This study aims to integrate data mining techniques of single cell transcriptomics and spatial transcriptomics, along with animal experiment validation, so as to systematically characterize the protective effects of Jianpi Tongluo Formula(JTF) on the cartilage in knee osteoarthritis(KOA) and elucidate the underlying molecular mechanisms. Single cell transcriptomics and spatial transcriptomics datasets(GSE254844 and GSE255460) of the cartilage tissue obtained from KOA patients were analyzed to map the single cell-spatial heterogeneity and identify key pathogenic factors. After that, a KOA rat model was established via knee joint injection of papain. The intervention effects of JTF on the expression features of these key factors were assessed through real-time quantitative polymerase chain reaction(PCR), Western blot, and immunohistochemical staining. As a result, the integrated single cell and spatial transcriptomics data identified distinct cell subsets with different pathological changes in different regions of the inflamed cartilage tissue in KOA, and their differentiation trajectories were closely related to the inflammatory fibrosis-like pathological changes of chondrocytes. Accordingly, the expression levels of the two key effect targets, namely nuclear receptor coactivator 4(NCOA4) and high mobility group box 1(HMGB1) were significantly reduced in the articular surface and superficial zone of the inflamed joints when JTF effectively alleviated various pathological changes in KOA rats, thus reversing the abnormal chondrocyte autophagy level, relieving the inflammatory responses and fibrosis-like pathological changes, and promoting the repair of chondrocyte function. Collectively, this study revealed the heterogeneous characteristics and dynamic changes of inflamed cartilage tissue in different regions and different cell subsets in KOA patients. It is worth noting that NCOA4 and HMGB1 were crucial in regulating chondrocyte autophagy and inflammatory reaction, while JTF could reverse the regulation of NCOA4 and HMGB1 and correct the abnormal molecular signal axis in the target cells of the inflamed joints. The research can provide a new research idea and scientific basis for developing a personalized therapeutic schedule targeting the spatiotemporal heterogeneity characteristics of KOA.
Animals ; Drugs, Chinese Herbal/administration & dosage* ; Rats ; Osteoarthritis, Knee/pathology* ; Humans ; Male ; Cartilage, Articular/metabolism* ; Chondrocytes/metabolism* ; Rats, Sprague-Dawley ; Female ; Protective Agents/administration & dosage* ; Single-Cell Analysis ; Middle Aged ; HMGB1 Protein/metabolism*

OBJECTIVE: To analyze the differences in the effects of different mechanical stimuli on cells, cytokines, and proteins in synovial fluid of osteoarthritis joints, and to elucidate the indirect mechanism by which mechanical signals remodel the synovial fluid microenvironment through tissue cells. METHODS: Systematically integrate recent literature, focusing on the regulatory effects of different mechanical stimuli on the physicochemical properties of synovial fluid. Analyze the dynamic process by which mechanical stimuli regulate secretory and metabolic activities through tissue cells, thereby altering the physicochemical properties of cytokines and proteins. RESULTS: Appropriate mechanical stimuli activate mechanical signals in chondrocytes, macrophages, and synovial cells, thereby influencing cellular metabolic activities, including inhibiting the release of pro-inflammatory factors and promoting the secretion of anti-inflammatory factors, and regulating the expression of matrix and inflammation-related proteins such as cartilage oligomeric matrix protein, peptidoglycan recognition protein 4, and matrix metalloproteinases. CONCLUSION Mechanical stimuli act on tissue cells, indirectly reshaping the synovial fluid microenvironment through metabolic activities, thereby regulating the pathological process of osteoarthritis.
Humans ; Osteoarthritis/physiopathology* ; Synovial Fluid/chemistry* ; Chondrocytes/metabolism* ; Cytokines/metabolism* ; Macrophages/metabolism* ; Stress, Mechanical ; Cartilage Oligomeric Matrix Protein/metabolism* ; Matrix Metalloproteinases/metabolism* ; Synovial Membrane/cytology*

OBJECTIVES: To explore the mechanism by which Tougu Xiaotong Capsule (TXC) promotes chondrogenic differentiation and cartilage repair in mice with osteoarthritis (OA). METHODS: Fifty 8-week-old male C57BL mice were randomly divided into normal control group, cartilage damage (induced by subchondral ring-shaped drilling) model group and TXC treatment groups at low, moderate and high doses (184, 368 and 736 mg/kg, respectively). Saline (in normal control and model groups) and TXC were administered after modeling by daily gavage for 6 consecutive weeks. The changes of cartilage damage in the mice were assessed by measuring thermal withdrawal latency (TWL) and mechanical withdrawal threshold (MWT) and using micro-CT, modified safranine O and fast green staining, HE staining, and qPCR. Primary cultures of mouse synovial mesenchymal stem cells (SMSCs) with lentivirus vector transfection for interfering CXCL12, TXC treatment, or both for 24 h were examined for chondrogenic differentiation using immunofluorescence staining, scratch assay, immunocytochemistry, and Western blotting. RESULTS: In mouse models with cartilage damage, TXC treatment at the moderate dose significantly alleviated joint pain, promoted cartilage repair, and upregulated the mRNA expression levels of CXCL12, GDF5, collagen II, aggrecan, Comp and Sox9 in the cartilage tissue. In primary mouse SMSCs, CXCL12 knockdown resulted in significant reduction of GDF5 protein expression, migration ability and Sox9 protein expression, and these changes were obviously reversed by TXC treatment. CONCLUSIONS TXC promotes chondrogenic differentiation of mouse SMSCs to promote repair of cartilage damage in mice by activating the CXCL12/GDF5 pathway.
Animals ; Drugs, Chinese Herbal/therapeutic use* ; Osteoarthritis/metabolism* ; Male ; Growth Differentiation Factor 5/metabolism* ; Mice, Inbred C57BL ; Mice ; Chemokine CXCL12/metabolism* ; Signal Transduction/drug effects* ; Cell Differentiation/drug effects* ; Cartilage, Articular/drug effects* ; Mesenchymal Stem Cells/cytology*

Abnormal accumulation of collagen fibrils is a hallmark feature of oral submucous fibrosis (OSF). However, the precise characteristics and underlying mechanisms remain unclear, impeding the advancement of potential therapeutic approaches. Here, we observed that collagen I, the main component of the extracellular matrix, first accumulated in the lamina propria and subsequently in the submucosa of OSF specimens as the disease progressed. Using RNA-seq and Immunofluorescence in OSF specimens, we screened the cartilage oligomeric matrix protein (COMP) responsible for the abnormal collagen accumulation. Genetic COMP deficiency reduced arecoline-stimulated collagen I deposition significantly in vivo. In comparison, both COMP and collagen I were upregulated under arecoline stimulation in wild-type mice. Human oral buccal mucosal fibroblasts (hBMFs) also exhibited increased secretion of COMP and collagen I after stimulation in vitro. COMP knockdown in hBMFs downregulates arecoline-stimulated collagen I secretion. We further demonstrated that hBMFs present heterogeneous responses to arecoline stimulation, of which COMP-positive fibroblasts secrete more collagen I. Since COMP is a molecular bridge with Fibril-associated collagens with Interrupted Triple helices (FACIT) in the collagen network, we further screened and identified collagen XIV, a FACIT member, co-localizing with both COMP and collagen I. Collagen XIV expression increased under arecoline stimulation in wild-type mice, whereas it was hardly expressed in the Comp^-/- mice, even with under stimulation. In summary, we found that COMP may mediates abnormal collagen I deposition by functions with collagen XIV during the progression of OSF, suggesting its potential to be targeted in treating OSF.
Oral Submucous Fibrosis/pathology* ; Cartilage Oligomeric Matrix Protein/genetics* ; Animals ; Mice ; Humans ; Fibroblasts/metabolism* ; Collagen Type I/metabolism* ; Arecoline/pharmacology* ; Mouth Mucosa/metabolism* ; Cells, Cultured ; Fluorescent Antibody Technique

OBJECTIVES: This study aims to investigate the effects and mechanisms of chondroitin sulfate (CS), dermatan sulfate (DS), and heparin (HEP) on chondrogenesis of murine chondrogenic cell line (ATDC5) cells and the maintenance of murine articular cartilage in vitro. METHODS: ATDC5 and articular cartilage tissue explant were cultured in the medium containing different sulfated glycosaminoglycans. Cell proliferation, differentiation, cartilage formation, and mechanism were observed using cell proliferation assay, Alcian blue staining, real-time quantitative polymerase chain reaction (RT-qPCR), and Western blot, respectively. RESULTS: Results showed that HEP and DS primarily activated the bone morphogenetic protein (BMP) signal pathway, while CS primarily activated the protein kinase B (AKT) signal pathway, further promoted ATDC5 cell proliferation and matrix production, and increased Sox9, Col2a1, and Aggrecan expression. CONCLUSIONS This study investigated the differences and mechanisms of different sulfated glycosaminoglycans in chondrogenesis and cartilage homeostasis maintenance. HEP promotes cartilage formation and maintains the normal state of cartilage tissue in vitro, while CS plays a more effective role in the regeneration of damaged cartilage tissue.
Animals ; Mice ; Cartilage/metabolism* ; Cell Differentiation ; Cells, Cultured ; Chondrocytes/metabolism* ; Chondrogenesis/physiology* ; Glycosaminoglycans/pharmacology*

OBJECTIVE: To investigate the effect of electroacupuncture on osteoarthritis in rats and explore the possible mechanism. METHODS: Thirty SD rats were randomly divided into osteoarthritis model group, electro-acupuncture group and control group (n=10), and in the former two groups, early osteoarthritis was induced using a modified DMM surgical modeling method. After successful modeling, the rats in the electro-acupuncture group were treated with electro-acupuncture at bilateral "Housanli" and "Anterior knee point". Behavioral tests of the rats were performed and scored using the LequesneMG scale. Subchondral bone degeneration was observed in each group, and serum levels of IL-1β, ADAMTS-7, MMP-3 and COMP were measured using ELISA. The mRNA and protein expressions of IL-1β, Wnt-7B, β-catenin, ADAMTS-7, and MMP-3 in the cartilage tissue of the knee joints were detected using RT-PCR and Western blotting. RESULTS: In behavioral tests, the rats in the model and electroacupuncture groups had significantly higher LequesneMG scores after modeling than those in the control group (P < 0.05). After 20 days of treatment, LequesneMG scores were significantly lowered in rats in the electroacupuncture as compared with the model rats (P < 0.05). Imaging examination revealed obvious subchondral bone damage in both the electroacupuncture group and the model group, but the damages were significantly milder with former group. Compared with the model rats, the rats receiving electroacupuncture had significantly lower serum levels of IL-1β, ADAMTS-7, MMP-3 and COMP (P < 0.05) with also lower expressions of IL-1β, Wnt-7B, β-catenin, ADAMTS-7 and MMP-3 in the cartilage tissues at both the mRNA and protein levels (P < 0.05). CONCLUSION Electroacupuncture can alleviate joint pain and improve subchondral bone damage in rats with osteoarthritis by reducing IL-1β levels in the joint cartilage tissue and serum to alleviate joint inflammation and by reducing such cytokines as ADAMTS-7 and MMP-3 via regulating the Wnt-7B/β-catenin signaling pathway.
Rats ; Animals ; Electroacupuncture ; Matrix Metalloproteinase 3/metabolism* ; Rats, Sprague-Dawley ; beta Catenin/metabolism* ; Osteoarthritis/metabolism* ; Wnt Signaling Pathway ; Cartilage, Articular ; Inflammation/metabolism*

OBJECTIVE: To summarize the role of chondrocyte mitochondrial homeostasis imbalance in the pathogenesis of osteoarthritis (OA) and analyze its application prospects. METHODS: The recent literature at home and abroad was reviewed to summarize the mechanism of mitochondrial homeostasis imbalance, the relationship between mitochondrial homeostasis imbalance and the pathogenesis of OA, and the application prospect in the treatment of OA. RESULTS: Recent studies have shown that mitochondrial homeostasis imbalance, which is caused by abnormal mitochondrial biogenesis, the imbalance of mitochondrial redox, the imbalance of mitochondrial dynamics, and damaged mitochondrial autophagy of chondrocytes, plays an important role in the pathogenesis of OA. Abnormal mitochondrial biogenesis can accelerate the catabolic reaction of OA chondrocytes and aggravate cartilage damage. The imbalance of mitochondrial redox can lead to the accumulation of reactive oxygen species (ROS), inhibit the synthesis of extracellular matrix, induce ferroptosis and eventually leads to cartilage degradation. The imbalance of mitochondrial dynamics can lead to mitochondrial DNA mutation, decreased adenosine triphosphate production, ROS accumulation, and accelerated apoptosis of chondrocytes. When mitochondrial autophagy is damaged, dysfunctional mitochondria cannot be cleared in time, leading to ROS accumulation, which leads to chondrocyte apoptosis. It has been found that substances such as puerarin, safflower yellow, and astaxanthin can inhibit the development of OA by regulating mitochondrial homeostasis, which proves the potential to be used in the treatment of OA. CONCLUSION The mitochondrial homeostasis imbalance in chondrocytes is one of the most important pathogeneses of OA, and further exploration of the mechanisms of mitochondrial homeostasis imbalance is of great significance for the prevention and treatment of OA.
Humans ; Reactive Oxygen Species/metabolism* ; Chondrocytes/metabolism* ; Osteoarthritis/metabolism* ; Homeostasis ; Mitochondria/metabolism* ; Cartilage, Articular/metabolism*

In growing children, growth plate cartilage has limited self-repair ability upon fracture injury always leading to limb growth arrest. Interestingly, one type of fracture injuries within the growth plate achieve amazing self-healing, however, the mechanism is unclear. Using this type of fracture mouse model, we discovered the activation of Hedgehog (Hh) signaling in the injured growth plate, which could activate chondrocytes in growth plate and promote cartilage repair. Primary cilia are the central transduction mediator of Hh signaling. Notably, ciliary Hh-Smo-Gli signaling pathways were enriched in the growth plate during development. Moreover, chondrocytes in resting and proliferating zone were dynamically ciliated during growth plate repair. Furthermore, conditional deletion of the ciliary core gene Ift140 in cartilage disrupted cilia-mediated Hh signaling in growth plate. More importantly, activating ciliary Hh signaling by Smoothened agonist (SAG) significantly accelerated growth plate repair after injury. In sum, primary cilia mediate Hh signaling induced the activation of stem/progenitor chondrocytes and growth plate repair after fracture injury.
Mice ; Animals ; Hedgehog Proteins/genetics* ; Receptors, G-Protein-Coupled/metabolism* ; Cilia/metabolism* ; Cartilage/metabolism* ; Regeneration

OBJECTIVE: To investigate whether Salvianolic acid A (SAA) can restore cartilage endplate cell degeneration of intervertebral discs and to identify the mechanism via regulation of micro-RNA. METHODS: Cartilage endplate cells were isolated from lumbar intervertebral disc surgical samples and were treated with serum containing a series of concentrations of SAA (2, 5, and 10 ?M) for 24, 48, and 72 h to identify a proper dose and treatment time of SAA. The effect SAA on interlenkin-1β (IL-1β)-induced extracellular matrix degradation of cartilage endplate cells were analyzed by Alcian blue staining and assessment of the expression levels of ADAMTS-5, MMP3 and Col2a1. Further, the potential target miRNAs were preliminarily screened by micro-RNA sequencing combining qRT-PCR and Western blot, and then, the miRNAs mimics and inhibitors were used to verify the regulatory effect of SAA on potential target miRNAs. RESULTS: The 10 μM SAA treatment for 48 h significantly enhanced the viability of cartilage endplate cells, and increased Col2a1 expression and glycosaminoglycan accumulation that were repressed by IL-1β, and reduced the effect of IL-1β on ADAMTS-5, and MMP3. Screening analysis based on micro-RNA sequencing and Venny analysis identified the downstream micro-RNAs, including miR-940 and miR-576-5p. Then, the miR-940-mimic or miR-576-5p-mimic were transfected into CEPCs. Compared with the SAA group, the expression of ADAMTS-5 and MMP3 increased significantly and the expression of COL2A1 obviously decreased after overexpression of miR-940 or miR-576-5p in CEPCs. CONCLUSION Salvianolic acid A attenuated the IL-1β-induced extracellular matrix degradation of cartilage endplate cells by targeting regulate the miR-940 and the miR-576-5p.
Humans ; Apoptosis ; Cartilage/metabolism* ; Chondrocytes/metabolism* ; Interleukin-1beta/metabolism* ; Matrix Metalloproteinase 3/metabolism* ; MicroRNAs/metabolism*

OBJECTIVE: To explore and verify that transient receptor potential vanilloid 4(TRPV4) affects chondrocyte degeneration. METHODS: Neonatal SD rats were selected, primary chondrocytes were extracted, and identified by toluidine blue staining and alcian blue staining;an in vitro chondrocyte inflammation model was constructed by IL-1β, and TRPV4 inhibitor was used to treat chondrocytes under inflammatory conditions, and the chondrocytes were treated by RT-PCR method was used to detect matrix metallopeptidase 13(MMP-13), a disintegrin and metalloproteinase with thrombospondin 5, (ADAMTS-5)、nitric oxide synthase 2(NOS2)、Collagen, type II alpha 1(Col2α1)and aggrecan (Acan) mRNA in chondrocytes; primary chondrocytes were treated with different concentrations of TRPV4 overexpression plasmid, and the optimal overexpression dose was screened. The mRNA expressions of TRPV4, MMP-13, ADAMTS-5, NOS2, Col2α1 and Acan in chondrocytes under the optimal TRPV4 overexpression dose were detected. RESULTS: Toluidine blue staining and Alcian blue staining identified the extracted cells as primary chondrocytes;RT-PCR showed that TRPV4, MMP-13, ADAMTS-5, NOS2 mRNA in chondrocytes treated with TRPV4 inhibitor under inflammatory conditions. The expression of Col2α1 mRNA was significantly decreased (P<0.05), and the expression of Col2α1 mRNA was increased (P<0.05). Although there was no significant difference in the expression of Acan mRNA, the overall trend was also increasing. The expression of Col2α1 and Acan mRNA in chondrocytes was significantly decreased (P<0.05), and the expression of NOS2 mRNA was increased(P<0.05), but there was no significant difference in MMP-13 and ADAMTS-5 (P>0.05). CONCLUSION Inhibiting the expression of TRPV4 can down-regulate the expression of genes related to chondrocyte degeneration.
Animals ; Rats ; Aggrecans/metabolism* ; Cartilage, Articular ; Cells, Cultured ; Chondrocytes ; Interleukin-1beta/metabolism* ; Matrix Metalloproteinase 13/metabolism* ; Rats, Sprague-Dawley ; RNA, Messenger/metabolism* ; TRPV Cation Channels/metabolism*