Acacetin targets STING to alleviate the destabilization of the medial meniscus-induced osteoarthritis in mice.

Osteoarthritis (OA) is a common joint disorder affecting about 7% of the global population, primarily characterized by the gradual loss of articular cartilage. This degeneration results from local inflammation, matrix depletion, and direct cartilage damage. A critical element in this process is the activation of the stimulator of the interferon genes (STING) pathway. Emerging evidence highlights its potential as a therapeutic target, with natural products showing promise as inhibitors. Our study centers on Acacetin, a basic unit of polyketides known for its anti-inflammatory properties. Prior research has highlighted its potential interaction with STING based on the structure. Thus, this study aimed to assess the effectiveness of Acacetin as a STING inhibitor and its protective role against OA. In vitro experiments showed that Acacetin pretreatment not only mitigated interleukin-1ß (IL-1ß)-induced cytotoxicity but also decreased the inflammatory response and degeneration in chondrocytes stimulated IL-1ß. In vivo studies revealed that Acacetin administration significantly reduced articular cartilage destruction, abnormal bone remodeling, and osteophyte formation in a model of OA induced by destabilization of the medial meniscus (DMM). Mechanistically, Acacetin was found to interact directly with STING, and inhibit IL-1ß-induced activation of STING, along with the subsequent phosphorylation of the TBK1/NF-κB pathway in chondrocytes. In conclusion, our findings establish Acacetin as an effective inhibitor of STING that protects chondrocytes from IL-1ß-induced damage and slows the progression of OA in mice.

Correlation of meniscus tear type with synovial inflammation and the therapeutic potential of docosapentaenoic acid.

BACKGROUND: Synovitis, characterized by inflammation of the synovial membrane, is commonly induced by meniscus tears. However, significant differences in inflammatory responses and the key inflammatory mediators of synovium induced by different types of meniscal tears remain unclear. METHODS: Magnetic resonance imaging (MRI) was employed to identify the type of meniscus tear, and the quantification of synovial inflammation was assessed through H&E staining assay. Transcription and expression levels of IL-1ß and IL-6 were evaluated using bioinformatics, ELISA, RT-qPCR, and IHC of CD68 staining assays. The therapeutic potential of Docosapentaenoic Acid (DPA) was determined through network pharmacology, ELISA, and RT-qPCR assays. The safety of DPA was assessed using colony formation and EdU staining assays. RESULTS: The results indicate that both IL-1ß and IL-6 play pivotal roles in synovitis pathogenesis, with distinct expression levels across various subtypes. Among tested meniscus tears, oblique tear and bucket handle tear induced the most severe inflammation, followed by radial tear and longitudinal tear, while horizontal tear resulted in the least inflammation. Furthermore, in synovial inflammation induced by specific meniscus tears, the anterior medial tissues exhibited significantly higher local inflammation than the anterior lateral and suprapatellar regions, highlighting the clinical relevance and practical guidance of anterior medial tissues' inflammatory levels. Additionally, we identified the essential omega-3 fatty acid DPA as a potential therapeutic agent for synovitis, demonstrating efficacy in blocking the transcription and expression of IL-1ß and IL-6 with minimal side effects. CONCLUSION: These findings provide valuable insights into the nuanced nature of synovial inflammation induced by various meniscal tear classifications and contribute to the development of new adjunctive therapeutic agents in the management of synovitis.

Testing Hypoxia in Pig Meniscal Culture: Biological Role of the Vascular-Related Factors in the Differentiation and Viability of Neonatal Meniscus.

Menisci play an essential role in shock absorption, joint stability, load resistance and its transmission thanks to their conformation. Adult menisci can be divided in three zones based on the vascularization: an avascular inner zone with no blood supply, a fully vascularized outer zone, and an intermediate zone. This organization, in addition to the incomplete knowledge about meniscal biology, composition, and gene expression, makes meniscal regeneration still one of the major challenges both in orthopedics and in tissue engineering. To overcome this issue, we aimed to investigate the role of hypoxia in the differentiation of the three anatomical areas of newborn piglet menisci (anterior horn (A), central body (C), and posterior horn (P)) and its effects on vascular factors. After sample collection, menisci were divided in A, C, P, and they were cultured in vitro under hypoxic (1% O2) and normoxic (21% O2) conditions at four different experimental time points (T0 = day of explant; T7 = day 7; T10 = day 10; T14 = day 14); samples were then evaluated through immune, histological, and molecular analyses, cell morpho-functional characteristics; with particular focus on matrix composition and expression of vascular factors. It was observed that hypoxia retained the initial phenotype of cells and induced extracellular matrix production resembling a mature tissue. Hypoxia also modulated the expression of angiogenic factors, especially in the early phase of the study. Thus, we observed that hypoxia contributes to the fibro-chondrogenic differentiation with the involvement of angiogenic factors, especially in the posterior horn, which corresponds to the predominant weight-bearing portion.

Antiosteoarthritic Effect of Morroniside in Chondrocyte Inflammation and Destabilization of Medial Meniscus-Induced Mouse Model.

Osteoarthritis (OA) is a common degenerative disease that results in joint inflammation as well as pain and stiffness. A previous study has reported that Cornus officinalis (CO) extract inhibits oxidant activities and oxidative stress in RAW 264.7 cells. In the present study, we isolated bioactive compound(s) by fractionating the CO extract to elucidate its antiosteoarthritic effects. A single bioactive component, morroniside, was identified as a potential candidate. The CO extract and morroniside exhibited antiosteoarthritic effects by downregulating factors associated with cartilage degradation, including cyclooxygenase-2 (Cox-2), matrix metalloproteinase 3 (Mmp-3), and matrix metalloproteinase 13 (Mmp-13), in interleukin-1 beta (IL-1ß)-induced chondrocytes. Furthermore, morroniside prevented prostaglandin E2 (PGE2) and collagenase secretion in IL-1ß-induced chondrocytes. In the destabilization of the medial meniscus (DMM)-induced mouse osteoarthritic model, morroniside administration attenuated cartilage destruction by decreasing expression of inflammatory mediators, such as Cox-2, Mmp3, and Mmp13, in the articular cartilage. Transverse microcomputed tomography analysis revealed that morroniside reduced DMM-induced sclerosis in the subchondral bone plate. These findings suggest that morroniside may be a potential protective bioactive compound against OA pathogenesis.

Gut microbiome dysbiosis alleviates the progression of osteoarthritis in mice.

Gut microbiota dysbiosis has been studied under the pathological conditions of osteoarthritis (OA). However, the effect of antibiotic-induced gut flora dysbiosis on OA remains incompletely understood at present. Herein, we used a mouse (8 weeks) OA model of destabilization of the medial meniscus (DMM) and gut microbiome dysbiosis induced by antibiotic treatment with ampicillin and neomycin for 8 weeks. The results show that antibiotic-induced intestinal microbiota dysbiosis reduced the serum level of lipopolysaccharide (LPS) and the inflammatory response, such as suppression of the levels of tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6), which can lead to decreased matrix metalloprotease-13 (MMP-13) expression and improvement of OA after joint injury. In addition, trabecular thickness (Tb.Th) and osteophyte scores were increased significantly in antibiotic-induced male mice compared with female mice. We further used network correlation analysis to verify the effect of gut microbiota dysbiosis on OA. Therefore, the present study contributes to our understanding of the gut-joint axis in OA and reveals the relationship between the inflammatory response, sex and gut microbiota, which may provide new strategies to prevent the symptoms and long-term sequelae of OA. Conclusion: Our data showed that gut microbiome dysbiosis alleviates the progression of OA.

Non-ionic CT contrast solutions rapidly alter bovine cartilage and meniscus mechanics.

OBJECTIVE: To evaluate effects of a common CT contrast agent (iohexol) on the mechanical behaviors of cartilage and meniscus. METHODS: Indentation responses of juvenile bovine cartilage and meniscus were monitored following exposure to undiluted contrast agent (100% CA), 50% CA/water, 50% CA/Phosphate Buffered Saline (PBS) or PBS alone, and during re-equilibration in PBS. The normalized peak force (Fpk¯), effective osmotic strain (εosm), and normalized effective contact modulus (Ec¯) were calculated for every cycle, with time constants determined for both exposure and recovery via mono- or biexponential fits to Fpk¯. RESULTS: All cartilage CA groups exhibited long-term increases in Fpk¯ following exposure, although the hyperosmolal 100% CA and 50% CA/PBS groups showed an initial transient decrease. Meniscus presented opposing trends, with decreasing Fpk¯ for all CA groups. Re-equilibration in PBS for 1hr after exposure to 100% CA produced recovery to baseline Fpk¯ in cartilage but not in meniscus, and extended tests indicated that meniscus required ∼2.5 h to recover halfway. Ec¯ increased with CA exposure time for cartilage but decreased for meniscus, suggesting an increased effective stiffness for cartilage and decreased stiffness for meniscus. Long-term changes to εosm in both tissues were consistent with changes in Ec¯. CONCLUSION: Exposure to iohexol solutions affected joint tissues differentially, with increased cartilage stiffness, likely relating to competing hyperosmotic and hypotonic interactions with tissue fixed charges, and decreased meniscus stiffness, likely dominated by hyperosmolarity. These altered tissue mechanics could allow non-physiological deformation during ambulatory weight-bearing, resulting in an increased risk of tissue or cell damage.

Morusin Ameliorates IL-1ß-Induced Chondrocyte Inflammation and Osteoarthritis via NF-κB Signal Pathway.

PURPOSE: Osteoarthritis (OA) is one of the most common degenerative joint diseases in the world, characterized primarily by the progressive degradation of articular cartilage. Accumulating evidence has shown that Morusin, a flavonoid derived from the root bark of Morus alba (mulberry) plants, exerts unique protective properties in several diseases. However, its effects on OA, specifically, have not yet been characterized. METHODS: In this study, we evaluated the anti-inflammatory effect of Morusin on mouse chondrocytes and its underlying mechanism in vitro. In addition, the protective effect of Morusin on destabilization of the medial meniscus (DMM) model was also explored in vivo. RESULTS: In vitro, IL-1ß-induced activation of inflammatory factors (TNF-α, IL-6, INOS and COX2) was dramatically suppressed by Morusin. Further, Morusin treatment inhibited the expression of ADAMTS5 and metalloproteinase (MMPs), both of which regulate extracellular matrix degradation. Morusin also decreased IL-1ß-induced p65 phosphorylation and IκBα degradation. In vivo, degradation of the articular cartilage following surgical DMM, which mimicked OA pathology, was abrogated following treatment with Morusin, thus demonstrating a protective effect in the DMM model. CONCLUSION: Herein, we demonstrate that Morusin reduces the OA inflammatory response in vitro and protects against articular cartilage degradation in vivo potentially via regulation of the NF-κB pathway. Hence, Morusin may prove to be an effective candidate for novel OA therapeutic strategies.

Loganin ameliorates cartilage degeneration and osteoarthritis development in an osteoarthritis mouse model through inhibition of NF-κB activity and pyroptosis in chondrocytes.

ETHNOPHARMACOLOGICAL RELEVANCE: Corni Fructus (CF), the red fruit of Cornus officinalis Siebold & Zucc, has been used both as food and medicinal herb in traditional Chinese medicine (TCM). Loganin is a major iridoid glycoside and one of the quality control indexes of CF. In TCM clinical practice, prescription containing CF is commonly used to treat osteoarthritis (OA), but the underlying mechanisms of loganin are not yet utterly understood. AIM OF THE STUDY: The aims of the present study are to confirm the therapeutic effects of loganin in an OA mouse model and to determine the mechanisms involved in the OA protective effects. MATERIALS AND METHODS: The destabilization of the medial meniscus (DMM) procedure was performed on the right knee of 8-week-old C57BL/6 male mice. 30 or 100 µg/ml of loganin was then injected into articular space twice a week for 8 and 12-week. Safranin O/Fast green staining, H&E staining, micro-CT analysis were performed to analyze structural and morphological changes. The protein expression of collagen type II (Col2), metalloproteinase-3 (Mmp3), matrix metalloproteinase 13 (Mmp13) collagen type X (Col10), cryopyrin and caspase-1 were detected by immunochemistry staining. Immuno-fluorescence assay was performed to assess changes in expression of CD31, endomucin, p65 and p-I-κB. RESULTS: Results of histomorphometry showed that loganin delays the progression of OA in the DMM model. In cartilage, loganin decreased the OARSI score, increasing hyaline cartilage (HC) thickness and decreasing calcified cartilage (CC) thickness. Moreover, loganin inhibited osteophyte formation, reduced the bone volume fraction (BV/TV), lowered trabecular thickness (Tb.Th) and increased trabecular separation (Tb.Sp) in subchondral bone. Mechanistically, loganin increased the expressions of Col2, decreases the expression of Mmp3, Mmp13, Col10, cryopyrin and caspase-1 in cartilage. In parallel, loganin inhibited the expression of CD31 and endomucin in subchondral bone. Furthermore, loganin suppressed nuclear translocation of p65 protein, and decreased the amount of p-I-κB in chondrocytes. CONCLUSIONS: In summary, these results uncovered that loganin inhibits NF-κB signaling and attenuates cartilage matrix catabolism and pyroptosis of chondrocytes in articular cartilage. Loganin may serve as a potential therapeutic agent for OA treatment.

Dopamine delays articular cartilage degradation in osteoarthritis by negative regulation of the NF-κB and JAK2/STAT3 signaling pathways.

BACKGROUND: The progressive loss of cartilage matrix and the breakdown of articular cartilage induced by inflammation play an essential role in osteoarthritis (OA) pathogenesis. Dopamine (DA) is a critical neurotransmitter that is not only involved in controlling exercise, emotion, cognition and neuroendocrine activity but also has anti-inflammatory effects. This study aimed to investigate the effects of DA on OA in vitro and in vivo. METHODS: OA progression was evaluated in a mouse model with surgically induced destabilization of the medial meniscus. Cartilage degradation and OA were analyzed using Safranin O/Fast Green staining. Additionally, qRT-PCR and Western blotting were applied to detect catabolic and anabolic factors involved in cartilage degeneration and underlying mechanisms in OA chondrocytes treated with Interleukin-1ß. RESULTS: In vitro, DA treatment inhibited the production of inducible nitric oxide synthase, cyclooxygenase-2, matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13, while increasing type II collagen and glycosaminoglycan content. Mechanistically, DA reversed IL-1ß-treated nuclear factor-kappa B activation and JAK2/STAT3 phosphorylation. Furthermore, DA suppressed the degradation of cartilage matrix and reduced Osteoarthritis Research Society International scores in the surgically induced OA models. CONCLUSION: DA may be a novel therapeutic agent for OA treatment.

Cirsium japonicum var. maackii and apigenin block Hif-2α-induced osteoarthritic cartilage destruction.

Although Hif-2α is a master regulator of catabolic factor expression in osteoarthritis development, Hif-2α inhibitors remain undeveloped. The aim of this study was to determine whether Cirsium japonicum var. maackii (CJM) extract and one of its constituents, apigenin, could attenuate the Hif-2α-induced cartilage destruction implicated in osteoarthritis progression. In vitro and in vivo studies demonstrated that CJM reduced the IL-1ß-, IL-6, IL-17- and TNF-α-induced up-regulation of MMP3, MMP13, ADAMTS4, ADAMTS5 and COX-2 and blocked osteoarthritis development in a destabilization of the medial meniscus mouse model. Activation of Hif-2α, which directly up-regulates MMP3, MMP13, ADAMTS4, IL-6 and COX-2 expression, is inhibited by CJM extract. Although cirsimarin, cirsimaritin and apigenin are components of CJM and can reduce inflammation, only apigenin effectively reduced Hif-2α expression and inhibited Hif-2α-induced MMP3, MMP13, ADAMTS4, IL-6 and COX-2 expression in articular chondrocytes. IL-1ß induction of JNK phosphorylation and IκB degradation, representing a critical pathway for Hif-2α expression, was completely blocked by apigenin in a concentration-dependent manner. Collectively, these effects indicate that CJM and one of its most potent constituents, apigenin, can lead to the development of therapeutic agents for blocking osteoarthritis development as novel Hif-2α inhibitors.

Alleviation of Cartilage Destruction by Sinapic Acid in Experimental Osteoarthritis.

Sinapic acid (SA) modulates the nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathway in chondrocytes. In order to test the hypothesis that SA is protective against the development of osteoarthritis (OA), primary mouse chondrocytes were treated in vitro with SA and the promoter transactivation activity of heme oxygenase 1 (HO-1), nuclear translocation of Nrf2, and protein expression of HO-1 were assayed. To test the hypothesis in vivo, a destabilization of the medial meniscus (DMM) model was used to induce OA in the knees of mice and SA was delivered orally to the experimental group. The chondrocytes were harvested for further analysis. The expression of HO-1 was similarly upregulated in cartilage from both the experimental mice and human chondrocytes from osteoarthritic knees. SA was found to enhance the promoter transactivation activity of heme oxygenase 1 (HO-1) and increase the expression of Nrf2 and HO-1 in primary chondrocytes. Histopathologic scores showed that the damage induced by the DMM model was significantly lower in the SA treatment group. The addition of a HO-1 inhibitor with SA did not show additional benefit over SA alone in terms of cartilage degradation or histopathologic scores. The expression of TNF-α, IL-1ß, IL-6, MMP-1, MMP-3, MMP-13, ADAMTS4, and ADAMTS5 was significantly reduced both in vitro and in vivo by the presence of SA. Protein expressions of HO-1 and Nrf2 were substantially increased in knee cartilage of mice that received oral SA. Our results suggest that SA should be further explored as a preventative treatment for OA.

Ultrasound-assisted biofabrication and bioprinting of preferentially aligned three-dimensional cellular constructs.

A critical consideration in tissue engineering is to recapitulate the microstructural organization of native tissues that is essential to their function. Scaffold-based techniques have focused on achieving this via the contact guidance principle wherein topographical cues offered by scaffold fibers direct migration and orientation of cells to govern subsequent cell-secreted extracellular matrix organization. Alternatively, approaches based on acoustophoretic, electrophoretic, photophoretic, magnetophoretic, and chemotactic principles are being investigated in the biofabrication domain to direct patterning of cells within bioink constructs. This work describes a new acoustophoretic three-dimensional (3D) biofabrication approach that utilizes radiation forces generated by superimposing ultrasonic bulk acoustic waves (BAW) to preferentially organize cellular arrays within single and multi-layered hydrogel constructs. Using multiphysics modeling and experimental design, we have characterized the effects of process parameters including ultrasound frequency (0.71, 1, 1.5, 2 MHz), signal voltage amplitude (100, 200 mVpp), bioink viscosity (5, 70 cP), and actuation duration (10, 20 min) on the alignment characteristics, viability and metabolic activity of human adipose-derived stem cells (hASC) suspended in alginate. Results show that the spacing between adjacent cellular arrays decreased with increasing frequency (p < 0.001), while the width of the arrays decreased with increasing frequency and amplitude (p < 0.05), and upon lowering the bioink viscosity (p < 0.01) or increasing actuation duration (p < 0.01). Corresponding to the computational results wherein estimated acoustic radiation forces demonstrated a linear relationship with amplitude and a nonlinear relationship with frequency, the interaction of moderate frequencies at high amplitudes resulted in viscous perturbations, ultimately affecting the hASC viability (p < 0.01). For each combination of frequency and amplitude at the extremities of the tested range, the hASC metabolic activity did not change over 4 d, but the activity of the low frequency-high amplitude treatment was lower than that of the high frequency-low amplitude treatment at day 4 (p < 0.01). In addition to this process-structure characterization, we have also demonstrated the 3D bioprinting of a multi-layered medial knee meniscus construct featuring physiologically-relevant circumferential organization of viable hASC. This work contributes to the advancement of scalable biomimetic tissue manufacturing science and technology.

Short-Term Outcomes of Percutaneous Trephination with a Platelet Rich Plasma Intrameniscal Injection for the Repair of Degenerative Meniscal Lesions. A Prospective, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study.

Meniscal tears are the most common orthopaedic injuries, with chronic lesions comprising up to 56% of cases. In these situations, no benefit with surgical treatment is observed. Thus, the purpose of this study was to investigate the effectiveness and safety of percutaneous intrameniscal platelet rich plasma (PRP) application to complement repair of a chronic meniscal lesion. This single centre, prospective, randomized, double-blind, placebo-controlled study included 72 patients. All subjects underwent meniscal trephination with or without concomitant PRP injection. Meniscal non-union observed in magnetic resonance arthrography or arthroscopy were considered as failures. Patient related outcome measures (PROMs) were assessed. The failure rate was significantly higher in the control group than in the PRP augmented group (70% vs. 48%, P = 0.04). Kaplan-Meyer analysis for arthroscopy-free survival showed significant reduction in the number of performed arthroscopies in the PRP augmented group. A notably higher percentage of patients treated with PRP achieved minimal clinically significant difference in visual analogue scale (VAS) and Knee injury and Osteoarthritis Outcome Score (KOOS) symptom scores. Our trial indicates that percutaneous meniscal trephination augmented with PRP results in a significant improvement in the rate of chronic meniscal tear healing and this procedure decreases the necessity for arthroscopy in the future (8% vs. 28%, P = 0.032).

Are the Biological and Biomechanical Properties of Meniscal Scaffolds Reflected in Clinical Practice? A Systematic Review of the Literature.

The aim of this PRISMA review was to assess whether the CMI and Actifit scaffolds, when used in clinical practice, improve clinical outcomes and demonstrate the ideal biological and biomechanical properties of scaffolds: being chondroprotective, porous, resorbable, able to mature and promote regeneration of tissue. This was done by only including studies that assessed clinical outcome and used a scale to assess both integrity of the scaffold and its effects on articular cartilage via MRI. A search was performed on PubMed, EMBASE, Scopus and clinicaltrials.gov. 2457 articles were screened, from which eight studies were selected: four used Actifit, three used CMI and one compared the two. All studies reported significant improvement in at least one clinical outcome compared to baseline. Some studies suggested that the scaffolds appeared to show porosity, mature, resorb and/or have possible chondroprotective effects, as assessed by MRI. The evidence for clinical translation is limited by differences in study methodology and small sample sizes, but is promising in terms of improving clinical outcomes in the short to mid-term. Higher level evidence, with MRI and histological evaluation of the scaffold and articular cartilage, is now needed to further determine whether these scaffolds exhibit these useful properties.

Intraperitoneal injection of thalidomide alleviates early osteoarthritis development by suppressing vascular endothelial growth factor expression in mice.

Vascular endothelial growth factor (VEGF) is expressed in articular cartilage and increases in expression levels have been associated with the progression of osteoarthritis (OA). Thalidomide is a drug that has been reported to inhibit angiogenesis and reduce VEGF production by downregulating VEGF expression. The objective of the present study was to determine whether intraperitoneal administration of thalidomide may attenuate early OA development in mice. Male C57BL/6 mice (10­weeks­old) were randomly assigned into the destabilization of the medial meniscus (Dmm) with thalidomide treatment (Dmm+Th), Dmm and Sham groups equally. An OA model was induced surgically in Dmm+Th and Dmm groups, and mice of the Dmm+Th group were subsequently treated with an intraperitoneal injection of thalidomide (200 mg/kg/day). At 2 and 4 weeks following surgery, the pathological alterations in cartilage samples were assessed qualitatively by hematoxylin and eosin staining and Safranin O/Fast green staining, and quantitatively by the Osteoarthritis Research Society International scoring system. The mRNA expression levels of matrix metalloproteinase­13 (MMP­13) and VEGF were measured by reverse transcription­quantitative polymerase chain reaction. The protein expression levels of MMP­13 and VEGF were detected by immunofluorescence and immunohistochemistry, respectively. The production of VEGF in serum was evaluated via an ELISA assay. Pathological scores were significantly higher in the Dmm and the Dmm+Th groups than those in the Sham group; however, the Dmm+Th group exhibited markedly less severe pathological changes compared with the Dmm group. Compared with the Sham group, the mRNA and protein expression levels of VEGF and MMP­13 in the Dmm and the Dmm+Th groups were significantly increased. The Dmm+Th group exhibited significantly decreased expression levels of VEGF and MMP­13, as well as significantly decreased serum VEGF concentration compared with the Dmm group. Thus, the results of the present study demonstrated that intraperitoneal administration of thalidomide may alleviate the development of early OA by suppressing VEGF expression in mice and may have potential as a novel therapy for the treatment of OA.

Bushenhuoxue formula attenuates cartilage degeneration in an osteoarthritic mouse model through TGF-ß/MMP13 signaling.

BACKGROUND: Articular cartilage degeneration plays a key role in the pathogenesis of osteoarthritis (OA). Bushenhuoxue formula (BSHXF) has been widely used in the treatment of OA in clinics. However, the molecular mechanisms responsible for the chondroprotective effect of BSHXF remain to be elucidated. The purpose of this study was to explore the effects of BSHXF on OA mice model. METHODS: In this study, we investigated the effects of BSHXF on destabilization of the medial meniscus (DMM)-induced chondrocyte degradation in OA mice model. At 12 weeks post-surgery, the joints were harvested for tissue analyses, including histology, histomorphometry, TUNEL, OARSI scoring, micro-CT and immunohistochemistry for COL2, TGFBR2, pSMAD2 and MMP13. Additionally, we also evaluated the effects of BSHXF on Mmp13 mRNA and protein expression in chondrogenic ATDC5 cells through real-time PCR and Western blot respectively. Moreover, we investigated the chondroprotective effect of BSHXF on mice with Tgfbr2 conditional knockout (Tgfbr2 Col2ER mice) in chondrocyte, including the relative experiments mentioned above. We transfected Tgfbr2 siRNA in ATDC5 to further evaluate the changes of Mmp13 mRNA and protein expression followed by BSHXF treatment. RESULTS: Amelioration of cartilage degradation and chondrocyte apoptosis were observed in DMM-induced mice, with increases in cartilage area and thickness, proteoglycan matrix, COL2 content and decreases in OARSI score at 12 weeks post surgery. Moreover, the elevated TGFBR2 and pSMAD2, and reduced MMP13 positive cells were also revealed in DMM-induced mice treated with BSHXF. Besides, decreased Mmp13 mRNA and protein expression were observed inchondrogenic ATDC5 cells culture in serum containing BSHXF. As expected, Tgfbr2 Col2ER mice exhibited significant OA-like phenotype. Interestingly, obvious improvement in articular cartilage structure was still observed in Tgfbr2 Col2ER mice after BSHXF treatment via up-regulated pSMAD2 and down-regulated MMP13 expressional levels in articular cartilage. CONCLUSIONS: BSHXF could inhibit cartilage degradation through TGF-ß/MMP13 signaling, and be considered a good option for the treatment of OA.

Articular cartilage degradation is prevented by tanshinone IIA through inhibiting apoptosis and the expression of inflammatory cytokines.

The present study aimed to investigate the effect of tanshinone IIA on the degradation of articular cartilage in a rat model of osteoarthritis (OA). The OA rat model was established by anterior cruciate ligament transection (ACLT) and medial meniscus resection (MMx). The animals were treated for 28 days with 0.25­0.5 mg/kg doses of tanshinone IIA following ACLT + MMx. The knee joints of the rats in the ACLT + MMx group exhibited marked alterations in articular cartilage histopathology and higher Mankin scores, compared with those in the normal group. Tanshinone IIA treatment at a dose of 0.5 mg/kg significantly inhibited cartilage degradation and improved Mankin scores in the OA rat model (P<0.002). Tanshinone IIA treatment completely inhibited the ACLT + MMx­induced accumulation of inflammatory cells and disintegration of synovial lining in the rats. An increase in the dose of tanshinone IIA between 0.25 and 0.5 mg/kg reduced the proportion of apoptotic chrondrocytes from 41 to 2% on day 29. Treatment of the rats in the ACLT + MMx group with 0.5 mg/kg doses of tanshinone IIA markedly inhibited the expression level of matrix metalloproteinase and increased the expression of tissue inhibitor of metalloproteinase in the rat articular cartilage tissues. Tanshinone IIA treatment significantly reduced the levels of inflammatory cytokines, including interleukin­1ß, tumor necrosis factor­α and nitric oxide in rat serum samples. The protein expression levels of bone morphogenetic protein and transforming growth factor­ß were significantly increased by tanshinone IIA in the ACLT + MMx rats. Therefore, tanshinone IIA inhibited articular cartilage degradation through inhibition of apoptosis and expression levels of inflammatory cytokines, offering potential for use in the treatment of OA.

Effects of a viscosupplementation therapy on rabbit menisci in an anterior cruciate ligament transection model of osteoarthritis.

The aim of this study was to evaluate the morphological, microstructural, and mechanical effects of a viscosupplementation therapy on rabbit menisci at an early stage of osteoarthritis (OA). Anterior cruciate ligament transection (ACLT) was performed in twelve male New-Zealand White rabbits on the right knee joint. Six of these twelve rabbits received a mono intra-articular injection of high molecular weight hyaluronic acid (HA) two weeks after ACLT. Six additional healthy rabbits served as controls. Medial menisci were removed from all right knees (n=18) six weeks after ACLT and were graded macroscopically. Indentation-relaxation tests were performed in the anterior and posterior regions of the menisci. Collagen fiber organization and glycosaminoglycan (GAG) content were assessed by biphotonic confocal microscopy and histology, respectively. Viscosupplementation significantly (p=0.002) improved the surface integrity of the medial menisci compared to the operated non-treated group. Moreover, the injection seems to have an effect on the GAG distribution in the anterior region of the menisci. However, the viscoelastic properties of both operated groups were similar and significantly lower than those of the healthy group, which was explained by their modified collagen fiber organization. They displayed disruption of the tie fibers due to structural alterations of the superficial layers from which they emanate, leading to modifications in the deep zone. To conclude, the viscosupplementation therapy prevents macroscopic lesions of the menisci, but it fails to restore their collagen fiber organization and their viscoelastic properties. This finding supports the role of this treatment in improving the lubrication over the knee.

IL-10 ameliorates TNF-α induced meniscus degeneration in mature meniscal tissue in vitro.

BACKGROUND: Joint inflammation causes meniscus degeneration and can exacerbate post-traumatic meniscus injuries by extracellular matrix degradation, cellular de-differentiation and cell death. The aim of this study was to examine whether anti-inflammatory interleukin-10 exerts protective effects in an in vitro model of TNF-α-induced meniscus degeneration. METHODS: Meniscus tissue was harvested from the knees of adult cows. After 24 h of equilibrium explants were simultaneously treated with bovine TNF-α and IL-10. After an incubation time of 72 h cell death was measured histomorphometrically (nuclear blebbing, NB) and release of glycosaminoglycans (GAG, DMMB assay) and nitric oxide (NO, Griess-reagent) were analysed. Transcription levels (mRNA) of matrix degrading enzymes, collagen type X (COL10A1) and nitric oxide synthetase 2 (NOS2) were measured by quantitative real time PCR. TNF-α-dependent formation of the aggrecanase-specific aggrecan neoepitope NITEGE was visualised by immunostaining. Differences between groups were calculated using a one-way ANOVA with a Bonferroni post hoc test. RESULTS: Administration of IL-10 significantly prevented the TNF-α-related cell death (P .001), release of NO (P .003) and NOS2 expression (P .04). Release of GAG fragments (P .001), NITEGE formation and expression of MMP3 (P .007), -13 (P .02) and ADAMTS4 (P .001) were significantly reduced. The TNF-α-dependent increase in COL10A1 expression was also antagonized by IL-10 (P .02). CONCLUSION: IL-10 prevented crucial mechanisms of meniscal degeneration induced by a key cytokine of OA, TNF-α. Administration of IL-10 might improve the biological regeneration and provide a treatment approach in degenerative meniscus injuries and in conditions of post-traumatic sports injuries.

Fisetin inhibits IL-1ß-induced inflammatory response in human osteoarthritis chondrocytes through activating SIRT1 and attenuates the progression of osteoarthritis in mice.

Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage degradation and inflammation. Fisetin, a polyphenol extracted from fruits and vegetables, has been reported to have anti-inflammatory effects. Our study aimed to investigate the effect of fisetin on OA both in vitro and in vivo. In vitro, chondrocytes were pretreated with fisetin alone or fisetin combined with sirtinol (an inhibitor of SIRT1) for 2h before IL-1ß stimulation. Production of NO, PGE2, TNF-α and IL-6 were evaluated by the Griess reaction and ELISAs. The mRNA (COX-2, iNOS, MMP-3, MMP-13, ADAMTS-5, Sox-9, aggrecan and collagen-II) and protein expression (COX-2, iNOS, MMP-3, MMP-13, ADAMTS-5 and SIRT1) were measured by qRT-PCR and Western blot respectively. Immunofluorescence was used to assess the expression of collagen-II and SIRT1. SIRT1 activity was quantified with SIRT1 fluorometric assay kit. The in vivo effect of fisetin was evaluated by gavage in mice OA models induced by destabilization of the medial meniscus (DMM). We found that fisetin inhibited IL-1ß-induced expression of NO, PGE2, TNF-α, IL-6, COX-2, iNOS, MMP-3, MMP-13, ADAMTS-5. Besides, fisetin remarkably decreased IL-1ß-induced degradation of Sox-9, aggrecan and collagen-II. Furthermore, fisetin significantly inhibited IL-1ß-induced SIRT1 decrease and inactivation. However, the inhibitory effect of fisetin was obvious abolished by sirtinol, suggesting that fisetin exerts anti-inflammatory effects through activating SIRT1. In vivo, fisetin-treated mice exhibited less cartilage destruction and lower OARSI scores. Moreover, fisetin reduced subchondral bone plate thickness and alleviated synovitis. Taken together, these findings indicate that fisetin may be a potential agent in the treatment of OA.