The PI3K/AKT/mTOR signaling pathway in osteoarthritis: a narrative review

An engineered M2 macrophage-derived exosomes-loaded electrospun biomimetic periosteum promotes cell recruitment, immunoregulation, and angiogenesis in bone regeneration

The periosteum, a fibrous tissue membrane covering bone surfaces, is critical to osteogenesis and angiogenesis in bone reconstruction. Artificial periostea have been widely developed for bone defect repair, but most of these are lacking of periosteal bioactivity. Herein, a biomimetic periosteum (termed PEC-Apt-NP-Exo) is prepared based on an electrospun membrane combined with engineered exosomes (Exos). The electrospun membrane is fabricated using poly(ε-caprolactone) (core)-periosteal decellularized extracellular matrix (shell) fibers via coaxial electrospinning, to mimic the fibrous structure, mechanical property, and tissue microenvironment of natural periosteum. The engineered Exos derived from M2 macrophages are functionalized by surface modification of bone marrow mesenchymal stem cell (BMSC)-specific aptamers to further enhance cell recruitment, immunoregulation, and angiogenesis in bone healing. The engineered Exos are covalently bonded to the electrospun membrane, to achieve rich loading and long-term effects of Exos. In vitro experiments demonstrate that the biomimetic periosteum promotes BMSC migration and osteogenic differentiation via Rap1/PI3K/AKT signaling pathway, and enhances vascular endothelial growth factor secretion from BMSCs to facilitate angiogenesis. In vivo studies reveal that the biomimetic periosteum promotes new bone formation in large bone defect repair by inducing M2 macrophage polarization, endogenous BMSC recruitment, osteogenic differentiation, and vascularization. This research provides valuable insights into the development of a multifunctional biomimetic periosteum for bone regeneration.

Periplocin targets LRP4 to regulate metabolic homeostasis and anti-inflammation for the treatment of IVDD

BACKGROUND

Intervertebral disc degeneration (IVDD) is characterized by deteriorating intervertebral discs, leading primarily to low back pain and leg pain. Most current treatments for IVDD primarily address symptoms without targeting the underlying degenerative process. Moreover, tumor necrosis factor-α (TNF-α)-mediated inflammation and degradation of the nucleus pulposus (NP) extracellular matrix (ECM) influence this pathological process. Periplocin, a cardiotonic steroid extracted from periplocin forrestii, has demonstrated a wide range of medical benefits, including cardiotonic, anticancer, anti-inflammatory, and wound healing properties. Nevertheless, the effects of periplocin on IVDD remain unexplored.

OBJECTIVE

Our study explores the mechanism of action and the potential target of periplocin in mitigating IVDD pathology.

METHODS

Rat models of IVDD were established using acupuncture, and the affected discs underwent analysis via Safranin O-Fast Green (S-O) and Hematoxylin and Eosin (H&E) staining. Nucleus pulposus cells (NPCs) were harvested from IVDD patients and experimental animals for examination. A variety of techniques, including Western blot analysis, quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) assay, immunofluorescence staining, Alcian Blue staining and Immunohistochemistry (IHC) staining, were utilized to evaluate inflammation-related proteins, mRNAs and the ECM metabolism. In order to ascertain the potential protein targets of periplocin, the binding site of periplocin to LRP4 was elucidated through the utilisation of molecular docking experiments. Subsequently, the expression of low-density lipoprotein receptor-related protein 4 (LRP4) in NPCs was modified through the use of small interfering RNA (siRNA) knockdown and overexpression vectors, which were employed for the purposes of target validation.

RESULTS

We conclude from the present study that periplocin alleviates the progression of IVDD mainly through the following aspects: periplocin inhibits TNF-α-induced inflammatory; periplocin reduces matrix degradation; periplocin promotes matrix anabolism and regulates metabolic homeostasis. Moreover, the present study demonstrates that LRP4 is involved as a potential target in the multiple pathways mentioned above to protect the intervertebral disc.

CONCLUSION

Our research suggests that periplocin may serve as a promising treatment for IVDD, offering anti-inflammatory benefits, preventing ECM degradation, and promoting ECM anabolism.

Hierarchical interconnected porous scaffolds with regulated interfacial nanotopography exhibit antimicrobial, alleviate inflammation, neovascularization, and tissue integration for bone regeneration

Novel interconnected porous scaffolds featuring suitable micro-interface structures hold significance in bone regeneration. Therefore, a hierarchical interconnected porous scaffold with nanotopography interface of pores, mimicking natural bone structure and extracellular matrix microenvironment, are designed to enhance bone regeneration by improving cell adhesion, proliferation, alleviate inflammation, and tissue integration capabilities. The scaffold is fabricated through Pickering emulsion templating method, with aminated gelatin and copper-hydroxyapatite nanoparticles serving as co-stabilizers. This process results in a dual nanoparticles-decorated interface, which could provide ample anchoring points for cells. Adjusting the ratio of the two nanoparticles leads to scaffold with different interfacial roughness. The resultant scaffold increases the number of cellular focal adhesions, enhancing cell adhesion, while its high porosity supports cell recruitment, proliferation and immunomodulation. Copper-hydroxyapatite adsorption at the pore interface reduces copper ion usage and exposes nanoparticles for direct cell contact, endowing the scaffold with enhanced antibacterial and angiogenic properties. An initial burst release phase of copper ions exerts inhibitory effects on mRNA expression, followed by a sustained and optimal release phase that promotes osteogenesis. The molecular mechanism underlying the scaffold of osteogenic potential has been elucidated through RNA sequencing analysis, along with the regulation of inflammatory cytokine expression. In vitro and in vivo studies alike verify its neovascularization-promoting capacity. The efficacy shown in a rat model with critical cranial defects underscores its clinical promise for bone regeneration, as Cu-doped scaffolds retain osteoinductive qualities after 10 weeks in vivo. This study innovates a manufacturing method for a novel scaffold in bone tissue engineering.

Advancements in bone organoids: perspectives on construction methodologies and application strategies

BACKGROUND

In clinical practice and research, bone defects due to tumor growth, trauma, and different pathological conditions are significant challenges. Although bone possesses an intrinsic capacity for regeneration, extensive bone abnormalities necessitate applying advanced methods for regenerating bone. Bone organoids have made methodological breakthroughs in this field, and the use of bone organoids to repair bone defects has gained wide acceptance in the scientific community, supported by a large body of experimental evidence.

AIM OF REVIEW

This review synthesizes existing literature and ground-breaking studies to provide an in-depth examination of the bone organoid model, exploring the fundamental architecture and development of bone and emphasizing recent advancements in bone organoid fabrication, such as the application of 3D bioprinting technology in bone organoid fabrication. Furthermore, the study suggests potential directions for future research, highlighting the critical role of interdisciplinary collaboration in fully harnessing the potential of this rapidly evolving field. Key scientific concepts of review Bone organoids involve the 3D self-organization of in vitro-cultured bone-associated stem cells, optionally including extracellular matrix components. This process generates tissue closely resembling the original bone tissue's functional, genetic, and structural features. Bone organoids are more promising than traditional methods of bone defect repair. In addition, tissue engineering technologies such as 3D bioprinting have opened up new opportunities for constructing bone organoids. Future research should prioritize the development of composite bone organoids, enhancement of bone organoid stiffness, and improvement of bioactive materials, as well as the exploration and development of novel bioinks to facilitate the application of bone organoids in bone repair and regeneration.

Sirt4 Overexpression Modulates the JAK2/STAT3 and PI3K/AKT/mTOR Axes to Alleviate Sepsis-Induced Acute Lung Injury

BACKGROUND

Sepsis-induced acute lung injury (ALI) is a severe organ dysfunction characterized by lung inflammation and apoptosis. The mechanisms underlying sepsis-induced ALI remain poorly understood. Here, we determined the effects of sirtuin 4 (SIRT4) on sepsis-induced ALI.

METHODS

Lipopolysaccharide (LPS)-induced injury cell and cecal ligation and puncture (CLP) animal models were established. Overexpression vectors and lentiviral transfections were used to upregulate SIRT4 expression. Lung cell apoptosis, inflammation, and the levels of associated factors were evaluated. Changes in the PI3K/AKT/mTOR and JAK2/STAT3 pathways were measured, and their potential involvement was examined using LY294002 (PI3K inhibitor), 740 Y-P (PI3K agonist), AG490 (JAK2 inhibitor), and coumermycin A1 (JAK2 agonist).

RESULTS

Lower SIRT4 expression was observed in LPS-exposed A549 cells and CLP rats. In LPS-induced A549 cells, Sirt4 overexpression enhanced cell viability, resisted apoptosis, restored the expression of apoptosis-associated proteins (HMB1, cleaved CASP3, BAX, and BCL), and reduced the secretion of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α). In CLP rats, Sirt4 overexpression prolonged survival time, alleviated lung histopathological damage, reduced pulmonary edema, mitigated lung infection, decreased lung apoptosis, and lowered serum levels of inflammatory cytokines. Furthermore, Sirt4 overexpression blocked JAK2/STAT3/AKT/mTOR phosphorylation. 740 Y-P and coumermycin A1 reversed the protective effects of Sirt4 overexpression in LPS-treated A549 cells, resulting in decreased cell viability and increased apoptosis. LY294002 and AG490 enhanced the protective effects of Sirt4 overexpression in LPS-treated A549 cells.

CONCLUSION

SIRT4 alleviates sepsis-induced ALI by inhibiting JAK2/STAT3/PI3K/AKT/mTOR signaling. Upregulating SIRT4 expression may serve as an innovative therapeutic approach for lung injury management in sepsis.

Macrophages-derived small extracellular vesicles regulate chondrocyte proliferation and affect osteoarthritis progression via upregulating Osteopontin expression

Small extracellular vesicles (sEVs) are considered promising gene-delivery vehicles for the treatment of osteoarthritis (OA). This study aimed to explore the molecular mechanism by which M2 macrophage-derived sEVs (M2-sEVs) modulate chondrocyte proliferation and apoptosis, thereby affecting OA progression. M2 macrophages were successfully induced, and M2-sEVs were successfully isolated. The sEVs were small vesicles with diameters ranging from 50 to 150 nm. The exosomal markers, including CD9, CD63, and CD81, were highly expressed, whereas the negative marker calnexin was absent in M2-sEVs. M2-sEVs effectively alleviated OA tissue and chondrocyte damage in both in vivo and in vitro models, evidenced by reduced rat knee joint injury, increased chondrocyte viability, and decreased chondrocyte apoptosis and extracellular matrix (ECM) degradation. Furthermore, M2-sEVs decreased the levels of pro-inflammatory cytokines IL-6 and TNF-α. Osteopontin (OPN) was upregulated within rats with OA and IL-1β-induced chondrocytes. Silencing of OPN exacerbated IL-1β-induced chondrocyte damage and partially abrogated the therapeutic effects of M2-sEVs. Additionally, M2-sEVs enhanced OPN expression and activated CD44 and the PI3K/AKT signaling pathway. In conclusion, M2-sEVs promoted OPN expression to improve knee joint tissue damage in rats with OA and chondrocyte damage. This protective effect of M2-sEVs might be associated with the activation of CD44 and the PI3K/AKT signaling.

The interaction of HT-2 toxin and Akt1 on gene expression regulation in Kashin-Beck disease pathogenesis

BACKGROUND

This study investigates the effects of T-2 toxin metabolite HT-2 alone or combined with Akt1 on chondrocyte gene expression to elucidate their roles in Kashin-Beck disease (KBD) pathogenesis.

METHODS

Lentiviral transfection was employed to silence Akt1 in C28/I2 human chondrocytes. High-throughput RNA sequencing and bioinformatics analysis methods were used to identify and compare differentially expressed genes (DEGs) and pathways in HT-2, siAkt1, HT-2-siAkt1 and Control (non-treatment) group. Co-expressed genes and co-expressed modules were investigated using WGCNA. Protein-protein interaction (PPI) networks were constructed using the STRING database, and hub genes were identified by the MCC algorithm.

RESULTS

A total of 2086 DEGs were identified in the HT-2 vs Control comparison, with significant upregulation observed for CCND2, MMP9 and TIMP4. The adhesion and PI3K-Akt signaling pathways were upregulated, while ECM-receptor interactions was downregulated. In the siAkt1 vs Control comparison, 695 DEGs were detected. VAMP7 and CXCR4 were significantly upregulated, while PFKL and ALDOA were significantly downregulated. Fructose and mannose metabolism, amino acid biosynthesis, and glucose/energy metabolic pathways were significantly downregulated. There were 411 DEGs when HT-2-siAkt1 vs HT-2, and CCND2, MMP9, WTAPP1 and TIMP4 were significantly downregulated. Adhesion, NF-κB signaling pathway and PI3K-Akt signaling pathway were significantly downregulated. Under, WGCNA, in the module most associated with HT-2, FRMD3B, ALDH1A3, ANTXR2, SERINC2 and SRGN were identified as hub genes; in the module most associated with siAkt1, TNFRSF11B, CECR2, TMOD1, ZNF704 and RHOBTB1 were identified as hub genes; in the module most associated with HT-2-siAkt1, the hub genes were GNAL, SLC25A32, ACADSB, CABLES1 and GINS4.

CONCLUSION

Akt1 primarily affects the expression of genes in chondrocytes under HT-2 exposure that involved in autophagy, cell proliferation and glycolysis and other cell functions, potentially contributing to the pathogenesis of KBD.

TrkC protects against osteoarthritis progression by maintaining articular cartilage homeostasis

Osteoarthritis (OA) is a degenerative disease with a series of metabolic changes accompanied by chondrocyte apoptosis. Chondrocytes express multiple receptors for neurotrophin, however, the role of neurotrophin receptor in chondrocyte metabolism remains unelucidated. Here, we first clarify the role of neurotrophin 3 (NT3) and its receptor tropomyosin receptor kinase C (TrkC) of chondrocytes in OA pathogenesis, using inducible TrkC-deficient mice (TrkCfl/fl; Col2a1-CreERT2 mice). Our findings show that TrkC levels are decreased in the chondrocytes and cartilage of patients with OA and OA-model mice. Chondrocyte-specific TrkC deficiency aggravates cartilage destruction during OA development. However, intra-articular TrkC-overexpressing adeno-associated virus (AAV) injection delays experimental OA progression. TrkC deficiency leads to decreased anabolic and increased catabolic activities in chondrocytes and stimulates chondrocyte apoptosis, thereby accelerating OA progression. Whereas TrkC overexpression rescues the imbalance between extracellular matrix synthesis and degradation and chondrocyte apoptosis through PI3K/Akt signaling. NT3, a multifunctional protein with high affinity for TrkC, effectively protects against cartilage degeneration in OA models in vitro and in vivo and relieves pain sensitivity in mice with OA. Our results indicate that TrkC is crucial for maintaining cartilage homeostasis and OA progression. Targeting TrkC with NT3 could be a novel strategy for OA treatment.

Effect of urolithin A on intracellular survival of Mycobacterium tuberculosis by regulating AKT-FOXO1-mediated autophagy

Tuberculosis (TB), resulting from Mycobacterium tuberculosis (Mtb), is one of the leading causes of morbidity and mortality in humans worldwide. Host-directed therapy (HDT) is a novel approach for treating TB, particularly those with drug resistance. Urolithin A (UroA) produced through bioconversion of plant-derived ellagic acid by gut microbes has been proven to have multiple beneficial effects in a variety of diseases without showing undesired adverse reactions. However, whether UroA has antimycobacterial effect and the underlying mechanism has not yet been reported. Here, we found that UroA significantly inhibited Mtb growth within both macrophages and mice. Moreover, UroA promoted the activation of autophagy in Mtb-infected macrophages via the protein kinase B-Forkhead box protein O1 signaling pathway, which contributed to the antimycobacterial effect of UroA. Additionally, UroA suppressed the survival of clinically isoniazid (INH)-resistant Mtb (C2) within macrophages, and the combination of UroA and INH synergistically enhanced host elimination of Mtb H37Rv. Therefore, UroA may be utilized as a potential candidate for HDT and as an adjunctive therapy with first-line anti-TB drugs.IMPORTANCEHost-directed therapy (HDT) is a novel approach for treating tuberculosis (TB), particularly those with drug resistance. Urolithin A (UroA) produced through bioconversion of plant-derived ellagic acid by gut microbes has been proven to have multiple beneficial effects in a variety of diseases without showing undesired adverse reactions. We found that UroA significantly inhibited Mycobacterium tuberculosis (Mtb) growth within macrophages. Moreover, UroA suppressed the survival of clinically isoniazid (INH)-resistant Mtb (C2) within macrophages, and the combination of UroA and INH synergistically enhanced host elimination of Mtb H37Rv. Therefore, UroA may be utilized as a potential candidate for HDT and as an adjunctive therapy with first-line anti-TB drugs.

Bioactive protein/polysaccharide hydrogel functionalized bone implants surface for enhanced osteogenesis

Bone implants play a critical role in the treatment of orthopedic diseases, however, conventional polymer or ceramic or metal implants possess various problems in enhancing bone repair and osteointegration. Recent years, the bioactive bone implants with biomimetic mechanical surface with natural extracellular matrix has shown promising role in reinforcing bone integration and regeneration. Biomedical hydrogels coating strategy has attracted much attention in bone implants modification, due to their adjustable surface biomechanics, bioactivities and drug release ability. Based on the principles of mechanical compatibility for biodegradable scaffold materials, it facilitates a "soft-hard synergy" in bone repair. This review provides an overview of recent advances in the field of hydrogel modification for bone implants, including the polysaccharide hydrogels (such as chitosan, alginate, and hyaluronic acid) and protein hydrogels (such as gelatin and collagen). Furthermore, this review explores the current understanding of the biomechanical mechanisms underlying bone formation in hydrogel-modified implants within the body, presents the challenges and future directions in this field. This study integrates engineering, developmental biology, and clinical perspectives, offering unique insights for the development of functional strategies for bone implants aimed at enhancing the treatment of orthopedic diseases.

Anti-inflammatory effects of Elsholtzia ciliata extract on Poly I:C-treated RAW264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Inflammation is a vital biological response to noxious stimuli, including physical injury and pathogenic infection, and involves immune cells and various inflammatory mediators, limiting cell damage and eliminating pathogens. Although essential for healing, inflammation can cause symptoms, such as fever, swelling, pain, and itching, potentially reducing quality of life. Elsholtzia ciliata used in traditional medicine has numerous medicinal characteristics such as antiviral, antibacterial, antipyretic, diaphoretic, carminative, astringent, and diuretic effects.

AIM OF THE STUDY

This study aimed to evaluate the anti-inflammatory properties of E. ciliata extract (ECE) in RAW264.7 cells treated with polyinosinic polycytidylic acid (Poly I:C).

MATERIALS AND METHODS

PGE2, IL-1β, TNF-α, IFN-β, and IL-6 levels were quantified by ELISA and/or real-time PCR. COX-2 and iNOS expression was analyzed using western blotting and real-time PCR. Phosphorylation and expression levels of signaling proteins, including AKT, IRF3, TBK1, STAT1, MAPKs, IκB, and IκK were analyzed using western blotting. The active substance of ECE was determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS).

RESULTS

Our detections revealed that ECE inhibited the levels of nitric oxide and central inflammatory mediators, such as iNOS and COX-2. Furthermore, ECE downregulated the expression of pro-inflammatory cytokines, including PGE2, IL-1β, TNF-α, IFN-β, and IL-6. Additionally, ECE inhibited the phosphorylation of several cell signaling pathways, including AKT, TBK1/IRF3, MAPK, and NF-κB, in Poly I:C-treated RAW264.7 cells.

CONCLUSIONS

These results highlight E. ciliata as a candidate for mitigating virus-induced inflammation, providing valuable insights into its use in the development of new anti-inflammatory therapeutics.

Genetic predictors of longevity and survival in cellular homeostasis genes: A case-control study

BACKGROUND

Longevity is defined by the ability to maintain both physical and mental health throughout a long life and may results from adaptive mechanisms that mitigate aging's detrimental effects.

METHODS

The 20-year follow-up study of 3,312 unrelated individuals aged 18-114 years from the Volga-Ural region of Eurasia investigated variants in cellular homeostasis genes IGF1, PIK3R1, AKT1, MTOR, NFE2L2, KEAP1, HIF1A, TP53, and SIRT1, to identify associations with clinical aging phenotypes and healthy longevity.

RESULTS

In men, KEAP1 (rs1048290) CC genotype was a longevity and survival marker (OR = 2.39, P = 3E-05, HR = 0.54, P = 2.4E-03). NFE2L2 (rs6721961) TT genotype was linked to higher mortality (HR = 1.77, P = 0.031), particularly combined with KEAP1 (rs1048290) G and AKT1 (rs3803304) C alleles (HR = 2.8, P = 0.023). In women, AKT1 (rs3803304) C allele interacted with NFE2L2 (rs6721961) TT genotype (SF = 0.13, P = 3.6E-03), and was linked to longevity (OR = 2.22, P = 6.3E-03) and protection against cerebrovascular diseases (OR = 0.62, P = 5.1E-03). AKT1 (rs3803304) GG genotype, along with HIF1A (rs11549465) T and SIRT1 (rs3758391) T alleles (SF = 2.52, P = 1.5E-03), promoted survival (HR = 0.71, P = 0.014). In men, HIF1A (rs11549465) TT genotype predicted cardiovascular mortality (HR = 7.5, P = 5.5E-03). SIRT1 (rs3758391) TT genotype was associated with improved survival in individuals with diabetes (HR = 0.4, P = 5.8E-03) and multimorbidity (HR = 0.48, P = 0.025).

CONCLUSION

Variants in NFE2L2, KEAP1, SIRT1, AKT1, and HIF1A, along with their interactions, were significantly associated with survival in age-related diseases and healthy longevity.

Research on the role and mechanism of the PI3K/Akt/mTOR signalling pathway in osteoporosis

Osteoporosis is a systemic metabolic bone disease characterised mainly by reduced bone mass, bone microstructure degradation, and loss of bone mechanical properties. As the world population ages, more than 200 million people worldwide suffer from the pain caused by osteoporosis every year, which severely affects their quality of life. Moreover, the prevalence of osteoporosis continues to increase. The pathogenesis of osteoporosis is highly complex and is closely related to apoptosis, autophagy, oxidative stress, the inflammatory response, and ferroptosis. The PI3K/Akt/mTOR signalling pathway is one of the most crucial intracellular signal transduction pathways. This pathway is not only involved in bone metabolism and bone remodelling but also closely related to the proliferation and differentiation of osteoblasts, osteoclasts, and bone marrow mesenchymal stem cells. Abnormal activation or inhibition of the PI3K/Akt/mTOR signalling pathway can disrupt the balance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption, ultimately leading to the development of osteoporosis. This review summarises the molecular mechanisms by which the PI3K/Akt/mTOR signalling pathway mediates five pathological mechanisms, namely, apoptosis, autophagy, oxidative stress, the inflammatory response, and ferroptosis, in the regulation of osteoporosis, aiming to provide a theoretical basis for the development of novel and effective therapeutic drugs and intervention measures for osteoporosis prevention and treatment.

PI3Kδ as a Novel Therapeutic Target for Aggressive Prostate Cancer

Phosphoinositide 3-kinases (PI3Ks) signaling represents an important pathway regulating cell proliferation, survival, invasion, migration, and metabolism. Notably, PI3K/AKT/mTOR signaling is frequently dysregulated in the majority of malignancies. Among the class IA PI3Ks (PI3Kα/β/δ), emerging evidence has implicated that PI3Kδ is not only overexpressed in leukocytes but also in solid tumors, including prostate cancer. The critical role of PI3Kδ in tumorigenesis and in the creation of a suppressive tumor microenvironment, along with the recent finding of PI3Kδ splice isoforms in promoting tumor aggressiveness and resistance, further demonstrates the potential of developing novel PI3Kδ-targeted cancer therapies. In this review, we comprehensively describe the functional mechanisms underlying the PI3Kδ-driven tumor progression and immune regulation in prostate cancer diseases. Furthermore, the recent preclinical and clinical studies on the development of PI3Kδ-/PI3K-targeted inhibitors as single agents and in combination therapies (with chemotherapy, radiation, hormone therapy, or immunotherapy) are summarized. Finally, we discuss the potential novel therapies for improving the treatment efficacies, as well as the current limitations and challenges of PI3Kδ-based therapies for prostate cancer.

Unraveling the Molecular Mechanisms of Osteoarthritis: The Potential of Polyphenols as Therapeutic Agents

The complex nature of osteoarthritis (OA), driven by the intricate interplay of genetic, environmental, and lifestyle factors, necessitates the development of a single treatment method, which is highly challenging. The long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids often leads to adverse side effects like kidney damage and stomach ulcers. Major health threats like obesity and aging create a milieu of chronic low-grade inflammation and increased mechanical stress on the joints resulting in cartilage deterioration. Additionally, postmenopausal women with lower circulating 17β-estradiol levels experience accelerated joint deterioration due to increased immune activity resulting in the increased production of pro-inflammatory cytokines, with elevated MMP expression and decreased type II collagen synthesis. Polyphenols are nature's gifted magic molecules, which possess diverse biological properties like anti-oxidant, anti-bacterial, anti-inflammatory, estrogenic, and insulin-sensitizing effects, which can manage and treat all the multi-factorial contributing factors of OA effectively. Certain polyphenols can act as phytoestrogens and mimic the effects of natural estrogen by binding to ERα and ERβ and can act as SERMs and prevent degradation of the articular cartilage thereby alleviating osteoarthritic conditions. These molecules downregulate the expression of various pro-inflammatory cytokines, apoptotic genes, and matrix-degrading proteases (MMPs) while upregulating major ECM proteins like type II collagen, aggrecan, and proteoglycans in various osteoarthritic animal models. This review provides a comprehensive overview of the molecular mechanisms involved in OA development and also explores the therapeutic potential of different polyphenols in mitigating joint inflammation and their protective effect in inhibiting the degradation of cartilage extracellular matrix (ECM) and enhancing joint homeostasis.

Primary cilia and inflammatory response: unveiling new mechanisms in osteoarthritis progression

Osteoarthritis (OA) is a common degenerative joint disease that can lead to chronic pain and disability. The pathogenesis of OA involves chronic low-grade inflammation, characterized by the degradation of chondrocytes, inflammation of the synovium, and systemic low-grade inflammation. This inflammatory response accelerates the progression of OA and contributes to pain and functional impairment. Primary cilia play a crucial role in cellular signal transduction and the maintenance of cartilage matrix homeostasis, and their dysfunction is closely linked to inflammatory responses. Given these roles, primary cilia may significantly contribute to the pathogenesis of OA. This review explores inflammation-associated signaling pathways in OA, including NF-κB, MAPK, JAK/STAT, and PI3K/AKT/mTOR signaling. In addition, we place particular emphasis on cilia-mediated inflammatory modulation in OA. Primary cilia mediate chondrocyte responses to mechanical loading and inflammatory cytokines via pathways including NF-κB, MAPK, TRPV4, and Hedgehog signaling. Notably, alterations in the length and incidence of primary cilia in chondrocytes during OA further underscore their potential role in disease pathogenesis. The identification of biomarkers and therapeutic targets related to primary cilia and inflammatory pathways offers new potential for the treatment and management of OA.

Nitazoxanide Modulates Mitochondrial Function and Inflammatory Metabolism in Chondrocytes from Patients with Osteoarthritis via AMPK/mTORC1 Signaling

Osteoarthritis (OA) is a long-term degenerative condition of the joints, characterized by persistent inflammation, progressive cartilage breakdown, and impaired mitochondrial function. Recent studies have shown that hyperactivation of the mTORC1 pathway and metabolic reprogramming of chondrocytes contribute to disease progression. Nitazoxanide (NTZ), an oral antiparasitic agent approved by the Food and Drug Administration, has shown anti-inflammatory and mitochondrial protective effects in various disease situations; despite this, its application in osteoarthritis has yet to be fully investigated. Here, we assessed the therapeutic efficacy of NTZ using IL-1β-stimulated primary chondrocytes derived from patients with OA. NTZ substantially reduced the expression of proinflammatory cytokines and matrix metalloproteinases, restored mitochondrial membrane potential, and reduced mitochondrial reactive oxygen species levels. NTZ also effectively reversed IL-1β-induced glycolytic metabolic changes by inhibiting glucose uptake and GLUT1 expression. Mechanistically, NTZ inhibited the activation of the mTORC1 pathway and substantially increased AMPK phosphorylation. The siRNA-mediated AMPK knockdown negated NTZ-induced mitochondrial and metabolic improvements, suggesting that AMPK is a key upstream regulator of the protective actions of NTZ. NTZ can, therefore, effectively inhibit inflammatory metabolic reprogramming and mitochondrial dysfunction in OA chondrocytes through AMPK-dependent mTORC1 signaling inhibition, highlighting its potential as a disease-modifying therapy for OA.

REDOX Imbalance and Oxidative Stress in the Intervertebral Disc: The Effect of Mechanical Stress and Cigarette Smoking on ER Stress and Mitochondrial Dysfunction

Low back pain is a widespread condition that significantly impacts quality of life, with intervertebral disc degeneration (IDD) being a major contributing factor. However, the underlying mechanisms of IDD remain poorly understood, necessitating further investigation. Environmental risk factors, such as mechanical stress and cigarette smoke, elevate reactive oxygen species levels from both endogenous and exogenous sources, leading to redox imbalance and oxidative stress. The endoplasmic reticulum (ER) and mitochondria, two key organelles responsible for protein folding and energy production, respectively, are particularly vulnerable to oxidative stress. Under oxidative stress conditions, ER stress and mitochondrial dysfunction occur, resulting in unfolded protein response activation, impaired biosynthetic processes, and disruptions in the tricarboxylic acid cycle and electron transport chain, ultimately compromising energy metabolism. Prolonged and excessive ER stress can further trigger apoptosis through ER-mitochondrial crosstalk. Given the unique microenvironment of the intervertebral disc (IVD)-characterized by hypoxia, glucose starvation, and region-specific cellular heterogeneity-the differential effects of environmental stressors on distinct IVD cell populations require further investigation. This review explores the potential mechanisms through which environmental risk factors alter IVD cell activities, contributing to IDD progression, and discusses future therapeutic strategies aimed at mitigating disc degeneration.

Irisin in the modulation of bone and cartilage homeostasis: a review on osteoarthritis relief potential

Osteoarthritis, a progressive and degenerative joint disease, disrupts the integrity of the entire joint structure, underscoring the urgency of identifying more effective therapeutic strategies and innovative targets. Among these, exercise therapy is considered a key component in the early management of osteoarthritis, functioning by stimulating the secretion of myokines from the skeletal muscle system. Irisin, a myokine predominantly secreted by skeletal muscle during exercise and encoded by the FNDC5 gene, has garnered attention for its regulatory effects on bone health. Emerging evidence suggests that irisin may play a protective role in osteoarthritis by promoting tissue homeostasis, enhancing subchondral bone density and microstructure, and inhibiting chondrocyte apoptosis. By improving chondrocyte viability, preserving extracellular matrix integrity, and maintaining homeostasis in osteoblasts, osteoclasts, and osteocytes, irisin emerges as a promising therapeutic target for osteoarthritis. This review delves into the role of irisin in osteoarthritis pathogenesis, highlighting its influence on cartilage and bone metabolism as well as its dynamic relationship with exercise. Additionally, this review suggests that further exploration on its specific molecular mechanisms, optimization of drug delivery systems, and strategic utilization of exercise-induced benefits will be pivotal in unlocking the full potential of irisin as a novel intervention for osteoarthritis.

Plant-Based Therapies to Ameliorate Neuroinflammation in Parkinson's Disease, Alzheimer's Disease, and Epilepsy: A Narrative Review

Neuroinflammation plays a crucial role in the etiology of neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), and epilepsy. Several key inflammatory pathways are pivotal in the development of neuroinflammation in PD, AD, and epilepsy. The NF-κB pathway is a central regulator of inflammation, and its chronic activation triggers the transcription of genes that drive inflammatory responses. JAK-STAT signaling system triggers the production of cytokines and chemokines that generate neuroinflammation; mitogen-activated protein kinases mediate the p38 pathway and control the synthesis of cytokines. Activation of the NO signaling pathway causes oxidative stress and neuronal damage. Plant-based therapeutics are gaining attention due to their anti-neuroinflammatory and neuroprotective phytochemicals, which shield the neurons from damage. Some of the examples are curcumin, resveratrol, ginsenosides, cannabidiol, notoginseng, quercetin, and so on. Clinical studies also indicate that certain plant-based formulations like Wei Li Bai, IPX066, Bushen huoxue, and so on can be effective alternatives to presently available remedies. The review is an attempt at assimilating the information from available literature on the role of different neurotransmitters involved in neuroinflammation and their connection in AD, PD, and epilepsy and applications of plant-based therapies in the prevention and cure of the above-mentioned diseases.

Research progress on pharmacokinetics, anti-inflammatory and immunomodulatory effects of kaempferol

Chronic inflammation (an abnormal state) and autoimmune disease (AD) can both cause multiple organ damage. AD is a heterogeneous group of diseases due to immune dysfunction. Chronic inflammation is closely related to AD and is an important part of AD. With the increasing prevalence of AD, researchers are constantly exploring new drugs with small side effects, considerable curative effects, and lower costs. Kaempferol, a flavonoid, possesses a range of biological functions, including antioxidant, anti-inflammatory, anti-neoplastic, and immunomodulatory capabilities. This compound is prevalent in a variety of plant sources, such as vegetables, fruits, and medicinal herbs traditionally used in Chinese medicine. A plethora of empirical evidence from animal-based research supports the assertion that this particular substance exhibits both anti-inflammatory and immunomodulatory effects, with the curative effect being significant and application prospects. This article mainly summarizes and discusses the pharmacokinetics, drug delivery system, and the mechanism of kaempferol on immune cells, cytokines, signaling pathways, and other aspects. This paper summarizes the existing kaempferol drug delivery system, analyzes the possibility and limitations of kaempferol as a new anti-inflammatory and immunomodulatory drug, and discusses how to apply it in clinical practice. Therefore, kaempferol can more effectively exert its anti-inflammatory and immune-modulating effects, thereby demonstrating therapeutic potential in clinical settings, while reducing patient burden.

Quercetin-primed MSC exosomes synergistically attenuate osteoarthritis progression

BACKGROUND

Osteoarthritis (OA), a degenerative joint disease characterized by cartilage degradation and inflammation, lacks effective disease-modifying therapies. Quercetin, a bioactive flavonoid derived from Traditional Chinese Medicine, exhibits anti-inflammatory and chondroprotective properties but is limited by poor bioavailability. Mesenchymal stem cell-derived exosomes (MSC-Exos) offer a promising strategy for targeted drug delivery and cartilage regeneration.

METHODS

Bone marrow-derived MSC exosomes (Que-Exo) were isolated after preconditioning with quercetin (1µM, 24 h). Their effects were evaluated in IL-1β-stimulated chondrocytes via RT-qPCR, Western blot, transcriptomics, and proteomics. An ACLT-induced OA mouse model received intra-articular injections of Que-Exo, with cartilage integrity assessed by Safranin O staining and OARSI scoring.

RESULTS

Que-Exo significantly reduced IL-1β-induced pro-inflammatory markers (MMP9 and COX-2) and restored cartilage repair genes (SOX9 and Collagen II) compared to untreated exosomes. Multi-omics analyses revealed activation of PI3K-AKT signaling and glutathione metabolism pathways. In vivo, Que-Exo mitigated cartilage degradation and preserved proteoglycan content.

CONCLUSIONS

Quercetin-preconditioned MSC exosomes synergistically enhance chondroprotection and anti-inflammatory effects, offering a novel therapeutic strategy for OA by combining herbal bioactive compounds with exosome-mediated delivery.

Mechanistic Integration of Network Pharmacology and In Vivo Validation: TFRD Combat Osteoporosis via PI3K/AKT Pathway Activation

In the context of osteoporosis closely linked to bone metabolism imbalance caused by estrogen deficiency, total flavonoids of Rhizoma Drynariae (TFRD) exhibit potential anti-osteoporotic activity, yet their multicomponent synergistic mechanism and association with the PI3K/AKT signaling pathway remain unclear. This study aimed to systematically elucidate the molecular mechanisms by which TFRD regulate bone metabolism and improve osteoporosis in ovariectomized (OVX) rats through the PI3K/AKT pathway, integrating network pharmacological predictions with animal experimental validation. Methods involved identifying TFRD's active components using UPLC/MS-MS, predicting targets with SwissTargetPrediction, constructing a "component-target-disease" network, and performing GO/KEGG enrichment analysis with MetaScape (v3.5). In vivo experiments established an OVX rat model, randomized into sham, OVX, low-/high-dose TFRD, and sim groups, assessing bone mineral density (BMD) and mandibular Micro-CT parameters after 12 weeks. Western blot analyzed PI3K, p-AKT1, and related protein expressions. Results showed the high-dose TFRD group significantly increased BMD, improved trabecular bone quantity and structure, and upregulated PI3K, p-PI3K, and p-AKT1 protein expressions compared to the OVX group. Molecular docking confirmed stable binding energy between core components and PI3K/AKT targets. TFRD may ameliorate estrogen deficiency-induced osteoporosis by activating the PI3K/AKT signaling pathway, inhibiting bone resorption, and promoting osteogenic differentiation, providing pharmacological evidence for multitarget treatment of osteoporosis with traditional Chinese medicine.

FHL2 deteriorates IL-1β induced inflammation, apoptosis, and extracellular matrix degradation in chondrocyte-like ATDC5 cells by mTOR and NF-ĸB pathways

BACKGROUND

The role of nuclear translocation in osteoarthritis (OA) pathogenesis has garnered increasing attention in recent years. Extensive research has demonstrated that FHL2 acts as a nuclear transmitter through interactions with other nuclear transcription factors. We aimed to investigate the role of FHL2 in an osteoarthritis cell model.

METHODS

OA cartilage model was established by chondrocyte-like ATDC5 cells induced by 1% insulin-transferrin-selenium and then treated with interleukin-1β (IL-1β, 10 ng/mL). Lentivirus transfection was employed to suppress the expression of FHL2. Immunofluorescence and flow cytometry were used to examine nuclear transcription and apoptosis, respectively. Western blotting was performed to analyze the expression of metabolism-related proteins, autophagy-related proteins, apoptosis-related proteins, as well as proteins associated with the NF-ĸB and mTOR pathways.

RESULTS

The elevated expression of FHL2 occurred in both the cytoplasm and the nucleus. Knockdown of FHL2 could inhibit IL-1β-induced phosphorylation of NF-ĸB p65 and stabilize the extracellular matrix (ECM) by decreasing MMP-3 and MMP-13 expression, to suppress COL II degradation in chondrocyte-like ATDC5 cells. Meanwhile, the knockdown of FHL2-activated autophagy in IL-1β-treated chondrocytes through mTOR signaling, characterized by an increased LC3-II/LC3-I ratio and Beclin-1. FHL2 downregulation inhibited IL-1β-induced apoptosis by suppressing BAX and Caspase-3 expression, while enhancing BCL-2 protein levels. This mechanism may involve AKT phosphorylation and decreased expression of p-NF-ĸB p65.

CONCLUSIONS

FHL2 knockdown activated autophagy while suppressing inflammation, apoptosis, and ECM degradation. The mechanism underlying these processes may involve the inhibition of the mTOR and NF-ĸB signaling pathways.

Regulation of Skeletogenic Pathways by m6A RNA Modification: A Comprehensive Review

In the complex process of skeletal development, the significance of m6A RNA methylation-a predominant form of RNA modification-has not been fully explored. This review discuss how m6A RNA methylation plays an important, though not yet fully understood, role in regulating skeletal formation. It examines how m6A influences key signaling pathways essential for skeletal development and homeostasis, suggesting various possible interactions between m6A methylation and these critical pathways. While the exact mechanisms for many of these interactions remain to be elucidated, m6A RNA methylation is anticipated to be a key emerging regulator in skeletal structure development across vertebrates. Highlighting the need for further research, this overview provides an in-depth look at the potential regulatory interactions of m6A RNA methylation within skeletal system. Uniquely, this review is the most comprehensive compilation of evidence linking components of m6A RNA methylation to signaling pathways involved in skeletogenesis.

Laminin expression profiles of osteogenic-and chondrogenic-induced dECM sheets

Decellularized extracellular matrix sheets (dECMSs) produced by stem cells have attracted attention because they preserve the natural biological activity of the ECM to direct lineage-specific differentiation with less immunogenicity. As a core ECM protein, laminin modulates cellular phenotype and differentiation. Nevertheless, no studies thus far have explored the distribution and abundance of laminins in diverse dECMSs. Herein, we first compared the differential expression of laminins among dECMSs in osteogenic-induced medium (OI-dECMS), chondrogenic-induced medium (CI-dECMS), and standard medium (dECMS), employing a defined mass spectrometry (MS)-based proteomic analysis. In vitro, dECMSs were verified to be successfully decellularized. Cluster analysis identified a marked fluctuation in the expression of 7 laminins and 17 laminin-associated proteins in OI-dECMS vs dECMS and CI-dECMS vs dECMS. Two significantly changed pathways were selected from the KEGG pathway enrichment analysis: the FAK/ERK pathway and the PI3K/AKT pathway. Moreover, Alkaline Phosphatase (ALP) activity, Alcian blue staining, and RT-qPCR results for recellularization showed that CI-dECMS promotes chondrogenesis while OI-dECMS inhibits osteogenesis compared with dECMS. In vivo experiments were conducted to implant dECMSs in a rat osteochondral defect, demonstrating that dECMS and CI-dECMS promoted bone and cartilage repair. Furthermore, the inhibitory analysis was performed to verify the function of specific laminin isoforms modulating osteogenesis and chondrogenesis, which might be related to FAK/ERK and PI3K/AKT pathways. In summary, this study constructed dECMS, OI-dECMS, and CI-dECMS and uncovered the internal comprehensive molecular regulatory network centralized by laminins, thus proposing a biomimetic substitute for bone and cartilage regeneration.

Sodium Hyaluronate-PDGF Repairs Cartilage and Subchondral Bone Microenvironment via HIF-1α-VEGF-Notch and SDF-1-CXCR4 Inhibition in Osteoarthritis

Chronic degenerative changes in cartilage and subchondral bone that lead to instability of the cartilage microenvironment are essential for the development of osteoarthritis (OA) in the old. Synchronous repair of cartilage and subchondral bone may be a key strategy for OA treatment. PDGF-BB effectively promoted chondrocyte regeneration and angiogenesis. However, the mechanisms by which PDGF-BB affects subchondral bone and the delivery of PDGF-BB to the joint cavity need to be further explored. In this study, we used sodium hyaluronate to deliver PDGF-BB (SH-PDGF) to the joint space and aimed to determine the mechanisms of SH-PDGF in repairing cartilage and subchondral bone and stabilising the cartilage microenvironment. In this research, we determined the pharmacokinetics of PDGF-BB and SH-PDGF in cartilage. Moreover, we investigated the effects of PDGF-BB and SH-PDGF on cartilage and the subchondral bone microenvironment by identifying changes in the HIF-VEGF-Notch axis and SDF-1-CXCR4 axis in an OA rat model. The results showed that PDGF-BB increased cell viability, decreased HIF-1α levels, inhibited inflammation and improved matrix metabolism in osteoarthritic chondrocytes under hyperoxic or hypoxic conditions. We also found that PDGF-BB and SH-PDGF showed similar effects on repairing cartilage and subchondral bone simultaneously. However, SH-PDGF had some advantages over PDGF-BB in prolonging the injection interval and decreasing the injection time. These protective effects were mediated by the inhibition of both the HIF-1α-VEGF-Notch axis and the SDF-1-CXCR4 axis. The underlying mechanisms include the inhibition of HIF-1α-VEGF-Notch-mediated vessel invasion and SDF-1-CXCR4 axis-mediated crosstalk between cartilage and subchondral tissue.

Osteogenic Effects of Bioactive Compounds Found in Fruits on Mesenchymal Stem Cells: A Review

Phytochemicals, which are bioactive compounds contained in fruits, vegetables, and teas, have a positive effect on human health by having anti-inflammatory, antioxidant, and anticarcinogenic effects. Several studies have highlighted the ability of bioactive compounds to activate key cellular enzymes associated with important signaling pathways related to cell division and proliferation, as well as their role in inflammatory and immunological responses. Some phytochemicals are associated with increased proliferation, differentiation, and expression of markers related to osteogenesis, bone formation, and mineralization by activating various signaling pathways. The objective of this study was to clarify which bioactive compounds present in fruits have osteogenic effects on mesenchymal stem cells and the possible associated mechanisms. A literature search was conducted in the LILACS, MEDLINE, and PubMed databases for pertinent articles published between 2014 and 2024. This review included 34 articles that report the osteogenic effects of various bioactive compounds found in different fruits. All the articles reported that phytochemicals play a role in enhancing the regenerative properties of mesenchymal cells, such as proliferation, osteogenic differentiation, secretion of angiogenic factors, and extracellular matrix formation. This review highlights the potential of these phytochemicals in the prevention and treatment of bone diseases. However, more studies are recommended to identify and quantify the therapeutic dose of phytochemicals, investigate their mechanisms in humans, and ensure their safety and effectiveness for health, particularly for bone health.

The Role of Exerkines in the Treatment of Knee Osteoarthritis: From Mechanisms to Exercise Strategies

With the increasing prevalence of knee osteoarthritis (KOA), the limitations of traditional treatments, such as their limited efficacy in halting disease progression and their potential side effects, are becoming more evident. This situation has prompted scientists to seek more effective strategies. In recent years, exercise therapy has gained prominence in KOA treatment due to its safety, efficacy, and cost-effectiveness, which are underpinned by the molecular actions of exerkines. Unlike conventional therapies, exerkines offer specific advantages by targeting inflammatory responses, enhancing chondrocyte proliferation, and slowing cartilage degradation at the molecular level. This review explores the potential mechanisms involved in and application prospects of exerkines in KOA treatment and provides a comprehensive analysis of their role. Studies show that appropriate exercise not only promotes overall health, but also positively impacts KOA by stimulating exerkine production. The effectiveness of exerkines, however, is influenced by exercise modality, intensity, and duration of exercise, making the development of personalized exercise plans crucial for KOA patients. Based on these insights, this paper proposes targeted exercise strategies designed to maximize exerkine benefits, aiming to provide novel perspectives for KOA prevention and treatment.

Proliferative behaviours of CD90-expressing chondrocytes under the control of the TSC1-mTOR/PTHrP-nuclear localisation segment pathway

OBJECTIVE

Some cells in temporomandibular joint (TMJ) cartilage undergo proliferation in response to negative pressure, which can be induced in vivo by creating bilateral anterior elevation (BAE). TMJ cartilage harbours CD90-expressing cells, and CD90 expression increases under certain controlled conditions. The parathyroid hormone-related peptide (PTHrP) nuclear localisation segment (NLS) promotes chondrocyte proliferation, and mammalian target of rapamycin (mTOR) signalling plays a regulatory role in promoting PTHrP transcription. The purpose of this study was to determine the role of the mTOR/PTHrP-NLS axis in the proliferative responses of CD90+ chondrocytes in TMJ cartilage to BAE.

METHODS

CD90+ cells were isolated from TMJ cartilage and subjected to negative pressure followed by RNA sequencing (RNA-seq). A PTHrP-NLS conditional mutation (CD90-CreER;Pthlh84STOP-fl/fl) mouse model was developed to obtain CD90+ cell-specific PTHrP-NLS conditional mutation (Pthlh84STOP) littermate. CD90-Cre;Tsc1fl/fl mice and CD90-Cre;mTORfl/fl mice were generated to obtain Mtor conditional knockout (Mtor-CKO) and Tsc1-CKO littermates.

RESULTS

Using RNA-seq, the mTOR signalling pathway was identified as the most significant biological process occurring in superficial zone cells of the TMJ condylar cartilage under negative pressure. Proliferation of CD90+ cells was stimulated in Tsc1-CKO littermates but inhibited in both Mtor-CKO and Pthlh84STOP littermates. BAE did not promote chondrocyte proliferation in either Mtor-CKO or Pthlh84STOP littermates. Administration of the PTHrP87-139 peptide to Mtor-CKO mice restored chondrocyte proliferation and rescued the promoting effect of BAE in TMJ cartilage.

CONCLUSIONS

CD90+ chondrocytes in TMJ cartilage proliferate in response to negative pressure under the control of the TSC1-mTOR/PTHrP-NLS pathway.

MiR-103-3p regulates chondrocyte autophagy, apoptosis, and ECM degradation through the PI3K/Akt/mTOR pathway by targeting CPEB3

BACKGROUND

Chondrocyte apoptosis is associated with the severity of cartilage destruction and matrix degeneration in the progression of osteoarthritis. Increasing evidence indicates that autophagy has a significant cytoprotective effect against chondrocyte apoptosis. Here, we investigated the role of microRNA-103-3p (miR-103-3p) in regulating chondrocyte function and elucidated the underlying mechanism.

METHODS

MiR-103-3p expression in interleukin-1β (IL-1β)-stimulated chondrocytes was evaluated using RT-qPCR. The targets of miR-103-3p predicted by online databases were verified using biotin-based pulldown assay and luciferase reporter assay. IL-1β stimulated-chondrocytes were transfected with miR-103-3p inhibitor along with siRNA targeting cytoplasmic polyadenylation element-binding protein3 (siCPEB3), the autophagy inhibitor 3-MA, or the PI3K agonist 740 Y-P. Chondrocyte proliferation was evaluated using cell counting kit-8. Apoptosis was detected by flow cytometry. The levels of apoptosis-, extracellular matrix (ECM)-, autophagy-, and the PI3K/Akt/mTOR pathway-related proteins in chondrocytes were detected using immunoblotting or immunofluorescence.

RESULTS

We found that IL-1β stimulation upregulated miR-103-3p and downregulated CPEB3 in mouse chondrocytes. Inhibiting miR-103-3p reduced IL-1β-induced apoptosis and ECM macromolecule degradation while enhancing autophagy in chondrocytes. MiR-103-3p targeted CPEB3, and its downregulation rescued the expression of level in IL-1β stimulated-chondrocytes. MiR-103-3p downregulation inhibited the PI3K/Akt/mTOR pathway in IL-1β stimulated-chondrocytes by upregulating CPEB3. 3-MA, 740 Y-P, or CPEB3 knockdown counteracted the effect of miR-103-3p downregulation on chondrocyte apoptosis, ECM macromolecule degradation, and autophagy.

CONCLUSION

Overall, inhibition of miR-103-3p reduces IL-1β-induced apoptosis and ECM macromolecule degradation in chondrocytes by enhancing autophagy through the CPEB3/PI3K/Akt/mTOR pathway.

Low-intensity pulsed ultrasound inhibits chondrocyte senescence by inhibiting PI3K/AKT/mTOR signaling

Cellular senescence is an important cause of age-related degenerative diseases, including osteoarthritis (OA). Chondrocyte senescence is crucial in OA onset and progression. As a non-invasive, safe, and widely used physical rehabilitation factor, the effect and mechanism of low intensity pulsed ultrasound (LIPUS) on chondrocyte senescence remain unclear. This study evaluated the inhibitory effect of LIPUS on OA chondrocyte senescence in vitro and in vivo. The effect of LIPUS on chondrocyte senescence was examined by RT-qPCR, enzyme-linked immunosorbent assay (ELISA), and western blotting. Changes in levels of reactive oxygen species (ROS) and γ-h2ax foci in senescent chondrocytes were detected using fluorescent staining. Chondrocyte senescence was evaluated by senescence-associated β-galactosidase (SA-β-gal) staining. The PI3K inhibitor LY294002 and the PI3K agonist 740Y-P were used to investigate whether PI3K/AKT/mTOR signalling was involved in the effect of LIPUS in senescent chondrocytes. Chondrocyte senescence and cartilage degeneration were analyzed in a destabilization of the medial meniscal (DMM) mouse model by immunohistochemistry, hematoxylin and eosin staining, and safranin-O/fast green staining. LIPUS inhibited the expression of the senescence-associated secretory phenotype (SASP) factors CCL4 and CCL2 and the senescence phenotype in doxorubicin-treated chondrocytes by inhibiting the PI3K/AKT/mTOR pathway. LIPUS alleviated chondrocyte senescence and attenuated OA progression in the DMM mice. These results demonstrated a novel role for LIPUS in inhibiting chondrocyte senescence and the SASP by modulating PI3K/AKT/mTOR signalling. Our findings expanded the clinical application of LIPUS and provide a new, non-invasive, and safe treatment approach to prevent and treat age-related degenerative joint disorders.

Perspectives of exosomal ncRNAs in the treatment of bone metabolic diseases: Focusing on osteoporosis, osteoarthritis, and rheumatoid arthritis

Bone metabolic disorders, constituting a group of prevalent and grave conditions, currently have a scarcity of therapeutic alternatives. Over the recent past, exosomes have been at the forefront of research interest, owing to their nanoparticulate nature and potential for therapeutic intervention. ncRNAs are a class of heterogeneous transcripts that they lack protein-encoding capacity, yet they can modulate the expression of other genes through multiple mechanisms. Mounting evidence underscores the intricate role of exosomes as ncRNAs couriers implicated in the pathogenesis of bone metabolic disorders. In this review, we endeavor to elucidate recent insights into the roles of three ncRNAs - miRNAs, lncRNAs, and circRNAs - in bone metabolic ailments such as osteoporosis, osteoarthritis, and rheumatoid arthritis. Additionally, we examine the viability of exosomal ncRNAs as innovative, cell-free modalities in the diagnosis and therapeutic management of bone metabolic disorders. We aim to uncover the critical function of exosomal ncRNAs within the context of bone metabolic diseases.

Calycosin alleviates ovariectomy-induced osteoporosis by promoting BMSCs autophagy via the PI3K/Akt/mTOR pathway

Calycosin, the main extract from the traditional Chinese medicine (TCM) Astragalus membranaceus, has demonstrated anti-osteoporotic properties in ovariectomized (OVX) mice. However, the specific pathways through which it prevents osteoporosis remain unexplored. This study aimed to investigate the pathways by which calycosin promotes autophagy in bone marrow mesenchymal stem cells (BMSCs) and alleviates ovariectomy-induced osteoporosis. Mice were divided into three groups: sham, OVX, and OVX + calycosin. Following a 12-week intervention period, assessments included analysis of bone microstructure, serum concentrations of LC3II and ALP, and evaluation of Trap expression in femoral tissue. Immunohistochemical staining was used to assess the expression levels of PI3K, Runx2, and Beclin-1 in bone tissue. Additionally, levels of Runx2, ALP, p-PI3K, PI3K, mTOR, p-mTOR, Beclin-1, and ULK1 were analyzed. Osteogenic differentiation of BMSCs was evaluated using ALP and Alizarin red staining. OVX significantly impaired BMSCs osteogenic differentiation, resulting in bone loss. In contrast, calycosin increased bone mass, promoted osteogenesis, and reduced cancellous bone loss. Parameters, such as BMD, BV/TV, Tb.N, and Tb.Th, were significantly higher in the OVX + calycosin group compared to the OVX group. Additionally, Tb.Sp was notably reduced in the OVX + calycosin group. Calycosin also upregulated levels of Runx2, ALP, p-PI3K, p-mTOR, ULK1, and Beclin-1. In cellular studies, calycosin promoted BMSCs osteogenesis under OVX conditions; however, this effect was inhibited by LY294002. Calycosin effectively combats bone loss and improves bone structure. Its mechanism likely involves the promotion of autophagy in osteoblasts, thereby stimulating BMSC osteogenic differentiation. This effect may be mediated through the PI3K/Akt/mTOR pathway. These findings suggest that calycosin has the potential to serve as an alternative therapy for treating osteoporosis.

Orientin alleviates chondrocyte senescence and osteoarthritis by inhibiting PI3K/AKT pathway

AIMS

Osteoarthritis (OA) is a common degenerative disease that leads to pain, disability, and reduced quality of life. Orientin exhibits considerable anti-inflammatory and antioxidative properties, but its role in chondrocyte senescence and OA progress has not yet been fully characterized. The aim of this study was to evaluate the protective effects of orientin on OA.

METHODS

The role of orientin in extracellular matrix (ECM) degradation, mitochondrial homeostasis, and chondrocyte senescence was investigated in vitro. Meanwhile, we used molecular docking, small molecular inhibitors, and RNA interference to screen and validate candidate proteins regulated by orientin. In an anterior cruciate ligament transection (ACLT) rat model, radiograph, micro-CT, and various histological examinations were applied to evaluate the therapeutic effects of orientin on OA.

RESULTS

We found that orientin inhibited ECM degradation and senescence-associated secretory phenotype (SASP) factor expression in interleukin (IL)-1β-treated chondrocytes. Additionally, orientin reduced the level of reactive oxygen species (ROS) and improved mitochondrial homeostasis. Furthermore, orientin suppressed IL-1β-induced activation of the nuclear factor kappa B (NF-κB) signalling pathway. We also found that orientin bound to phosphoinositide 3-kinase (PI3K) and inhibited NF-κB cascades via the PI3K/AKT pathway. In vivo, we demonstrated that orientin improved cartilage wear and reduced synovial inflammation and osteophyte in an ACLT rat model.

CONCLUSION

Orientin improves mitochondrial homeostasis, inhibits chondrocyte senescence, and alleviates OA progress via the PI3K/AKT/NF-κB axis, which suggests that orientin is a potential effective therapeutic agent for OA.

Exosomes in cartilage microenvironment regulation and cartilage repair

Osteoarthritis (OA) is a debilitating disease that predominantly impacts the hip, hand, and knee joints. Its pathology is defined by the progressive degradation of articular cartilage, formation of bone spurs, and synovial inflammation, resulting in pain, joint function limitations, and substantial societal and familial burdens. Current treatment strategies primarily target pain alleviation, yet improved interventions addressing the underlying disease pathology are scarce. Recently, exosomes have emerged as a subject of growing interest in OA therapy. Numerous studies have investigated exosomes to offer promising therapeutic approaches for OA through diverse in vivo and in vitro models, elucidating the mechanisms by which exosomes from various cell sources modulate the cartilage microenvironment and promote cartilage repair. Preclinical investigations have demonstrated the regulatory effects of exosomes originating from human cells, including mesenchymal stem cells (MSC), synovial fibroblasts, chondrocytes, macrophages, and exosomes derived from Chinese herbal medicines, on the modulation of the cartilage microenvironment and cartilage repair through diverse signaling pathways. Additionally, therapeutic mechanisms encompass cartilage inflammation, degradation of the cartilage matrix, proliferation and migration of chondrocytes, autophagy, apoptosis, and mitigation of oxidative stress. An increasing number of exosome carrier scaffolds are under development. Our review adopts a multidimensional approach to enhance comprehension of the pivotal therapeutic functions exerted by exosomes sourced from diverse cell types in OA. Ultimately, our aim is to pinpoint therapeutic targets capable of regulating the cartilage microenvironment and facilitating cartilage repair in OA.

Aberrant anabolism hinders constructive metabolism of chondrocytes by pharmacotherapy in osteoarthritis

Osteoarthritis (OA) is a highly prevalent and disabling disease with an unmet therapeutic need. The characteristic cartilage loss and alteration of other joint structures result from a complex interaction of multiple risk factors, with mechanical overload consistently playing a central role. This overload generates an inflammatory response in the cartilage due to the activation of the innate immune response in chondrocytes, which occurs through various cellular mechanisms. Moreover, risk factors associated with obesity, being overweight, and metabolic syndrome enhance the inflammatory response both locally and systemically. OA chondrocytes, the only cells present in articular cartilage, are therefore inflamed and initiate an anabolic process in an attempt to repair the damaged tissue, which ultimately results in an aberrant and dysfunctional process. Under these circumstances, where the cartilage continues to be subjected to chronic mechanical stress, proposing a treatment that stimulates the chondrocytes' anabolic response to restore tissue structure does not appear to be a therapeutic target with a high likelihood of success. In fact, anabolic drugs proposed for the treatment of OA have yet to demonstrate efficacy. By contrast, multiple therapeutic strategies focused on pharmacologically managing the inflammatory component, both at the joint and systemic levels, have shown promise. Therefore, prioritizing the control of chronic innate pro-inflammatory pathways presents the most viable and promising therapeutic strategy for the effective management of OA. As research continues, this approach may offer the best opportunity to alleviate the burden of this incapacitating disease.

The phenotypic and genetic spectrum of AKT3-related neurodevelopmental condition

This study was undertaken to expand the phenotypic and genetic spectrum of AKT3-related neurodevelopmental disorders and to investigate genotype-phenotype correlations. To date, more than 200 patients with AKT3-related disorders have been identified, including those with AKT3 single nucleotide variants and copy number variations affecting the AKT3 gene. Adding our three newly diagnosed patients, the total number of patients with AKT3 single nucleotide variant-related neurodevelopmental disorders is now 61. A total of 20 distinct AKT3 variants have been identified, with p.E17K and p.R465W being potential mutation "hotspots". Approximately 77% (47/61) of the patients experienced macrocephaly, and 81.9% (50/61) had megalencephaly. Seizures were present in 62.3% (38/61) of individuals, and 29.5% (18/61) of patients displayed a thick corpus callosum. In addition, 57 patients with pathogenic or likely pathogenic AKT3 duplications and 175 patients with AKT3 deletions were also reviewed. Among the 68 patients with AKT3 deletions and detailed information reported previously, 97% (66/68) have microcephaly, 72% (49/68) have agenesis or hypoplasia of the corpus callosum, and 63.2% (43/68) suffer from epilepsy. In the 5 patients with pure AKT3 deletion, 100% have microcephaly, while none suffer from epilepsy or abnormal corpus callosum. Patients with AKT3 gain-of-function variants typically present with megalencephaly and structural brain abnormalities. In contrast, AKT3 loss-of-function variants may have a stronger correlation with microcephaly.

The prospect and underlying mechanisms of Chinese medicine in treating periodontitis

Inflammation represents a critical immune response triggered by cellular activities and inflammatory mediators following tissue damage. It plays a central role in the pathological progression of diverse diseases, including psychiatric disorders, cancer, and immunological conditions, rendering it an essential target for therapeutic intervention. Periodontitis, a prevalent oral inflammatory disease, is a leading cause of tooth loss and poses significant health challenges globally. Traditionally, inflammatory diseases such as periodontitis have been treated with systemic administration of synthetic chemicals. However, recent years have witnessed challenges, including drug resistance and microbial dysbiosis associated with these treatments. In contrast, natural products derived from Chinese medicine offer numerous benefits, such as high safety profiles, minimal side effects, innovative pharmacological mechanisms, ease of extraction, and multiple targets, rendering them viable alternatives to conventional antibiotics for treating inflammatory conditions. Numerous effective anti-inflammatory natural products have been identified in traditional Chinese medicine (TCM), including alkaloids, flavonoids, terpenoids, lignans, and other natural products that exhibit inhibitory effects on inflammation and are potential therapeutic agents. Several studies have confirmed the substantial anti-inflammatory and immunomodulatory properties of these compounds. This comprehensive review examines the literature on the anti-inflammatory effects of TCM-derived natural products from databases such as PubMed, Web of Science, and CNKI, focusing on terms like "inflammation", "periodontitis", "pharmacology", and "traditional Chinese medicine". The analysis systematically summarizes the molecular pharmacology, chemical composition, and biological activities of these compounds in inflammatory responses, alongside their mechanisms of action. This research seeks to deepen understanding of the mechanisms and biological activities of herbal extracts in managing inflammatory diseases, potentially leading to the development of promising new anti-inflammatory drug candidates. Future applications could extend to the treatment of various inflammatory conditions, including periodontitis.

Targeting Long Noncoding RNA H19 in Subchondral Bone Osteocytes and the Alleviation of Cartilage Degradation in Osteoarthritis

OBJECTIVE

Emerging evidence suggests long noncoding RNA H19 is associated with osteoarthritis (OA) pathology. However, how H19 contributes to OA has not been reported. This study aims to investigate the biologic function of H19 in OA subchondral bone remodeling and OA progression.

METHODS

Clinical joint samples and OA animal models induced by surgical destabilization of the medial meniscus (DMM) were used to verify the causal relationship between osteocyte H19 and OA subchondral bone and cartilage changes. MLO-Y4 osteocyte cells subjected to fluid shear stress were used to verify the mechanism underlying H19-mediated mechanoresponse. Finally, the antisense oligonucleotide (ASO) against H19 was delivered to mice knee joints by magnetic metal-organic framework (MMOF) nanoparticles to develop a site-specific delivery method for targeting osteocyte H19 for OA treatment.

RESULTS

Both clinical OA subchondral bone and wildtype mice with DMM-induced OA exhibit aberrant higher subchondral bone mass, with more H19 mice expressing osteocytes. On the contrary, mice with osteocyte-specific deletion of H19 are less vulnerable to DMM-induced OA phenotype. In MLO-Y4 cells, H19-mediated osteocyte mechanoresponse through PI3K/AKT/GSK3 signal activation by EZH2-induced H3K27me3 regulation on protein phosphatase 2A inhibition. Targeted inhibition of H19 (using ASO-loaded MMOF) substantially alleviates subchondral bone remodeling and OA phenotype.

CONCLUSION

In summary, our results provide new evidence that the elevated H19 expression in osteocytes may contribute to aberrant subchondral bone remodeling and OA progression. H19 appears to be required for the osteocyte response to mechanical stimulation, and targeting H19 represents a new promising approach for OA treatment.

Diagnostic value of TRIM22 in diabetic kidney disease and its mechanism

PURPOSE

Diabetic kidney disease (DKD) is the primary reason of chronic kidney disease. Our objective was to discover potential autophagy-related biomarkers of tubulointerstitial injury in DKD and assess their clinical value.

METHODS

We retrieved four datasets (GSE104954, GSE30122, GSE30529, and GSE99340) of renal tubule samples from Gene Expression Omnibus (GEO) and used two algorithms (LASSO and SVM-RFE) to screen for autophagy-related differentially expressed genes (ARDEGs) in DKD. Tripartite motif containing 22 (TRIM22) was identified for subsequent validation. Validation of TRIM22 and autophagic indicators expression in clinical samples and HK-2 cells stimulated by high glucose using immunohistochemistry, immunofluorescence, and western blot.

RESULTS

We identified four ARDEGs (TRIM22, PLK2, HTR2B, and FAS) using a diagnostic gene model. ROC curves further confirmed that TRIM22 had the best diagnostic efficacy for DKD. Both clinical samples and HK-2 cells stimulated by high glucose showed high protein expression of TRIM22. The correlation analysis revealed that TRIM22 correlates with SQSTM1, NGAL, and some clinical and pathological indicators in patients with DKD.

CONCLUSION

We identified TRIM22 as a potential diagnostic biomarker for DKD, revealing its high diagnostic value in patients with DKD with moderate-to-severe interstitial fibrosis and tubular atrophy (IFTA). TRIM22 is involved in tubulointerstitial injury and autophagy dysregulation in DKD.

Inflammation-induced PFKFB3-mediated glycolysis promoting myometrium contraction through the PI3K-Akt-mTOR pathway in preterm birth mice

Inflammation is a significant risk factor for preterm birth. Inflammation enhances glycolytic processes in various cell types and contributes to the development of myometrial contractions. However, the potential of inflammation to activate glycolysis in pregnant murine uterine smooth muscle cells (mUSMCs) and its role in promoting inflammatory preterm birth remain unexplored. In this study, lipopolysaccharide was employed to establish both cell and animal inflammation models. We found that inflammation of mUSMCs during late pregnancy could initiate glycolysis and promote cell contraction. Subsequently, the inhibition of glycolysis using the glycolysis inhibitor 2-deoxyglucose can reverse inflammation-induced cell contraction. The expression of 6-phosphofructokinase 2 kinase (PFKFB3) was significantly upregulated in mUSMCs following lipopolysaccharide stimulation. In addition, lactate accumulation and enhanced contraction were observed. Inhibition of PFKFB3 reversed the lactate accumulation and enhanced contraction induced by inflammation. We also found that inflammation activated the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (Akt)-mammalian target of the rapamycin (mTOR) pathway, leading to the upregulation of PFKFB3 expression. The PI3K-Akt pathway inhibitor LY294002 and the mTOR pathway inhibitor rapamycin effectively inhibited the upregulation of PFKFB3 protein expression, lactate production, and the enhancement of cell contraction induced by lipopolysaccharide. This study indicates that inflammation regulates PFKFB3 through the PI3K-Akt-mTOR pathway, which enhances the glycolytic process in pregnant mUSMCs, ultimately leading to myometrial contraction.NEW & NOTEWORTHY Expression of PFKFB3, a key enzyme in glycolysis, was significantly upregulated both in the mUSMCs and myometrium of mice during late pregnancy after lipopolysaccharide stimulation. Activation of the PI3K-Akt-mTOR pathway enhanced PFKFB3 expression, which is involved in the initiation of glycolysis. Inflammation-activated PFKFB3 via the PI3K-Akt-mTOR pathway, which enhances the cellular glycolytic process and thus promotes myometrium contraction in pregnancy.

Potential and challenges of utilizing exosomes in osteoarthritis therapy (Review)

Exosomes are integral to the pathophysiology of osteoarthritis (OA) due to their roles in mediating intercellular communication and regulating inflammatory processes. Exosomes are integral to the transport of bioactive molecules, such as proteins, lipids and nucleic acids, which can influence chondrocyte behavior and joint homeostasis. Given their properties of regeneration and ability to target damaged tissues, exosomes represent a promising therapeutic avenue for OA treatment. Exosomes have potential in promoting cartilage repair, reducing inflammation and improving overall joint function. However, several challenges remain, including the need for standardized isolation and characterization methods, variability in exosomal content, and regulatory hurdles. The present review aims to provide a comprehensive overview of the current understanding of exosome mechanisms in OA and their therapeutic potential, while also addressing the ongoing challenges faced in translating these findings into clinical practice. By consolidating existing research, the present review aims to pave the way for future studies aimed at optimizing exosome‑based therapies for effective OA management.

Danggui niantong decoction attenuates synovial fibrosis through regulating PI3k/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCY

Danggui Niantong Decoction (DGNTD) is a traditional Chinese medicine compound formula that has been demonstrated to possess efficacy in the treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), as well as for dispelling moisture and relieving pain. As mentioned before, DGNTD is essential for synovial inflammation in RA. The primary features of the OA synovial membrane are low-grade inflammation, hyperplasia with enhanced fibroblast-like synoviocytes (FLS) proliferation, and fibrosis, which can cause pain and stiffness. However, it is still unknown how DGNTD functions in the OA synovium.

AIM OF THE STUDY

Clarify the influence of DGNTD on OA synovium and investigate potential mechanisms of action.

METHODS AND MATERIALS

The principal constituents of DGNTD were detected using liquid chromatography-mass spectrometry (LC-MS) analysis. To evaluate the effect of DGNTD on synovial inflammation and fibrosis, a transforming growth factor beta (TGF-β)-stimulated rat FLS cell model and a rat OA animal model based on anterior cruciate ligament transection (ACLT) and partial medial meniscectomy (MMx) were employed.

RESULTS

Our results showed that 322 components were detected using LC-MS. In vivo, DGNTD therapy reduced pain, synovial inflammation, and fibrosis. The therapy significantly reduced levels of pain-related molecules, specifically calcitonin gene-related peptide (CGRP) and inducible nitric oxide synthase (iNOS), as well as fibrotic markers, including alpha smooth muscle actin (α-SMA) and type III collagen alpha-1 (Col3a1), in the synovium. A proteomics study demonstrated that DGNTD decreased the fibrotic protein Col3a1. DGNTD reduced the mRNA expression of pro-inflammatory and fibrotic markers (tumor necrosis factor alpha (TNF-α), interleukin-1 beta(IL-1β), interleukin-6(IL-6), α-SMA, Col3a1and TGF-β) in TGF-β-induced FLS. Furthermore, the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and validation results revealed that DGNTD inhibits synovial fibrosis via the phosphatidylinositol 3-kinase (PI3K)/protein Kinase B (AKT) signaling pathway.

CONCLUSIONS

DGNTD partially relieves pain, synovitis, and synovial fibrosis by regulating the PI3K/AKT pathway. These findings provide fresh information about the underlying mechanisms and successful therapy of OA, as well as a theoretical and experimental foundation for the clinical management of OA using DGNTD.

Akt2 inhibition alleviates temporomandibular joint osteoarthritis by preventing subchondral bone loss

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Adipose Tissue-Derived Exosome Maintains Metabolic Balance of Extracellular Matrix in Rat Nucleus Pulposus Cells

Purpose

This study aimed to investigate the protective effect of adipose tissue-derived exosomes (AT-Exo) on rat nucleus pulposus cells (NPCs).

Methods

Ultracentrifugation was used to extract exosomes from rat adipose tissue. Transmission electron microscopy (TEM), Western blot, and nanoparticle tracking analysis (NTA) were used to characterize the exosomes. Tert-butyl hydrogen peroxide (TBHP) was used to induce apoptosis of rat NPCs. Cell viability was determined by CCK-8 assay. AT-Exo was administered to investigate its effect on rat NPCs using Western blot and immunofluorescence staining.

Results

AT-Exo was successfully extracted and characterized by NTA, TEM, and Western blots. Uptake assay showed that AT-Exo can be taken up by the NPCs. TBHP (60 μM) resulted in decreased cell viability and increased apoptosis of NPCs. Interestingly, AT-Exo protected NPCs against TBHP, indicated by increased cell viability, decreased apoptosis, upregulated Aggrecan and type II collagen deposition, and downregulated matrix metalloproteinase 3/13.

Conclusion

In summary, rat adipose tissue-derived exosomes can increase the levels of Aggrecan, type II collagen, and Bcl2, and decrease the levels of matrix metalloproteinase 3/13, cleaved caspase3, and Bax. Therefore, rat adipose tissue-derived exosomes can maintain metabolic balance of extracellular matrix and protect against apoptosis in rat nucleus pulposus cells.

A novel PTH1R mutation causes primary failure of eruption via the cAMP-PI3K/AKT pathway

BACKGROUND

Primary failure of eruption (PFE) is a rare disorder characterized by a posterior open bite. While mutations in the parathyroid hormone 1 receptor (PTH1R) gene have been demonstrated to cause PFE, the underlying mechanisms remain largely unknown.

METHODS

Whole exome sequencing was conducted to identify PTH1R variants in a PFE family. MG63 cells that stably expressed the corresponding mutant PTH1R were established using lentiviruses. Next, osteogenesis was assessed by measuring cell alkaline phosphatase activity, conducting alizarin red staining, and evaluating osteoblast-specific gene expression. Then, computational analysis of binding affinity and RNA sequencing were carried out. Lastly, rescue experiments were performed to validate the mechanism underlying the pathogenesis of PFE.

RESULTS

A novel PTH1R missense mutation (c.904G > A, p.E302K) was identified in a Chinese family affected by PFE. Moreover, the E302K mutation inhibited the expression of osteogenic-specific genes and proteins in MG63 cells. Computational analysis revealed the E302K mutation decreased the binding affinity of Gαs to the PTH1R protein. Consistently, cAMP accumulation assays demonstrated that the E302K mutation impaired the intracellular PTH1-34 -induced accumulation of cAMP. Further RNA sequencing analysis and validation experiments revealed that the PI3K-AKT signaling pathway was predominantly down-regulated in response to the E302K mutation. Finally, forskolin partially restored the effects of the E302K mutation on osteogenesis.

CONCLUSIONS

This study indicated that the E302K mutation in PTH1R decreased the binding affinity of PTH1R protein for Gαs, down-regulated the cAMP-PI3K/AKT signaling pathway, and inhibited osteogenesis, eventually leading to PFE. This study not only expands the genotypic spectrum of PTH1R mutations but also elucidates the underlying pathogenic mechanism of PTH1R-associated PFE.

Identification of the key role of IL-17RB in the treatment of osteoarthritis with Shaoyao Gancao decoction: Verification based on RNA-seq and bioinformatics analysis

BACKGROUND

Shaoyao Gancao Decoction (SGD) is a classic and representative oral administration of traditional Chinese medicine formula. It is composed of two Chinese herbal medicines, Paeoniae Radix Alba [Paeonia lactiflora Pall] and Glycyrrhizae Radix et Rhizoma. The clinical study found SGD could effectively reduce clinical symptoms and improve the level of inflammation in osteoarthritis (OA) patients.

PURPOSE

The aim of this study is to identify the efficacy and molecular mechanism of SGD in the treatment of OA, and find the new therapeutic target through RNA sequencing (RNA-Seq) to provide theoretical support for its clinical application.

METHODS

Destabilization of the medial meniscus (DMM) OA rat model was established in vivo. Hematoxylineosin staining, safranin O/fast green staining and immunohistochemistry were used to observe changes of cartilage Histology and extracellular matrix (ECM) of cartilage cells. In vitro, the chondrocyte-like cells were derived from ATDC5 cells and induced by interleukin-1 beta to establish the model. The medial meniscotibial ligament (MTT) test was used to identify the effects of SGD on chondrocyte-like cell proliferation, and immunocytochemistry was used to assess changes in chondrocyte ECM. The differentially expressed genes (DEGs) were obtained by RNA-Seq. Meanwhile, the core targets were found through bioinformatics analysis, and then verified by qRT-PCR and Western Blotting. The inflammatory factors IL-1β, IL-6 and TNF-α were detected by ELISA.

RESULTS

SGD could alleviate cartilage degeneration, and reduce ECM degradation in OA by upregulating COL2A1 and downregulating MMP-13. 120 key targets were screened from DEGs by RNA-Seq. Based on further bioinformatics analysis, interleukin 17 receptor B (IL-17RB), interleukin 23 receptor and growth differentiation factor 5 were finally selected as core targets. IL-17RB has rarely been reported in previous studies about OA, and worthy of further study. Subsequently, it was found that the gene and protein expressions of IL-17RB were significantly reversed in model group after SGD treatment. Moreover, SGD could inhibit the release of inflammatory factors by mediating IL-17RB in OA.

CONCLUSIONS

SGD reduced the release of inflammatory factors IL-1β, IL-6 and TNF-α, upregulated COL2A1 and downregulated MMP-13 to alleviate degradation of ECM, and reduced the cartilage degeneration and progression of OA by reducing IL-17RB in articular cartilage.

The dual anti-inflammatory and anticoagulant effects of Jianpi Huashi Tongluo prescription on Rheumatoid Arthritis through inhibiting the activation of the PI3K/AKT signaling pathway

Background

Rheumatoid arthritis (RA) is often accompanied by abnormal changes in inflammatory responses and coagulation-fibrinolysis indicators. Jianpi Huashi Tongluo Prescription - Xinfeng Capsule (XFC), a traditional Chinese medicine formulation comprising multiple herbal ingredients, is widely used clinically for the treatment of RA. It exhibits dual anti-inflammatory and anticoagulant effects. However, the specific mechanisms underlying its actions remain to be further investigated.

Objective

This study aims to elucidate the anti-inflammatory and anticoagulant mechanisms of XFC in the treatment of RA.

Methods

A multidimensional methodological framework was employed. Firstly, through retrospective clinical data mining, combined with the Apriori algorithm and random walk models, an in-depth analysis was conducted to explore the potential associations between XFC treatment and improvements in clinical inflammatory and coagulation markers among RA patients. Secondly, an adjuvant-induced arthritis rat model was established to directly observe the anti-inflammatory and anticoagulant effects of XFC in vivo. Furthermore, bioinformatics and network pharmacology techniques were applied to decipher the major active components and their targets of XFC. Lastly, a co-culture system of RA patient-derived peripheral blood mononuclear cells (RA-PBMCs) and vascular endothelial cells (VECs) was established to mimic the in vivo microenvironment, and the anti-inflammatory and anticoagulant mechanisms of XFC were validated in vitro.

Results

Data mining analysis revealed abnormally elevated levels of inflammatory and coagulation markers such as fibrinogen (FBG), erythrocyte sedimentation rate (ESR), high-sensitivity C-reactive protein (Hs-CRP), and rheumatoid factor (RF) in RA patients (p < 0.001), and emphasized the close correlation between XFC treatment and the improvement of these markers including Hs-CRP, ESR, and RF (confidence >60% and lift >1). Animal experimental data indicated that XFC effectively reduced the levels of inflammatory and coagulant markers (IL-6, D-D, FBG, PAF, VEGF, and TF) in adjuvant-induced arthritis (AA) rats while enhancing the expression of anti-inflammatory factors (IL-10) (p < 0.05). Furthermore, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) results suggested that the pharmacodynamic mechanism of XFC may be closely related to the regulation of the PI3K/AKT signaling pathway. Additionally, network pharmacology and molecular docking results show that the main active components of XFC, namely, calycosin-7-O-beta-D-glucoside, calycosin, and formononetin, exhibit excellent docking with the core targets HIF1A, PTGS2, and MMP9. In vitro co-culture model showed that XFC inhibited RA-related inflammatory responses and hypercoagulable states by suppressing the activation of the PI3K/AKT signaling pathway.

Conclusion

This study demonstrates that XFC exerts its dual anti-inflammatory and anticoagulant effects, at least in part, by inhibiting the activation of the PI3K/AKT signaling pathway, providing potential insights into targeted therapy for RA.

The efficient prediction of inflammatory osteolysis caused by polylactic acid through network toxicology and molecular docking strategy

Polylactic acid (PLA), as a bioplastic, is extensively utilized in bone tissue engineering for its biocompatibility, adaptability and affordability. However, the toxicological research of PLA is still limited. The hydrolysis products of PLA induced inflammatory response which caused inflammatory osteolysis mediated by oxidative damage through the recruitment of macrophages and the accumulation of foreign body multinucleated giant cells, ultimately leading to the failure of bone tissue regeneration. The lack of effective treatments highlights the importance of finding new therapies. This study systematically investigated the potential molecular mechanisms of PLA-induced inflammatory osteolysis by employing network toxicology and molecular docking techniques. We first conducted a network toxicology-based assessment according to the molecular structure of PLA. The result from integrating and screening targets from multiple databases identified 126 potential targets associated with PLA-induced inflammatory osteolysis, and then an interaction network diagram of the targets was constructed. Gene ontology (GO)/KEGG enrichment analysis clarified that PLA may cause inflammatory osteolysis via metabolic pathways and pathways in cancer, as well as lipid and atherosclerosis. Further analysis by STRING and Cytoscape software screened 25 core targets including HSP90AA1, AKT1, SRC, STAT1 and FYN. We found that the enriched highly correlated pathways covered 18 of the 25 core targets, supporting the scientific hypothesis that PLA induces inflammatory osteolysis. Moreover, the results of molecular docking confirmed that PLA displayed a strong binding ability with the core targets and formed stable binding. Taken together, this study not only revealed the potential biological mechanism of PLA-induced inflammatory osteolysis, but also provided new evidence for the future prevention and treatment of PLA-induced inflammation.