoprecipitation-mass spectrometry (IP-MS) was employed to identify proteins interacting with miR-6879-5p target genes in hPDLSCs.

RESULTS

Knockdown of miR-6879-5p in the exosomes reduced the expression of osteogenic markers and inhibited calcified nodule formation in hPDLSCs. Overexpression of TRIM26 attenuated the osteogenic differentiation of hPDLSCs, an effect that was reversed by miR-6879-5p overexpression. IP-MS identified 410 TRIM26-interacting proteins in hPDLSCs. These proteins were associated with ubiquitination, aerobic glycolysis, and amino acid metabolism. The hub proteins in the TRIM26-associated PPI network included RPL and RPS family proteins, as well as glycolysis-associated proteins. CO-IP confirmed an interaction between TRIM26 and PKM, and showed that TRIM26 increased PKM ubiquitination. Overexpression of PKM rescued TRIM26-mediated suppression of osteogenic marker expression and mineralized nodule formation in hPDLSCs.

CONCLUSION

miR-6879-5p carried by M2 macrophage-derived exosomes promotes osteogenic differentiation and aerobic glycolysis in hPDLSCs via modulating TRIM26-mediated ubiquitination of PKM.

Progress of ursolic acid on the regulation of macrophage: summary and prospect

Ursolic acid (UA), a prevalent pentacyclic triterpenoid found in numerous fruits and herbs, has garnered significant attention for its vital role in anti-inflammatory processes and immune regulation. The study of immune cells has consistently been a focal point, particularly regarding macrophages, which play crucial roles in antigen presentation, immunomodulation, the inflammatory response, and pathogen phagocytosis. This paper reveals the underlying regulatory effects of UA on the function of macrophages and the specific therapeutic effects of UA on a variety of diseases. Owing to the superior effect of UA on macrophages, different types of macrophages in different tissues have been described. Through the multifaceted regulation of macrophage function, UA may provide new ideas for the development of novel anti-inflammatory and immunomodulatory drugs. However, to facilitate its translation into actual medical means, the specific mechanism of UA in macrophages and its clinical application still need to be further studied.

The alterations of molecular repertoire of the RANKL-induced osteoclastogenesis in the M1 macrophage-derived inflammatory milieu

Inflammation have been linked to bone diseases such as osteoporosis or bone destruction. However, whether M1 inflammatory stimuli exert a stimulatory or inhibitory effect on the differentiation of osteoclasts remained controversial. Also, how inflammatory milieu influence cell proliferation and survival during osteoclastogenesis have not been determined. Here we reported the molecular repertoire alterations of RANKL-stimulated osteoclastogenesis from RAW264.7 at different stages in the inflammatory environments. Adding conditioned medium collected from LPS-stimulated macrophage, which are the primary source of extracellular inflammatory mediators, resulted in a biphasic change in cell number among differentiating preosteoclasts. The inflammatory milieu induced a transient proliferation of preosteoclasts during the initial 48 h, which was followed by a significant decline in cell numbers from the fourth day onwards. Proliferation-related AKT and ERK were transiently activated in the inflammatory environments, which also upregulated the expressions of c-myc, a major transcription factor for osteoclast differentiation, and pro-inflammatory genes, such as Tnf-a and Nos2. Following prolonged exposure to an inflammatory environment, undifferentiated osteoclast precursors undergo apoptosis. Our findings suggest that short-term inflammatory exposure transiently promotes the proliferation and differentiation of preosteoclasts, whereas long-term exposure leads to apoptosis, potentially due to the enhancement of inflammatory signals.

Genetic markers associated with bone strength and density in Rhode Island Red laying hens

Damage to the keel bone in commercial laying hens represent one of the greatest welfare issues in laying hens. This study aims to identify the DNA markers and candidate genes for bone strength and density traits in a Rhode Island Red laying hen population. We conducted genome-wide association studies (GWAS) on bone quality traits using a sample of 925 Rhode Island Red laying hens genotyped with a genotyping array consisting of 60 000 DNA markers. With a univariate linear mixed model, we identified 52 suggestive genetic markers located within 28 candidate genes that are associated with the humerus, keel, and tibia strength and density. We also found overlaps between the GWAS results for medullary bone score and tibia strength and density with published quantitative trait loci (QTL) for eggshell effective layer thickness and abdominal fat weight, respectively. Heritability estimates for the humerus stiffness, tibia stiffness, medullary bone score and minor bone diameter ranged from 0.21 to 0.34. Annotation term enrichment analysis of genes within 2 Megabases of suggestive markers found that mTOR signalling pathway, tryptophan metabolism, TGF-β signalling pathway, and apoptosis were significantly enriched. These loci do not overlap previously published associations, and thus appear to be novel.

A sinomenine derivative alleviates bone destruction in collagen-induced arthritis mice by suppressing mitochondrial dysfunction and oxidative stress via the NRF2/HO-1/NQO1 signaling pathway

Bone destruction in rheumatoid arthritis (RA) leads to significant disability, yet effective treatments are limited. Sinomenine (Sino) demonstrates anti-arthritic and bone-protective effects but requires high doses. In this study, we developed a Sino derivative, SINX, and evaluated its efficacy in RA. Safety assessments in mice confirmed its suitability for further study. In vitro, SINX inhibited osteoclast differentiation by reducing TRAP-positive cells, disrupting F-actin ring formation, and suppressing bone resorption pits, alongside downregulating osteoclast-specific genes. It also showed strong anti-inflammatory properties by reducing inflammatory cytokine levels. In vivo, using a collagen-induced arthritis (CIA) mouse model, SINX improved bone integrity by reducing joint inflammation, maintaining trabecular bone density, and preventing erosion. Histological and micro-CT analyses confirmed its effects, including suppressed osteoclast activity and reduced bone resorption-related gene expression. Mechanistically, SINX ameliorated mitochondrial dysfunction, decreased ROS levels, and activated the NRF2/HO-1/NQO1 pathway, enhancing antioxidant defenses. Compared to Sino, SINX achieved similar results at lower doses. These findings highlight the potential of SINX as a safe, effective treatment for RA-related bone destruction.

Molecular mechanisms and treatment strategies for estrogen deficiency-related and glucocorticoid-induced osteoporosis: a comprehensive review

Osteoporosis, a debilitating condition characterized by reduced bone mass and increased fracture risk, is notably influenced by estrogen deficiency and glucocorticoid treatment. This comprehensive review elucidates the molecular mechanisms underpinning estrogen deficiency-related osteoporosis (EDOP) and glucocorticoid-induced osteoporosis (GIOP). The role of estrogen in bone metabolism is critically examined, highlighting its regulatory effects on bone turnover and formation through various signaling pathways. Conversely, this review explores how glucocorticoids disrupt bone homeostasis, focusing on their impact on osteoclast and osteoblast function and the subsequent alteration of bone remodeling processes. The pathogenesis of both conditions is intertwined, with estrogen receptor signaling pathways and the role of inflammatory cytokines being pivotal in driving bone loss. A detailed analysis of pathogenetic and risk factors associated with EDOP and GIOP is presented, including lifestyle and genetic factors contributing to disease progression. Modern therapeutic approaches emphasize pharmacologic, non-pharmacologic, and herbal treatments for managing EDOP and GIOP. In summary, current therapeutic strategies highlight the efficacy and the safety of various interventions. This review concludes with future directions for research, suggesting a need for novel treatment modalities and a deeper understanding of the underlying mechanisms of osteoporosis. By addressing the multifaceted nature of EDOP and GIOP, this work aims to provide insights into developing targeted therapeutic strategies and improving patient outcomes in osteoporosis management.

Resveratrol-Loaded Solid Lipid Nanoparticles Reinforced Hyaluronic Hydrogel: Multitarget Strategy for the Treatment of Diabetes-Related Periodontitis

Background/Objectives: Periodontitis and diabetes mellitus share a well-established bidirectional relationship, where hyperglycemia exacerbates periodontal inflammation, and periodontal disease further impairs glycemic control. Within the diabetic periodontal microenvironment, an imbalance between pro-inflammatory (M1) and anti-inflammatory (M2) macrophages promotes chronic inflammation, oxidative stress, delayed healing, and alveolar bone resorption. Resveratrol (RSV), a polyphenol with antioxidant, anti-inflammatory, and pro-osteogenic properties, holds potential to restore macrophage balance. However, its clinical application is limited by poor bioavailability and instability. This study aimed to develop and evaluate a novel RSV delivery system to overcome these limitations and promote periodontal tissue regeneration under diabetic conditions. Methods: A drug delivery system comprising RSV-loaded solid lipid nanoparticles embedded within a cross-linked hyaluronic acid hydrogel (RSV@CLgel) was formulated. The system was tested under hyperglycemic and inflammatory conditions for its effects on macrophage polarization, cytokine expression, oxidative stress, mitochondrial function, and osteoblast differentiation. Results: RSV@CLgel effectively suppressed pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) while upregulating anti-inflammatory markers (IL-10, TGF-β). It significantly reduced oxidative stress by decreasing ROS and lipid peroxidation levels and improved mitochondrial function and antioxidant enzyme activity. Furthermore, RSV@CLgel enhanced osteoblast differentiation, as evidenced by increased ALP activity, calcium nodule formation, and upregulation of osteogenic genes (COL-I, RUNX2, OCN, OPN). It also inhibited RANKL-induced osteoclastogenesis, contributing to alveolar bone preservation. Conclusions: The RSV@CLgel delivery system presents a promising multifunctional strategy for the management of diabetic periodontitis. By modulating immune responses, reducing oxidative stress, and promoting periodontal tissue regeneration, RSV@CLgel addresses key pathological aspects of diabetes-associated periodontal disease.

Cell communication and relevant signaling pathways in osteogenesis-angiogenesis coupling

Osteogenesis is the process of bone formation mediated by the osteoblasts, participating in various bone-related physiological processes including bone development, bone homeostasis and fracture healing. It exhibits temporal and spatial interconnectivity with angiogenesis, constructed by multiple forms of cell communication occurring between bone and vascular endothelial cells. Molecular regulation among different cell types is crucial for coordinating osteogenesis and angiogenesis to facilitate bone remodeling, fracture healing, and other bone-related processes. The transmission of signaling molecules and the activation of their corresponding signal pathways are indispensable for various forms of cell communication. This communication acts as a "bridge" in coupling osteogenesis to angiogenesis. This article reviews the modes and processes of cell communication in osteogenesis-angiogenesis coupling over the past decade, mainly focusing on interactions among bone-related cells and vascular endothelial cells to provide insights into the mechanism of cell communication of osteogenesis-angiogenesis coupling in different bone-related contexts. Moreover, clinical relevance and applications are also introduced in this review.

The Nexus Between Traditional Chinese Medicine and Immunoporosis: Implications in the Treatment and Management of Osteoporosis

Osteoporosis (OP) is a globally prevalent bone disease characterized by reduced bone mass and heightened fracture risk, posing a significant health and economic challenge to aging societies worldwide. Osteoimmunology-an emerging field of study-investigates the intricate relationship between the skeletal and the immune systems, providing insights into the immune system's impact on bone health and disease progression. Recent research has demonstrated the essential roles played by various immune cells (T cells, B cells, macrophages, dendritic cells, mast cells, granulocytes, and innate lymphoid cells) in regulating bone metabolism, homeostasis, formation, and remodeling through interactions with osteoclasts (OC) and osteoblasts (OB). These findings underscore that osteoimmunology provides an essential theoretical framework for understanding the pathogenesis of various skeletal disorders, including OP. Traditional Chinese medicine (TCM) and its active ingredients have significant clinical value in OP treatment. Unfortunately, despite their striking multieffect pathways in the pharmacological field, current research has not yet summarized them in a comprehensive and detailed manner with respect to their interventional roles in immune bone diseases, especially OP. Consequently, this review addresses recent studies on the mechanisms by which immune cells and their communication molecules contribute to OP development. Additionally, it explores the potential therapeutic benefits of TCM and its active components in treating OP from the perspective of osteoimmunology. The objective is to provide a comprehensive framework that enhances the understanding of the therapeutic mechanisms of TCM in treating immune-related bone diseases and to facilitate the development of novel therapeutic strategies.

Exosomes secreted from M2-polarized macrophages inhibit osteoclast differentiation via CYLD

OBJECTIVE

Bone resorption mediated by osteoclast differentiation induces the occurrence of bone-related diseases. Macrophages, an origin of osteoclasts, whose M2 type can reduce inflammation-induced bone damage. We aimed to investigate the effect of M2 macrophage-derived exosomes on osteoclast formation and elucidate its underlying mechanism.

MATERIALS AND METHODS

Exosomes were isolated from M2 macrophages (M2-exo) and were used to treat osteoclast-like cells. Osteoclast formation was evaluated using tartrate-resistant acid phosphatase, quantitative real-time polymerase chain reaction (qRT-PCR), and Western blotting. The molecular mechanism of M2-exo function was analyzed by qRT-PCR, phosphor-kinase array analysis, and Western blotting.

RESULTS

M2-exo was internalized by osteoclasts and inhibited osteoclast differentiation in vitro. Moreover, CYLD was highly expressed in M2 macrophages and M2-exo-treated osteoclasts, and knockdown of it abrogated the inhibition of osteoclast differentiation caused by M2-exo. Additionally, CYLD suppressed the phosphorylation of STAT3, and STAT3 activator colivelin reversed the inhibition of osteoclast differentiation induced by CYLD overexpression.

CONCLUSION

M2-exo inhibits osteoclast differentiation via delivering CYLD, which inactivates STAT3 signaling. These findings may provide a novel therapeutic option for bone diseases including periodontitis.

Tm4sf19 inhibition ameliorates inflammation and bone destruction in collagen-induced arthritis by suppressing TLR4-mediated inflammatory signaling and abnormal osteoclast activation

Rheumatoid arthritis (RA) is an autoimmune disease characterized by inflammation and abnormal osteoclast activation, leading to bone destruction. We previously demonstrated that the large extracellular loop (LEL) of Tm4sf19 is important for its function in osteoclast differentiation, and LEL-Fc, a competitive inhibitor of Tm4sf19, effectively suppresses osteoclast multinucleation and prevent bone loss associated with osteoporosis. This study aimed to investigate the role of Tm4sf19 in RA, an inflammatory and abnormal osteoclast disease, using a mouse model of collagen-induced arthritis (CIA). Tm4sf19 expression was observed in macrophages and osteoclasts within the inflamed synovium, and Tm4sf19 expression was increased together with inflammatory genes in the joint bones of CIA-induced mice compared with the sham control group. Inhibition of Tm4sf19 by LEL-Fc demonstrated both preventive and therapeutic effects in a CIA mouse model, reducing the CIA score, swelling, inflammation, cartilage damage, and bone damage. Knockout of Tm4sf19 gene or inhibition of Tm4sf19 activity by LEL-Fc suppressed LPS/IFN-γ-induced TLR4-mediated inflammatory signaling in macrophages. LEL-Fc disrupted not only the interaction between Tm4sf19 and TLR4/MD2, but also the interaction between TLR4 and MD2. μCT analysis showed that LEL-Fc treatment significantly reduced joint bone destruction and bone loss caused by hyperactivated osteoclasts in CIA mice. Taken together, these findings suggest that LEL-Fc may be a potential treatment for RA and RA-induced osteoporosis by simultaneously targeting joint inflammation and bone destruction caused by abnormal osteoclast activation.

Omentin-1 modulates interleukin expression and macrophage polarization: Implications for rheumatoid arthritis therapy

BACKGROUND

Rheumatoid arthritis (RA) is a systemic inflammatory and autoimmune disorder in which monocytes/macrophage infiltrate synovial membrane, differentiating into the pro- and anti-inflammatory M1 and M2 macrophage phenotypes. Omentin-1 is one of the adipokines that has anti-inflammatory and immunomodulatory effects; nevertheless, investigators have yet to elucidate the function of omentin-1 in RA development. It is still unclear how omentin-1 affects human autoimmune disease and what its beneficial role is. Thus, we show that omentin-1 exhibits a therapeutic effect on RA.

METHODS

Utilizing patient or animal tissue, MH7A cell-line, ELISA, and qPCR, we examined the expression of omentin-1 and inflammatory cytokines in the GEO databases. Omentin-1's effects on macrophage polarization were investigated using Immunofluorescence staining (IF) and qPCR. Additionally, the method by which omentin-1 regulates interleukins was discovered by IF labeling for STAT6 translocation, siRNA transfection, IPA software using several and pharmacological inhibitors. Omentin-1's effects were examined in an in vivo investigation using the type II collagen-induced arthritis model, micro-CT, and histological evaluation.

RESULTS

Results from the GSE97779 dataset and patients' tissues discovered that the level of omentin-1 and M2 macrophage markers are downregulated in human RA tissue samples compared to healthy tissue and negatively correlated with the expression of pro-inflammatory interleukins (ILs) and M1 macrophage. Stimulation of RA synovial fibroblasts with omentin-1 augmented IL-4 synthesis and subsequently enhanced anti-inflammatory ability as well as M2 polarization. The STAT6 transactivation through AMPK, PI3K, ERK, and JAK cascades regulates omentin-1-induced promotion of IL-4. Importantly, intra-articular injection of omentin-1 blocked collagen-induced arthritis-augmented pro-inflammatory response, cartilage degradation, and bone loss through upregulating IL-4 and M2 macrophages in vivo.

CONCLUSION

Our findings support a potential therapy goal for RA and a tenable mechanism to explain the relationship between omentin-1.

The Genetic and Biological Basis of Pseudoarthrosis in Fractures: Current Understanding and Future Directions

Pseudoarthrosis-the failure of normal fracture healing-remains a significant orthopedic challenge affecting approximately 10-15% of long bone fractures, and is associated with significant pain, prolonged disability, and repeated surgical interventions. Despite extensive research into the pathophysiological mechanisms of bone healing, diagnostic approaches remain reliant on clinical findings and radiographic evaluations, with little innovation in tools to predict or diagnose non-union. The present review evaluates the current understanding of the genetic and biological basis of pseudoarthrosis and highlights future research directions. Recent studies have highlighted the potential of specific molecules and genetic markers to serve as predictors of unsuccessful fracture healing. Alterations in mesenchymal stromal cell (MSC) function, including diminished osteogenic potential and increased cellular senescence, are central to pseudoarthrosis pathogenesis. Molecular analyses reveal suppressed bone morphogenetic protein (BMP) signaling and elevated levels of its inhibitors, such as Noggin and Gremlin, which impair bone regeneration. Genetic studies have uncovered polymorphisms in BMP, matrix metalloproteinase (MMP), and Wnt signaling pathways, suggesting a genetic predisposition to non-union. Additionally, the biological differences between atrophic and hypertrophic pseudoarthrosis, including variations in vascularity and inflammatory responses, emphasize the need for targeted approaches to management. Emerging biomarkers, such as circulating microRNAs (miRNAs), cytokine profiles, blood-derived MSCs, and other markers (B7-1 and PlGF-1), have the potential to contribute to early detection of at-risk patients and personalized therapeutic approaches. Advancing our understanding of the genetic and biological underpinnings of pseudoarthrosis is essential for the development of innovative diagnostic tools and therapeutic strategies.

Effects of aged garlic extract on macrophage functions: a short review of experimental evidence (Review)

Macrophages play crucial roles in both the innate and adaptive immune systems, contributing to the removal of pathogens and subsequent immune responses. Conversely, aberrant macrophage functions are associated with the onset and progression of various diseases, highlighting macrophages as potential therapeutic targets. Aged garlic extract (AGE) is derived from garlic that has undergone a maturation process of over 10 months in an ethanol solution and contains a variety of bioactive components which are produced in the aging process. Previous animal studies and clinical trials have demonstrated that AGE and its constituents exert a range of health benefits, including immune modulation and amelioration of disease conditions. Experimental studies indicate that AGE modulates macrophage functions associated with pathological conditions. To facilitate understanding of AGE's potential as a functional alleviation for macrophage-associated diseases, the present short review summarizes experimental evidence supporting the notion that AGE and its components modify macrophage functions, including phagocytosis, production of reactive oxygen species and polarization.

A call for standardization: Evaluating different methodologies to induce in vitro foreign body giant cell formation for biomaterials research and design

Foreign body giant cells (FBGCs) are crucial in the foreign body reaction at the biomaterial-tissue interface, forming through the fusion of cells from the monocyte/macrophage lineage and performing functions such as material degradation and fibrous encapsulation. Yet, their presence and role in biomaterials research is only slowly unveiled. This review analyzed existing FBGC literature identified through a search string and sources from FBGC articles to evaluate the most commonly used methods and highlight the challenges in establishing a standardized protocol. Our findings revealed a fragmented research landscape marked by significant variability in in vitro culture conditions, i.e., cell origin and type, culture media and sera, fusion-inducing factors, seeding density, culture surface, and inconsistencies in the read-outs. This complicates efforts toward standardization and hampers cross-study comparisons. Based on these results, we highlight the need and propose guidelines for standardized culture protocols for FBGC research. Overall, this review aims to underscore the relevance of improving reproducibility and reliability in FBGC research, facilitating effective cross-study comparisons and advancing understanding of FBGC formation and function, ultimately contributing to designing more effective biomaterial-based therapies. STATEMENT OF SIGNIFICANCE: Foreign body giant cells (FBGCs) are crucial in the body's response to implanted biomaterials. Yet, current research addressing their role and impact is highly fragmented. This review comprehensively and systematically examines the diverse methodologies and definitions used in FBGC research and identifies critical gaps and inconsistencies hindering the reproducibility and comparison of findings. By advocating for standardized protocols, we aim to enhance the reliability and equivalence of research, thus providing a stronger foundation for understanding biomaterial-driven FBGC formation and function. Establishing such a framework will impact biomaterial-based therapies, supporting their effectiveness and safety in medical applications, and is thus of relevance for scientists, companies, and clinicians in the biomaterial and medical device communities.

Osteoclast-derived apoptotic bodies accelerate the pathological progression of osteoarthritis via disturbing subchondral bone remodeling

Objective

To investigate the role of osteoclast-derived apoptotic bodies (OC-ABs) in osteoarthritis (OA), specifically their impact on subchondral bone remodeling and disease progression, and to explore potential therapeutic strategies targeting OC-AB-induced pathways.

Methods

We utilized a mouse model of anterior cruciate ligament transection (ACLT) to simulate post-traumatic osteoarthritis (PTOA). Levels of OC-ABs were assessed in subchondral bone and correlated with OA severity. Additionally, apoptotic body-deficient MRL/lpr mice were analyzed to evaluate the direct contribution of OC-ABs to OA progression and subchondral bone remodeling. The involvement of OC-ABs in osteogenesis was further examined using mesenchymal stem cells (MSCs), with a focus on the RANKL reverse signaling pathway. The therapeutic potential of rapamycin to counteract OC-AB effects was tested.

Results

Increased OC-AB accumulation in subchondral bone was positively correlated with OA severity in ACLT-induced mice. Apoptotic body-deficient MRL/lpr mice demonstrated slower OA progression and maintained more stable subchondral bone architecture, indicating a pathogenic role of OC-ABs in OA. OC-ABs significantly stimulated osteogenesis in MSCs via the RANKL reverse signaling pathway. Treatment with rapamycin effectively reversed OC-AB-induced subchondral bone formation, mitigated OA progression, and inhibited the RANKL reverse signaling pathway.

Conclusion

OC-ABs play a critical role in exacerbating OA by promoting subchondral bone remodeling via the RANKL reverse signaling pathway. Rapamycin presents as a promising therapeutic agent capable of mitigating OC-AB-driven pathology, highlighting new avenues for targeted OA treatment.

The incidence of conversion to hip arthroplasty after core decompression

Aims

Core decompression is a commonly performed procedure to treat osteonecrosis of the femoral head (ONFH) prior to femoral head collapse. The aim of the study was to identify the incidence of hip arthroplasty after core decompression and the potential risk factors for conversion through a nationwide population-based study.

Methods

Patients who received core decompression for ONFH between 1 January 2009 and 31 December 2018 and were followed up until 31 December 2019 (mean 33 months (0.2 to 132)) were retrieved from Taiwan's National Health Insurance claims database. A total of 2,918 patients were identified and included in the study. The mean age at the time of core decompression was 46 years (SD 12.5), with a male-to-female ratio of 7:3. The first total hip arthroplasty or hip hemiarthroplasty after the index core decompression was considered as the outcome of conversion to hip arthroplasty. For the analysis of conversion risk, patients' demographic characteristics, economic status, comorbidities, and data on the type of hospital and surgeons' experience were included.

Results

Overall, 20.05% of patients received a hip arthroplasty within six months following core decompression, with the incidence rising to 60.6% by five years and 66.4% by ten years. Multivariable analysis revealed that patients aged over 40 years (HR 1.18 (95% CI 1.07 to 1.30); p = 0.002), who had a history of alcohol abuse (HR 1.57 (95% CI 1.22 to 2.02); p < 0.001), and had their procedures performed at district-level hospitals (HR 1.13 (95% CI 1.00 to 1.26; p = 0.044), were at increased risk of conversion to hip arthroplasty following core decompression.

Conclusion

The five- and ten-year cumulative incidence of conversion to hip arthroplasty after core decompression was 60.6% and 66.4%, respectively. Significant risk factors for conversion to hip arthroplasty included age over 40 years, history of alcohol abuse, and procedures performed at district hospitals.

Akt2 inhibition alleviates temporomandibular joint osteoarthritis by preventing subchondral bone loss

BACKGROUND

This study aimed to investigate the role and mechanism of the Akt2 pathway in different stages of anterior disc displacement (ADD)-induced temporomandibular joint osteoarthritis (TMJOA).

METHODS

A rat model for TMJOA that simulates anterior disc displacement was established. For inhibit Akt2 expression in subchondral bone, rats were intravenously injected with adeno-associated virus carrying Akt2 shRNA at a titer of 1 × 1012 transducing units/mL 10 days before the ADD or sham operations. The rats were euthanized and evaluated 1 or 8 weeks after surgery, as these time points represented the early or advanced stage of ADD. Immunostaining was performed to examine the expression and location of phosphorylated Akt2 in different stages of ADD. Microcomputed tomography, hematoxylin and eosin staining, toluidine blue staining, Western blotting, immunohistochemical and immunofluorescence staining were used to elucidate the pathological changes and potential mechanisms underlying ADD-induced TMJOA.

RESULTS

In the rat model of ADD-induced TMJOA, rapid condylar bone loss occurred with increased phosphorylation of Akt2 in subchondral bone macrophages within 1 week post-surgery. At 8 weeks after surgery, abnormal remodeling of subchondral bone and degenerative changes in cartilage were observed. Inhibiting Akt2 reduced condylar bone resorption following ADD surgery while improving condylar bone morphology at 8 weeks post-surgery. Additionally, inhibition of Akt2 alleviated cartilage degeneration characterized by a decreased number of apoptotic chondrocytes, reduced expression of matrix metalloproteinases, and increased collagen type II expression in cartilage tissue.

CONCLUSIONS

The Akt2 pathway is activated mainly in subchondral bone macrophages during the early stage of ADD and plays an important role in regulating subchondral bone remodeling. Inhibition of Akt2 could serve as a prophylactic treatment to slow the progression of ADD-induced TMJOA.

Fractures Associated with Immune Checkpoint Inhibitors: A Disproportionality Analysis of the World Health Organization Pharmacovigilance Database

Background/Objectives: The risk of fractures associated with immune checkpoint inhibitors (ICIs) is increasing; however, the relationship between fracture risk and potential factors, such as osteoporosis and hyperthyroidism, remains unclear. Methods: Using VigiBase, the World Health Organization's global pharmacovigilance database, we investigated the signals for osteoporosis, hyperthyroidism, and fractures associated with ICIs (nivolumab, pembrolizumab, atezolizumab, durvalumab, ipilimumab, and tremelimumab) by calculating information components (ICs) and their 95% confidence intervals (CIs). Furthermore, we estimated the association between the occurrence of fractures in patients receiving ICIs and osteoporosis or hyperthyroidism. Results: Signals of hyperthyroidism (IC = 4.66, 95% CI: 4.58-4.73), but not osteoporosis (IC = -1.79, 95% CI: -2.22 to -1.36) or fractures (IC = -0.21, 95% CI: -0.36 to -0.06), were detected in patients using ICIs. Osteoporosis (odds ratio: 118.00, 95% CI: 61.00-230.00) was associated with an increased reporting frequency of fractures related to ICIs, whereas hyperthyroidism (odds ratio: 0.60, 95% CI: 0.19-1.87) was not associated with such an increase. Conclusions: The VigiBase analysis indicates that the use of ICIs does not increase the reporting frequency of osteoporosis or fractures. Additionally, hyperthyroidism did not increase the reporting frequency of fractures associated with ICIs.

Impact of Different Cell Types on the Osteogenic Differentiation Process of Mesenchymal Stem Cells

The skeleton is an important organ in the human body. Bone defects caused by trauma, inflammation, tumors, and other reasons can impact the quality of life of patients. Although the skeleton has a certain ability to repair itself, the current most effective method is still autologous bone transplantation due to factors such as blood supply and defect size. Modern medicine is attempting to overcome these limitations through cell therapy, with mesenchymal stem cells (MSCs) playing a crucial role. MSCs can be extracted from different tissues, and their differentiation potential varies depending on the source. Various cells and cell secretions can influence this process. This article, based on previous research, reviews the effects of macrophages, endothelial cells (ECs), nerve cells, periodontal cells, and even some bacteria on MSC osteogenic differentiation, aiming to provide a reference for multicell coculture strategies related to osteogenesis.

Exploring the Role of Macrophages and Their Associated Structures in Rheumatoid Arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, invasive autoimmune disease characterized by symmetrical polyarthritis involving synovial inflammation. Epidemiological studies indicate that the incidence of RA continues to rise, yet the pathogenesis of this disease remains not fully understood. A significant infiltration of macrophages is observed in the synovium of RA patients. It can be inferred that macrophages likely play a crucial role in the onset and progression of RA.

SUMMARY

This review aims to summarize the research progress on the mechanisms by which macrophages and their associated structures contribute to RA, as well as potential therapeutic approaches, aiming to provide new insights into the study of RA pathogenesis and its clinical treatment.

KEY MESSAGES

During the course of RA, besides the inherent roles of macrophages, these cells respond to microenvironmental changes such as pathogen invasion or tissue damage by undergoing polarization, pyroptosis, or forming macrophage extracellular traps (METs), all of which influence inflammatory responses and immune homeostasis, thereby mediating the occurrence and development of RA. Additionally, macrophages secrete exosomes, which participate in intercellular communication and signal transduction processes, thus contributing to the progression of RA. Therefore, it is critical to elucidate how macrophages and their related structures function in RA.

BACKGROUND

Rheumatoid arthritis (RA) is a chronic, invasive autoimmune disease characterized by symmetrical polyarthritis involving synovial inflammation. Epidemiological studies indicate that the incidence of RA continues to rise, yet the pathogenesis of this disease remains not fully understood. A significant infiltration of macrophages is observed in the synovium of RA patients. It can be inferred that macrophages likely play a crucial role in the onset and progression of RA.

SUMMARY

This review aims to summarize the research progress on the mechanisms by which macrophages and their associated structures contribute to RA, as well as potential therapeutic approaches, aiming to provide new insights into the study of RA pathogenesis and its clinical treatment.

KEY MESSAGES

During the course of RA, besides the inherent roles of macrophages, these cells respond to microenvironmental changes such as pathogen invasion or tissue damage by undergoing polarization, pyroptosis, or forming macrophage extracellular traps (METs), all of which influence inflammatory responses and immune homeostasis, thereby mediating the occurrence and development of RA. Additionally, macrophages secrete exosomes, which participate in intercellular communication and signal transduction processes, thus contributing to the progression of RA. Therefore, it is critical to elucidate how macrophages and their related structures function in RA.

Advances in the application and research of biomaterials in promoting bone repair and regeneration through immune modulation

With the ongoing development of osteoimmunology, increasing evidence indicates that the local immune microenvironment plays a critical role in various stages of bone formation. Consequently, modulating the immune inflammatory response triggered by biomaterials to foster a more favorable immune microenvironment for bone regeneration has emerged as a novel strategy in bone tissue engineering. This review first examines the roles of various immune cells in bone tissue injury and repair. Then, the contributions of different biomaterials, including metals, bioceramics, and polymers, in promoting osteogenesis through immune regulation, as well as their future development directions, are discussed. Finally, various design strategies, such as modifying the physicochemical properties of biomaterials and integrating bioactive substances, to optimize material design and create an immune environment conducive to bone formation, are explored. In summary, this review comprehensively covers strategies and approaches for promoting bone tissue regeneration through immune modulation. It offers a thorough understanding of current research trends in biomaterial-based immune regulation, serving as a theoretical reference for the further development and clinical application of biomaterials in bone tissue engineering.

Role of macrophage in intervertebral disc degeneration

Intervertebral disc degeneration is a degenerative disease where inflammation and immune responses play significant roles. Macrophages, as key immune cells, critically regulate inflammation through polarization into different phenotypes. In recent years, the role of macrophages in inflammation-related degenerative diseases, such as intervertebral disc degeneration, has been increasingly recognized. Macrophages construct the inflammatory microenvironment of the intervertebral disc and are involved in regulating intervertebral disc cell activities, extracellular matrix metabolism, intervertebral disc vascularization, and innervation, profoundly influencing the progression of disc degeneration. To gain a deeper understanding of the inflammatory microenvironment of intervertebral disc degeneration, this review will summarize the role of macrophages in the pathological process of intervertebral disc degeneration, analyze the regulatory mechanisms involving macrophages, and review therapeutic strategies targeting macrophage modulation for the treatment of intervertebral disc degeneration. These insights will be valuable for the treatment and research directions of intervertebral disc degeneration.

Bioinspired adhesive polydopamine-metal-organic framework functionalized 3D customized scaffolds with enhanced angiogenesis, immunomodulation, and osteogenesis for orbital bone reconstruction

Critical-sized orbital bone defects can lead to significant maxillofacial deformities and even eye movement disorders. The challenges associated with these defects, including their complicated structure, inadequate blood supply, and limited availability of progenitor cells that hinder successful repair. To overcome these issues, we developed a novel approach using computer numerical control (CNC) material reduction manufacturing technology to produce a customized polyetheretherketone (PEEK) scaffold that conforms to the specific shape of orbital bone defects. Deferoxamine (DFO) was in situ encapsulated into polydopamine-hybridized zeolitic imidazolate framework-8 (pZIF8-DFO) nanoparticles, which was subsequently adhered to the sulfonated PEEK (sPEEK) scaffold through polydopamine modification. This functionalization enhanced drug loading efficiency and imparted anti-inflammatory properties to the nanoparticle system. Our in vitro findings demonstrated that the sustained release of DFO from the sPEEK/pZIF8-DFO scaffolds extended over 14 days and significantly promoted angiogenesis and progenitor cell recruitment, as evidenced by increased expression of HIF-1α, VEGF, and SDF-1α expression in human umbilical vein endothelial cells (HUVECs). Moreover, sPEEK/pZIF8-DFO scaffolds exhibited superior immunomodulation and osteogenic differentiation capabilities on Raw 264.7 cells and rabbit bone marrow mesenchymal stem cells (rBMSCs), respectively. Most notably, our in vivo rabbit orbital bone defects revealed that sPEEK/pZIF8-DFO scaffolds resulted in a greater volume of new bone formation than on sPEEK and sPEEK/pZIF8 scaffolds, with partial bone connection to the sPEEK/pZIF8-DFO scaffolds. In summary, we develop a novel PEEK scaffold that combines enhanced angiogenesis, stem cell recruitment, immunomodulation, and osteogenic differentiation, showcasing its promising potential for orbital bone reconstruction.

Histone lactylation in macrophage biology and disease: from plasticity regulation to therapeutic implications

Epigenetic modifications have been identified as critical molecular determinants influencing macrophage plasticity and heterogeneity. Among these, histone lactylation is a recently discovered epigenetic modification. Research examining the effects of histone lactylation on macrophage activation and polarization has grown substantially in recent years. Evidence increasingly suggests that lactate-mediated changes in histone lactylation levels within macrophages can modulate gene transcription, thereby contributing to the pathogenesis of various diseases. This review provides a comprehensive analysis of the role of histone lactylation in macrophage activation, exploring its discovery, effects, and association with macrophage diversity and phenotypic variability. Moreover, it highlights the impact of alterations in macrophage histone lactylation in diverse pathological contexts, such as inflammation, tumorigenesis, neurological disorders, and other complex conditions, and demonstrates the therapeutic potential of drugs targeting these epigenetic modifications. This mechanistic understanding provides insights into the underlying disease mechanisms and opens new avenues for therapeutic intervention.

Targeting dipeptidyl peptidase-8/9 to combat inflammation-induced osteoclastogenesis in RAW264.7 macrophages and analysis of anti-osteoclastogenesis potential of chrysin

Objectives

Osteoclasts drive bone resorption under inflammation, with cytokines promoting osteoclastogenesis. The role of proline enzymes like dipeptidyl peptidase-8 and 9 (DPP-8/9) in this process remains unclear. This study aimed to explore the DPP-8/9 involvement in inflammation-driven osteoclastogenesis using the RAW264.7 macrophage model.

Materials and Methods

Receptor activator of nuclear factor-κB ligand (RANKL) and lipopolysaccharide (LPS) induced osteoclastogenesis, raising interleukin-6 (IL-6), tumor necrosis factor (TNF-α), and IL-23 levels. Using RAW264.7 cells, DPP-8/9 protein and tartrate-resistant acid phosphatase (TRAPc) were assayed. Antibodies for cluster of differentiation (CD86 and CD206) were used to analyze macrophage polarization, while molecular docking was used to assess flavonoid binding to DPP-8/9. Western blot confirmed DPP-8/9 expression in treated macrophages.

Results

Administering RANKL and LPS increased IL-6 and TNF-α levels, significantly promoting osteoclastogenesis in RAW264.7 macrophages. This treatment also elevated the levels of the inflammatory macrophage marker IL-23. Osteoclast formation was confirmed by measuring TRAPc levels in the culture. Analysis of the cell supernatant revealed elevated DPP-8/9 levels in the RANKL+LPS group. Inhibition of DPP-8/9 with 1G244 decreased inflammatory cytokines and TRAPc levels in the cell culture. Molecular docking analysis of various flavonoids identified chrysin as a potential molecule with sufficient binding energy against DPP-8/9, a finding confirmed by blotting assay.

Conclusion

This study emphasizes the involvement of DPP-8/9 in inflammatory osteoclastogenesis in RAW264.7 macrophages. Inhibition of DPP-8/9 reduced osteoclastogenesis markers and inflammatory cytokines levels, indicating decreased osteoclast formation. Additionally, chrysin demonstrated potential as an anti-DPP-8/9 agent, highlighting its possible role in future therapeutic strategies targeting inflammation-induced osteoclastogenesis.

Repetitive Overuse Injury Causes Entheseal Damage and Palmar Muscle Fibrosis in Older Rats

Overuse injury is a frequent diagnosis in occupational medicine and athletics. Using an established model of upper extremity overuse, we sought to characterize changes occurring in the forepaws and forelimbs of mature female rats (14-18 months of age). Thirty-three rats underwent a 4-week shaping period, before performing a high-repetition low-force (HRLF) task for 12 weeks, with the results being compared to 32 mature controls. HRLF animals showed a reduced grip strength versus controls. ELISAs carried out in the HRLF rats, versus controls, showed elevated levels of IL1-α in tendons, IL1-α and TNF-α in distal bones/entheses, and TNF-α, MIP1-α/CCL3, and CINC-2/CXCL-3 in serum, as well as IL-6 in forelimb muscles and tendons, and IL-10 in serum. HRLF rats had elevated collagen deposition in the forepaw intrinsic muscles (i.e., fibrosis), entheseal microdamage, and articular cartilage degradation versus the control rats. CD68/ED1+ osteoclasts and single-nucleated cells were elevated in distal forelimb metaphyses of the HRLF animals, versus controls. Declines in grip strength correlated with muscle fibrosis, entheseal microdamage, articular cartilage damage, distal bone/enthesis IL1-α, and serum IL-6. These data demonstrate inflammatory and persistent degradative changes in the forearm/forepaw tissues of mature female animals exposed to prolonged repetitive tasks, changes with clinical relevance to work-related overuse injuries in mature human females.

Inhibition of fibulin-3 ameliorates periodontal inflammation through reducing M1 macrophage polarization via EGFR/PI3K/AKT pathway

BACKGROUND

This study aimed to evaluate the role of fibulin-3 (FBLN3) in macrophage polarization, its mechanism, and its effect on periodontitis.

METHODS

We conducted studies on periodontitis using both clinical samples and ligature-induced mouse periodontitis model. The inflammatory state was assessed using microcomputed tomography, hematoxylin and eosin staining, immunohistochemical staining, and immunofluorescence staining. In vitro, bone marrow-derived macrophages, and RAW 264.7 macrophages were treated with lipopolysaccharide (LPS) and interleukin (IL)-4 to induce polarization. The role of FBLN3 in macrophage polarization was investigated using overexpression plasmids or siRNAs. Furthermore, local injection of adeno-associated virus was employed to suppress FBLN3 expression in periodontal tissues.

RESULTS

FBLN3 levels were greater in periodontitis tissues. FBLN3 promoted M1 polarization and suppressed M2 polarization in macrophages. The overexpression of FBLN3 promoted M1 polarization via the EGFR/PI3K/AKT signaling pathway, an effect that the epidermal growth factor receptor (EGFR) inhibitor PD153035 reversed. Suppressing FBLN3 expression improved periodontal inflammation and reduced alveolar bone loss in periodontitis.

CONCLUSIONS

FBLN3 suppression can mitigate periodontitis by decreasing the M1 macrophage ratio. FBLN3 regulates M1 macrophage polarization through the EGFR/PI3K/AKT signaling pathway.

PLAIN LANGUAGE SUMMARY

Disruption in the collaboration between extracellular matrix (ECM) and immune system is a significant pathology in periodontitis. Macrophages are a crucial part of the immune system and have unique functions, such as polarization. Fibulin-3, an ECM protein, may play a vital role in this dynamic interplay. Fibulin-3 expression is elevated in periodontitis and is closely related to immune cell function. Inhibiting fibulin-3 can alleviate periodontitis by reducing infiltration of immune cells and M1 macrophage ratio. Furthermore, fibulin-3 promoted macrophage M1 polarization by activating the PI3K/AKT signaling pathway through EGFR binding. Our findings offer a clinically relevant rationale for immune response modulation through fibulin-3.

Potential mechanisms of rheumatoid arthritis therapy: Focus on macrophage polarization

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that affects multiple organs and systems in the human body, often leading to disability. Its pathogenesis is complex, and the long-term use of traditional anti-rheumatic drugs frequently results in severe toxic side effects. Therefore, the search for a safer and more effective antirheumatic drug is extremely important for the treatment of RA. As important immune cells in the body, macrophages are polarized. Under pathological conditions, macrophages undergo proliferation and are recruited to diseased tissues upon stimulation. In the local microenvironment, they polarize into different types of macrophages in response to specific factors and perform unique functions and roles. Previous studies have shown that there is a link between macrophage polarization and RA, indicating that certain active ingredients can ameliorate RA symptoms through macrophage polarization. Notably, Traditional Chinese medicine (TCM) monomer component and compounds demonstrate a particular advantage in this process. Building upon this insight, we reviewed and analyzed recent studies to offer valuable and meaningful insights and directions for the development and application of anti-rheumatic drugs.

How the bone microenvironment shapes the pre-metastatic niche and metastasis

The bone is a frequent metastatic site, with changes in the mineralized bone and the bone marrow milieu that can also prime other sites for metastasis by educating progenitor cells to support metastatic spread. Stromal and immune populations cooperatively maintain the organizationally complex bone niches and are dysregulated in the presence of a distant primary tumor and metastatic disease. Interrogating the bone niches that facilitate metastatic spread using innovative technologies holds the potential to aid in preventing metastasis in and mediated by the bone. Here, we review recent advances in bone niche biology and its adaptations in the context of cancer.

Single-cell analysis reveals a unique microenvironment in peri-implantitis

AIM

This study aimed to reveal the unique microenvironment of peri-implantitis through single-cell analysis.

MATERIALS AND METHODS

Herein, we performed single-cell RNA sequencing (scRNA-seq) of biopsies from patients with peri-implantitis (PI) and compared the results with healthy individuals (H) and patients with periodontitis (PD).

RESULTS

Decreased numbers of stromal cells and increased immune cells were found in the PI group, which implies a severe inflammatory infiltration. The fibroblasts were found to be heterogeneous and the specific pro-inflammatory CXCL13+ sub-cluster was more represented in the PI group, in contrast to the PD and H groups. Furthermore, more neutrophil infiltration was detected in the PI group than in the PD group, and cell-cell communication and ligand-receptor pairs revealed most neutrophils were recruited by CXCL13+ fibroblasts through CXCL8/CXCL6-CXCR2/CXCR1. Notably, our study demonstrated that the unique microenvironment of the PI group promoted the differentiation of monocyte/macrophage lineage cells into osteoclasts, which might explain the faster and more severe bone resorption in the progression of PI than PD.

CONCLUSIONS

Collectively, this study suggests a unique immune microenvironment of PI, which may explain the differences between PI and PD in the clinic. These outcomes will aid in finding new specific and effective treatments for PI.

Macrophage polarization in human periapical lesions in relation to histopathological diagnosis, clinical features and lesion volume: An ex vivo study

AIM

To evaluate M1 and M2 macrophage polarization in radicular cysts and periapical granulomas through an immunohistochemical analysis and the correlation between macrophage polarization and histopathological diagnosis, clinical characteristics and lesion volume using cone-beam computed tomography.

METHODOLOGY

Periapical biopsies diagnosed as radicular cysts (n = 52) and periapical granulomas (n = 51) were analysed by immunohistochemical method. Teeth with periapical lesion with no history of root canal treatment (primary lesion) and lesions persistent to root canal treatment (persistent lesions) were included. Pathological diagnosis, patients' age, gender and clinical characteristics were obtained from treatment records. A cone-beam computed tomographic periapical volume index (CBCTPAVI) score was assigned to each periapical lesion based on the volume of the lesion. Immuno-expressions of CD68 and CD163 were quantified. The CD68/CD163 ratio was adopted to represent M1 or M2 macrophage polarization. Mann-Whitney U test was used to determine the different CD68/CD163 ratio between groups of radicular cyst and periapical granuloma. Spearman's correlation test was performed to assess the correlation between the CD68/CD163 ratio and lesion volume and CBCTPAVI score.

RESULTS

Radicular cysts and periapical granulomas had CD68/CD163 median of 2.05 (IQR = 1.33) and 1.26 (IQR = 0.81), respectively. A significantly higher CD68/CD163 ratio was observed in radicular cysts (p < .001). In contrast, periapical granulomas had significantly lower median of CD68/CD163 ratio. Larger lesions had a higher median of CD68/CD163 ratio, while smaller lesions had lower median of CD68/CD163 ratio (p = .007, rs = .262). CD68/CD163 ratio was significantly correlated with the CBCTPAVI score in the overall periapical lesions (p = .002, rs = .306). The higher CD68/CD163 ratio in larger lesions indicated a higher degree of M1 polarization compared to smaller lesions. Regarding the pathological diagnosis, there was a significant positive correlation between CBCTPAVI score and CD68/CD163 ratio in periapical granulomas (p < .001, rs = .453), whereas the negative correlation was observed for radicular cysts (p < .001, rs = -.471).

CONCLUSIONS

Periapical granulomas are characterized by a M2-dominant macrophage polarization, while radicular cysts have significantly higher M1 macrophages. The higher degree of M1 macrophage polarization was significantly correlated with larger volume and higher CBCTPAVI scores of overall periapical lesion and periapical granuloma.

Prospective and challenges of locally applied repurposed pharmaceuticals for periodontal tissue regeneration

Periodontitis is a persistent inflammatory condition that causes periodontal ligament degradation, periodontal pocket development, and alveolar bone destruction, all of which lead to the breakdown of the teeth's supporting system. Periodontitis is triggered by the accumulation of various microflora (especially anaerobes) in the pockets, which release toxic substances and digestive enzymes and stimulate the immune system. Periodontitis can be efficiently treated using a variety of techniques, both regional and systemic. Effective therapy is dependent on lowering microbial biofilm, minimizing or eradicating pockets. Nowadays, using local drug delivery systems (LDDSs) as an adjuvant therapy to phase I periodontal therapy is an attractive option since it controls drug release, resulting in improved efficacy and lesser adverse reactions. Choosing the right bioactive agent and mode of delivery is the foundation of an efficient periodontal disease management approach. The objective of this paper is to shed light on the issue of successful periodontal regeneration, the drawbacks of currently implemented interventions, and describe the potential of locally delivered repurposed drugs in periodontal tissue regeneration. Because of the multiple etiology of periodontitis, patients must get customized treatment with the primary goal of infection control. Yet, it is not always successful to replace the lost tissues, and it becomes more challenging as the defect gets worse. Pharmaceutical repurposing offers a viable, economical, and safe alternative for non-invasive, and predictable periodontal regeneration. This article clears the way in front of researchers, decision-makers, and pharmaceutical companies to explore the potential, effectiveness, and efficiency of the repurposed pharmaceuticals to generate more economical, effective, and safe topical pharmaceutical preparations for periodontal tissue regeneration.

Primary Osteoporosis Induced by Androgen and Estrogen Deficiency: The Molecular and Cellular Perspective on Pathophysiological Mechanisms and Treatments

Primary osteoporosis is closely linked to hormone deficiency, which disrupts the balance of bone remodeling. It affects postmenopausal women but also significantly impacts older men. Estrogen can promote the production of osteoprotegerin, a decoy receptor for RANKL, thereby preventing RANKL from activating osteoclasts. Furthermore, estrogen promotes osteoblast survival and function via activation of the Wnt signaling pathway. Likewise, androgens play a critical role in bone metabolism, primarily through their conversion to estrogen in men. Estrogen deficiency accelerates bone resorption through a rise in pro-inflammatory cytokines (IL-1, IL-6, TNF-α) and RANKL, which promote osteoclastogenesis. In the classic genomic pathway, estrogen binds to estrogen receptors in the cytoplasm, forming a complex that migrates to the nucleus and binds to estrogen response elements on DNA, regulating gene transcription. Androgens can be defined as high-affinity ligands for the androgen receptor; their combination can serve as a ligand-inducible transcription factor. Hormone replacement therapy has shown promise but comes with associated risks and side effects. In contrast, the non-genomic pathway involves rapid signaling cascades initiated at the cell membrane, influencing cellular functions without directly altering gene expression. Therefore, the ligand-independent actions and rapid signaling pathways of estrogen and androgen receptors can be harnessed to develop new drugs that provide bone protection without the side effects of traditional hormone therapies. To manage primary osteoporosis, other pharmacological treatments (bisphosphonates, teriparatide, RANKL inhibitors, sclerostin inhibitors, SERMs, and calcitonin salmon) can ameliorate osteoporosis and improve BMD via actions on different pathways. Non-pharmacological treatments include nutritional support and exercise, as well as the dietary intake of antioxidants and natural products. The current study reviews the processes of bone remodeling, hormone actions, hormone receptor status, and therapeutic targets of primary osteoporosis. However, many detailed cellular and molecular mechanisms underlying primary osteoporosis seem complicated and unexplored and warrant further investigation.

Heat-killed Lancefieldella Rimae Induces Bone Resorption by Promoting Osteoclast Differentiation

INTRODUCTION

Apical periodontitis, mainly caused by bacterial infection in the dental pulp, is often accompanied by abscess, periapical inflammation, and alveolar bone loss. Lancefieldella rimae has been detected in the root canals of patients with apical periodontitis. Here, we investigated whether L. rimae is associated with bone resorption.

METHODS

L. rimae was anaerobically cultured and heat-killed (HKLr). A mouse calvarial implantation model was used to determine the bone resorption in vivo. Committed osteoclasts prepared from C57BL/6 wild-type or Toll-like receptor 2 (TLR2)-deficient mice were differentiated into mature osteoclasts in the presence or absence of HKLr. The mRNA expression of tartrate-resistant acid phosphatase (TRAP), ATPase H+ transporting V0 subunit D2, cathepsin K, interleukin-6, tumor necrosis factor-α, and glyceraldehyde 3-phosphate dehydrogenase was quantified using real-time reverse transcription-polymerase chain reaction. The protein levels of c-Fos and NFATc1 were determined by Western blot analysis.

RESULTS

Implantation of HKLr onto the mouse calvaria induced the bone destruction with an increase of TRAP-positive areas. While HKLr enhanced the differentiation of osteoclasts, this effect was not observed in TLR2-deficient osteoclasts. HKLr dose-dependently increased the mRNA expression of genes associated with osteoclast differentiation including TRAP, ATPase H+ transporting V0 subunit D2, and cathepsin K. In addition, HKLr enhanced the expression of c-Fos and NFATc1, which are important transcription factors for osteoclast differentiation. Moreover, HKLr increased the expression of interleukin-6 and tumor necrosis factor-α.

CONCLUSION

L. rimae induces bone resorption by enhancing osteoclast differentiation through the TLR2 signaling pathway, implying that L. rimae is a causative agent responsible for the alveolar bone resorption accompanying apical periodontitis.

Histamine and Th2 cytokines independently and synergistically upregulate MMP12 expression in human M2 macrophages

Beyond Th2 cells and various immune cells, M2 macrophages have been identified in lesional skin of atopic dermatitis (AD) indicating their involvement in the disease's underlying mechanisms. MMP12, a matrix-degrading enzyme, which is predominantly produced by macrophages, is increased in skin lesions of AD patients. In this study we investigated the expression of MMP12 mRNA in lesional AD skin at single cell level through RNA sequencing (scRNA-seq) and the expression of MMP12 in M2 macrophages from healthy individuals and AD patients in response to Th2 cytokines and histamine using quantitative PCR and ELISA. Additionally, we analyzed macrophages from dupilumab-treated AD patients using the same methods to assess the influence of Th2 cytokines on MMP12 expression ex-vivo. ScRNA-seq identified macrophages as the primary producers of MMP12 in lesional AD skin. In-vitro, both MMP12 mRNA and protein expression were significantly increased in monocytes during differentiation to M2 macrophages in the presence of histamine, of Th2 cytokines or of Th2 cytokines in combination with histamine. In M2 macrophages obtained from dupilumab-treated AD patients, the upregulation of MMP12 expression by IL-4 and IL-13 was attenuated. Our findings unveil a novel mechanism whereby Th2 cytokines and histamine regulate MMP12 expression, potentially impacting skin barrier homeostasis in AD.

Relationship between Helicobacter pylori infection, osteoporosis, and fracture

Osteoporotic fracture is a prevalent noncommunicable disease globally, causing significant mortality, morbidity, and disability. As the population ages, the healthcare and economic burden of osteoporotic fracture is expected to increase further. Due to its multifactorial features, the development of osteoporotic fracture involves a complex interplay of multiple risk factors, including genetic, environmental, and lifestyle factors. Helicobacter pylori, which infects approximately 43% of the world's population, has been associated with increased fracture risk due to hypochlorhydria from atrophic gastritis and systemic inflammation from elevated pro-inflammatory cytokines. However, the potential impact of H. pylori infection and eradication on fracture risk remains contentious among various studies due to the study design and inadequate adjustment of confounding factors including baseline gastritis phenotype. In this review, we provided a comprehensive evaluation of the current evidence focusing on the underlying mechanisms and clinical evidence of the association between H. pylori infection and osteoporotic fracture. We also discussed the potential benefits of H. pylori eradication on fracture risk.

Microbiota-immune-brain interactions: A new vision in the understanding of periodontal health and disease

This review highlights the significance of interactions between the microbiota, immune system, nervous and hormonal systems, and the brain on periodontal health and disease. Microorganisms in the microbiota, immune cells, and neurons communicate via homeostatic nervous and hormonal systems, regulating vital body functions. By modulating pro-inflammatory and anti-inflammatory adaptive immune responses, these systems control the composition and number of microorganisms in the microbiota. The strength of these brain-controlled responses is genetically determined but is sensitive to early childhood stressors, which can permanently alter their responsiveness via epigenetic mechanisms, and to adult stressors, causing temporary changes. Clinical evidence and research with humans and animal models indicate that factors linked to severe periodontitis enhance the responsiveness of these homeostatic systems, leading to persistent hyperactivation. This weakens the immune defense against invasive symbiotic microorganisms (pathobionts) while strengthening the defense against non-invasive symbionts at the gingival margin. The result is an increased gingival tissue load of pathobionts, including Gram-negative bacteria, followed by an excessive innate immune response, which prevents infection but simultaneously destroys gingival and periodontal tissues. Thus, the balance between pro-inflammatory and anti-inflammatory adaptive immunity is crucial in controlling the microbiota, and the responsiveness of brain-controlled homeostatic systems determines periodontal health.

Nanoscale ZnO doping in prosthetic polymers mitigate wear particle-induced inflammation and osteolysis through inhibiting macrophage secretory autophagy

Wear particles produced by joint replacements induce inflammatory responses that lead to periprosthetic osteolysis and aseptic loosening. However, the precise mechanisms driving wear particle-induced osteolysis are not fully understood. Recent evidence suggests that autophagy, a cellular degradation process, plays a significant role in this pathology. This study aimed to clarify the role of autophagy in mediating inflammation and osteolysis triggered by wear particles and to evaluate the therapeutic potential of zinc oxide nanoparticles (ZnO NPs). We incorporated ZnO into the prosthetic material itself, ensuring that the wear particles inherently carried ZnO, providing a targeted and sustained intervention. Our findings reveal that polymer wear particles induce excessive autophagic activity, which is closely associated with increased inflammation and osteolysis. We identified secretory autophagy as a key mechanism for IL-1β secretion, exacerbating osteolysis. Both in vitro and in vivo experiments demonstrated that ZnO-doped particles significantly inhibit autophagic overactivation, thereby reducing inflammation and osteolysis. In summary, this study establishes secretory autophagy as a critical mechanism in wear particle-induced osteolysis and highlights the potential of ZnO-doped prosthetic polymers for targeted, sustained mitigation of periprosthetic osteolysis.

Macrophage-to-osteocyte communication: Impact in a 3D in vitro implant-associated infection model

Macrophages and osteocytes are important regulators of inflammation, osteogenesis and osteoclastogenesis. However, their interactions under adverse conditions, such as biomaterial-associated infection (BAI) are not fully understood. We aimed to elucidate how factors released from macrophages modulate osteocyte responses in an in vitro indirect 3D co-culture model. Human monocyte-derived macrophages were cultured on etched titanium disks and activated with either IL-4 cytokine (anti-inflammatory M2 phenotype) or Staphylococcus aureus secreted virulence factors to simulate BAI (pro-inflammatory M1 phenotype). Primary osteocytes in collagen gels were then stimulated with conditioned media (CM) from these macrophages. The osteocyte response was analyzed by gene expression, protein secretion, and immunostaining. M1 phenotype macrophages were confirmed by IL-1β and TNF-α secretion, and M2 macrophages by ARG-1 and MRC-1.Osteocytes receiving M1 CM revealed bone inhibitory effects, denoted by reduced secretion of bone formation osteocalcin (BGLAP) and increased secretion of the bone inhibitory sclerostin (SOST). These osteocytes also downregulated the pro-mineralization gene PHEX and upregulated the anti-mineralization gene MEPE. Additionally, exhibited pro-osteoclastic potential by upregulating pro-osteoclastic gene RANKL expression. Nonetheless, M1-stimulated osteocytes expressed a higher level of the potent pro-osteogenic factor BMP-2 in parallel with the downregulation of the bone inhibitor genes DKK1 and SOST, suggesting a compensatory feedback mechanisms. Conversely, M2-stimulated osteocytes mainly upregulated anti-osteoclastic gene OPG expression, suggesting an anti-catabolic effect. Altogether, our findings demonstrate a strong communication between M1 macrophages and osteocytes under M1 (BAI)-simulated conditions, suggesting that the BAI adverse effects on osteoblastic and osteoclastic processes in vitro are partly mediated via this communication. STATEMENT OF SIGNIFICANCE: Biomaterial-associated infections are major challenges and the underlying mechanisms in the cellular interactions are missing, especially among the major cells from the inflammatory side (macrophages as the key cell in bacterial clearance) and the regenerative side (osteocyte as main regulator of bone). We evaluated the effect of macrophage polarization driven by the stimulation with bacterial virulence factors on the osteocyte function using an indirect co-culture model, hence mimicking the scenario of a biomaterial-associated infection. The results suggest that at least part of the adverse effects of biomaterial associated infection on osteoblastic and osteoclastic processes in vitro are mediated via macrophage-to-osteocyte communication.

Inhibition of ferroptosis rescues M2 macrophages and alleviates arthritis by suppressing the HMGB1/TLR4/STAT3 axis in M1 macrophages

Ferroptosis is a type of programmed cell death driven by iron-dependent lipid peroxidation. The TNF-mediated biosynthesis of glutathione has been shown to protect synovial fibroblasts from ferroptosis in the hyperplastic synovium. Ferroptosis induction provides a novel therapeutic approach for rheumatoid arthritis (RA) by reducing the population of synovial fibroblasts. The beginning and maintenance of synovitis in RA are significantly influenced by macrophages, as they generate cytokines that promote inflammation and contribute to the destruction of cartilage and bone. However, the vulnerability of macrophages to ferroptosis in RA remains unclear. In this study, we found that M2 macrophages are more vulnerable to ferroptosis than M1 macrophages in the environment of the arthritis synovium with a high level of iron, leading to an imbalance in the M1/M2 ratio. During ferroptosis, HMGB1 released by M2 macrophages interacts with TLR4 on M1 macrophages, which in turn triggers the activation of STAT3 signaling in M1 macrophages and contributes to the inflammatory response. Knockdown of TLR4 decreased the level of cytokines induced by HMGB1 in M1 macrophages. The ferroptosis inhibitor liproxstatin-1 (Lip-1) started at the presymptomatic stage in collagen-induced arthritis (CIA) model mice, and GPX4 overexpression in M2 macrophages at the onset of collagen antibody-induced arthritis (CAIA) protected M2 macrophages from ferroptotic cell death and significantly prevented the development of joint inflammation and destruction. Thus, our study demonstrated that M2 macrophages are vulnerable to ferroptosis in the microenvironment of the hyperplastic synovium and revealed that the HMGB1/TLR4/STAT3 axis is critical for the ability of ferroptotic M2 macrophages to contribute to the exacerbation of synovial inflammation in RA. Our findings provide novel insight into the progression and treatment of RA.

Immune mediated support of metastasis: Implication for bone invasion

Bone is a common organ affected by metastasis in various advanced cancers, including lung, breast, prostate, colorectal, and melanoma. Once a patient is diagnosed with bone metastasis, the patient's quality of life and overall survival are significantly reduced owing to a wide range of morbidities and the increasing difficulty of treatment. Many studies have shown that bone metastasis is closely related to bone microenvironment, especially bone immune microenvironment. However, the effects of various immune cells in the bone microenvironment on bone metastasis remain unclear. Here, we described the changes in various immune cells during bone metastasis and discussed their related mechanisms. Osteoblasts, adipocytes, and other non-immune cells closely related to bone metastasis were also included. This review also summarized the existing treatment methods and potential therapeutic targets, and provided insights for future studies of cancer bone metastasis.

Osteointegration of Ti Bone Implants: A Study on How Surface Parameters Control the Foreign Body Response

The integration of titanium (Ti)-based implants with bone is limited, resulting in implant failure. This lack of osteointegration is due to the foreign body response (FBR) that occurs after the implantation of biodevices. The process begins with protein adsorption, which is governed by implant surface properties, e.g., chemistry, charge, wettability, and/or topography. The distribution and composition of the protein layer in turn influence the recruitment, differentiation, and modulation of immune and bone cells. The subsequent events that occur at the bone-material interface will ultimately determine whether the implant is encapsulated or will integrate with bone. Despite the numerous studies evaluating the influence of surface properties in the various stages of the FBR, the factors that affect tissue-material interactions are often studied in isolation or in small correlations due to the technical challenges involved in assessing them in vitro or in vivo. Consequently, the influence of protein conformation on the Ti bone implant surface design remains an unresolved research question. The objective of this review is to comprehensively evaluate the existing literature on the effect of surface parameters of Ti and its alloys in the stages of FBR, with a particular focus on protein adsorption and osteoimmunomodulation. This evaluation aims to systematically describe these effects on bone formation.

Chitosan-based biomaterials promote bone regeneration by regulating macrophage fate

The development of various osteogenic biomaterials has not only promoted the development of bone tissue engineering but also provided more possibilities for bone defect repair. However, most previous studies have focused on the interaction of biomaterials on endogenous or exogenous stem cells involved in the bone regeneration process while neglecting the effect of changes in the immune microenvironment of bone defect sites on bone regeneration after biomaterial implantation into the host. With the development of bone immunology, the role of various immune cells, especially macrophages, in bone regeneration has gradually attracted the attention of researchers. An increasing number of studies have begun to target macrophages to better promote bone regeneration by modulating the fate of macrophages in a spatiotemporally ordered manner to mimic the changes in the immune microenvironment of bone defect sites during the natural repair process of bone tissue. Chitosan is one of the most abundant natural polysaccharides in the world. In recent years, various chitosan-based biomaterials have been widely used in macrophage fate modulation and bone regeneration. In this review, we review the interaction between macrophages and scaffold materials, general information about chitosan, the modulation of macrophage fate by chitosan-based biomaterials, and their application in bone regeneration.

TNF reduces osteogenic cell fate in PDL cells at transcriptional and functional levels without alteration of periodontal proliferative capacity

AIMS

To investigate the effect of tumor necrosis factor (TNF) on the growth of human periodontal ligament (PDL) cells, their osteogenic differentiation and modulation of their matrix secretion in vitro.

METHODS

The influence of 10 ng/ml TNF on proliferation and metabolic activity of PDL cells was analyzed by cell counting (DAPI [4',6-diamidino-2-phenylindole] staining) and the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. In addition, cells were cultured under control conditions and osteogenic conditions (media containing 10 mM β-glycerophosphate). Quantitative expression analysis of genes encoding the osteogenic markers alkaline phosphatase (ALP), collagen type I alpha 1 chain (COL1A1), osteoprotegerin (OPG), and osteopontin (OPN) was performed after 7 and 14 days of cultivation. Calcium deposits were stained with alizarin red.

RESULTS

Our studies showed that 10 ng/ml TNF did not affect the survival and metabolic activity of PDL cells. Quantitative expression analysis revealed that long-term cultures with TNF impaired osteogenic cell fate at early and late developmental stages. Furthermore, TNF significantly reduced matrix secretion in PDL cells.

CONCLUSION

The present data confirm TNF as a regulatory factor of proinflammatory remodeling that influences the differentiation behavior but not the metabolism and cell proliferation of the periodontium. Therefore, TNF represents an interesting target for the regulation of orthodontic remodeling processes in the periodontium.

Low-Intensity Pulsed Ultrasound: A Physical Stimulus with Immunomodulatory and Anti-inflammatory Potential

Ultrasound has expanded into the therapeutic field as a medical imaging and diagnostic technique. Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound that plays a vital role in promoting fracture healing, wound repair, immunomodulation, and reducing inflammation. Its anti-inflammatory effects are manifested by decreased pro-inflammatory cytokines and chemokines, accelerated regression of immune cell invasion, and accelerated damage repair. Although the anti-inflammatory mechanism of LIPUS is not very clear, many in vitro and in vivo studies have shown that LIPUS may play its anti-inflammatory role by activating signaling pathways such as integrin/Focal adhesion kinase (FAK)/Phosphatidylinositol 3-kinase (PI3K)/Serine threonine kinase (Akt), Vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), or inhibiting signaling pathways such as Toll-like receptors (TLRs)/Nuclear factor kappa-B (NF-κB) and p38-Mitogen-activated protein kinase (MAPK). As a non-invasive physical therapy, the anti-inflammatory and immunomodulatory effects of LIPUS deserve further exploration.

CGRP promotes osteogenic differentiation by regulating macrophage M2 polarization through HDAC6/AKAP12 signaling pathway

Aim: To determine the mechanism of Calcitonin gene-related peptide (CGRP) in bone healing.Materials & methods: Alkaline phosphatase (ALP) activity and inflammatory-factor levels were detected using ELISA. Osteogenic differentiation was assessed using Alizarin red staining technique. The interaction between histone deacetylase 6 (HDAC6) and A-kinase anchoring protein 12 (AKAP12) was investigated through Co- immunoprecipitation.Results: CGRP treatment promoted rat bone marrow-derived macrophages (BMDMs) M2 polarization. CGRP facilitated osteogenic differentiation by enhancing M2 polarization of BMDMs. Mechanistically, CGRP promoted AKAP12 acetylation to activate the extracellular regulated protein kinases pathway by HDAC6 inhibition.Conclusion: CGRP promoted M2 polarization of rat BMDMs and facilitated osteogenic differentiation through the HDAC6/AKAP12/extracellular regulated protein kinases signaling pathway, thereby promoting bone healing.

Fat Phagocytosis Promotes Anti-Inflammatory Responses of Macrophages in a Mouse Model of Osteonecrosis

Osteonecrosis (ON) of the femoral head (ONFH) is a devastating bone disease affecting over 20 million people worldwide. ONFH is caused by a disruption of the blood supply, leading to necrotic cell death and increased inflammation. Macrophages are the key cells mediating the inflammatory responses in ON. It is unclear what the dynamic phenotypes of macrophages are and what mechanisms may affect macrophage polarization and, therefore, the healing process. In our preliminary study, we found that there is an invasion of macrophages into the repair tissue during ON healing. Interestingly, in both ONFH patients and a mouse ON model, fat was co-labeled within macrophages using immunofluorescence staining, indicating the phagocytosis of fat by macrophages. To study the effects of fat phagocytosis on the macrophage phenotype, we set up an in vitro macrophage and fat co-culture system. We found that fat phagocytosis significantly decreased M1 marker expression, such as IL1β and iNOS, in macrophages, whereas the expression of the M2 marker Arg1 was significantly increased with fat phagocytosis. To investigate whether the polarization change is indeed mediated by phagocytosis, we treated the cells with Latrunculin A (LA, which inhibits actin polymerization and phagocytosis). LA supplementation significantly reversed the polarization marker gene changes induced by fat phagocytosis. To provide an unbiased transcriptional gene analysis, we submitted the RNA for bulk RNA sequencing. Differential gene expression (DGE) analysis revealed that the top upregulated genes were related to anti-inflammatory responses, while proinflammatory genes were significantly downregulated. Additionally, using pathway enrichment and network analyses (Metascape), we confirmed that gene-enriched categories related to proinflammatory responses were significantly downregulated in macrophages with fat phagocytosis. Finally, we validated the similar macrophage phenotype changes in vivo. To summarize, we discovered that fat phagocytosis occurs in both ONFH patients and an ON mouse model, which inhibits proinflammatory responses with increased anabolic gene expression in macrophages. This fat-phagocytosis-induced macrophage phenotype is consistent with the in vivo changes shown in the ON mouse model. Our study reveals a novel phagocytosis-mediated macrophage polarization mechanism in ON, which fills in our knowledge gaps of macrophage functions and provides new concepts in macrophage immunomodulation as a promising treatment for ON.

A triple growth factor strategy for optimizing bone augmentation in mice

With dental implant treatment becoming the gold standard, the need for effective bone augmentation prior to implantation has grown. This study aims to evaluate a bone augmentation strategy integrating three key growth factors: bone morphogenetic protein-2 (BMP-2), insulin-like growth factor 1 (IGF-1), and vascular endothelial growth factor (VEGF). Collagen scaffolds incorporating BMP-2, IGF-1, or VEGF were fabricated and categorized into five groups based on their content: scaffold alone; BMP-2 alone (BMP-2); BMP-2 and IGF-1 (BI); BMP-2, IGF-1, and VEGF (BIV); and BMP-2 and IGF-1 with an earlier release of VEGF (BI + V). The prepared scaffolds were surgically implanted into the calvarias of C57BL/6JJcl mice, and hard tissue formation was assessed after 10 and 28 days through histological, tomographic, and biochemical analyses. The combination of BMP-2 and IGF-1 induced a greater volume of hard tissue augmentation compared with that of BMP-2 alone, regardless of VEGF supplementation, and these groups had increased levels of cartilage compared with others. The volume of hard tissue formation was greatest in the BIV group. In contrast, the BI + V group exhibited a hard tissue volume similar to that of the BI group. While VEGF and CD31 levels were highest in the BIV group at 10 days, there was no correlation at the same time point between hard tissue formation and the quantity of M2 macrophages. In conclusion, the simultaneous release of BMP-2, IGF-1, and VEGF proved to be effective in promoting bone augmentation.