Cinnamic Aldehyde, the main monomer component of Cinnamon, exhibits anti-inflammatory property in OA synovial fibroblasts via TLR4/MyD88 pathway.

Cinnamon is a wildly used traditional Chinese herbal medicine for osteoarthritis (OA) treatment, but the underlying mechanism remains ambiguous. The purpose of this study is to explore the mechanism of cinnamic aldehyde (CA), a bioactive substance extracted from Cinnamon, on synovial inflammation in OA. A total of 144 CA-OA co-targeted genes were identified by detect databases (PubChem, HIT, TCMSP, TTD, DrugBank and GeneCards). The results of GO enrichment analysis indicated that these co-targeted genes have participated in many biological processes including 'inflammatory response', 'cellular response to lipopolysaccharide', 'response to drug', 'immune response', 'lipopolysaccharide-mediated signalling pathway', etc. KEGG pathway analysis showed these co-targeted genes were mainly enriched in 'Toll-like receptor signalling pathway', 'TNF signalling pathway', 'NF-kappa B signalling pathway', etc. Molecular docking demonstrated that CA could successfully bind to TLR2 and TLR4. The results of in vitro experiments showed no potential toxicity of 10, 20 and 50 µM/L CA on human OA FLS, and CA can significantly inhibit the inflammation in LPS-induced human FLS. Further experimental mechanism evidence confirmed CA can inhibited the inflammation in LPS-induced human OA FLS via blocking the TLR4/MyD88 signalling pathway. Our results demonstrated that CA exhibited strong anti-inflammation effect in OA FLS through blocking the activation of TLR4/MyD88 signalling pathway, suggesting its potential as a hopeful candidate for the development of novel agents for the treatment of OA.

Synovial tissue-derived extracellular vesicles induce chondrocyte inflammation and degradation via NF-κB signalling pathway: An in vitro study.

Osteoarthritis (OA) is a whole-joint disease characterized by synovial inflammation and cartilage degeneration. However, the relationship between synovial inflammation and cartilage degeneration remains unclear. The modified Hulth's method was adopted to establish a knee OA (KOA) rabbit model. Synovial tissue was collected after 8 weeks, and synovial tissue-derived extracellular vesicles (ST-EVs) were extracted by filtration combined with size exclusion chromatography (SECF), followed by identification through transmission electron microscopy (TEM), nanoparticle tracer analysis (NTA) and Western blot (WB). The collagenase digestion method was used to extract normal rabbit chondrocytes, which were then treated with the SF-EVs to observe the effect and mechanism of SF-EVs on chondrocytes. The morphology, particle size and labelled protein marker detection confirmed that SECF successfully extract ST-EVs. The ST-EVs in the KOA state significantly inhibited chondrocyte proliferation and promoted chondrocytes apoptosis. Moreover, the ST-EVs also promoted the expression of pro-inflammatory cytokines (IL-1ß, IL-6, TNF-α and COX-2) and cartilage degradation-related enzymes (MMP13, MMP9 and ADAMTS5) in the chondrocytes. Mechanistically, the ST-EVs significantly promoted the activation of NF-κB signalling pathway in chondrocytes. Inhibition the activation of the NF-κB signalling pathway significantly rescued the expression of inflammatory cytokines and cartilage degradation-related enzymes in the ST-EVs-induced chondrocytes. In conclusion, the ST-EVs promote chondrocytes inflammation and degradation by activating the NF-κB signalling pathway, providing novel insights into the occurrence and development of OA.

Paeoniflorin, the Main Monomer Component of Paeonia lactiflora, Exhibits Anti-inflammatory Properties in Osteoarthritis Synovial Inflammation.

OBJECTIVE: To explore the mechanism of paeoniflorin (PF) on osteoarthritis (OA) synovial inflammation from network pharmacology to experimental pharmacology. METHODS: Targets of OA were constructed by detecting the database of network database platforms (Therapeutic Target database, DrugBank and GeneCards), and the targets of PF were constructed by PubChem and Herbal Ingredients' Targets database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of these co-targeted genes were conducted via Database for Annotation, Visualization, and Integrated Discovery (DAVID) database, and protein-protein interaction (PPI) networks were conducted via the search tool for the retrieval of interacting genes (STRING) database. Cell counting kit-8 (CCK-8) assay was performed to assess the potential toxicity of PF on human OA fibroblast-like synoviocytes (FLS), quantitative real-time polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA) and Western blot were used to verify the potential mechanism of PF in synovial inflammation. RESULTS: Twenty-six co-targeted genes were identified. GO enrichment results showed that these co-targeted genes were most likely localized in the cytoplasm, and the biological processes mainly involved 'cellular response to hypoxia' 'lipopolysaccharide (LPS)-mediated signaling pathway' and 'positive regulation of gene expression'. KEGG pathway analysis indicated that these co-targeted genes may function through pathways associated with 'hypoxia-inducible factor-1 (HIF-1) signaling pathway' and 'tumor-necrosis factor (TNF) signaling pathway'. The PPI network showed that the top 3 hub genes were TP53, TNF, and CASP3. Molecular docking results showed that PF was well docking with TNF. CCK-8 showed no potential toxicity of 10, 20 and 50 µmol/L PF on human OA FLS. And PF significantly decreased the expression levels of interleukin-1 ß, interleukin-6, TNF-α matrix metalloproteinase 13 (MMP13), and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) and TNF-α in LPS-induced OA FLS. CONCLUSION: PF exhibited potent anti-inflammatory effect in OA synovial inflammation.

Efficacy and Mechanism of Electroacupuncture Treatment of Rabbits With Different Degrees of Knee Osteoarthritis: A Study Based on Synovial Innate Immune Response.

Knee osteoarthritis (KOA) is a chronic degenerative bone and joint disease, which is often clinically manifested as pain, joint swelling, and deformity. Its pathological manifestations are mainly synovial inflammation and cartilage degeneration. This study aims to investigate the efficacy of electro-acupuncture (EA) on model rabbits with varying degrees of KOA and to study the mechanism of EA on KOA based on the innate immune response. Mild and moderate rabbit KOA models were established using a modified Hluth method, and EA was given to both the mild and moderate model groups. The Lequesne-MG index was used to evaluate the behavioral changes in the rabbits before and after EA treatment. Morphological changes in the synovial membrane and cartilage of each group were observed by H&E staining. The Mankin scoring standard and the Krenn scoring standard were used to score the pathology of the cartilage tissue and synovial tissue, respectively. The inflammatory factors and metalloproteinases were detected in the serum of each group by ELISA. The protein and messenger RNA (mRNA) expressions of important elements related to Toll-like receptors (TLRs)-mediated innate immune response in the synovial tissue were detected by Western blot and quantitative PCR (qPCR). The Lequesne-MG index score of the rabbits gradually increased with the modeling prolonged but decreased significantly after EA treatment, indicating that EA has a better effect on alleviating the pain and improving the dysfunction. The morphological analysis showed that the inflammation of and the damage to the synovial membrane and the cartilage tissue gradually deteriorated with the modeling prolonged. However, the synovial membrane inflammation was significantly relieved after EA treatment, and the cartilage injury showed signs of repair. The ELISA analysis showed that, with the modeling prolonged, the serum-related inflammatory factors and mechanism of metalloproteinases gradually increased but decreased after EA treatment. The tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), and matrix metalloproteinase3 (MMP3) of EA1 group were significantly lower than those of EA2 group. Both Western blot and qPCR results showed that the protein and mRNA expressions of the elements related to the innate immune response in the synovial membrane increased gradually with the modeling prolonged, but decreased significantly after EA treatment. Additionally, the expression of some components in EA1 group was significantly lower than that in EA2 group. These results confirm that synovial inflammation gradually aggravated with time from the early to mid-stage of KOA. EA alleviated the inflammation and histological changes in KOA rabbits by inhibiting the TLRs-mediated innate synovial immune response. This suggests that using EA in the early stage of KOA may achieve a desirable efficacy.

Extraction and identification of synovial tissue-derived exosomes by different separation techniques.

OBJECTIVE: The aim of this study is to compare the efficiency of different separation techniques for extracting synovial tissue-derived exosomes. METHODS: The synovial tissue discarded during knee arthroscopy or total knee arthroplasty surgery was collected from the Third Affiliated Hospital of Beijing University of Chinese Medicine. Ultracentrifugation (UC), filtration combined with size exclusion chromatography (SECF), and 8% polyethylene glycol (PEG) were used to extract synovial tissue-derived exosomes. Transmission electron microscopy (TEM), nanoparticle tracer analysis (NTA), and Western Blot (WB) were used to detect the morphology, particle size, and biomarker proteins (CD9, CD63, Flotillin-1, and calnexin) of exosomes. RESULTS: The extracts of enriched round and discoid vesicles were successfully extracted with UC, SECF, and PEG. The results of TEM have shown that all three extraction methods can extract circular or elliptical vesicles with disc- and cup-shaped structures from the synovial tissue, with the diameter is about 30-150 nm. NTA suggested the main peaks of three groups of exosomes are around 100-120 nm, and the concentration of the three groups of exosomes was greater than 1 × 1010/ml. The results of WB showed that three positive protein markers (CD9, CD63, and Flotillin-1) were highly expressed in the suspension extracted by the three methods and low in the synovial tissue. However, the negative protein (calnexin) was highly expressed in synovial tissues and PEG group, while low in UC and SECF group. CONCLUSION: Morphology, particle size, and labeled protein marker detection confirmed that UC, SECF, and PEG can extract exosomes derived from synovial tissue; UC and SECF are more recommended for the extraction of synovial tissue-derived exosomes, which provides a methodological basis for studying the function and mechanism of synovial tissue exosomes in the future.

Cinnamic Aldehyde Inhibits Lipopolysaccharide-Induced Chondrocyte Inflammation and Reduces Cartilage Degeneration by Blocking the Nuclear Factor-Kappa B Signaling Pathway.

Osteoarthritis (OA), as one of the top 10 causes of physical disability, is characterized by inflammation of the synovial membrane and progressive destruction of the articular cartilage. Cinnamic aldehyde (CA), an α,ß-unsaturated aldehyde extracted from the traditional Chinese herbal medicine cinnamon (Cinnamomum verum J.Presl), has been reported to have anti-inflammatory, antioxidant, and anticancer properties. However, the anti-inflammatory effect of CA on OA remains unclear. The purpose of the present study was to investigate the effects of CA on inflammation, and cartilage degeneration in OA. A CCK-8 assay was performed to assess the potential toxicity of CA on cultured human OA chondrocytes. Following treatment with lipopolysaccharide (LPS) and CA, the expression of proinflammatory cytokines, including interleukin (IL)-1ß, IL-6, and tumor necrosis factor-alfa (TNF-α), was evaluated using quantitative real-time polymerase chain reaction (RT-qPCR) analysis, enzyme-linked immunosorbent assay, and Western blotting (WB). The production of matrix metalloproteinase-13 (MMP-13) and a disintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS-5) was also examined using RT-qPCR and WB. Furthermore, to investigate the potential anti-inflammatory mechanism of CA, biomarkers of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway (p65, IKB-α) were detected using WB. The results demonstrated that CA significantly inhibited the expressions of IL-1ß, IL-6, TNF-α, MMP-13, and ADAMTS-5 in LPS-induced OA chondrocytes. CA dramatically suppressed LPS-stimulated NF-κB activation. Collectively, these results suggest that CA treatment may effectively prevent OA.

[Effect of Tongluo Zhitong (, TLZT) gel preparation on p53 /miR-502-5p /NF-κBp65 in synovial tissue of knee osteoarthritis].

OBJECTIVE: To observe effects of Tongluo Zhitong (, TLZT) gel preparation on p53, miR-502-5p, NF-κBp65 in synovial tissue of knee osteoarthritis (KOA), and to explore mechanism of TLZT gel preparation in treating KOA. METHODS: Thirthy-six Wistar rats aged 8 weeks and weighed 200 to 220 g (meaned 208 g) were randomly divided into normal group, model group and traditional Chinese medicine (TCM) group, 12 rats in each group. KOA model was established by modified Hulth method. After 4 weeks of modeling, TCM group treated with TLZT gel preparation for external use, 3 times daily for 2 weeks;normal group and model group were fed normally without intervention. After treatment, morphological changes of specimens in each group were observed, changes of miR-502-5p in synovial tissue were detected by qPCR, and contents of p53, NF-κBp65, IL-1ß, TNF-α, MMP-13 in synovial tissue were detected by qPCR and Western Blot respectively. RESULTS: (1)Morphological observation of specimens showed that the articular cartilage in model group was hyaline and uneven, the synovial membranes were hypertrophic and proliferative with a large number of inflammatory cells infiltrating, the joint fluid was thicker in texture;the articular cartilage in TCM group was more transparent and smooth, synovial hyperplasia was mild with a small amount of inflammatory cell infiltration, the texture of articular fluid was clear and sparse. (2) Compared with normal group, content of miR-502-5p of synovial tissue in model and TCM group were increased, mRNA and expression of p53 decreased, expression of NF-κBp65, IL-1ß, TNF-α, MMP-13 increased. (3)Compared with model group, content of miR-502-5p in synovial tissue of TCM group decreased (P<0.05), mRNA and protein expression of p53 increased (P<0.05), mRNA and protein expression of NF-κBp65, IL-1ß, TNF-α, MMP-13 decreased (P<0.05). CONCLUSION: Expression of p53, miR-502 -5p, NF -κBp65 in synovial tissue is closely related to synovial hyperplasia and inflammatory reaction, TLZT gel preparation may reduce proliferation and inflammatory reaction of KOA synovium by regulating the expression of p53, miR- 502-5p, NF-κBp65 in synovial tissues.

Intra-articular platelet-rich plasma injection for knee osteoarthritis: a summary of meta-analyses.

OBJECTIVE: The purpose of this study was (1) to perform a summary of meta-analyses comparing platelet-rich plasma (PRP) injection with hyaluronic acid (HA) and placebo injection for KOA patients, (2) to determine which meta-analysis provides the best available evidence to making proposals for the use of PRP in the treatment of KOA patients, and (3) to highlight gaps in the literature that require future investigation. MATERIAL AND METHODS: PubMed, EMBASE, and Cochrane databases search were performed for meta-analyses which compared PRP injection with HA or placebo. Clinical outcomes and adverse events were extracted from these meta-analyses. Meta-analysis quality was assessed using the Quality of Reporting of Meta-analyses (QUOROM) systems and the Oxman-Guyatt quality appraisal tool. The Jadad decision algorithm was also used to determine which meta-analysis provided the best available evidence. RESULTS: Four meta-analyses were included in our study, and all of these articles were Level I evidence. The QUOROM score of each included meta-analysis range from 14 to 17 points (mean score 15, maximum score 18), and the Oxman-Guyatt score range from 4 to 6 points (mean score 5, maximum score 7). Three meta-analyses indicated PRP showed more benefit in pain relief and functional improvement than the control group, and the other one suggested no difference between these groups. All included meta-analyses found no statistical difference in adverse events between these groups. In addition, a meta-analysis conducted by Shen et al. got the highest methodological quality score and suggested that PRP provided better pain relief and function improvement in the treatment of KOA. CONCLUSIONS: For short-term follow-up (≤1 year), intra-articular PRP injection is more effective in terms of pain relief and function improvement in the treatment of KOA patients than HA and placebo, and there is no difference in the risk of an adverse event between PRP and HA or placebo. LEVEL OF EVIDENCE: Level I evidence, a summary of meta-analyses TRIAL REGISTRATION: PROSPERO ID CRD42018116168.

[Expression and significance of ß-catenin and NF-κB signaling pathway in knee osteoarthritis synovial inflammation].

OBJECTIVE: To explore expression of ß-catenin and NF-κB signaling pathway in synovial tissue of rats with different degrees of knee osteoarthritis (KOA). METHODS: Forty-eight SPF male rats weighed (200±20) g were randomly divided into three groups, namely model group (32 rats), sham operation group (8 rats) and control group (8 rats). KOA model rats were established by Hulth method, and 8 rats were killed at 2, 4, 8, 12 weeks respectively after modeling, in order to establish KOA model rats with moderate, early, mild and severe degree. Sham operation group was only cut off capsule of knee joint and suture to exclude interference factor, control group was untreated. Behavior, synovial hyperplasia and cartilage degeneration of rats among each group were observed. Expression of NF-κB and signaling pathway and ß-catenin in synovial tissue of rats were detected by real-time PCR. RESULTS: KOA rat model was successfully established, and synovial hyperplasia was observed in KOA model at mild and early degree, and then gradually decreased; while cartilage degeneration in the early moderate and severe KOA model was significantly expressed, and gradually aggravated with time. The results of PCR showed that expression of ß-catenin in 4-week group (8.57±0.46) and 8-week group (4.23±0.09) were higher than those in control group (P<0.05); expression of TLR-2 in 2-week group (12.04±4.02) and 4-week group (8.54±2.13) were higher than those in control group(P<0.05), and TLR-4 in 2-week group(5.04±0.93), 4-week group (3.29±0.58) and 8-week group (1.63±0.12) were higher than those in control group; expression of NF-κB was significantly higher in 2-week group (10.15±2.04), 4-week group (15.97±4.17), 8-week group (7.69±1.48) and 12-week group (6.70±1.58) than that in control group (P<0.05), and expression of IL-1ß was significantly higher in 4-week group (2.79±0.25) and 8-week group (2.46±0.32) than that of control group (P<0.05). CONCLUSIONS: On the RNA expression level, both of ß-catenin and NF-κB signaling pathways are involved in synovial inflammation in KOA model rats, and they play a regulatory role in expression of IL-1ß, degeneration of KOA.