Rate and Timing of Progression to Total Knee Arthroplasty After Anterior Cruciate Ligament Reconstruction in Patients With Systemic Inflammatory Disease: A Long-term Propensity-Matched Cohort Study

BACKGROUND

Anterior cruciate ligament reconstruction (ACLR) is one of the most common orthopaedic procedures and one of the most well studied. Despite extensive research dedicated to ACLR, there is limited understanding of how chronic inflammatory systemic diseases (CIDs) such as rheumatoid arthritis and systemic lupus erythematosus affect outcomes.

PURPOSE

To compare the outcomes of ACLR in cohorts of patients with and without CID.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective query of a regional data set was conducted for all patients who underwent ACLR from 1990 to 2021 for traumatic ACL rupture. All patients with CID were identified and propensity matched to non-CID controls. Baseline characteristics and clinical outcomes were identified through retrospective chart review, and patients were contacted for subjective outcomes.

RESULTS

A total of 30 patients with ACLR and a diagnosis of CID were identified. These patients were propensity matched to 120 non-CID controls. Baseline demographic and surgical characteristics demonstrated no statistical differences. Follow-up duration was similar between the CID and non-CID groups (mean, 14.6 vs 14.2 years; P = .868). The CID cohort had a higher arthrofibrosis rate (16.7% vs 4.3%; P = .031), higher osteoarthritis rate (33.3% vs 16.7%; P = .041), higher total knee arthroplasty (TKA) rate (16.7% vs 3.3%; P = .016), and earlier time to TKA (14.7 vs 23.5 years; P = .032). Knee range of motion, infection rate, retear rate, time to retear, and time to osteoarthritis were not statistically different between the cohorts. The CID cohort had higher visual analog scale pain scores (mean, 2.00 vs 1.20; P = .043) but slightly higher satisfaction (mean, 3.92 vs 3.39; P = .043). There were no differences in preinjury Tegner, postoperative Tegner, change in Tegner, or IKDC score. In a univariate Cox regression model, the CID cohort had a retear hazard ratio of 1.43 (95% CI, 0.46-4.51; P = .537). Kaplan-Meier survival revealed no significant differences in retear-free survival between the CID and non-CID cohorts at 25 years (85.7% vs 87.3%; P = .53). The CID cohort had a TKA hazard ratio of 3.94 (95% CI, 1.05-14.8; P = .042). Kaplan-Meier survival demonstrated significantly decreased TKA-free survival at 25 years in the CID cohort (64.9% vs 91.2%; P = .029).

CONCLUSION

CID increases the incidence of arthrofibrosis, osteoarthritis, and TKA in those undergoing ACLR. Patients with CID also undergo TKA significantly sooner than non-CID counterparts. Notably, the majority of patient-reported outcome measures are no worse in patients who have a CID diagnosis. Thus, ACLR constructs themselves may not necessarily fare worse in patients with CID. Nonetheless, these patients need to be cautiously counseled on the clinical outlook after their ACLR.

Interplay between lipid dysregulation and ferroptosis in chondrocytes and the targeted therapy effect of metformin on osteoarthritis

INTRODUCTION

Osteoarthritis (OA) is a devastating whole-joint disease affecting a large population worldwide; the role of lipid dysregulation in OA and mechanisms underlying targeted therapy effect of lipid-lowering metformin on OA remains poorly defined.

OBJECTIVES

To investigate the effects of lipid dysregulation on OA progression and to explore lipid dysregulation-targeting OA treatment of metformin.

METHODS

RNA-Seq data, biochemical, and histochemical assays in human and murine OA cartilage as well as primary chondrocytes were utilized to determine lipid dysregulation. Effects of metformin, a potent lipid-lowering medication, on ACSL4 expression and chondrocyte metabolism were determined. Further molecular experiments, including RT-qPCR, western blotting, flow cytometry, and immunofluorescence staining, were performed to investigate underlying mechanisms. Mice with intra-articular injection of metformin were utilized to determine the effects on ACLT-induced OA progression.

RESULTS

ACSL4 and 4-HNE expressions were elevated in human and ACLT-induced mouse OA cartilage and IL-1β-treated chondrocytes (P < 0.05). Ferrostatin-1 largely rescued IL-1β-induced MDA, lipid peroxidation, and ferroptotic mitochondrial morphology (P < 0.05). Metformin decreased the levels of OA-related genes (P < 0.05) and increased the levels of p-AMPK and p-ACC in IL-1β-treated chondrocytes. Intra-articular injection of metformin alleviated ACLT-induced OA lesions in mice, and reverted the percentage of chondrocytes positive for MMP13, Col2a1, ACSL4 and 4-HNE in ACLT mice (P < 0.05). Ferroptotic chondrocytes promoted the recruitment and chemotaxis of RAW264.7 cells via CCL2, which was blocked by metformin in vitro (P < 0.05).

CONCLUSION

We establish a critical role of polyunsaturated fatty acids metabolic process in OA cartilage degradation and define metformin as a potential OA treatment. Metformin reshapes lipid availability and ameliorates chondrocyte ferroptosis sensitivity via the AMPK/ACC pathway. In the future, gene-edited animals and extensive omics technologies will be utilized to reveal detailed lipids' involvement in cartilage lesions.

Directional Freeze-Casting Cryogel Loaded with Quaternized Chitosan Modified Gallium Metal-Organic Frameworks to Capture and Eradicate the Resistant Bacteria for Guided Regeneration in Infected Bone Defects

Antimicrobial resistance and impaired bone regeneration are the great challenges in treating infected bone defects. Its recurrent and resistant nature, high incidence rate, long-term hospitalization, and high medical costs have driven the efforts of the scientific community to develop new therapies to improve the situation. Considering the complex microenvironment and persistent mechanisms mediated by resistant bacteria, it is crucial to develop an implant with enhanced osseointegration and sustained and effective infection clearance effects. Here, a positively charged quaternized chitosan (QCS) coated gallium-based metal-organic framework (GaMOF) is designed, to capture the antibiotic-resistant bacteria (Methicillin-resistant Staphylococcus aureus, MRSA) as a "captor", and rejuvenate Methicillin (Me) via disturbing the tricarboxylic acid (TCA) cycle. Then, a radially oriented porous cryogel loaded with the Me and QCSGaMOF is fabricated by the directional freeze-casting method. The oriented porous structure has an enhanced osseointegration effect by guiding the ingrowth of osteogenic cells. In vitro and in vivo experiments prove the advantages of as-prepared Me/QCSGa-MOF@Cryogel in combating resistant bacteria and guiding bone regeneration in infected bone defects.

Methyltransferase-like 3 mediates m6A modification of heme oxygenase 1 mRNA to induce ferroptosis of renal tubular epithelial cells in acute kidney injury

Acute kidney injury (AKI) involves a series of syndromes characterized by a rapid increase in creatinine levels. Ferroptosis, as an iron-dependent mode of programmed cell death, reportedly participates in the pathogenesis of AKI. Methyltransferase-like 3 (METTL3)-mediated N6-methyladenosine (m6A) modification has been recently associated with various kidney diseases; however, the mechanism of METTL3 crosstalk with the molecules involved in ferroptosis is not clearly understood. Here, we investigated the crosstalk between METTL3-mediated m6A modification and ferroptosis in AKI. METTL3-mediated m6A modification was elevated in patients with AKI, folic acid-AKI mice, and tert-butyl hydrogen peroxide-stimulated TCMK-1 cells. Inhibition of METTL3 expression in vivo and in vitro alleviated the damage and ferroptosis in renal tubular cells. Methylated RNA immunoprecipitation sequencing showed that heme oxygenase 1 (Hmox1/HO-1) was the METTL3 target. RNA immunoprecipitation-qPCR indicated that anti-insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) could be used as a reader to bind to the methylated site of Hmox1 mRNA to maintain its stability. Hmox1 knockdown in vitro reduced the accumulation of iron ions and alleviated ferroptosis. METTL3 mediates the m6A modification of Hmox1 mRNA and maintains its stability in an IGF2BP3-dependent manner, which causes iron overload in renal tubular epithelial cells, leading to ferroptosis and AKI.

Combining functionalities-nanoarchitectonics for combatting bacterial infection

New antimicrobial and anti-inflammatory therapeutics are needed because of antibiotic resistance development and resulting complications such as inflammation, ultimately leading to septic shock. The antimicrobial effects of various nanoparticles (NPs) are currently attracting intensive research interest. Although various NPs display potent antimicrobial effects against strains resistant to conventional antibiotics, the therapeutic use of such materials is restricted by poor selectivity between bacteria and human cells, leading to adverse side effects. As a result, increasing research efforts during the last few years have focused on targeting NPs against bacteria and other components in the infection micro-environment. Examples of approaches explored include peptide-, protein- and nucleic acid-based NP coatings for bacterial membrane recognition, as well as NP conjugation with enzyme substrates or other moieties that respond to bacterial or other enzymes present in the infection micro-environment. In general, this study aims to add to the literature on the antimicrobial effects of nanomaterials by discussing surface modification strategies for targeting bacterial membranes and membrane components, as well as how such surface modifications can improve the antimicrobial effects of nanomaterials and simultaneously decrease toxicity towards human cells and tissues. In doing so, the biological effects observed are related throughout to the physico-chemical modes of action underlying such effects.

Mechanisms of Ferroptosis in bone disease: A new target for osteoporosis treatment

Osteoporosis (OP) is a common disease in the elderly, characterized by decreased bone strength, reduced bone density, and increased fracture risk. There are two clinical types of osteoporosis: primary osteoporosis and secondary osteoporosis. The most common form is postmenopausal osteoporosis, which is caused by decreased estrogen production after menopause. Secondary osteoporosis, on the other hand, occurs when certain medications, diabetes, or nutritional deficiencies lead to a decrease in bone density. Ferroptosis, a new iron-dependent programmed cell death process, is critical in regulating the development of osteoporosis, but the underlying molecular mechanisms are complex. In the pathologic process of osteoporosis, several studies have found that ferroptosis may occur in osteocytes, osteoblasts, and osteoclasts, cell types closely related to bone metabolism. The imbalance of iron homeostasis in osteoblasts and excessive iron accumulation can promote lipid peroxidation through the Fenton reaction, which induces ferroptosis in osteoblasts and affects their role in regulating bone metabolism. Ferroptosis in osteoblasts inhibits bone formation and reduces the amount of new bone production. Osteoclast-associated ferroptosis abnormalities, on the other hand, may alter the homeostasis of bone resorption. In this paper, we start from the molecular mechanism of ferroptosis, and introduce the ways in which ferroptosis affects the physiological and pathological processes of the body. After that, the effects of ferroptosis on osteoblasts and osteoclasts will be discussed separately to elucidate the molecular mechanism between ferroptosis and osteoporosis, which will provide a new breakthrough for the prevention and treatment of osteoporosis and a more effective and better idea for the treatment strategy of osteoporosis.

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.

Enzyme-crosslinked hyaluronic acid hydrogel scaffolds for BMSCs microenvironment and wound healing

Tissue engineering utilizing hydrogel scaffolds in combination with exogenous stem cells holds significant potential for promoting wound regeneration. However, the microenvironment provided by existing skin tissue engineering scaffold materials is often inadequate. Herein, we demonstrate an enzyme-crosslinked hyaluronic acid hydrogel to provide a growth microenvironment for exogenous bone marrow mesenchymal stem cells and promote acute wound healing. This material is developed by grafting dopamine onto hyaluronic acid, followed by enzyme crosslinking using horseradish peroxidase and hydrogen peroxide, which creates a loose, porous structure. The hydrogel possesses adhesive and self-healing properties, offering a microenvironment with excellent cell compatibility for exogenous BMSCs. In vivo studies showed that this hydrogel significantly accelerated the healing of acute full-thickness skin wounds, resulting in the formation of appendages such as hair follicles and minimal scarring. This study not only presents a novel skin tissue engineering scaffold but also offers a promising clinical strategy for achieving scar-minimized wound healing.

Sympathetic innervation induces exosomal miR-125 transfer from osteoarthritic chondrocytes, disrupting subchondral bone homeostasis and aggravating cartilage damage in aging mice

INTRODUCTION

Osteoarthritis (OA) is a progressive disease that poses a significant threat to human health, particularly in aging individuals: Although sympathetic activation has been implicated in bone metabolism, its role in the development of OA related to aging remains poorly understood. Therefore, this study aimed to investigate how sympathetic regulation impacts aging-related OA through experiments conducted both in vivo and in vitro.

METHODS

To analyze the effect of sympathetic regulation on aging-related OA, we conducted experiments using various mouse models. These models included a natural aging model, a medial meniscus instability model, and a load-induced model, which were used to examine the involvement of sympathetic nerves. In order to evaluate the expression levels of β1-adrenergic receptor (Adrβ1) and sirtuin-6 (Sirt6) in chondrocytes of naturally aging OA mouse models, we performed assessments. Additionally, we investigated the influence of β1-adrenergic receptor knockout or treatment with a β1-adrenergic receptor blocker on the progression of OA in aging mice and detected exosome release and detected downstream signaling expression by inhibiting exosome release. Furthermore, we explored the impact of sympathetic depletion through tyrosine hydroxylase (TH) on OA progression in aging mice. Moreover, we studied the effects of norepinephrine(NE)-induced activation of the β1-adrenergic receptor signaling pathway on the release of exosomes and miR-125 from chondrocytes, subsequently affecting osteoblast differentiation in subchondral bone.

RESULTS

Our findings demonstrated a significant increase in sympathetic activity, such as NE levels, in various mouse models of OA including natural aging, medial meniscus instability, and load-induced models. Notably, we observed alterations in the expression levels of β1-adrenergic receptor and Sirt6 in chondrocytes in OA mouse models associated with natural aging, leading to an improvement in the progression of OA. Critically, we found that the knockout of β1-adrenergic receptor or treatment with a β1-adrenergic receptor blocker attenuated OA progression in aging mice and the degraded cartilage explants produced more exosome than the nondegraded ones, Moreover, sympathetic depletion through TH was shown to ameliorate OA progression in aging mice. Additionally, we discovered that NE-induced activation of the β1-adrenergic receptor signaling pathway facilitated the release of exosomes and miR-125 from chondrocytes, promoting osteoblast differentiation in subchondral bone.

CONCLUSION

In conclusion, our study highlights the role of sympathetic innervation in facilitating the transfer of exosomal miR-125 from osteoarthritic chondrocytes, ultimately disrupting subchondral bone homeostasis and exacerbating cartilage damage in aging mice. These findings provide valuable insights into the potential contribution of sympathetic regulation to the pathogenesis of aging-related OA.

Substrate stiffness modulates osteogenic and adipogenic differentiation of osteosarcoma through PIEZO1 mediated signaling pathway

Most osteosarcoma (OS) cases exhibit poor differentiation at the histopathological level. Disruption of the normal osteogenic differentiation process results in the unregulated proliferation of precursor cells, which is a critical factor in the development of OS. Differentiation therapy aims to slow disease progression by restoring the osteogenic differentiation process of OS cells and is considered a new approach to treating OS. However, there are currently few studies on the mechanism of differentiation of OS, which puts the development of differentiation therapeutic drugs into a bottleneck. Substrate stiffness can regulate differentiation in mesenchymal stem cells. Evidence supports that mesenchymal stem cells and osteoblast precursors are the origin of OS. In this study, we simulated different stiffnesses in vitro to investigate the mechanism of substrate stiffness affecting differentiation of OS. We demonstrate that Piezo type mechanosensitive ion channel component 1 (PIEZO1) plays a critical regulatory role in sensing substrate stiffness in osteogenic and adipogenic differentiation of OS. When OS cells are cultured on the stiff substrate, integrin subunit beta 1 (ITGB1) increases and cooperates with PIEZO1 to promote Yes-Associated Protein (YAP) entering the nucleus, and may inhibit EZH2, thereby inhibiting H3K27me3 and increasing RUNX2 expression, and cells differentiate toward osteogenesis. Our results provide new insights for research on differentiation treatment of OS and are expected to help identify new targets for future drug design.

Targeting PTGDS Promotes ferroptosis in peripheral T cell lymphoma through regulating HMOX1-mediated iron metabolism

BACKGROUND

Peripheral T cell lymphoma (PTCL) is characterized by high heterogeneity, strong aggressiveness, and extremely poor prognosis. Ferroptosis, a novel form of programmed cell death, has been involved in tumor development and targeting ferroptosis holds great potential for tumor therapy.

METHODS

Lentiviral transfection was performed to regulate gene expression, followed by Tandem mass tag (TMT)-mass spectrometry and RNA-sequencing. Tumor xenograft models were established for in vivo experiments.

RESULTS

High expression of prostaglandin D2 synthase (PTGDS) was closely associated with poor prognosis of PTCL patients. PTGDS knockdown and AT56 treatment significantly inhibited the progression of PTCL through regulating cell viability, proliferation, apoptosis, cell cycle and invasion in vitro and in vivo. We further revealed that targeting PTGDS promoted ferroptosis process and enhanced the sensitivity of PTCL cells to ferroptosis inducers Sorafenib in vitro and in vivo. Mechanically, PTGDS interacted with heme-degrading enzymes HMOX1, and targeting PTGDS increased the level of iron and induced ferroptosis in PTCL through promoting HMOX1-mediated heme catabolism and ferritin autophagy process. Through the construction of H25A mutation, the specific gene site of HMOX1 corresponding to its role was identified.

CONCLUSIONS

Taken together, our findings firstly identified that targeting PTGDS promotes the ferroptosis in PTCL through regulating HMOX1-mediated iron metabolism, and highlighted novel therapeutic strategies to improve the efficacy of ferroptosis-targeted therapy in PTCL patients.

Targeted Management of Diabetic Osteoporosis by Biocatalytic Cascade Reaction Nanoplatform

Diabetic osteoporosis (DOP) is a chronic complication of diabetes mellitus (DM) that impairs bone health, and effective management of DOP remains a formidable challenge. In this study, we developed a biocatalytic cascade nanoplatform, GOx@SrCaP-CAT-Tet, offering osteogenic, angiogenic, and anti-inflammatory activities for targeted DOP management. The platform includes glucose oxidase (GOx) and catalase (CAT), encapsulated in strontium-doped calcium phosphate (SrCaP), converting glucose into gluconic acid and hydrogen peroxide (H2O2), alleviating the hyperglycemia and promoting hypoxia-induced vascularization. Both the generated H2O2 and any overabundance of H2O2 in the DOP microenvironment can be scavenged by CAT, thus relieving inflammation. Via a surface modified with tetracycline (Tet) for bone targeting, the release of Sr2+, Ca2+, and PO43- can stimulate osteogenesis and suppress osteoclastogenesis, thereby hastening bone formation and reversing osteoporosis. This nanoplatform shows promise in managing DOP both in vitro and in vivo. Our findings open a new horizon for managing DOP through biocatalytic cascade reactions.

Mesenchymal stem cells and mesenchymal stem cell-derived exosomes: a promising strategy for treating retinal degenerative diseases

Mesenchymal stem cells (MSCs) have emerged as a promising therapeutic strategy in regenerative medicine, demonstrating significant potential for clinical applications. Evidence suggests that MSCs not only exhibit multipotent differentiation potential but also exert critical therapeutic effects in retinal degenerative diseases via robust paracrine mechanisms. MSCs protect retinal cells from degenerative damage by modulating inflammation, inhibiting apoptosis, alleviating oxidative stress, and suppressing cell death pathways. Furthermore, MSCs contribute to retinal structural and functional stability by facilitating vascular remodeling and donating mitochondria to retinal cells. Of particular interest, MSC-derived exosomes have gained widespread attention as a compelling cell-free therapy. Owing to their potent anti-inflammatory, anti-apoptotic, and vascular-stabilizing properties, exosomes show significant promise for the treatment of retinal degenerative diseases.

Integrating Machine Learning into Additive Manufacturing of Metallic Biomaterials: A Comprehensive Review

The global increase in osteomuscular diseases, particularly bone defects and fractures, has driven the growing demand for metallic implants. Additive manufacturing (AM) has emerged as a transformative technology for producing high-precision metallic biomaterials with customized properties, offering significant advantages over traditional manufacturing methods. The integration of machine learning (ML) with AM has shown great promise in optimizing the fabrication process, enhancing material performance, and predicting long-term behavior, particularly in the development of orthopedic implants and vascular stents. This review explores the application of ML in AM of metallic biomaterials, focusing on four key areas: (1) component design, where ML guides the optimization of multi-component alloys for improved mechanical and biological properties; (2) structural design, enabling the creation of intricate porous architectures tailored to specific functional requirements; (3) process control, facilitating real-time monitoring and adjustment of manufacturing parameters; and (4) parameter optimization, which reduces costs and enhances production efficiency. This review offers a comprehensive overview of four key aspects, presenting relevant research and providing an in-depth analysis of the current state of ML-guided AM techniques for metallic biomaterials. It enables readers to gain a thorough understanding of the latest advancements in this field. Additionally, the this review addresses the challenges in predicting in vivo performance, particularly degradation behavior, and how ML models can assist in bridging the gap between in vitro tests and clinical outcomes. The integration of ML in AM holds great potential to accelerate the design and production of advanced metallic biomaterials.

The Role of Copper Intake in Bone Health: A Quantitative Analysis in Postmenopausal Spanish Women

(1) Background: Copper is a crucial trace element which is vital to growth and development and is especially important in bone health. Copper intake is now the focus of much broader research beyond its associations with nail growth, looking at copper's potential in contributing to bone integrity to prevent a high risk of osteoporosis as well. (2) Methods: This study included postmenopausal women from a larger longitudinal study conducted between 2019 and 2022. Bone health was assessed using three quantitative techniques: heel QUS, DXA and pQCT. Copper intake was evaluated using a 131-item, 7-day food frequency questionnaire. Data from these assessments were used to analyze the relationship between copper intake and bone health. (3) Results: In the unadjusted multiple linear regression model, associations were found between copper intake levels and both BUA (dB/MHz) and pQCT cortical + subcortical density (mg/cm3), with copper intake acting as a negative predictor in both instances. However, these associations lost statistical significance after adjusting for participant age and weight. No further associations were identified for the other parameters assessed. (4) We conclude that our study does not reveal an association between copper intake and bone health in postmenopausal Spanish women.

Articular cartilage degeneration and aberrant osteocyte perilacunar/canalicular remodeling in subchondral bone of patients with developmental dysplasia of the hip

BACKGROUND

Developmental dysplasia of the hip (DDH) is a congenital musculoskeletal disease that impairs the hip joint and exacerbates hip osteoarthritis. This study aims to investigate the alterations of osteocytic characteristics including apoptosis, lacuna-canalicular network, and perilacunar/canalicular remodeling (PLR) activity in subchondral bone from DDH patients, and potential relationship of these alterations between the cartilage degeneration and DDH progression.

METHODS

The femoral head specimens were acquired from 16 patients with hip fractures who received total hip arthroplasty operation, 24 patients with primary hip OA and 25 patients with DDH. The femoral head were scanned by a micro-computed tomography and the volume of interest was used for a micro-finite element analysis. Histological and immunohistochemical staining was used to observe chondrocytes in cartilage and osteocytes in subchondral bone. Terminal deoxynucleotidyl transferase dUTP nick end labeling staining was used to investigate the apoptotic osteocytes in subchondral bone. Ploton silver staining was used to visualize lacunocanalicular network and picrosirius red staining was to visualize collagen fiber orientation in subchondral bone.

RESULTS

The DDH group showed the highest apoptosis rate of osteocytes and increased PLR activity among the three groups. The micro-finite-element analysis revealed that DDH group had deteriorative microstructural and biomechanical properties of subchondral bone. The histological and immunohistochemical analyses showed that the cartilage degeneration in DDH group was the most severe. Linear regression analysis revealed a significant correlation between osteocytic activity in subchondral bone and cartilage degeneration in DDH.

CONCLUSIONS

Our findings indicate that the abnormal osteocyte activity in subchondral bone might contribute to the deterioration of subchondral bone structure, which accelerates cartilage degeneration and DDH progression. Targeting subchondral bone remodeling could offer a promising therapeutic strategy for DDH.

Ferroptosis in senescence and age-related diseases: pathogenic mechanisms and potential intervention targets

As the global population continues to age, the prevalence of age-related diseases is increasing, significantly influencing social and economic development, the stability of social security systems, and progress in medical technology. Ferroptosis, a recently discovered form of programmed cell death driven by iron-dependent lipid peroxidation, has emerged as a key area of research. Studies have revealed a strong association between ferroptosis and senescence. In this article, we systematically summarize the molecular mechanisms and associated signaling pathways underlying ferroptosis, emphasizing its pivotal role in the onset and progression of age-related diseases. By providing new perspectives, we aim to advance understanding of the pathogenesis of age-related diseases and guide the development of effective intervention strategies.

The Gut Microbiota Metabolite Butyrate Modulates Acute Stress-Induced Ferroptosis in the Prefrontal Cortex via the Gut-Brain Axis

Stress has been implicated in the onset of mental disorders such as depression, with the prefrontal cortex (PFC) playing a crucial role. However, the underlying mechanisms remain to be fully elucidated. Metabolites secreted by intestinal flora can enter the bloodstream and exert regulatory effects on the body. Consequently, this study aims to investigate the molecular mechanisms by which gut flora influences ferroptosis in PFC neurons, thereby affecting depression-like behavioral changes in mice subjected to acute stress. Initially, we established a mouse model of acute restraint stress (3-day duration) and verified that stress-induced ferroptosis of PFC neurons contributed to depression-like behavioral alterations in mice, as evidenced by morphological, behavioral, and molecular biology assessments. Subsequently, through fecal microbiota transplantation (FMT) experiments, we established a significant correlation between gut microbiota and ferroptosis of PFC neurons in acute stress-exposed mice. 16S rDNA sequencing identified butyric acid-producing bacteria, specifically g_Butyricimonas and its primary metabolite, butyric acid, as critical regulators of ferroptosis in PFC neurons in acutely stressed mice. Furthermore, the intervention of butyrate demonstrated its potential to ameliorate damage to the intestinal and blood-brain barriers in these mice. This intervention also mitigated depression-like behaviors induced by ferroptosis of PFC neurons by alleviating systemic inflammatory responses. The findings of this study indicate that acute stress-induced ferroptosis of PFC neurons plays a critical role in depression-like behavioral changes in mice. Additionally, the gut microbiota metabolite butyrate can modulate ferroptosis and depression-like behavioral changes through the gut-brain axis.

Progress in multi-omics studies of osteoarthritis

Osteoarthritis (OA), a ubiquitous degenerative joint disorder, is marked by pain and disability, profoundly impacting patients' quality of life. As the population ages, the global prevalence of OA is escalating. Omics technologies have become instrumental in investigating complex diseases like OA, offering comprehensive insights into its pathogenesis and progression by uncovering disease-specific alterations across genomics, transcriptomics, proteomics, and metabolomics levels. In this review, we systematically analyzed and summarized the application and recent achievements of omics technologies in OA research by scouring relevant literature in databases such as PubMed. These studies have shed light on new potential therapeutic targets and biomarkers, charting fresh avenues for OA diagnosis and treatment. Furthermore, in our discussion, we highlighted the immense potential of spatial omics technologies in unraveling the molecular mechanisms of OA and in the development of novel therapeutic strategies, proposing future research directions and challenges. Collectively, this study encapsulates the pivotal advances in current OA research and prospects for future investigation, providing invaluable references for a deeper understanding and treatment of OA. This review aims to synthesize the recent progress of omics technologies in the realm of OA, aspiring to furnish theoretical foundations and research orientations for more profound studies of OA in the future.

Investigating the molecular mechanisms of Jiangu Decoction in treating type 2 diabetic osteoporosis

ETHNOPHARMACOLOGICAL RELEVANCE

Type 2 diabetic osteoporosis (T2DOP) is a metabolic bone disease characterized by impaired bone structure and decreased bone strength in diabetic patients. Jiangu Decoction (JGD), a traditional Chinese poly-herbal formulation, has shown efficacy in mitigating osteoporosis (OP) and fractures caused by osteoporosis in diabetic patients in clinical trials. In addition, JGD has been proven to promote the proliferation of osteoblasts. However, the specific mechanisms underlying these effects remain unclear.

AIM OF THE STUDY

This study aimed to elucidate the molecular mechanisms underlying the therapeutic effects of JGD in treating T2DOP.

MATERIALS AND METHODS

Liquid chromatography-mass spectrometry (LC-MS) was utilized to elucidate the chemical profile of JGD. A T2DOP mouse model (C57BL/6) was established by combining a high-fat diet with streptozotocin (STZ). Micro-computed tomography (micro-CT) imaging, three-point bending tests, and histological staining were utilized to assess alterations in bone mass, bone quality, and bone strength in mice. Mouse Calvaria 3T3-E1 (MC3T3-E1) cells were treated with 33 mmol/L D-glucose (HG), and the protective effect of JGD on the high glucose injury model was observed. Western blotting and qRT-PCR were employed to analyze alterations in biomarkers associated with the Keap1/Nrf2/HO-1 signaling pathway, both in vivo and in vitro.

RESULTS

A total of 909 compounds were identified in JGD using LC-MS. Subsequently, the function of JGD was evaluated both in vitro and in vivo. The findings indicated that JGD promoted bone formation, enhanced bone microstructure, and ameliorated diabetic symptoms in T2DOP mice. Additionally, JGD increased alkaline phosphatase (ALP) activity, facilitated bone mineralization, and upregulated the expression levels of osteogenic marker genes such as runt-related transcription factor 2 (Runx2), osteocalcin (Ocn), and collagen type 1 alpha (Col1a1). Importantly, JGD reduced oxidative stress levels and decreased the accumulation of reactive oxygen species by modulating the Keap1/Nrf2/HO-1 axis both in vivo and in vitro.

CONCLUSION

Our study suggests that JGD could alleviate T2DOP impairment, closely linked to the Keap1/Nrf2/HO-1 signaling pathway.

Stimuli-responsive mesoporous silica nanoplatforms for smart antibacterial therapies: From single to combination strategies

The demand for new antibacterial therapies is urgent and crucial in the clinical setting because of the growing degree of antibiotic resistance and the limits of conventional antibacterial therapies. Stimuli- responsive nanoplatforms, are sensitive to endogenous or exogenous stimulus (pH, temperature, light, and magnetic fields, etc.) which activate cargo release locally and on-demand, hold great potential in developing next generation personalized precision medicine. For instance, pH-sensitive nanoplatforms can selectively release antibacterial agents in the acidic environment of infection sites. To achieve the stimuli-responsive delivery, mesoporous silica nanoplatforms (MSNs) have demonstrated as prospective candidates for efficient cargo loading and controlled release through strategies such as tunable pore engineering, versatile surface modification/coating, and tailored framework composition. Furthermore, aiming for more precise delivery of MSNs, current research interests are increasingly shifting from single-stimuli antibacterial strategy to integrated strategy that combine multiple-stimulus. In this review, we briefly discuss the microenvironment of bacterial infections and provide a comprehensive summary of current stimuli-responsive strategies, and associated materials design principles of stimuli-responsive mesoporous silica-based smart nanoplatforms (SRMSNs). Additionally, integrative antibacterial strategies with synergistic effects, combining chemodynamic, photodynamic, photothermal, sonodynamic and gas therapies, have also been elaborated. Present research advances and limitations of SRMSNs-based antibacterial therapies, such as limited biodegradability and potential cytotoxicity, have been overviewed with future outlooks presented. This review aims to inspire and guide future research in developing novel antibacterial strategies with integrative solutions.

The application of procyanidins in diabetes and its complications: a review of preclinical studies

Diabetes mellitus (DM) and its various complications, including diabetic nephropathy, retinopathy, neuropathy, cardiovascular disease, and ulcers, pose significant challenges to global health. This review investigates the potential of procyanidins (PCs), a natural polyphenolic compound, in preventing and managing diabetes and its complications. PCs, recognized for their strong antioxidant, anti-inflammatory, and anti-hyperglycemic properties, play a crucial role in reducing oxidative stress and enhancing endothelial function, which are essential for managing diabetic complications. This review elucidates the molecular mechanisms by which PCs improve insulin sensitivity and endothelial health, thereby providing protection against the various complications of diabetes. The comprehensive analysis underscores the promising therapeutic role of PCs in diabetes care, indicating the need for further clinical studies to confirm and leverage their potential in comprehensive diabetes management strategies.

Changes in spino-pelvis-lower extremity alignment in patients with knee osteoarthritis: a prospective radiographic study

PURPOSE

Osteoarthritis (OA) is a prevalent, debilitating ailment among the elderly. Humans need a correct sagittal spino-pelvis-lower extremity alignment to stand upright. Pathology in trunk or lower extremity section might disrupt this harmony, causing compensatory alterations in other segments. The aim of the present study was to evaluate spino-pelvis-lower extremity alignment and association among the various spino-pelvic, knee, and ankle radiological angles in patients with knee osteoarthritis (OA).

MATERIALS AND METHODS

This prospective study enrolled 70 adults over 50 years of age of either sex who complained of knee pain and met the American College of Rheumatology criteria for symptomatic OA of at least one knee. The radiological assessment comprised anteroposterior and lateral lower extremity full-length scans, as well as the Kellgren-Lawrence radiographic classification of OA. We measured hip, knee, ankle, and spino-pelvic angles using Horos software. We calculated descriptive statistics and linear correlation between continuous variables.

RESULTS

There was a significant association (p < 0.05) between age and the majority of the spino-pelvic, knee, and ankle angles and between age and severity of OA. Significant variables linked with 'SFA' include HKAA (p = 0.008), mLDFA (p < 0.001), TJLA, FS-TS, Cond-Plateau, and femoral bowing (p = 0.007). We found significant associations between 'PFA' and mMPTA (p = 0.005), Cond-Plateau (p = 0.005), Tibial Bowing (p = 0.003), and 'LL' with HKAA, mLDFA, FS-TS, and Cond-Plate. SSA was significantly associated with mLDFA, mMPTA, TJLA, Cond-Plateau, and HKAA; while, FI' was significantly associated with FS-TS, femoral bowing, and tibial bowing (p < 0.001). The variables 'SS' was substantially linked with TTA (p = 0.008), TT (p = 0.004), PP (< 0.001), GP (p < 0.001), and GT (p = 0.010). 'PI' was substantially linked to TT (p = 0.001), GP (p = 0.005), and GT (p = 0.042), and 'PT' to TT (p < 0.001) and GT (p = 0.012). 'SFA' and 'PFA' only correlated with TT (p = 0.012 and 0.010). Lower limb angles were significantly associated with TT, PP, GP, GT, mLDFA, and mMPTA (p = 0.031, p = 0.026, p = 0.009, p = 0.009, TT, GP, GT, p < 0.001). GP was the sole significant association for 'TJLA' (p = 0.016). 'FS-TS' substantially correlated with PP (p = 0.015), GP (p < 0.001), and GT (p < 0.001). "Femoral Bowing" was significantly linked to PP (p = 0.017), GP (p = 0.007), and GT (p < 0.001), and "Cond-Plateau" was significantly linked to GP (p = 0.002) and GT. "Tibial Bowing" was significantly linked to TTA (p < 0.001), TAS (p = 0.003), LDTA (p = 0.002), TC (p < 0.001), GP (p = 0.007), and GT (p < 0.001). Age, gender, BMI, and the severity of knee OA significantly influenced the association among these various angles.

CONCLUSION

Osteoarthritis of the knee disrupts the harmonious alignment of the spine and pelvis with the lower limbs, resulting in compensatory changes in the ankle and spine. The severity of knee osteoarthritis and the patient's gender, age, and BMI impact compensatory adaptations.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

CTRI/2021/08/036088 [Registered on: 31/08/2021] - Trial Registered Prospectively.

C-reactive protein to serum calcium ratio as a novel biomarker for predicting severity in acute pancreatitis: a retrospective cross-sectional study

Background

Acute pancreatitis (AP) is a prevalent gastrointestinal emergency with a wide spectrum of clinical outcomes, varying from mild cases to severe forms. The early identification of high-risk patients is essential for improving prognosis. However, the predictive and prognostic potential of the C-reactive protein to serum calcium ratio (CCR) in AP has not been investigated. This study aims to explore the association between CCR and disease severity in patients with AP.

Methods

This retrospective cross-sectional study included 476 AP patients. The CCR was calculated from C-reactive protein and serum calcium levels within the first 24 h of admission. Multivariable logistic regression models were used to evaluate the relationship between CCR and AP severity, with restricted cubic spline analysis and receiver operating characteristic (ROC) analysis to assess dose-response and predictive performance, respectively.

Results

Of the 476 patients, 176 (37%) had mild acute pancreatitis (MAP) and 300 (63%) had moderate to severe AP. The CCR distribution had a median value of 17.5, with an interquartile range (IQR) of 3.0 to 60.2. Each unit increase in CCR was associated with a 7% increase in the risk of developing moderate to severe AP (OR: 1.07; 95% CI: 1.06-1.09). In fully adjusted models, this association remained statistically significant. The area under the curve (AUC) for CCR in predicting moderate to severe AP was 86.9%, with a sensitivity of 73.7% and specificity of 89.2%.

Conclusion

The CCR measured within the first 24 h of admission shows promise as a valuable biomarker for predicting the severity of AP. However, further multicenter prospective cohort studies are needed to confirm its clinical utility and investigate its role in improving treatment strategies and patient management.

Signaling Pathways Driving MSC Osteogenesis: Mechanisms, Regulation, and Translational Applications

Mesenchymal stem cells (MSCs) are crucial for skeletal development, homeostasis, and repair, primarily through their differentiation into osteoblasts and other skeletal lineage cells. Key signaling pathways, including Wnt, TGF-β/BMP, PTH, Hedgehog, and IGF, act as critical regulators of MSC osteogenesis, playing pivotal roles in maintaining bone homeostasis and facilitating regeneration. These pathways interact in distinct ways at various stages of bone development, mineralization, and remodeling. This review provides an overview of the molecular mechanisms by which these pathways regulate MSC osteogenesis, their influence on bone tissue formation, and their implications in bone diseases and therapeutic strategies. Additionally, we explore the potential applications of these pathways in bone tissue engineering, with a particular focus on promoting the use of MSCs as seed cells for bone defect repair. Ultimately, this review aims to highlight potential avenues for advancing bone biology research, treating bone disorders, and enhancing regenerative medicine.

Targeting ferroptosis: opportunities and challenges of mesenchymal stem cell therapy for type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is characterized by progressive β-cell death, leading to β-cell loss and insufficient insulin secretion. Mesenchymal stem cells (MSCs) transplantation is currently one of the most promising methods for β-cell replacement therapy. However, recent studies have shown that ferroptosis is not only one of the key mechanisms of β-cell death, but also one of the reasons for extensive cell death within a short period of time after MSCs transplantation. Ferroptosis is a new type of regulated cell death (RCD) characterized by iron-dependent accumulation of lipid peroxides. Due to the weak antioxidant capacity of β-cells, they are susceptible to cytotoxic stimuli such as oxidative stress (OS), and are therefore susceptible to ferroptosis. Transplanted MSCs are also extremely susceptible to perturbations in their microenvironment, especially OS, which can weaken their antioxidant capacity and induce MSCs death through ferroptosis. In the pathophysiological process of T1DM, a large amount of reactive oxygen species (ROS) are produced, causing OS. Therefore, targeting ferroptosis may be a key way to protect β-cells and improve the therapeutic effect of MSCs transplantation. This review reviews the research related to ferroptosis of β-cells and MSCs, and summarizes the currently developed strategies that help inhibit cell ferroptosis. This study aims to help understand the ferroptosis mechanism of β-cell death and MSCs death after transplantation, emphasize the importance of targeting ferroptosis for protecting β-cells and improving the survival and function of transplanted MSCs, and provide a new research direction for stem cells transplantation therapy of T1DM in the future.

Fraxinellone-mediated targeting of cathepsin B leakage from lysosomes induces ferroptosis in fibroblasts to inhibit hypertrophic scar formation

BACKGROUND

Hypertrophic scar (HS) is a common fibrotic skin disorder characterized by the excessive deposition of extracellular matrix (ECM). Fibroblasts are the most important effector cells involved in HS formation. Currently no satisfactory treatment has been developed.

METHODS

The impact of fraxinellone (FRA) on the proliferation and migration capacity of human hypertrophic scar-derived fibroblasts (HSFs) was assessed by EdU proliferation, wound healing and transwell assays. Quantitative real-time PCR (qRT‒PCR), Western blot (WB), immunofluorescence staining and collagen gel contraction assays were performed to evaluate the collagen production and activation capacity of HSFs. Oxford Nanopore Technologies long-read RNA sequencing (ONT long-read RNA-seq) revealed the occurrence of ferroptosis in HSF and ferroptosis executioner-cathepsin B (CTSB). The mechanisms underlying FRA-induced HSF ferroptosis were examined through fluorescence staining, qRT‒PCR, WB and molecular docking study. The therapeutic efficacy of FRA was further validated in vivo using a rabbit ear scar model.

RESULTS

FRA treatment significantly suppressed the proliferation, migration, collagen production and activation capacity of HSFs. ONT long-read RNA-seq discovered that FRA modulated the expression of transcripts related to ferroptosis and lysosomes. Mechanistically, FRA treatment reduced the protein expression level of glutathione peroxidase 4 (GPX4) and induced the release of CTSB from lysosomes into the cytoplasm. CTSB further induced ferroptosis via spermidine/spermine-N1-acetyltransferase (SAT1)-mediated lipid peroxidation, mitochondrial damage and mitogen-activated protein kinase (MAPK) signalling pathway activation, eventually affecting the function of HSFs. Moreover, FRA treatment attenuated the formation of HS in rabbit ears via CTSB-mediated ferroptosis. The antifibrotic effects of FRA were abrogated by pretreatment with a CTSB inhibitor (CA-074-me).

CONCLUSIONS

This study reveals that FRA ameliorates HS by inducing CTSB leakage from lysosomes, causing SAT1-mediated lipid peroxidation, mitochondrial damage and MAPK signalling pathway activation, thus mediating HSF ferroptosis. Therefore, FRA could be a promising therapeutic agent for treating HS.

Effect of preoperative medial meniscus status on the outcomes of high tibial osteotomy with human umbilical cord-derived mesenchymal stem cells cartilage regeneration

BACKGROUND

The effect of medial meniscus (MM) status on outcomes following high tibial osteotomy (HTO) combined with cartilage regeneration using human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) remains unclear.

PURPOSE

This study aimed to evaluate the effect of preoperative MM status on the outcomes of HTO combined with cartilage regeneration using hUCB-MSCs. Specifically, clinical and radiological outcomes were compared between two groups of patients, which were divided according to their preoperative MM status. We hypothesized that patients with preserved meniscal integrity or those who underwent meniscal root repair would show better clinical and radiological outcomes compared to those with significant meniscal loss or untreated root tears.

METHODS

A retrospective analysis was performed on 47 patients who underwent HTO with hUCB-MSC implantation. Patients were divided into group P (preserved MM integrity or medial meniscal root repair) and group L (loss of MM integrity, defined as a peripheral rim width <3 mm, unable to maintain hoop function). Clinical outcomes were assessed using the International Knee Documentation Committee (IKDC) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores after a minimum follow-up of 2 years. Cartilage regeneration was evaluated with Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 score and International Cartilage Repair Society (ICRS) Cartilage Repair Assessment (CRA) score from second-look arthroscopy. Correlation analyses were conducted to examine the relationship between preoperative MM extrusion and cartilage repair.

RESULTS

Both groups demonstrated significant improvements in IKDC and WOMAC scores (p < 0.01). No significant differences were observed between groups in IKDC and WOMAC scores at final follow-up (p = 0.21, p = 0.42, respectively). MOCART 2.0 and ICRS CRA scores showed no significant differences between groups (p = 0.35, p = 0.08, respectively). Group P showed higher proportions of favorable outcomes compared to group L, including no major subchondral changes or only minor marrow edema (56% vs. 31.8%) and ICRS CRA grades I or II (84% vs. 72.7%). While these findings suggest potential differences in outcomes, neither comparison reached statistical significance (p = 0.09 and p = 0.48, respectively). Preoperative MM extrusion negatively correlated with MOCART 2.0 and subchondral bone changes (r = -0.24, p = 0.03; r = -0.29, p = 0.02, respectively).

CONCLUSION

HTO with hUCB-MSC implantation provided significant clinical improvements and effective cartilage regeneration regardless of preoperative MM status. However, preoperative MM extrusion may influence subchondral bone changes, emphasizing the need to consider MM status for long-term outcomes.

LEVEL OF EVIDENCE

III; retrospective comparative study.

Biological, Biomechanical, and Histopathological Evaluation of Polyetherketoneketone Bioactive Composite as Implant Material

While polyetherketoneketone is a high-performance thermoplastic polymer, its hydrophobicity and inertness limit bone adhesion. This study aimed to evaluate a novel PEKK/CaSiO3/TeO2 nanocomposite, comparing it to PEKK/15 wt.% CaSiO3 and PEKK groups. The in vitro study, involving 90 discs (n = 30), assessed the cytotoxicity of all groups after 24, 72, and 168 h. The in vivo animal study, using cylinder-type implants (n = 30), evaluated osseointegration through biomechanical push-out tests, descriptive histopathological examinations of decalcified sections stained with hematoxylin and eosin, and histomorphometric analysis of new bone formation area after 2- and 6-week healing intervals. The cytocompatibility of PEKK/15 wt.% CaSiO3/1 wt.% TeO2 composite confirmed its acceptance as a biomedical material. Additionally, in vivo study results showed that the PEKK/15 wt.% CaSiO3/1 wt.% TeO2 had the highest shear strength value and the highest new bone formation area compared to other experimental groups. The multimodal concept of adding CaSiO3 micro fillers and TeO2 nanofillers to PEKK produces a cytocompatible composite that enhances osseointegration and new bone formation in a rabbit's femur after 2- and 6-week healing intervals.

Functional hydrogel empowering 3D printing titanium alloys

Titanium alloys are widely used in the manufacture of orthopedic prosthesis given their excellent mechanical properties and biocompatibility. However, the primary drawbacks of traditional titanium alloy prosthesis are their much higher elastic modulus than cancellous bone and poor interfacial adhesion, which lead to poor osseointegration. 3D-printed porous titanium alloys can partly address these issues, but their bio-inertness still requires modifications to adapt to different physiological and pathological microenvironments. Hydrogels composed of three-dimensional networks of hydrophilic polymers can effectively simulate the extracellular matrix of natural bone and are capable of loading bioactive molecules such as proteins, peptides, growths factors, polysaccharides, or nucleotides for localized release within the human body, by directly participating in biological processes. Combining 3D-printed porous titanium alloys with hydrogels to construct a bioactive composite system that regulates cellular adhesion, proliferation, migration, and differentiation in the local microenvironment is of great significance for enhancing the bioactivity of the prosthesis surface. In this review, we focus on three aspects of the bioactive composite system: (Ⅰ) strategies for constructing bioactive interfaces with hydrogels, and (Ⅱ) how bioactive composite systems regulate the microenvironment under different physiological and pathological conditions to enhance the osteointegration and bone regeneration capability of prostheses. Considering the current research status in this field, innovations in orthopedic prosthesis can be achieved through material optimization, personalized customization, and the development of multifunctional composite systems. These advancements provide essential references for the clinical translation of osseointegration and bone regeneration in various physiological and pathological microenvironments.

In Situ Proefferocytosis Microspheres as Macrophage Polarity Converters Accelerate Osteoarthritis Treatment

Efferocytosis in macrophages typically engages an anti-inflammatory positive feedback regulatory mechanism. In osteoarthritis (OA), characterized by imbalanced inflammatory homeostasis, the proinflammatory state of macrophages in the immune microenvironment can be reversed through enhanced efferocytosis. This study develops an in situ proefferocytosis hydrogel microsphere (macrophage polarity converter, H-C@IL) for OA treatment. Immunoliposomes (IL), CD16/32 antibody-modified clodronate liposomes, are initially prepared using the Re-emulsion method. Then, the IL is loaded into CCL19-modified HAMA microspheres through microfluidic technology. In vitro, H-C@IL can specifically recruit M0 and M1 macrophages via CCL19, induce apoptosis in M1 macrophages through secondary targeting with IL, and provide "Find/Eat-me" signals to enhance in situ efferocytosis. Additionally, it promotes macrophage polarization toward the M2 phenotype. In vivo, behavioral, imaging, and histological analyses demonstrate that H-C@IL effectively facilitates macrophage polarization toward M2, inhibits inflammation, and promotes cartilage regeneration. Mechanistically, H-C@IL enhances efferocytosis by activating proteins such as PROS1 and TIMD4 in M0 macrophages. Concurrently, signaling pathways, including PQLC2-Arg-Rac1 and Pbx1/IL-10, are activated to drive the polarization of macrophages from M0 to M2. In summary, H-C@IL promotes M0 macrophage efferocytosis in situ, facilitates macrophage polarization toward M2, restores inflammatory homeostasis, and promotes cartilage regeneration, offering a comprehensive treatment strategy for OA.

Ginsenoside Rd-Loaded Antioxidant Polymersomes to Regulate Mitochondrial Homeostasis for Bone Defect Healing in Periodontitis

Periodontitis is the leading cause of tooth loss in adults. Initially triggered by bacterial infection, it is characterized by subsequent dysregulation of mitochondrial homeostasis, leading to ongoing loss of periodontal tissue. Mitophagic flux, a critical physiological mechanism for maintaining mitochondrial homeostasis, is compromised in periodontitis. Additionally, increased release of reactive oxygen species (ROS) exacerbates mitochondrial damage. In this study, a ginsenoside Rd (Rd)-loaded antioxidative polymersome (RdAP) is designed, which is self-assembled from a mitochondrial-protective and ROS-scavenging block copolymer, poly(ethylene oxide)-block-poly(phenylboronic acid pinacol ester-conjugated polylysine) (PEO113-b-P(Lys-PAPE)60). The phenylboronic acid pinacol ester (PAPE) segment exhibits excellent ROS-responsive properties, enabling effective ROS scavenging through antioxidant production. Rd significantly enhances mitophagic flux by 2.5-fold in periodontal ligament stem cells (PDLSCs) under oxidative stress. Together with the antioxidative polymersome, RdAPs restore mitochondrial homeostasis and enhance the osteogenic capacity of PDLSCs, bringing it closer to that of healthy controls. In a mouse model of periodontitis, the bone mass in the RdAP-treated group is 1.37 times greater than that in the untreated periodontitis group. Overall, the findings propose a novel strategy for addressing refractory periodontitis, which may also be applicable to other diseases characterized by mitochondrial homeostasis imbalance.

Current and emerging bone resorption inhibitors for the treatment of osteoporosis

INTRODUCTION

Osteoporosis is a metabolic skeletal disease characterized by low bone mass and strength, and increased risk for fragility fractures. It is a major health issue in aging populations, due to fracture-associated increased disability and mortality. Antiresorptive treatments are first line choices in most of the cases.

AREAS COVERED

Bone homeostasis is complicated, and multiple factors can compromise skeletal health. Bone turnover is a continuous process regulated by the coupled activities of bone cells that preserves skeletal strength and integrity. Imbalance between bone resorption and formation leads to bone loss and increased susceptibility to fractures. Antiresorptives prevent bone loss and reduce fracture risk, by targeting osteoclastogenesis and osteoclast function and survival. Their major drawback is the coupling of osteoclast and osteoblast activity, due to which any reduction in bone resorption is followed by suppression of bone formation.

EXPERT OPINION

During the last couple of decades significant progress has been made in understanding of the genetic and molecular basis of osteoporosis. Critical pathways and key molecules that mediate regulation of bone resorption have been identified. These factors may underpin novel therapeutic avenues for osteoporosis, but their potential for translation into clinical applications is yet to be tested.

Enhancing Rotator Cuff Repair in Rabbit Osteoporosis With Chitosan Quaternary Ammonium Salt-Coated Nickel-Titanium Memory Alloy Anchors

BACKGROUND

For patients with osteoporosis and rotator cuff tears, there is still no consensus on current treatment methods. The material, structure, and number of anchors have important effects on the repair outcome.

PURPOSE

To investigate the use of chitosan quaternary ammonium salt-coated nickel-titanium memory alloy (NTMA) anchors to treat rotator cuff injury in shoulders with osteoporosis in a rabbit osteoporosis model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A novel winged NTMA anchor was designed to test in normal and osteoporotic bone models in vitro. These models were assessed for maximum failure load and bone damage in various traction directions. A chitosan-sodium alginate composite was coated onto NTMA anchor surfaces using glutaraldehyde cross-linking and electrostatic layering techniques. An osteoporotic rabbit model was created using ovariectomy combined with glucocorticoid treatment. A rabbit model with acute injury to the supraspinatus muscle was established and repaired using titanium alloy anchors, NTMA anchors, and coated NTMA (CNTMA) anchors. To evaluate the efficacy of the anchors, biomechanical testing and staining with hematoxylin and eosin were performed 6 and 12 weeks after surgery. A micro-computed tomography scan was performed 12 weeks after surgery.

RESULTS

In the osteoporotic bone model, NTMA anchors exhibited greater failure loads than titanium anchors under 45° and 90° traction forces (P < .05). The surface-modified material showed a lower contact angle compared with unmodified material. Cell Counting Kit-8 (CCK-8) assays showed that the composite coating promoted osteoblast proliferation. The CNTMA anchor group exhibited the greatest maximum failure load at each time point. Hematoxylin and eosin staining revealed greater trabecular thickness in the CNTMA anchor group than in the other groups at 6 and 12 weeks after surgery. At 12 weeks after surgery, micro-computed tomography revealed an increased number and thickness of bone trabeculae in the NTMA anchor group, along with a widened trabecular gap (P < .05). After the NTMA anchor biplane unfolded, the gap between the biplane and anchor showed bone tissue growth.

CONCLUSION

Chitosan quaternary ammonium salt-coated NTMA anchors enhanced fixation strength and promoted local osteogenesis during osteoporotic rotator cuff repair, suggesting that the use of these anchors facilitates the repair of osteoporotic rotator cuff injuries in osteoporotic bones.

CLINICAL RELEVANCE

Innovations in anchor nailing may be effective in reducing rates of repair failure for rotator cuff tears combined with osteoporosis.

Ferrostatin-1 inhibits osteoclast differentiation and prevents osteoporosis by suppressing lipid peroxidation

BACKGROUND

Osteoporosis (OP) is a systemic disease characterized by low bone mass. New progress has been made in the study of OP, such as lipid peroxidation. However, the role of lipid peroxides in osteoclast differentiation is still unclear.

METHODS

Bone marrow macrophages (BMMs) were extracted from C57BL/6J mice and induced to differentiate into osteoclasts, which were observed via TRAP staining, Phalloidin staining and bone pit assays. Related substances of lipid peroxidation were detected during osteoclastogenesis. The levels of osteoclastogenesis and lipid peroxides were measured by qRT-PCR, Western Blot and immunofluorescence. Activation of the p38/JNK/MAPK pathway was detected by Western Blot. The capacity for osteogenesis and angiogenesis of cells after treatment with supernatant of BMMs was evaluated. Furthermore, Ferrostatin-1 (Fer-1), from which femur and serum samples were comprehensively evaluated, was used in OVX mice.

RESULTS

During osteoclastogenesis, the levels of ROS, MDA, ACSL4 and LPCAT3 increased with increasing duration of RANKL stimulation, while there were no significant changes in the levels of GSH or GPX4. Fer-1 inhibited osteoclast differentiation and decreased the level of lipid peroxides. In addition, Fer-1 inhibited osteoclast-related markers by inhibiting the p38/JNK/MAPK pathway. Furthermore, the supernatant of BMMs after Fer-1 treatment promoted osteogenesis and angiogenesis. Finally, Fer-1 successfully alleviated OP in OVX mice by reducing the level of lipid peroxidation in vivo.

CONCLUSION

Fer-1 suppresses osteoclast differentiation by reducing lipid peroxidation levels regulated by ACSL4, which is mediated through the p38/JNK/MAPK signaling pathway. Additionally, Fer-1 enhances the coupling between osteogenesis and angiogenesis and has an anti-OP effect in vivo.

Gelatin-based biomaterials as a delivery strategy for osteosarcoma treatment

Osteosarcoma is the most common primary malignant bone tumor. Although surgery and chemoradiotherapy have made some progress in the treatment of osteosarcoma. However, the high recurrence and metastasis rate of osteosarcoma and bone defects caused by surgery are still the main problems faced by osteosarcoma. Gelatin has excellent biocompatibility and biodegradability, and has made phased progress in tumor treatment. In the treatment of osteosarcoma, gelatin-based biomaterials can be used in delivery strategies to enhance the anti-tumor activity of osteosarcoma and can improve the appropriate compressive strength to improve the bone defects faced after surgery. At present, gelatin-based hydrogels, gelatin scaffolds, and gelatin-based nanoparticles have been reported in preclinical studies. In this article, we introduce the application of gelatin-based biomaterials in the treatment of osteosarcoma, and summarize and look forward to them.

Metabolism-Related Adipokines and Metabolic Diseases: Their Role in Osteoarthritis

Osteoarthritis (OA) affects several joints but tends to be more prevalent in those that are weight-bearing, such as the knees, which are the most heavily loaded joints in the body. The incidence and disability rates of OA have continued to increase and seriously jeopardise the quality of life of middle-aged and older adults. However, OA is more than just a wear and tear disease; its aetiology is complex, and its pathogenesis is poorly understood. Metabolic syndrome (MetS) has emerged as a critical driver of OA development. This condition contributes to the formation of a distinct phenotype, termed metabolic syndrome-associated osteoarthritis (MetS-OA),which differs from other metabolically related diseases by its unique pathophysiological mechanisms and clinical presentation. As key mediators of MetS, metabolic adipokines such as leptin, lipocalin, and resistin regulate inflammation and bone metabolism through distinct or synergistic signaling pathways. Their modulation of inflammatory responses and bone remodeling processes plays a critical role in the pathogenesis and progression of OA. Due to their central role in regulating inflammation and bone remodeling, metabolic adipokines not only deepen our understanding of MetS-OA pathogenesis but also represent promising targets for novel therapeutic strategies that could slow disease progression and improve clinical outcomes in affected patients.

Causal association among smoking, bitter beverage consumption, and risk of osteoporosis: a two-sample mendelian randomization-based study

OBJECTIVES

Two-sample MR methods were employed to analyze the impact of smoking and bitter beverage consumption on the risk of osteoporosis and osteoporosis with pathological fractures, in order to assess the causal association.

METHODS

Publicly available genome-wide association study summary data were analyzed using MR methods. The exposures investigated were smoking (smoking per day, smoking initiation, and lifetime smoking index) and bitter beverages (coffee, tea, bitter alcoholic beverages, bitter non-alcoholic beverages, and total bitter beverages). The outcomes examined were the risk of osteoporosis and osteoporosis with pathological fractures. The inverse-variance weighted (IVW) method was used as the main statistical model. The stability and reliability of the results were verified by the Cochran's Q test, the Egger-intercept test, and the leave-one-out analysis.

RESULTS

Smoking per day was causally associated with the risk of osteoporosis OR = 1.417, 95% CI = 1.119-1.794, P = 0.003), and lifetime smoking index had a possible genetic causal association with the risk of osteoporosis with pathological fractures (OR = 4.187, 95% CI = 1.909-9.184, P < 0.001). No genetic causal association was found between smoking initiation or lifetime smoking index and the risk of osteoporosis (P > 0.05). No genetic causal association was identified between smoking per day or smoking initiation and the risk of osteoporosis with pathological fractures (P > 0.05). Total and bitter non-alcoholic beverage consumption showed a potential effect on the risk of osteoporosis (OR = 3.687, 95% CI = 1.535-8.858, P = 0.003 and OR = 3.040, 95% CI = 1.466-6.304, P = 0.002, respectively).

CONCLUSIONS

This study found smoking raises the risk of osteoporosis and osteoporosis with pathological fractures based on genetics. Certain bitter beverages are linked to an increased osteoporosis risk.

Ameliorating macrophage pyroptosis via ANXA1/NLRP3/Caspase-1/GSDMD pathway: Ac2-26/OGP-loaded intelligent hydrogel enhances bone healing in diabetic periodontitis

Craniofacial bone defect healing in periodontitis patients with diabetes background has long been difficult due to increased blood glucose levels which cause overproduction of reactive oxygen species (ROS) and a low pH environment. These conditions negatively affect the function of macrophages, worsen inflammation and oxidative stress, and ultimately, hinder osteoblasts' bone repair potential. In this study, we for the first time found that annexin A1 (ANXA1) expression in macrophages was reduced in a diabetic periodontitis (DP) environment, with the activation of the NLRP3/Caspase-1/GSDMD signaling pathway, and, eventually, increased macrophage pyroptosis. Next, we have developed a new GPPG intelligent hydrogel system which was ROS and pH responsive, and loaded with Ac2-26, an ANXA1 bioactive peptide, and osteogenic peptide OGP as well. We found that Ac2-26/OGP/GPPG can effectively reduce ROS, mitigates macrophage pyroptosis via the ANXA1/NLRP3/Caspase-1/GSDMD pathway and enhanced osteogenic differentiation. The effect of Ac2-26/OGP/GPPG in regulation of pyroptosis and bone defect repair was also further validated by animal experiments on periodontitis-induced tooth loss model in diabetic rats. To conclude, our study unveils the effect of ANXA1 on macrophage pyroptosis in periodontitis patients with diabetes, based on which we introduced a promising innovative hydrogel system for improvement of bone defects repair in DP patients via targeting macrophage pyroptosis and enhancing osteogenic potential.

Correlation Between Blood Glucose Fluctuations and Osteoporosis in Type 2 Diabetes Mellitus

The purpose of this review is to investigate the impacts of blood glucose fluctuations on diabetic osteoporosis, a complication of Type 2 diabetes mellitus (T2DM) that remains poorly understood. We reviewed the current evidence of the relationship between blood glucose fluctuations and diabetic osteoporosis in patients with T2DM. The findings indicate that blood glucose fluctuations may contribute to inhibiting the processes of bone formation and resorption, promoting diabetic osteoporosis and fractures in T2DM. Mechanistic studies, both in vitro and in vivo, reveal that these effects are largely mediated by oxidative stress, advanced glycation end products, inflammatory mediators, and multiple pathways inducing cell apoptosis or autophagy. Thus, maintaining the long-term stability of blood glucose levels emerges as a target to be pursued in clinical practice in order to safely reduce mean blood glucose and for its direct effects on osteoporosis and fractures in T2DM.

Targeting ferroptosis to enhance the efficacy of mesenchymal stem cell-based treatments for intervertebral disc degeneration

Although mesenchymal stromal cell (MSC) implantation shows promise for repairing intervertebral disc (IVD) degeneration (IVDD), their limited retention within degenerative IVDs compromises therapeutic efficacy. The oxidative stress in the microenvironment of degenerated IVDs induces a surge in reactive oxygen species production within MSCs, disrupting the balance between oxidation and antioxidation, and ultimately inducing ferroptosis. Recent evidence has suggested that targeting ferroptosis in MSCs could enhance MSC retention, extend the survival of transplanted MSCs, and markedly delay the pathological progression of IVDD. By targeting ferroptosis, a novel approach emerges to boost the efficacy of MSC transplantation therapy for IVDD. In this review, current research on targeting ferroptosis in MSCs is discussed from various perspectives, including the targeting of specific genes and pathways, drug preconditioning, and hydrogel encapsulation. A detailed discussion on the effects of targeting ferroptosis in MSCs on the transplantation repair of degenerated IVDs is provided. Insights that could guide improvements in stem cell transplantation therapies are also offered. Significantly, this review presents specific ideas for our future foundational research. These insights outline promising avenues for future clinical translation and will contribute to developing and optimizing treatment strategies for MSC transplantation therapy, maximizing benefits for patients with lumbar IVDD.

Cell-free fat extract improves embryo development and clinical outcomes in older women with previous in-vitro fertilization failure

BACKGROUND

Preimplantation embryos in vivo are exposed to various growth factors in the female reproductive tract that are absent in in vitro embryo culture media. Cell-free fat extract exerts antioxidant, anti-ageing, and ovarian function-promoting effects. However, its effects on embryo quality are yet to be investigated.

METHODS

We assessed the effect of cell-free fat extract supplementation on embryo culture using a naturally ageing mouse model. We assessed the model's efficacy in influencing embryo development and pregnancy rates in older women with in vitro fertilization failure. In addition, we performed immunofluorescence staining, multiplex immunoassay, whole-genome amplification and DNA sequencing, time-lapse embryo monitoring, and in vitro experiments.

RESULTS

Cell-free fat extract-supplemented media has a suitable osmolarity and pH and contains high levels of bioactive growth factors. Cell-free fat extract promoted embryo development and implantation in aged mice, probably by increasing embryo growth rate, inhibiting cell apoptosis, and promoting blastocyst adhesion. Clinical results showed that the cell-free fat extract group had significantly higher rates of the day 3 available and high-quality embryos than the control group, and the rate of usable embryos tended to be higher in the cell-free fat extract group. Furthermore, implantation and clinical pregnancy rates improved in the cell-free fat extract group than in the control group.

CONCLUSIONS

Our study implies that cell-free fat extract supplementation can promote embryo development and clinical outcomes and may serve as a rescue strategy for older women with in vitro fertilization failure.

Regulation of enzymatic lipid peroxidation in osteoblasts protects against postmenopausal osteoporosis

Oxidative stress plays a critical role in postmenopausal osteoporosis, yet its impact on osteoblasts remains underexplored, limiting therapeutic advances. Our study identifies phospholipid peroxidation in osteoblasts as a key feature of postmenopausal osteoporosis. Estrogen regulates the transcription of glutathione peroxidase 4 (GPX4), an enzyme crucial for reducing phospholipid peroxides in osteoblasts. The deficiency of estrogen reduces GPX4 expression and increases phospholipid peroxidation in osteoblasts. Inhibition or knockout of GPX4 impairs osteoblastogenesis, while the elimination of phospholipid peroxides rescues bone formation and mitigates osteoporosis. Mechanistically, 4-hydroxynonenal, an end-product of phospholipid peroxidation, binds to integrin-linked kinase and triggers its protein degradation, disrupting RUNX2 signaling and inhibiting osteoblastogenesis. Importantly, we identified two natural allosteric activators of GPX4, 6- and 8-Gingerols, which promote osteoblastogenesis and demonstrate anti-osteoporotic effects. Our findings highlight the detrimental role of phospholipid peroxidation in osteoblastogenesis and underscore GPX4 as a promising therapeutic target for osteoporosis treatment.

Melanoma bone metastasis-induced osteocyte ferroptosis via the HIF1α-HMOX1 axis

Osteocytes are the main cells in mineralized bone tissue. Elevated osteocyte apoptosis has been observed in lytic bone lesions of patients with multiple myeloma. However, their precise contribution to bone metastasis remains unclear. Here, we investigated the pathogenic mechanisms driving melanoma-induced osteocyte death. Both in vivo models and in vitro assays were combined with untargeted RNA sequencing approaches to explore the pathways governing melanoma-induced osteocyte death. We could show that ferroptosis is the primary mechanism behind osteocyte death in the context of melanoma bone metastasis. HMOX1 was identified as a crucial regulatory factor in this process, directly involved in inducing ferroptosis and affecting osteocyte viability. We uncover a non-canonical pathway that involves excessive autophagy-mediated ferritin degradation, highlighting the complex relationship between autophagy and ferroptosis in melanoma-induced osteocyte death. In addition, HIF1α pathway was shown as an upstream regulator, providing a potential target for modulating HMOX1 expression and influencing autophagy-dependent ferroptosis. In conclusion, our study provides insight into the pathogenic mechanisms of osteocyte death induced by melanoma bone metastasis, with a specific focus on ferroptosis and its regulation. This would enhance our comprehension of melanoma-induced osteocyte death.

Enhanced osteo-angiogenic coupling by a bioactive cell-free fat extract (CEFFE) delivered through electrospun fibers

Regeneration of functional bone tissue relies heavily on achieving adequate vascularization in engineered bone constructs following implantation. This process requires the close integration of osteogenesis and angiogenesis. Cell-free fat extract (CEFFE or FE), a recently emerging acellular fat extract containing abundant growth factors, holds significant potential for regulating osteo-angiogenic coupling and promoting regeneration of vascularized bone tissue. However, its specific role in modulating the coupling between angiogenesis and osteogenesis remains unclear. Our previous research demonstrated that FE-decorated electrospun fibers of polycaprolactone/gelatin (named FE-PDA@PCL/GT) exhibited pro-vasculogenic capabilities both in vitro and in vivo (D. Li, Q. Li, T. Xu, X. Guo, H. Tang, W. Wang, W. Zhang and Y. Zhang, Pro-vasculogenic fibers by PDA-mediated surface functionalization using cell-free fat extract (CEFFE), Biomacromolecules 2024, 25, 1550-1562). Herein, we firstly demonstrated that the FE-PDA@PCL/GT fibers also significantly stimulated osteogenesis in a mouse calvaria osteoblast-like cell line MC3T3-E1 cells, as evidenced by the increased production of alkaline phosphatase (ALP), mineral deposits, and collagen I, as well as the upregulated expression of osteogenic marker genes in the osteoblasts. Using a transwell co-culture system, we further demonstrated that the release of FE from the FE-PDA@PCL/GT fibers not only promoted osteogenesis and angiogenesis but also markedly enhanced the paracrine functions and reciprocal communications between endothelial cells and osteoblasts. This dynamic interaction played a key role in the observed enhancement of osteo-angiogenic coupling. With the confirmed pro-osteogenic and pro-angiogenic properties of FE-PDA@PCL/GT, it is envisaged that these newly engineered bioactive fibers can be used to develop highly biomimicking bone constructs. These constructs are designed to promote native-like cell-scaffold and cell-cell interactions, which are essential for the effective regeneration of defected bone tissue with adequate vasculature.

Maltodextrin-derived nanoparticles resensitize intracellular dormant Staphylococcus aureus to rifampicin

Intracellular bacteria are recognized as a crucial factor in the persistence and recurrence of infections. The efficacy of current antibiotic treatments faces substantial challenges due to the dormant state formation of intracellular bacteria. In this study, we devised a strategy aimed at reverting intracellular dormant bacteria to a metabolically active state, thereby increasing their vulnerability to antibiotics. We found that oligosaccharides, especially maltodextrin (MD), can be absorbed by dormant S. aureus, leading to their revival and restoration of sensitivity to rifampicin (Rif). We then synthesized a reactive oxygen species (ROS)-responsive MD-prodrug by covalently binding MD with 4-(hydroxymethyl) phenylboronic acid pinacol ester (MD-PBAP) and prepared a ROS-responsive nanoparticles (MDNP) using a nanoprecipitation and self-assembly method. Once internalized by host cells, MDNP was degraded to MD, reactivating dormant S. aureus, and enhancing their susceptibility to Rif. More importantly, MDNP treatment restored the sensitivity of intracellular persistent S. aureus to Rif in both a reservoir transfer model and whole-body infection model. Additionally, MDNP have demonstrated excellent biocompatibility in both in vitro and in vivo settings. These results offer a promising therapeutic avenue for managing persistent intracellular bacterial infections by reviving and resensitizing intracellular dormant bacteria to conventional antibiotics.

Therapeutic Potential of Targeting Ferroptosis in Periprosthetic Osteolysis Induced by Ultra-High-Molecular-Weight Polyethylene Wear Debris

Background/Objectives: Periprosthetic osteolysis is the primary cause of arthroplasty failure in the majority of patients. Mechanistically, wear debris released from the articulating surfaces of a prosthesis initiates local inflammation and several modes of regulated cell death programs, such as ferroptosis, which represents a promising therapeutic target in various chronic inflammatory diseases. Thus, the current study aimed at exploring the therapeutic potential of targeting ferroptosis in a polyethylene-wear-debris-induced osteolysis model. Methods: Inverted cell culture model was used for stimulating the cells with wear debris in vitro, and calvarial osteolysis model was used for evaluating the therapeutic effects of inhibitors in vivo. Results: The immunostaining of periprosthetic bone tissues demonstrated a number of osteocytes expressing ferroptosis markers. Likewise, the expressions of ferroptosis markers were confirmed in polyethylene-wear-debris-stimulated osteocyte-like cells and primary osteoblasts in a direct stimulation model but not in an indirect stimulation model. Furthermore, polyethylene wear debris was implanted onto calvarial bone and mice were treated with the ferroptosis inhibitors DFO and Fer-1. These treatments alleviated the inflammatory and pathological bone resorption induced by the wear debris implantation. Conclusions: Our data broaden the knowledge of the pathogenesis of periprosthetic osteolysis and highlight ferroptosis as a promising therapeutic target.

Age-dependent interaction between serum zinc and triglyceride-glucose index among American adults: National Health and Nutrition Examination Survey

Introduction

Zinc plays a crucial role in glucose metabolism. The association between serum zinc and insulin resistance has recently been investigated as well, but the findings are inconsistent. The triglyceride-glucose index (TyG) is frequently utilized in epidemiological research to assess insulin resistance. The association between serum zinc levels and TyG has not yet been explored. Therefore, we designed this cross-sectional study to assess the relationship between serum zinc and TyG in adults using data from the National Health and Nutrition Examination Survey (NHANES).

Methods

A cross-sectional analysis was performed on 1,610 adults aged ≥20 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2011-2016. The participants were stratified by age, and the differences in log-transformed serum zinc quartiles and TyG were further evaluated in age groups <60 years and ≥60 years using multivariable linear regression with an interaction test. Additionally, a restricted cubic spline (RCS) model was employed to examine the dose-response relationships between log-transformed serum zinc and TyG.

Results

In this cross-sectional study, a significant interaction was observed between log-transformed serum zinc and TyG in individuals aged <60 years and those aged ≥60 years when log-transformed serum zinc was transformed into a categorical variable (P-value for the likelihood ratio test for the interaction was P = 0.017). Additionally, in the fully adjusted analyses, the association between log-transformed serum zinc and TyG in the age <60 years group demonstrated a J-shaped nonlinear pattern (P for nonlinearity = 0.014), with an inflection point at ~1.94 μg/dL. While in the age ≥60 years group, it exhibited an inverted-L shaped nonlinear pattern (P for nonlinearity < 0.001***).

Conclusion

There is a significant relationship between log-transformed serum zinc and TyG in adults in the United States, with age potentially influencing this association. Further prospective studies are needed to offer additional evidence and insights into these findings.

d-[5-11C]-Glutamine Positron Emission Tomography Imaging for Diagnosis and Therapeutic Monitoring of Orthopedic Implant Infections

Orthopedic implant infections (OIIs) present diagnostic and therapeutic challenges, owing to the lack of methods to distinguish between active infection and sterile inflammation. To address this unmet need, d-amino-acid-based radiotracers with unique metabolic profiles in microorganisms have emerged as a novel class of infection-specific imaging agents. Given the pivotal role of d-glutamine in bacterial biofilm formation and virulence, herein, we explored the potential of positron emission tomography (PET) imaging with d-[5-11C]-Glutamine (d-[5-11C]-Gln) for early detection and treatment monitoring of OIIs. In vitro studies confirmed an active uptake of d-[5-11C]-Gln by Staphylococcus aureus (S. aureus) biofilm commonly associated with OIIs. In vivo evaluations included PET imaging comparisons with d-[5-11C]-Gln vs l-[5-11C]-Gln or 2-deoxy-2-[18F]-fluoroglucose ([18F]-FDG) in a rat OII model with tibial implantation of sterile or S. aureus-colonized stainless-steel screws before and after treatment. These studies demonstrated that the uptake of d-[5-11C]-Gln was significantly higher in the infected screws than that in sterile screws (∼3.4-fold, p = 0.008), which displayed significantly higher infection-to-background muscle uptake ratios (∼2-fold, p = 0.011) with d-[5-11C]-Gln as compared to l-[5-11C]-Gln. Following a 3 week vancomycin treatment, imaging with d-[5-11C]-Gln showed a significant reduction in uptake at the infected sites (∼3-fold, p = 0.0008). Further regression analyses revealed a superior correlation of residual infection-associated radiotracer uptake with the postimaging ex vivo bacterial counts for d-[5-11C]-Gln (k = 0.473, R2 = 0.796) vs [18F]-FDG (k = 0.212, R2 = 0.434), suggesting that d-[5-11C]-Gln PET had higher sensitivity for detecting residual bacterial burden than [18F]-FDG PET. Our results demonstrate the translational potential of d-[5-11C]-Gln PET imaging for noninvasive detection and treatment monitoring of OIIs.

The association between varus knee deformity and morphological changes in the foot and ankle in patients with end-stage varus knee osteoarthritis

BACKGROUND

This study aimed to (1) determine the association between varus knee deformity and ipsilateral foot and ankle morphology, and (2) evaluate the relationship between varus knee deformity and foot and ankle pain in patients with end-stage varus knee osteoarthritis (KOA).

METHODS

A total of 213 patients who underwent primary total knee arthroplasty for end-stage varus KOA were enrolled in this study and divided into a 'severe varus group' (n = 119) and a 'mild varus group' (n = 94) based on preoperative knee varus degree. Morphological parameters and pain incidence in the foot and ankle were compared between the two groups. The correlation between knee varus and foot and ankle morphology was analyzed.

RESULTS

Significant differences in ankle morphology were observed between the two groups. The deformity magnitudes of the hindfoot valgus (P < 0.001) and hallux valgus (HVA, P = 0.028; IMA, P = 0.046) were significantly higher in the severe varus group. Additionally, the incidences of ankle osteoarthritis (OA) (P = 0.005) and hallux valgus (P = 0.028) were higher in the severe varus group. Patients with severe KOA were more likely to experience medial ankle pain (P = 0.023), hindfoot pain (P = 0.034), and multiple pain locations (P = 0.015).

CONCLUSION

Varus knee deformity was associated with morphological changes in the foot and ankle, and the incidence of ankle OA and hallux valgus deformity was significantly higher in patients with severe varus KOA. Patients with severe varus KOA were more prone to medial ankle pain, hindfoot pain, and multiple pain locations, which were associated with corresponding morphological changes.