IL-17 and immunologically induced senescence regulate response to injury in osteoarthritis

Pharmacological modulation of cellular senescence: Implications for breast cancer progression and therapeutic strategies

Senescence, defined by the cessation of cell proliferation, plays a critical and multifaceted role in breast cancer progression and treatment. Senescent cells produce senescence-associated secretory phenotypes (SASP) comprising inflammatory cytokines, chemokines, and small molecules, which actively shape the tumor microenvironment, influencing cancer development, progression, and metastasis. This review provides a comprehensive analysis of the types and origins of senescent cells in breast cancer, alongside their markers and detection methods. Special focus is placed on pharmacological strategies targeting senescence, including drugs that induce or inhibit senescence, their molecular mechanisms, and their roles in therapeutic outcomes when combined with chemotherapy and radiotherapy. By exploring these pharmacological interventions and their impact on breast cancer treatment, this review underscores the potential of senescence-targeting therapies to revolutionize breast cancer management.

Cellular senescence in age-related musculoskeletal diseases

Aging is typically associated with decreased musculoskeletal function, leading to reduced mobility and increased frailty. As a hallmark of aging, cellular senescence plays a crucial role in various age-related musculoskeletal diseases, including osteoporosis, osteoarthritis, intervertebral disc degeneration, and sarcopenia. The detrimental effects of senescence are primarily due to impaired regenerative capacity of stem cells and the pro-inflammatory environment created by accumulated senescent cells. The secreted senescence-associated secretory phenotype (SASP) can induce senescence in neighboring cells, further amplifying senescent signals. Although the removal of senescent cells and the suppression of SASP factors have shown promise in alleviating disease progression and restoring musculoskeletal health in mouse models, clinical trials have yet to demonstrate significant efficacy. This review summarizes the mechanisms of cellular senescence in age-related musculoskeletal diseases and discusses potential therapeutic strategies targeting cellular senescence.

Therapeutic application of regulatory T cell in osteoarthritis

Regulatory T cells (Tregs) are the specific T cell population that suppress inflammatory immunity. Independent of their inhibitory activities, Tregs exhibit unique capacity to repair tissue damage. Rapid progresses are made in the processing and engineering of Tregs for clinical applications. Tregs have been used in the treatment of autoimmune diseases, transplantation rejection and graft-versus-host disease. Osteoarthritis is one of the major diseases that affect at least 600 million people worldwide. Osteoarthritis is characterized by physical erosion of cartilage, accompanied with chronic and low-grade inflammation. Tregs possess abilities to increase osteoclast differentiation and bone resorption, repair bone physical damage, and increase bone mass. Tregs are therefore candidate therapeutics for osteoarthritis for both inflammation resolution and tissue repairing. In this review, we will summarize the recent development in using Tregs in immunotherapy, and the potential of using Tregs in osteoarthritis.

Senescent cell reduction does not improve recovery in mice under experimental autoimmune encephalomyelitis (EAE) induced demyelination

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS) characterized by immune cell-driven demyelination and progressive neurodegeneration. Senescent cells (SCs) have recently been observed in chronic MS lesions indicating their possible involvement in disease progression. However, the role of SCs and the potential therapeutic benefit of their reduction through senolytic therapy remains to be determined in experimental autoimmune encephalomyelitis (EAE), a widely used preclinical model of MS. Here, we show that senescent-like myeloid cells accumulate in the spinal cord parenchyma and meninges in mice after myelin oligodendrocyte glycoprotein (MOG33-55) EAE induction. Treatment with the senolytic cocktail, Dasatinib and Quercetin (DQ), effectively reduces the senescent-like myeloid cells, but this does not translate into improved clinical outcomes in EAE mice. Increasing DQ dosage or using INK-ATTAC transgenic mice also failed to ameliorate EAE severity. Additionally, histopathological analysis shows no significant differences in demyelination or axonal degeneration between treated and control groups. Our findings indicate that senescent-like myeloid cells are present in an immune-mediated demyelinating model of MS and can be reduced through senolytic therapy with Dasatinib and Quercetin. However, their reduction through DQ does not significantly impact inflammation or recovery, suggesting that the therapeutic potential of senolytics as disease-modifying drugs in MS may be limited.

Injury and obesity differentially and synergistically induce dysregulation of synovial immune cells in osteoarthritis

OBJECTIVES

The heterogeneity and phenotype of immune cells orchestrate many physiologic and pathologic processes. Recent evidence suggests that immune cells play critical roles in the progression of osteoarthritis (OA). We hypothesised that injury and obesity, two major risk factors for OA, affect the immunophenotype of the synovium, the primary reservoir of immune cells in the joint.

METHODS

Using single-cell transcriptomics, immunoprofiling, transgenic mouse models, and genetic fate mapping methods, we characterised the presence and fate of multiple populations of immune cells found in the knee joint capsule.

RESULTS

We found that joint injury and obesity differentially and synergistically alter the architectural, cellular, and molecular profiles of the synovial capsule. We observed fewer patrolling monocytes in obese animals and found a significantly higher influx of proinflammatory monocyte-derived macrophages in the first 3 days after joint injury in obese compared with that in control animals. We also showed a significant loss of barrier-forming synovial lining macrophages 3 days after destabilisation of medial meniscus surgery, with a significant restoration of their numbers in normal weight but not in obese mice in advanced stages of OA. Finally, we characterised the presence and changes of other immune cell subtypes, including T, B, and mast cells and neutrophils, as well as local synovial fluid cytokines associated with injury and obesity.

CONCLUSIONS

Our data revealed that injury and obesity independently and synergistically contribute to the dysregulation of the synovial immune landscape, providing new insight into their role in the pathogenesis of OA.

Higher levels of VEGF-A and TNFα in patients with immune checkpoint inhibitor-induced inflammatory arthritis

BACKGROUND

Immune checkpoint inhibitors (ICI), a type of cancer immunotherapy, can cause side effects including inflammatory arthritis (ICI-IA). Previous studies of ICI-IA do not include a thorough characterization of associated immune responses to provide potential targets for treatment. We aimed to identify cytokines uniquely increased in ICI-IA and determine correlations with IA severity and persistence.

METHODS

We evaluated patients diagnosed with ICI-IA by a rheumatologist (n = 80); control serum was obtained from ICI-treated cancer patients without any diagnosed irAEs (n = 17) or diagnosed with an unrelated irAE (n = 19). Serum was assayed to quantify 9 cytokine levels (IFN-γ, IL-4, IL-6, IL-10, IL-12p70, IL-1α, TNF-α, IL-17a, VEGF-A) using MSD U-PLEX assay. Mann-Whitney U tests were performed to evaluate differences in cytokine levels between control and ICI-IA groups. The Kruskal-Wallis test and multivariable ordinal logistic regression were used to determine difference in cytokine levels between patients of differing disease activity.

RESULTS

VEGF-A and TNFα were significantly elevated in patients with ICI-IA compared to ICI-controls; results persisted when restricting analyses to patients not treated with immunosuppressants at the time of sampling. ICI-IA patients were stratified by IA severity using CDAI score; there was significantly higher VEGF-A in those with higher disease activity. Ordinal logistic regression showed higher levels of IL-6 and VEGF-A were associated with higher disease activity.

CONCLUSION

Elevated levels of VEGF-A and TNFα are associated with ICI-IA. There was also higher IL-6 and VEGF-A among those with higher disease activity when controlling for confounding. These cytokines could be used as biomarkers of ICI-IA severity and present therapeutic targets.

Senescence cell signature associated with poor prognosis, epithelial-mesenchymal transition, solid histology, and spread through air spaces in lung adenocarcinoma

Cellular senescence is involved in critical processes in tumor progression. Despite this potential relationship, the relationship between tumor cell senescence, prognostic significance, spread through air spaces (STAS), and tumor histology has not been investigated in lung adenocarcinoma (LUAD). We used the LUAD PanCancer Atlas dataset to assess senescence cell signature (SCS) based on the SenMayo gene set. We examined the relationship between SCS, prognostic significance, STAS, and tumor histology. This relationship was confirmed in independent LUAD datasets by validation using immunohistochemical senescence markers. In the LUAD PanCancer Atlas dataset, patients with high SCS expression had a higher prevalence of solid histology and STAS patterns than those with low SCS expression. In the independent LUAD datasets, high p21 expression and low HMGB1 expression were correlated with solid histology or STAS patterns. SCS level was also independent prognostic factor in four different LUAD datasets. The HMGB1 expression was an independent prognostic factor in the independent LUAD dataset in multivariate analysis. The expression of p21 and the presence of solid histology were linked to the epithelial-mesenchymal transition (EMT) phenotype. In LUAD cell lines, inducing senescence with a DNA-damaging agent led to an increase in EMT marker expression. Our findings suggest a strong link between senescence, EMT, and solid histology, offering valuable insight into how cancer cell senescence may promote tumor progression through particular pathways.

Immunosenescence in autoimmune diseases

Autoimmune diseases (AIDs) are a group of disorders in which the immune system mistakenly attacks the body's own tissues, characterized by the loss of tolerance to self-antigens and destruction of tissues. Aging is a natural process of physiological decline that also alters the immune system, a condition known as immunosenescence. During immunosenescence, the immune system undergoes various changes, including modifications and antigenicity of self-antigens, abnormalities in the quantity, phenotype, and function of lymphocytes and antibodies, as well as a narrowing of the B and T cell receptor repertoire, changes that may increase susceptibility to AIDs. Additionally, senescent immune cells and the senescence-associated secretory phenotype (SASP) contribute to target organ involvement in AIDs, exacerbating chronic inflammation and tissue damage. Mitochondrial dysfunction and metabolic imbalances in AIDs lead to the accumulation of senescent cells, which act as upstream drivers of immunosenescence. In this review, we summarize the bidirectional relationship between AIDs and immunosenescence, as well as its potential mechanisms. Therapeutic approaches targeting immunosenescence in AIDs remain at an early stage. Strategies aimed at resetting or reversing the aging immune system are expected to become a novel direction in the future.

Osteoimmunology in Osteoarthritis: Unraveling the Interplay of Immunity, Inflammation, and Joint Degeneration

Osteoarthritis (OA) is a degenerative joint disease influenced by multiple factors, with its etiology arising from intricate interactions among mechanical stress, inflammatory processes, and disruptions in bone metabolism. Recent research in bone immunology indicates that immune-mediated mechanisms significantly contribute to the progression of OA, highlighting the interactions among immune cells, cytokine networks, and bone components. Immune cells interact with osteoclasts, osteoblasts, and chondrocytes in a variety of ways. These interactions foster a pro-inflammatory microenvironment, contributing to cartilage breakdown, synovial inflammation, and the sclerosis of subchondral bone. In this article, we present a comprehensive review of bone immunology in OA, focusing on the critical role of immune cells and their cytokine-mediated feedback loops in the pathophysiology of OA. In addition, we are exploring novel therapeutic strategies targeting bone immune pathways, including macrophage polarization, T-cell differentiation, and stem cell therapy to restore the metabolic balance between immunity and bone. By integrating cutting-edge research in bone immunology, this review integrates the latest advancements in bone immunology to construct a comprehensive framework for unraveling the pathogenesis of OA, laying a theoretical foundation for the development of innovative precision therapies.

Advances in biomarkers and diagnostic significance of organ aging

A complete understanding of aging is a critical first step in treating age-related diseases and postponing aging dysfunction in the context of an aging global population. Aging in organisms is driven by related molecular alterations that gradually occur in many organs. There has previously been a wealth of knowledge of how cells behave as they age, but when aging is investigated as a disease, the discovery and selection of aging biomarkers and how to diagnose the aging of the organism are crucial. Here, we provide a summary of the state of the field and suggest future potential routes for research on organ senescence markers. We reviewed research on biomarkers of risk of aging from the perspective of organ aging and summarized the biomarkers currently used on three scales. We emphasize that the combination of traditional markers with emerging multifaceted biomarkers may be a better way to diagnose age-related diseases.

SLC7A11 suppresses pyroptosis to alleviate rheumatoid arthritis development by modulating the IL-17 pathway

BACKGROUND

Rheumatoid arthritis (RA) is an autoimmune disease of unknown etiology. This study aims to explore the potential mechanisms by which solute carrier family 7 member 11 (SLC7A11) influences RA development.

METHODS

Collagen-induced arthritis (CIA) mice were constructed to observe disease onset and pathological scores. Pathological changes were examined using Hematoxylin-eosin and Safranin O-Fast Green staining. Levels of lactate dehydrogenase (LDH), inflammatory cytokines (tumor necrosis factor [TNF]-α, interleukin [IL]-18 and IL-1β), and oxidative stress (reactive oxygen species, malondialdehyde, and glutathione) were measured using ELISA. Western blotting was performed to detect the expression of pyroptosis- and pathway-related proteins. Fibroblast-like synoviocytes of RA (RA-FLS) were treated with TNF-α. Cell migration, invasion, and Caspase-1 levels were assessed through scratch assays, Transwell assays, and flow cytometry, respectively. The correlation between SLC7A11 and immune cell infiltration in RA was analyzed using bioinformatics. Additionally, downstream pathways of SLC7A11 in RA were screened, and the impacts of SLC7A11 on these pathways were validated in vitro.

RESULTS

CIA mice were successfully established, revealing significant downregulation of SLC7A11 in RA. Staining results indicated that overexpression of SLC7A11 significantly mitigated joint damage in CIA mice. In vitro experiments demonstrated that overexpression of SLC7A11 inhibited migration, invasion, and Caspase-1 expression levels in TNF-α-induced RA-FLSs. Furthermore, SLC7A11 suppressed inflammation, LDH release, and oxidative stress, while inhibiting pyroptosis. SLC7A11 expression was significantly different in multiple immune cells. The IL-17 pathway was identified as a downstream pathway of SLC7A11, and SLC7A11 inhibited the expression of IL-17 pathway proteins. Additionally, rhIL-17A, an activator of the IL-17 pathway, attenuated the inhibitory effects of SLC7A11 on inflammation, oxidative stress, and pyroptosis.

CONCLUSION

SLC7A11 suppresses pyroptosis to alleviate RA development by inhibiting the IL-17 pathway.

IL-23R is a senescence-linked circulating and tissue biomarker of aging

Cellular senescence is an aging mechanism characterized by cell cycle arrest and a senescence-associated secretory phenotype (SASP). Preclinical studies demonstrate that senolytic drugs, which target survival pathways in senescent cells, can counteract age-associated conditions that span several organs. The comparative efficacy of distinct senolytic drugs for modifying aging and senescence biomarkers in vivo has not been demonstrated. Here, we established aging- and senescence-related plasma proteins and tissue transcripts that changed in old versus young female and male mice. We investigated responsivity to acute treatment with venetoclax, navitoclax, fisetin or luteolin versus transgenic senescent cell clearance in aged p16-InkAttac mice. We discovered that age-dependent changes in plasma proteins, including IL-23R, CCL5 and CA13, were reversed by senotherapeutics, which corresponded to expression differences in tissues, particularly in the kidney. In plasma from humans across the lifespan, IL-23R increased with age. Our results reveal circulating factors as candidate mediators of senescence-associated interorgan signal transduction and translationally impactful biomarkers of systemic senescent cell burden.

Protein folding dependence on selenoprotein M contributes to steady cartilage extracellular matrix repressing ferroptosis via PERK/ATF4/CHAC1 axis

OBJECTIVE

Initiation of endoplasmic reticulum (ER) stress is pivotal to the advancement of osteoarthritis (OA). We aimed to explore the function of ER-resident selenoprotein M (SELM) in cartilage-forming chondrocytes, investigating how SELM participates in cartilage extracellular matrix (ECM) metabolism and ER stress modulation.

METHODS

Articular cartilage samples with knee OA undergoing total knee arthroplasty were categorised into OA-smooth and OA-damaged groups, with primary chondrocytes extracted from smooth areas. Destabilization of the medial meniscus was induced in male C57BL6/J mice, with sham operations on the left knee as controls. After 8 weeks, knee joint tissues were collected for analysis. Histology and immunohistochemistry examined cartilage damage. Molecular biology techniques investigated how SELM affects ECM metabolism and ER stress regulation. RNA sequencing revealed the pathway changes after SELM intervention. AlphaFold demonstrated how SELM interacts with other molecules. Cultured cartilage explants helped determine the effects of SELM supplementation.

RESULTS

SELM expression was reduced in the damaged cartilage. Increasing SELM levels positively impacted ECM equilibrium. Decreasing SELM expression activated genes linked to degenerative ailments and impaired the cellular response to misfolded proteins, initiating the PERK/P-EIF2A/ATF4 pathway and exacerbating GSH/GSSG imbalance via the ATF4/CHAC1 axis. SELM likely participated in protein folding and modification by leveraging its thioredoxin domains. In vitro SELM supplementation mitigated IL-1β effects on damaged cartilage explants and suppressed beneficial chondrocyte phenotypes.

CONCLUSIONS

Our results confirm the involvement of SELM in ER stress-induced cartilage damage as well as protein folding, pointing to new directions in molecular therapy for degenerative diseases.

Engineered MSC-sEVs as a Versatile Nanoplatform for Enhanced Osteoarthritis Treatment via Targeted Elimination of Senescent Chondrocytes and Maintenance of Cartilage Matrix Metabolic Homeostasis

Chondrocyte senescence is an important pathogenic factor causing osteoarthritis (OA) progression through persistently producing pro-inflammatory factors. Mesenchymal stem cells-derived small extracellular vesicles (MSC-sEVs) have shown anti-inflammatory effects in OA models, while persistent existence of senescent chondrocytes still promotes cartilage destruction. Therefore, improving the targeted elimination ability on senescent chondrocytes is required to facilitate the translation of MSC-sEVs in OA treatment. In this study, versatile engineered MSC-sEVs are developed to targetedly clear senescent chondrocytes and maintain cartilage metabolic homeostasis. Specifically, MSC-sEVs are loaded with siRNA mouse double minute 2 homologue (siMDM2) and modified with cartilage-targeting peptide WYRGRL-PEG2K-DSPE (WPD), named WPD-sEVssiMDM2. The results demonstrate versatile modification improves the cellular uptake of MSC-sEVs in chondrocytes, and thus improves the antiaging effects. Importantly, multifunctional modification enhances cartilage penetration ability and extends joint retention time of MSC-sEVs. In both post-traumatic OA mice and naturally aged mice, WPD-sEVssiMDM2 more effectively eliminates senescent chondrocytes and maintained matrix metabolic homeostasis. By using the P53 phosphorylation inhibitor, the essential role MDM2-P53 pathway in the antiaging function of WPD-sEVssiMDM2 on chondrocytes is verified. In ex vivo cultured human OA cartilage explants, it is confirmed that WPD-sEVssiMDM2 alleviates senescent phenotype. Altogether, the findings suggest that WPD-sEVssiMDM2 have promising translational potential for OA treatment.

An in-depth understanding of the role and mechanisms of T cells in immune organ aging and age-related diseases

T cells play a critical and irreplaceable role in maintaining overall health. However, their functions undergo alterations as individuals age. It is of utmost importance to comprehend the specific characteristics of T-cell aging, as this knowledge is crucial for gaining deeper insights into the pathogenesis of aging-related diseases and developing effective therapeutic strategies. In this review, we have thoroughly examined the existing studies on the characteristics of immune organ aging. Furthermore, we elucidated the changes and potential mechanisms that occur in T cells during the aging process. Additionally, we have discussed the latest research advancements pertaining to T-cell aging-related diseases. These findings provide a fresh perspective for the study of T cells in the context of aging.

Regulation of fibroblast phenotype in osteoarthritis using CDKN1A-loaded copper sulfide nanoparticles delivered by mesenchymal stem cells

This study aimed to investigate the regulation of fibroblast phenotypes by mesenchymal stem cells (MSCs) delivering copper sulfide (CuS) nanoparticles (NPs) loaded with CDKN1A plasmids and their role in cartilage repair during osteoarthritis (OA). Single-cell RNA sequencing data from the GEO database were analyzed to identify subpopulations within the OA immune microenvironment. Quality control, filtering, principal component analysis (PCA) dimensionality reduction, and tSNE clustering were performed to obtain detailed cell subtypes. Pseudotime analysis was used to understand the developmental trajectory of fibroblasts, and GO/KEGG enrichment analyses highlighted biological processes related to fibroblast function. Transcriptomic data and WGCNA identified CDKN1A as a key regulatory gene. A biomimetic CuS@CDKN1A nanosystem was constructed and loaded into MSCs to create MSCs@CuS@CDKN1A. The characterization of this system confirmed its efficient cellular uptake by fibroblasts. In vitro experiments demonstrated that MSCs@CuS@CDKN1A significantly modulated fibroblast phenotypes and improved the structure, proliferation, reduced apoptosis, and enhanced migration of IL-1β-stimulated chondrocytes. In vivo, an OA mouse model was treated with intra-articular injections of MSCs@CuS@CDKN1A. Micro-CT scans revealed a significant reduction in osteophyte formation and improved joint space compared with control groups. Histological analysis, including H&E, Safranin O-Fast Green, and toluidine blue staining, confirmed improved cartilage integrity, whereas the International Osteoarthritis Research Society (OARSI) scoring indicated reduced disease severity. Immunofluorescence showed upregulated CDKN1A expression, decreased MMP13, and reduced α-SMA expression in fibroblast subtypes. Major organs exhibited no signs of toxicity, confirming the biocompatibility and safety of the treatment. These findings suggest that MSCs@CuS@CDKN1A can effectively regulate fibroblast activity and promote cartilage repair, providing a promising therapeutic strategy for OA treatment.NEW & NOTEWORTHY This study introduces MSCs@CuS@CDKN1A, a nanoengineered MSC platform that targets fibroblast phenotypes in osteoarthritis (OA). By modulating CDKN1A expression, this innovative approach not only enhances cartilage repair but also effectively mitigates fibroblast-driven inflammation, marking a significant advancement in OA therapeutics with demonstrated efficacy and biocompatibility.

[Lupeol Alleviates Chondrocytes Senescence in Osteoarthritis by Regulating Autophagy via the Sirtuin 3/Mechanistic Target of Rapamycin Kinase Pathway]

Objective

To investigate the role of lupeol in mitigating chondrocyte senescence in osteoarthritis (OA) by regulating autophagy through the sirtuin 3 (SIRT3)/mechanistic target of rapamycin kinase (mTOR) pathway.

Methods

Knee articular chondrocytes from primary-generation mice were isolated and divided into different groups, including a control group, a lupeol group (given 2.5, 5, 10, 20, and 40 μmol/L lupeol), a tert-butyl hydrogen peroxide (TBHP) group (receiving 50 μmol/L TBHP), TBHP + lupeol group, TBHP + lupeol + chloroquine (CQ) group (receiving 20 μmol/L CQ, an autophagy inhibitor), TBHP + lupeol + si-NC group, and TBHP + lupeol + si-SIRT3 group. Cell proliferation, reactive oxygen species (ROS) levels, and apoptosis were determined by CCK-8, DCFH-DA probe, and flow cytometry. Cell senescence was evaluated by β-gal staining. Western blot was used to determine the expressions of SIRT3, mTOR, senescence marker proteins (p21 and p16), extracellular matrix (ECM) degradation-related proteins (aggrecan, collagen Ⅱ, ADAMTS5, and MMP13), and autophagy-related proteins (LC3BⅠ, LC3BⅡ, and P62). RT-qPCR was used to determine the mRNA levels of senescence-associated secretory phenotypes (SASP), including IL-6, Cxcl10, MCP1, and MMP3. The expression of LC3 was detected by immunofluorescence. Autophagosomes were observed by transmission electron microscopy. A total of 30 male wild-type C57BL/6 mice were divided into different groups (n = 10), including a Sham group, an OA group, and an OA + lupeol group receiving 50 mg/(kg·d) lupeol via gastric gavage. Cartilage damage was evaluated by safranin O-fast green staining.

Results

Based on the results of cell viability assay, 20 μmol/L lupeol treatment for 24 h was identified as the optimal intervention concentration and duration. Compared with that in the TBHP group, cell viability was elevated in the TBHP + lupeol group (P < 0.05); ROS production, the proportion of β-gal-positive cells, the protein expression levels of p21 and p16, and the mRNA levels of SASP were decreased (P < 0.05); the protein levels of aggrecan and collagen Ⅱ were elevated and the protein levels of ADAMTS5 and MMP13 were decreased (P < 0.05); apoptosis was reduced (P < 0.05); P62 protein levels were reduced and the LC3BⅡ/LC3BⅠ ratio, the intensity of LC3B fluorescence spots, and the number of autophagosomes were increased (P < 0.05); the expression level of SIRT3 was elevated and the level of mTOR phosphorylation was reduced (P < 0.05) in the TBHP+Lupeol group. CQ treatment effectively abolished the promotion effects of lupeol on cell viability and autophagy, and the inhibitory effects of lupeol on ROS level, cell senescence, ECM degradation, and apoptosis (P < 0.05). Silencing of SIRT3 reversed the inhibitory effect of lupeol on mTOR phosphorylation level and the promotion effect of lupeol on autophagy (P < 0.05). In the in vivo experiment, compared with the OA group, the OA + lupeol group showed reduced cartilage degeneration and lower scores for the Osteoarthritis Research Society International grading system (P < 0.05). The OA + lupeol group also showed up-regulated SIRT3 expression, reduced mTOR phosphorylation level, increased LC3BⅡ/LC3BⅠ ratio, reduced MMP13 protein level, and reduced mRNA level of SASP (P < 0.05).

Conclusion

Lupeol alleviates chondrocyte senescence in osteoarthritis by regulating autophagy through the SIRT3/mTOR pathway.

CDK8 mediated inflammatory microenvironment aggravates osteoarthritis progression

INTRODUCTION

Cyclin-Dependent Kinase 8 (CDK8), a CDK family member, regulates the development of inflammatory processes through transcriptional activation. The involvement of CDK8 in osteoarthritis (OA) progression is not yet understood.

OBJECTIVES

This study aims to investigate whether CDK8, through its transcriptional regulatory functions, collaborates with NF-κB in chondrocytes to regulate the transcription of senescence-associated secretory phenotype (SASP) genes, thereby exacerbating the inflammatory microenvironment in the progression of osteoarthritis (OA), and to explore the specific mechanisms involved.

METHODS

The effects of CDK8 silencing or overexpression will be assessed by measuring OA pathological markers through H&E staining, immunoblotting, Western blot, qRT-PCR, immunofluorescence and ELISA. The DMM surgery mouse model will be used as the OA model, and the PAM and Von Frey tests will be employed to measure the pain threshold in mice. Luciferase and ChIP assays will be conducted to explore the transcriptional regulation and elongation mechanisms of CDK8.

RESULT

CDK8 influences OA advancement by being recruited to the SASP promoter region in cooperation with NF-κB, leading to the elongation phosphorylation of Rpb1 CTD within the context of NF-κB-induced gene specificity, thereby regulating SASP transcription. The SASP secreted by chondrocytes during this process promotes the inflammatory microenvironment in the joint and drives macrophage differentiation into osteoclasts, further worsening the severity of osteoarthritis.

CONCLUSION

The SASP secreted by chondrocytes during the OA process plays a crucial role in worsening the severity of the disease. Inhibiting CDK8 expression can decrease its secretion by downregulating the transcription levels of SASP, which are co-regulated by CDK8 and NF-κB. This could offer a new target for osteoarthritis treatment.

Ultra-small quercetin-based nanotherapeutics ameliorate acute liver failure by combatting inflammation/cellular senescence cycle

Background: Acute liver failure (ALF) is marked by a substantial generation of reactive oxygen species (ROS), which can induce both cellular senescence and a pronounced inflammatory response. Senescent cells secrete factors collectively termed the senescence-associated secretory phenotype (SASP), which exacerbate inflammation, while inflammation can reciprocally promote cellular senescence. Quercetin (Que), recognized for its ROS-scavenging capabilities, holds the potential for anti-inflammatory and anti-senescent effects. However, its extremely low aqueous solubility constrains its clinical efficacy in treating inflammation. Methods: We employed a simple and stable coordination method to synthesize ultra-small quercetin-Fe nanoparticles (QFN) by complexing quercetin with iron ions. The ROS-scavenging, anti-inflammatory, and anti-senescent effects of QFN were evaluated in vitro. A lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced ALF mice model was used to investigate the therapeutic effects of QFN in vivo, and transcriptomic analysis was conducted to elucidate the mechanisms underlying QFN-mediated hepatoprotection. Results: Our findings demonstrate that QFN possesses remarkable water solubility and highly efficient ROS-scavenging properties. In vitro, QFN effectively inhibits macrophage-mediated inflammation and mitigates hepatocyte senescence. In vivo, QFN significantly attenuates LPS/D-GalN-induced ALF by protecting against macrophage inflammation and cellular senescence, thereby disrupting the self-perpetuating cycle of inflammation and aging. Moreover, its potent ROS scavenging capacity not only suppresses cellular apoptosis but also facilitates liver regeneration. Transcriptomic analyses further reveal that QFN exerts its protective effects through the modulation of key pathways involved in cellular senescence and inflammation. Conclusions: In summary, our study characterizes QFN as a potent ROS-scavenging modulator that exhibits both anti-inflammatory and anti-senescent properties, effectively disrupting the detrimental feedback loop between inflammation and cellular senescence. QFN holds considerable potential as a therapeutic agent for the treatment of ALF and other pathologies associated with inflammation and aging.

4-Octyl itaconate inhibits synovitis in the mouse model of post-traumatic osteoarthritis and alleviates pain

PURPOSE

To investigate the pathological changes of the synovium in mice with post-traumatic osteoarthritis (PTOA) treated with 4-octyl itaconate (4-OI) and evaluate the therapeutic effects of 4-OI.

METHODS

In the phenotypic validation experiment, the mice were randomly divided into 3 groups: wild-type (WT) group, sham group, and destabilization of the medial meniscus (DMM) group. Through MRI, micro-CT, and histological analysis, it was determined that the DMM surgery induced a mouse PTOA model with significant signs of synovitis. At 12 weeks post-DMM surgery, synovial tissues from the DMM group and WT group mice were collected for ribonucleic acid sequencing analysis. In the 4-OI treatment experiment, mice were randomly divided into the sham group, DMM group, DMM + 4-OI (50 mg/kg) group, and DMM + 4-OI (100 mg/kg) group. Von Frey tests and open field tests were conducted at intervals during the 12 weeks following the DMM surgery. After 12 weeks of surgery, the efficacy of 4-OI treatment on PTOA in mice was evaluated using MRI, micro-CT, histological analysis, and quantitative real-time polymerase chain reaction. Finally, we utilized network pharmacology analysis to predict the mechanism of 4-OI in treating PTOA synovitis and conducted preliminary validation. Statistical analysis was performed using one-way ANOVA and the Kruskal-Wallis test. Difference was considered statistically significant at p < 0.05.

RESULTS

The DMM surgery effectively induced a PTOA mouse model, which displayed significant symptoms of synovitis. These symptoms included a notable increase in both the number of calcified tissues and osteophytes (p < 0.001), an enlargement of the calcified meniscus and synovial tissue volume (p < 0.001), and thickening of the synovial lining layer attributable to M1 macrophage accumulation (p = 0.035). Additionally, we observed elevated histological scores for synovitis (p < 0.001). Treatment with 4-OI inhibited the thickening of M1 macrophages in the synovial lining layer of PTOA mice (p < 0.001) and reduced fibrosis in the synovial stroma (p = 0.004). Furthermore, it reduced the histological scores of knee synovitis in PTOA mice (p = 0.006) and improved the inflammatory microenvironment associated with synovitis. Consequently, this treatment alleviated pain in PTOA mice (p < 0.001) and reduced spontaneous activity (p = 0.003). Bioinformatics and network pharmacology analyses indicated that 4-OI may exert its therapeutic effects by inhibiting the differentiation of synovial Th17 cells. Specifically, compared to the lipopolysaccharide stimulation group, 4-OI reduced the levels of positive regulatory factors of Th17 cell differentiation (IL-1: p < 0.001, IL-6: p < 0.001), key effector molecules (IL-17A: p < 0.001, IL-17F: p = 0.004), and downstream effector molecules in the IL-17 signaling pathway (CCL2: p < 0.001, MMP13: p < 0.001).

CONCLUSION

4-OI is effective in inhibiting synovitis in PTOA, thereby alleviating the associated painful symptoms.

Metformin Exhibits Anti-Inflammatory Effects by Regulating microRNA-451/CXCL16 and B Cell Leukemia/Lymphoma 2 in Patients With Osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is the most common cause of chronic disability in joints among older individuals. The primary goal of OA treatment is pain relief to improve the quality of life. Inflammation and aging are involved in the pathogenesis of pain in OA. In this study, we evaluated the ability of metformin to regulate microRNAs, such as miR-451 and miR-15b, and their target proteins, CXCL16 and B cell leukemia/lymphoma 2 (BCL-2), involved in inflammation and apoptosis.

METHODS

In this double-blind placebo-controlled clinical trial, patients were randomly divided into two groups: one receiving metformin and the other receiving a placebo for four months (starting at 0.5 g/day for the first week, increasing to 1 g/day for the second week, and increasing to 1.5 g/day for the remaining period). In addition to evaluating the clinical response using the Knee Injury and Osteoarthritis Outcome Score questionnaire, miR-451 and miR-15b expression levels were detected using real-time polymerase chain reaction. The serum levels of CXCL16 and BCL-2 were evaluated using enzyme-linked immunosorbent assay kits before (time zero) and after treatment (month four).

RESULTS

Metformin increased miR-451 expression levels simultaneously with pain reduction, whereas miR-15b expression did not change significantly after four months of treatment. Also, metformin decreased the serum levels of BCL-2 and CXCL16 in patients with OA.

CONCLUSION

The effects of metformin in reducing pain can be attributed to many factors, including its anti-inflammatory and antiaging effects. Our findings suggest that metformin may reduce pain and inflammation in patients with OA through the regulation of miR-451/CXCL16 and BCL-2.

Synovial mast cells and osteoarthritis: Current understandings and future perspectives

Osteoarthritis (OA) is a prevalent joint disease worldwide that significantly impacts the quality of life of individuals, particularly those in middle-aged and elderly populations. OA was initially considered as non-inflammatory arthritis, but recent studies have identified a substantial number of immune responses in OA, leading to the recognition of inflammation as a key factor in its pathogenesis. An increasing number of studies have found that mast cell (MC) and MC-secreted inflammatory mediators and cytokines are notably increased in the synovial fluid of OA patients, indicating a potential association between MCs and the onset and progression of synovial inflammation. The present review aims to summarize the significance and mechanism of MCs in the pathogenesis of OA. Meanwhile, we also discuss the clinical potential of using MCs as therapeutic target for OA therapy. Modulating the activities of MCs or the mediators of MCs in the synovial fluid inflammatory microenvironment will be promising new options for the treatment of OA.

The senescence-associated secretory phenotype and its physiological and pathological implications

Cellular senescence is a state of terminal growth arrest associated with the upregulation of different cell cycle inhibitors, mainly p16 and p21, structural and metabolic alterations, chronic DNA damage responses, and a hypersecretory state known as the senescence-associated secretory phenotype (SASP). The SASP is the major mediator of the paracrine effects of senescent cells in their tissue microenvironment and of various local and systemic biological functions. In this Review, we discuss the composition, dynamics and heterogeneity of the SASP as well as the mechanisms underlying its induction and regulation. We describe the various biological properties of the SASP, its beneficial and detrimental effects in different physiological and pathological settings, and its impact on overall health span. Finally, we discuss the use of the SASP as a biomarker and of SASP inhibitors as senomorphic interventions to treat cancer and other age-related conditions.

S100A4 targets PPP1CA/IL-17 to inhibit the senescence of sheep endometrial epithelial cells

Background

Gonadotropin-releasing hormone (GnRH) is commonly used in animal reproduction and production, but it was previously reported that GnRH decreases the embryo implantation rate during artificial insemination or embryo transfer in sheep. In addition to the finding that GnRH can target S100A4 to inhibit endometrial epithelial cells proliferation, it was also found that endometrial cells were in poor condition and experienced cell death in S100A4 knockout mice, but the mechanism is unclear.

Methods

The protein PPP1CA, which interacts with S100A4, was detected by immunoprecipitation-mass spectrometry of overexpression and knockdown of S100A4 and PPP1CA. The effect of S100A4 and PPP1CA on cell senescence was detected by Galactosidase staining. To further reveal the mechanism effect of S100A4 and PPP1CA on cell senescence, transcriptome sequencing was conducted. Additionally, in vivo experiments were performed to assess PPP1CA protein expression in the endometrial tissue of S100A4 knockout mice.

Results

S100A4 inhibited cell senescence by activating PPP1CA, while PPP1CA overexpression suppressed the activation of the IL-17 signaling pathway. Inhibition of the IL-17 signaling pathway inhibited the senescence of endometrial cells.

Conclusion

S100A4 can target the PPP1CA/IL-17 signaling pathway and inhibit endometrial epithelial cell senescence.

Nordihydroguaiaretic acid microparticles are effective in the treatment of osteoarthritis

Several disease-modifying osteoarthritis (OA) drugs have emerged, but none have been approved for clinical use due to their systemic side effects, short half-life, and rapid clearance from the joints. Nordihydroguaiaretic acid (NDGA), a reactive oxygen species (ROS) scavenger and autophagy inducer, could be a potential treatment for OA. In this report, we show for the first time that sustained delivery of NDGA through polymeric microparticles maintains therapeutic concentrations of drug in the joint and ameliorates post-traumatic OA (PTOA) in a mouse model. In vitro treatment of oxidatively stressed primary chondrocytes from OA patients using NDGA-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles (NDGA-MP) inhibited 15-lipoxygenase, induced autophagy, prevented chondrosenescence, and sustained matrix production. In vivo intra-articular delivery of NDGA-MP was non-toxic and had prolonged retention time (up to 35 days) in murine knee joints. Intra-articular therapy using NDGA-MP effectively reduced cartilage damage and reduced pain in the surgery-induced PTOA mouse model. Our studies open new avenues to modulate the immune environment and treat post-traumatic OA using ROS quenchers and autophagy inducers.

Regulation of ferroptosis in osteoarthritis and osteoarthritic chondrocytes by typical MicroRNAs in chondrocytes

Osteoarthritis (OA) is a progressive degenerative disorder impacting bones and joints, worsened by chronic inflammation, immune dysregulation, mechanical stress, metabolic disturbances, and various other contributing factors. The complex interplay of cartilage damage, loss, and impaired repair mechanisms remains a critical and formidable aspect of OA pathogenesis. At the genetic level, multiple genes have been implicated in the modulation of chondrocyte metabolism, displaying both promotive and inhibitory roles. Recent research has increasingly focused on the influence of non-coding RNAs in the regulation of distinct cell types within bone tissue in OA. In particular, an expanding body of evidence highlights the regulatory roles of microRNAs in OA chondrocytes. This review aims to consolidate the most relevant microRNAs associated with OA chondrocytes, as identified in recent studies, and to elucidate their involvement in chondrocyte metabolic processes and ferroptosis. Furthermore, this study explores the complex regulatory interactions between long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) in OA, with an emphasis on microRNA-mediated mechanisms. Finally, critical gaps in the current research are identified, offering strategic insights to advance the understanding of OA pathophysiology and guide therapeutic developments in this field.

An injectable thermosensitive hydrogel delivering M2 macrophage-derived exosomes alleviates osteoarthritis by promoting synovial lymphangiogenesis

Osteoarthritis (OA) is a prevalent chronic degenerative disease affecting millions worldwide, with current treatment measures lacking efficacy in slowing disease progression. The synovial lymphatic system (SLS) has emerged as a crucial player in OA pathogenesis, with compromised drainage function contributing to disease advancement. Lymphatic endothelial cells (LECs) within the SLS are influenced by synovial macrophages, whose precise impact on LEC function remains unclear. Exosomes released by macrophages may serve as mediators of this interaction, with potential implications for OA progression. Here, we propose that polarized macrophages modulate LEC activity via exosome release in synovial tissue, with M2 macrophage-derived exosomes (M2Exo) promoting LEC proliferation, migration, and lymphangiogenesis, potentially offering a therapeutic avenue for OA. Moreover, we developed an injectable thermosensitive hydrogel with the characteristic of sustained release of M2Exo for alleviating OA. The hydrogel was prepared by dynamically linking hyaluronic acid (HA) and Pluronic F-127 and loading M2Exo, termed as M2Exo loaded HP hydrogel. The in vitro and in vivo experiments showed that M2Exo loaded HP hydrogel exhibits a controlled release profile of exosomes, thereby efficaciously fostering synovial lymphangiogenesis and enhancing synovial lymphatic drainage functionality under OA conditions, thus alleviating OA progression, and providing promising insights into OA therapeutic strategies. STATEMENT OF SIGNIFICANCE: Osteoarthritis (OA) is a widespread degenerative disease with limited effective treatments to halt its progression. This research highlights the critical role of the synovial lymphatic system (SLS) in OA, focusing on how macrophage-derived exosomes influence lymphatic endothelial cell (LEC) function. We propose that M2 macrophage-derived exosomes (M2Exo) enhance LEC activity, promoting lymphangiogenesis, and offering a therapeutic approach for OA. Furthermore, we developed an injectable thermosensitive hydrogel (M2Exo loaded HP hydrogel) for sustained M2Exo release. Our in vitro and in vivo experiments demonstrate that this hydrogel supports synovial lymphangiogenesis and improves lymphatic drainage, effectively alleviating OA progression. This study presents significant advancements in OA therapy, offering new insights into its management.

Metallothionein-1 mitigates the advancement of osteoarthritis by regulating Th17/Treg balance

Osteoarthritis (OA) is a chronic inflammatory joint disorder characterized by cartilage degradation and bone remodeling. This study investigated the regulatory role of metallothionein 1 (MT1) in modulating immune responses and the balance between regulatory T cells (Treg) and T helper 17 cells (Th17) in OA. Peripheral blood mononuclear cells (PBMCs) from healthy individuals and OA patients were assessed for cytokine expression linked to Treg/Th17 homeostasis. OA was induced in wild-type (WT) and Mt1 knockout (MT1KO) mice via surgical destabilization of the medial meniscus. Clinical scores, pathological features, inflammatory cytokines, and Treg/Th17 balance were evaluated. MT1KO mice showed significantly elevated Mt1, pro-inflammatory cytokines (IL-1, IL-6, TNF-α) and exacerbated OA progression, characterized by increased knee joint diameter, inflammatory infiltration, and cartilage destruction. Mechanistically, disrupted Treg/Th17 balance played a pivotal role in OA exacerbation, with MT1KO promoting Th17 differentiation and reducing Treg populations. Additionally, the compensatory elevation of anti-inflammatory interleukin-10 (IL-10) in OA patients hinted at a nuanced immune regulatory mechanism. The study illuminates intricate interactions involving MT1, Treg/Th17 cells, and pro-inflammatory cytokines in OA pathogenesis, suggesting MT1's potential as a pivotal regulatory factor and a therapeutic target for mitigating immune dysregulation in OA.

Targeting senescent cells in atherosclerosis: Pathways to novel therapies

Targeting senescent cells has recently emerged as a promising strategy for treating age-related diseases, such as atherosclerosis, which significantly contributes to global cardiovascular morbidity and mortality. This review elucidates the role of senescent cells in the development of atherosclerosis, including persistently damaging DNA, inducing oxidative stress and secreting pro-inflammatory factors known as the senescence-associated secretory phenotype. Therapeutic approaches targeting senescent cells to mitigate atherosclerosis are summarized in this review, which include the development of senotherapeutics and immunotherapies. These therapies are designed to either remove these cells or suppress their deleterious effects. These emerging therapies hold potential to decelerate or even alleviate the progression of AS, paving the way for new avenues in cardiovascular research and treatment.

Gene therapy for fat-1 prevents obesity-induced metabolic dysfunction, cellular senescence, and osteoarthritis

Obesity is one of the primary risk factors for osteoarthritis (OA), acting through cross talk among altered biomechanics, metabolism, adipokines, and dietary free fatty acid (FA) composition. Obesity and aging have been linked to cellular senescence in various tissues, resulting in increased local and systemic inflammation and immune dysfunction. We hypothesized that obesity and joint injury lead to cellular senescence that is typically associated with increased OA severity or with aging and that the ratio of omega-6 (ω-6) to omega-3 (ω-3) FAs regulates these pathologic effects. Mice were placed on an ω-6-rich high-fat diet or a lean control diet and underwent destabilization of the medial meniscus to induce OA. Obesity and joint injury significantly increased cellular senescence in subcutaneous and visceral fat as well as joint tissues such as synovium and cartilage. Using adeno-associated virus (AAV) gene therapy for fat-1, a fatty acid desaturase that converts ω-6 to ω-3 FAs, decreasing the serum ω-6:ω-3 FA ratio had a strong senomorphic and therapeutic effect, mitigating metabolic dysfunction, cellular senescence, and joint degeneration. In vitro coculture of bone marrow-derived macrophages and chondrocytes from control and AAV8-fat1-treated mice were used to examine the roles of various FA mediators in regulating chondrocyte senescence. Our results suggest that obesity and joint injury result in a premature "aging" of the joint as measured by senescence markers, and these changes can be ameliorated by altering FA composition using fat-1 gene therapy. These findings support the potential for fat-1 gene therapy to treat obesity- and/or injury-induced OA clinically.

Characterization of the single cell landscape in normal and osteoarthritic equine joints

Background

Osteoarthritis (OA) is a major source of pain and disability worldwide. Understanding of disease progression is evolving, but OA is increasingly thought to be a multifactorial disease in which the innate immune system plays a role in regulating and perpetuating low-grade inflammation. The aim of this study was to enhance our understanding of OA immunopathogenesis through characterization of the transcriptomic responses in OA joints, with the goal to facilitate the development of targeted therapies.

Methods

Single-cell RNA sequencing (scRNA-seq) was completed on cells isolated from the synovial fluid of three normal and three OA equine joints. In addition to synovial fluid, scRNA-seq was also performed on synovium from one normal joint and one OA joint.

Results

Characterization of 28,639 cells isolated from normal and OA-affected equine synovial fluid revealed the composition to be entirely immune cells (CD45+) with 8 major populations and 26 subpopulations identified. In synovial fluid, we found myeloid cells (macrophage and dendritic cells) to be overrepresented and T cells (CD4 and CD8) to be underrepresented in OA relative to normal joints. Through subcluster and differential abundance analysis of T cells we further identified a relative overrepresentation of IL23R+ gamma-delta (γδ) T cells in OA-affected joints (a cell type we report to be enriched in gene signatures associated with T helper 17 mediated immunity). Analysis of an additional 17,690 cells (11 distinct cell type clusters) obtained from synovium of one horse led to the identification of an OA-associated reduction in the relative abundance of synovial macrophages, which contrasts with the increased relative abundance of macrophages in synovial fluid. Completion of cell-cell interaction analysis implicated myeloid cells in disease progression, suggesting that the myeloid-myeloid interactions were increased in OA-affected joints.

Conclusions

Overall, this work provides key insights into the composition of equine synovial fluid and synovium in health and OA. The data generated in this study provides equine-specific cell type gene signatures which can be applied to future investigations. Furthermore, our analysis highlights the potential role of macrophages and IL23R+ γδ T cells in OA immunopathogenesis.

The syntaxin-binding protein STXBP5 regulates progerin expression

Hutchinson-Gilfor progeria syndrome (HGPS) is caused by a mutation in Lamin A resulting in the production of a protein called progerin. The accumulation of progerin induces inflammation, cellular senescence and activation of the P53 pathway. In this study, through public dataset analysis, we identified Syntaxin Binding Protein 5 (STXBP5) as an influencing factor of progerin expression. STXBP5 overexpression accelerated the onset of senescence, while STXBP5 deletion suppressed progerin expression, delayed senility, and decreased the expression of senescence-related factors. STXBP5 and progerin have synergistic effects and a protein-protein interaction. Through bioinformatics analysis, we found that STXBP5 affects ageing-related signalling pathways such as the mitogen-activated protein kinase (MAPK) pathway, the hippo pathway and the interleukin 17 (IL17) signalling pathway in progerin-expressing cells. In addition, STXBP5 overexpression induced changes in transposable elements (TEs), such as the human endogenous retrovirus H internal coding sequence (HERVH-int) changes. Our protein coimmunoprecipitation (Co-IP) results indicated that STXBP5 bound directly to progerin. Therefore, decreasing STXBP5 expression is a potential new therapeutic strategy for treating ageing-related phenotypes in patients with HGPS.

Benefit delayed immunosenescence by regulating CD4+T cells: A promising therapeutic target for aging-related diseases

CD4+T cells play a notable role in immune protection at different stages of life. During aging, the interaction between the body's internal and external environment and CD4+T cells results in a series of changes in the CD4+T cells pool making it involved in immunosenescence. Many studies have extensively examined the subsets and functionality of CD4+T cells within the immune system, highlighted their pivotal role in disease pathogenesis, progression, and therapeutic interventions. However, the underlying mechanism of CD4+T cells senescence and its intricate association with diseases remains to be elucidated and comprehensively understood. By summarizing the immunosenescent progress and network of CD4+T cell subsets, we reveal the crucial role of CD4+T cells in the occurrence and development of age-related diseases. Furthermore, we provide new insights and theoretical foundations for diseases targeting CD4+T cell subsets aging as a treatment focus, offering novel approaches for therapy, especially in infections, cancers, autoimmune diseases, and other diseases in the elderly.

Advances in targeted therapies for age-related osteoarthritis: A comprehensive review of current research

Osteoarthritis (OA) is a common degenerative joint disease that disproportionately impacts the elderly population on a global scale. As aging is a significant risk factor for OA, there is a growing urgency to develop specific therapies that target the underlying mechanisms of aging associated with this condition. This summary seeks to offer a thorough introduction of ongoing research efforts aimed at developing therapies to combat senescence in the context of OA. Cellular senescence plays a pivotal role in both the deterioration of cartilage integrity and the perpetuation of chronic inflammation and tissue remodeling. Consequently, targeting SnCs has emerged as a promising therapeutic approach to alleviate symptoms and hinder the progression of OA. This review examines a range of approaches, including senolytic drugs targeting SnCs, senomorphics that modulate the senescence-associated secretory phenotype (SASP), and interventions that enhance immune system clearance of SnCs. Novel methodologies, such as utilizing novel materials for exosome delivery and administering anti-aging medications with precision, offer promising avenues for the precise treatment of OA. Accumulating evidence underscores the potential of targeting senescence in OA management, potentially facilitating the development of more effective and personalized therapeutic interventions.

Age-associated Senescent - T Cell Signaling Promotes Type 3 Immunity that Inhibits the Biomaterial Regenerative Response

Aging is associated with immunological changes that compromise response to infections and vaccines, exacerbate inflammatory diseases and can potentially mitigate tissue repair. Even so, age-related changes to the immune response to tissue damage and regenerative medicine therapies remain unknown. Here, it is characterized how aging induces changes in immunological signatures that inhibit tissue repair and therapeutic response to a clinical regenerative biological scaffold derived from extracellular matrix. Signatures of inflammation and interleukin (IL)-17 signaling increased with injury and treatment both locally and regionally in aged animals, and computational analysis uncovered age-associated senescent-T cell communication that promotes type 3 immunity in T cells. Local inhibition of type 3 immune activation using IL17-neutralizing antibodies improves healing and restores therapeutic response to the regenerative biomaterial, promoting muscle repair in older animals. These results provide insights into tissue immune dysregulation that occurs with aging that can be targeted to rejuvenate repair.

Roles of Menin in T cell differentiation and function: Current knowledge and perspectives

The commitment to specific T lymphocytes (T cell) lineages is governed by distinct transcription factors, whose expression is modulated through epigenetic mechanisms. Unravelling these epigenetic mechanisms that regulate T cell differentiation and function holds significant importance for understanding T cells. Menin, a multifunctional scaffolding protein, is implicated in various cellular processes, such as cell proliferation, cell cycle control, DNA repair and transcriptional regulation, primarily through epigenetic mechanisms. Existing research indicates Menin's impact on T cell differentiation and function, while a comprehensive and systematic review is currently lacking to consolidate these findings. In the current review, we have highlighted recent studies on the role of Menin in T cell differentiation and function, focusing mainly on its impact on the memory Th2 maintenance, Th17 differentiation and maintenance, CD4+ T cell senescence, and effector CD8+ T cell survival. Considering Menin's crucial function in maintaining effector T cell function, the potential of inhibiting Menin activity in mitigating inflammatory diseases associated with excessive T cell activation has also been emphasised.

The role of mitochondrial autophagy in osteoarthritis

Osteoarthritis (OA) is a progressive degenerative joint disease, and the underlying molecular mechanisms of OA remain poorly understood. This study aimed to elucidate the relationship between mitochondrial autophagy and OA by identifying key regulatory genes and their biological functions. Utilizing bioinformatics analyses of RNA expression profiles from the GSE55235 dataset, we identified 2,136 differentially expressed genes, leading to the discovery of hub genes associated with mitochondrial autophagy and OA. Gene set enrichment analysis (GSEA) revealed their involvement in critical pathways, highlighting their potential roles in OA pathogenesis. Furthermore, our study explored the immunological landscape of OA, identifying distinct immune cell infiltration patterns that contribute to the disease's inflammatory profile. We also evaluated the therapeutic potential of drugs targeting these hub genes, suggesting potential approaches for OA treatment. Collectively, this study advances our knowledge of mitochondrial autophagy in OA and proposes promising biomarkers and therapeutic targets.

Single-cell transcriptome and crosstalk analysis reveals immune alterations and key pathways in the bone marrow of knee OA patients

Knee osteoarthritis (OA) is a significant medical and economic burden. To understand systemic immune effects, we performed deep exploration of bone marrow aspirate concentrates (BMACs) from knee-OA patients via single-cell RNA sequencing and proteomic analyses from a randomized clinical trial (MILES: NCT03818737). We found significant cellular and immune alterations in the bone marrow, specifically in MSCs, T cells and NK cells, along with changes in intra-tissue cellular crosstalk during OA progression. Unlike previous studies focusing on injury sites or peripheral blood, our probe into the bone marrow-an inflammation and immune regulation hub-highlights remote organ impact of OA, identifying cell types and pathways for potential therapeutic targeting. Our findings highlight increased cellular senescence and inflammatory pathways, revealing key upstream genes, transcription factors, and ligands. Additionally, we identified significant enrichment in key biological pathways like PI3-AKT-mTOR signaling and IFN responses, showing their potentially crucial role in OA onset and progression.

The role of Th/Treg immune cells in osteoarthritis

Osteoarthritis (OA) is a prevalent clinical condition affecting the entire joint, characterized by its multifactorial etiology and complex pathophysiology. The onset of OA is linked to inflammatory mediators produced by the synovium, cartilage, and subchondral bone, all of which are closely tied to cartilage degradation. Consequently, OA may also be viewed as a systemic inflammatory disorder. Emerging studies have underscored the significance of T cells in the development of OA. Notably, imbalances in Th1/Th2 and Th17/Treg immune cells may play a crucial role in the pathogenesis of OA. This review aims to compile recent advancements in understanding the role of T cells and their Th/Treg subsets in OA, examines the immune alterations and contributions of Th/Treg cells to OA progression, and proposes novel directions for future research, including potential therapeutic strategies for OA.

Identification and experimental validation of key genes in osteoarthritis based on machine learning algorithms and single-cell sequencing analysis

Purpose

Osteoarthritis (OA) is a prevalent cause of disability in older adults. Identifying diagnostic markers for OA is essential for elucidating its mechanisms and facilitating early diagnosis.

Methods

We analyzed 53 synovial tissue samples (n = 30 for OA, n = 23 for the control group) from two datasets in the Gene Express Omnibus (GEO) database. We identified differentially expressed genes (DEGs) between the groups and applied dimensionality reduction using six machine learning algorithms to pinpoint characteristic genes (key genes). We classified the OA samples into subtypes based on these key genes and explored the differences in biological functions and immune characteristics among subtypes, as well as the roles of the key genes. Additionally, we constructed a protein-protein interaction network to predict small molecules that target these genes. Further, we accessed synovial tissue sample data from the single-cell RNA dataset GSE152805, categorized the cells into various types, and examined variations in gene expression and their correlation with OA progression. Validation of key gene expression was conducted in cellular experiments using the qPCR method.

Results

Four genes AGMAT, MAP3K8, PER1, and XIST, were identified as characteristic genes of OA. All can independently predict the occurrence of OA. With these genes, the OA samples can be clustered into two subtypes, which showed significant differences in functional pathways and immune infiltration. Eight cell types were obtained by analyzing the single-cell RNA data, with synovial intimal fibroblasts (SIF) accounting for the highest proportion in each sample. The key genes were found over-expressed in SIF and significantly correlated with OA progression and the content of immune cells (ICs). We validated the relative levels of key genes in OA and normal cartilage tissue cells, which showed an expression trend consistency with the bioinformatics result except for XIST.

Conclusion

Four genes, AGMAT, MAP3K8, PER1, and XIST are closely related to the progression of OA, and play as diagnostic and predictive markers in early OA.

Do we understand sex-related differences governing dimorphic disease mechanisms in preclinical animal models of osteoarthritis?

Research conducted using murine preclinical models of osteoarthritis (OA) over the last three decades has brought forth many exciting developments showcasing mechanisms and pathways that drive disease pathogenesis. These models have identified therapeutic targets that can be modulated via innovative biologicals and pharmaceuticals. However, many of these approaches have failed to translate to humans and reach the clinic. This commentary aims to highlight some of the key hurdles in the translation of novel findings using preclinical OA models with a focus on sex-related differences and variations in chondrosenescence in these animal models. Notably, besides chondrosenescence, other signaling mechanisms have been shown to be affected by sexual dimorphism (i.e. TGFβ signaling, EGFR/integrin α1β1 and Trpv4). Preclinical models of OA mainly utilize male mice due to their capacity to manifest fast progressing OA structural phenotype compared to female mice. This experimental trend has overlooked and ignored the sex-related effects of numerous mechanisms affecting joint structure, that influence OA structural progression. Future work should focus on analyzing both sexes and understanding sex-related differences, which will enable us to gain a better understanding of the progression of OA based on sex-related mechanistic discrepancies, and potentially improve translatability.

Neural and immune roles in osteoarthritis pain: Mechanisms and intervention strategies

Pain is the leading symptom for most individuals with osteoarthritis (OA), a complex condition marked by joint discomfort. Recently, the dynamic interplay between the nervous and immune systems has become a focal point for understanding pain regulation. Despite this, there is still a substantial gap in our comprehensive understanding of the neuroimmune interactions and their effects on pain in OA. This review examines the bidirectional influences between immune cells and nerves in OA progression. It explores current approaches that target neuroimmune pathways, including promoting M2 macrophage polarization and specific neuronal receptor targeting, for effective pain reduction.

Translational potential statement

This review provides a comprehensive overview of the mechanisms underlying the interplay between the immune system and nervous system during the progression of OA, as well as their contributions to pain. Additionally, it compiles existing intervention strategies targeting neuroimmunity for the treatment of OA pain. This information offers valuable insights for researchers seeking to address the challenge of OA pain.

Musculoskeletal imaging of senescence

Senescent cells play a vital role in the pathogenesis of musculoskeletal (MSK) diseases, such as chronic inflammatory joint disorders, rheumatoid arthritis (RA), and osteoarthritis (OA). Cellular senescence in articular joints represents a response of local cells to persistent stress that leads to cell-cycle arrest and enhanced production of inflammatory cytokines, which in turn perpetuates joint damage and leads to significant morbidities in afflicted patients. It has been recently discovered that clearance of senescent cells by novel "senolytic" therapies can attenuate the chronic inflammatory microenvironment of RA and OA, preventing further disease progression and supporting healing processes. To identify patients who might benefit from these new senolytic therapies and monitor therapy response, there is an unmet need to identify and map senescent cells in articular joints and related musculoskeletal tissues. To fill this gap, new imaging biomarkers are being developed to detect and characterize senescent cells in human joints and musculoskeletal tissues. This review article will provide an overview of these efforts. New imaging biomarkers for senescence cells are expected to significantly improve the specificity of state-of-the-art imaging technologies for diagnosing musculoskeletal disorders.

Collagen Type II-Based Injectable Materials for In situ Repair and Regeneration of Articular Cartilage Defect

Repairing and regenerating articular cartilage defects (ACDs) have long been challenging for physicians and scientists. The rise of injectable materials provides a novel strategy for minimally invasive surgery to repair ACDs. In this study, we successfully developed injectable materials based on collagen type II, achieving hyaline cartilage repair and regeneration of ACDs. Analysis was conducted on the regenerated cartilage after materials injection. The histology staining demonstrated complete healing of the ACDs with the attainment of a hyaline cartilage phenotype. The biochemical and biomechanical properties are similar to the adjacent native cartilage without noticeable adverse effects on the subchondral bone. Further transcriptome analysis found that compared with the Native cartilage adjacent to the defect area, the Regenerated cartilage in the defect area repaired with type II collagen-based injection materials showed changes in cartilage-related pathways, as well as down-regulation of T cell receptor signaling pathways and interleukin-17 signaling pathways, which changed the immune microenvironment of the ACD area. Overall, these findings offer a promising injectable approach to treating ACDs, providing a potential solution to the challenges associated with achieving hyaline cartilage in situ repair and regeneration while minimizing damage to the surrounding cartilage.

c-Jun N-terminal kinase signaling in aging

Aging encompasses a wide array of detrimental effects that compromise physiological functions, elevate the risk of chronic diseases, and impair cognitive abilities. However, the precise underlying mechanisms, particularly the involvement of specific molecular regulatory proteins in the aging process, remain insufficiently understood. Emerging evidence indicates that c-Jun N-terminal kinase (JNK) serves as a potential regulator within the intricate molecular clock governing aging-related processes. JNK demonstrates the ability to diminish telomerase reverse transcriptase activity, elevate β-galactosidase activity, and induce telomere shortening, thereby contributing to immune system aging. Moreover, the circadian rhythm protein is implicated in JNK-mediated aging. Through this comprehensive review, we meticulously elucidate the intricate regulatory mechanisms orchestrated by JNK signaling in aging processes, offering unprecedented molecular insights with significant implications and highlighting potential therapeutic targets. We also explore the translational impact of targeting JNK signaling for interventions aimed at extending healthspan and promoting longevity.

Ageing-related bone and immunity changes: insights into the complex interplay between the skeleton and the immune system

Ageing as a natural irreversible process inherently results in the functional deterioration of numerous organ systems and tissues, including the skeletal and immune systems. Recent studies have elucidated the intricate bidirectional interactions between these two systems. In this review, we provide a comprehensive synthesis of molecular mechanisms of cell ageing. We further discuss how age-related skeletal changes influence the immune system and the consequent impact of immune system alterations on the skeletal system. Finally, we highlight the clinical implications of these findings and propose potential strategies to promote healthy ageing and reduce pathologic deterioration of both the skeletal and immune systems.

Periodontal disease as a model to study chronic inflammation in aging

Periodontal disease is a chronic inflammatory condition that results in the destruction of the teeth supporting tissues, eventually leading to the loss of teeth and reduced quality of life. In severe cases, periodontal disease can limit proper nutritional intake, cause acute pain and infection, and cause a withdrawal from social situations due to esthetic and phonetic concerns. Similar to other chronic inflammatory conditions, periodontal disease increases in prevalence with age. Research into what drives periodontal disease pathogenesis in older adults is contributing to our general understanding of age-related chronic inflammation. This review will present periodontal disease as an age-related chronic inflammatory disease and as an effective geroscience model to study mechanisms of age-related inflammatory dysregulation. The current understanding of the cellular and molecular mechanisms that drive inflammatory dysregulation as a function of age will be discussed with a focus on the major pathogenic immune cells in periodontal disease, which include neutrophils, macrophages, and T cells. Research in the aging biology field has shown that the age-related changes in these immune cells result in the cells becoming less effective in the clearance of microbial pathogens, expansion of pathogenic subpopulations, or an increase in pro-inflammatory cytokine secretions. Such changes can be pathogenic and contribute to inflammatory dysregulation that is associated with a myriad of age-related disease including periodontal disease. An improved understanding is needed to develop better interventions that target the molecules or pathways that are perturbed with age in order to improve treatment of chronic inflammatory conditions, including periodontal disease, in older adult populations.

Cartilage decellularized matrix hydrogel loaded with protocatechualdehyde for targeted epiphycan treatment of osteoarthritis

Osteoarthritis (OA) is a prevalent chronic disease, characterized by chronic inflammation and cartilage degradation. This study aims to deepen the understanding of OA's pathophysiology and to develop novel therapeutic strategies. Our study underscores the pivotal role of Epiphycan (EPYC) and the IL-17 signaling pathway in OA. EPYC, an essential extracellular matrix constituent, has been found to exhibit a positive correlation with the severity of OA. We have discovered that EPYC modulates the activation of the IL-17 signaling pathway within chondrocytes by regulating the interaction between IL-17A and its receptor, IL-17RA. This regulatory mechanism underscores the intricate interplay between the extracellular matrix and immune signaling in the pathogenesis of OA Another finding of our study is the therapeutic effectiveness of protocatechualdehyde (PAH) in OA. PAH significantly reduces chondrocyte hypertrophy and supports cartilage tissue recovery.by targets EPYC. To reduce the side effects of orally administered PAH and maintain its effective drug concentration, we have developed a decellularized matrix hydrogel loaded with PAH for intra-articular injection. This novel drug delivery system is advantageous in minimizing drug-related side effects and ensuring sustained release PAH within the joint cavity.

Combating Atherosclerosis with Chirality/Phase Dual-Engineered Nanozyme Featuring Microenvironment-Programmed Senolytic and Senomorphic Actions

Senescence plays a critical role in the development and progression of various diseases. This study introduces an amorphous, high-entropy alloy (HEA)-based nanozyme designed to combat senescence. By adjusting the nanozyme's composition and surface properties, this work analyzes its catalytic performance under both normal and aging conditions, confirming that peroxide and superoxide dismutase (SOD) activity are crucial for its anti-aging therapeutic function. Subsequently, the chiral-dependent therapeutic effect is validated and the senolytic performance of D-handed PtPd2CuFe across several aging models is confirmed. Through multi-Omics analyses, this work explores the mechanism underlying the senolytic action exerted by nanozyme in depth. It is confirm that exposure to senescent conditions leads to the enrichment of copper and iron atoms in their lower oxidation states, disrupting the iron-thiol cluster in mitochondria and lipoic acid transferase, as well as oxidizing unsaturated fatty acids, triggering a cascade of cuproptosis and ferroptosis. Additionally, the concentration-dependent anti-aging effects of nanozyme is validated. Even an ultralow dose, the therapeutic can still act as a senomorphic, reducing the effects of senescence. Given its broad-spectrum action and concentration-adjustable anti-aging potential, this work confirms the remarkable therapeutic capability of D-handed PtPd2CuFe in managing atherosclerosis, a disease involving various types of senescent cells.

Crosstalk between bone and the immune system

Bone functions not only as a critical element of the musculoskeletal system but also serves as the primary lymphoid organ harboring hematopoietic stem cells (HSCs) and immune progenitor cells. The interdisciplinary field of osteoimmunology has illuminated the dynamic interactions between the skeletal and immune systems, vital for the maintenance of skeletal tissue homeostasis and the pathogenesis of immune and skeletal diseases. Aberrant immune activation stimulates bone cells such as osteoclasts and osteoblasts, disturbing the bone remodeling and leading to skeletal disorders as seen in autoimmune diseases like rheumatoid arthritis. On the other hand, intricate multicellular network within the bone marrow creates a specialized microenvironment essential for the maintenance and differentiation of HSCs and the progeny. Dysregulation of immune-bone crosstalk in the bone marrow environment can trigger tumorigenesis and exacerbated inflammation. A comprehensive deciphering of the complex "immune-bone crosstalk" leads to a deeper understanding of the pathogenesis of immune diseases as well as skeletal diseases, and might provide insight into potential therapeutic approaches.