Induced Cartilage Damage Research Articles

A Reproducible Cartilage Impact Model to Generate Post-Traumatic Osteoarthritis in the Rabbit.

Post-traumatic osteoarthritis (PTOA) is responsible for 12% of all osteoarthritis cases in the United States. PTOA can be initiated by a single traumatic event, such as a high-impact load acting on articular cartilage, or by joint instability, as occurs with anterior cruciate ligament rupture. There are no effective therapeutics to prevent PTOA currently. Developing a reliable animal model of PTOA is necessary to better understand the mechanisms by which cartilage damage proceeds and to investigate novel treatment strategies to alleviate or prevent the progression of PTOA. This protocol describes an open, drop tower-based rabbit femoral condyle impact model to induce cartilage damage. This model delivered peak loads of 579.1 ± 71.1 N, and peak stresses of 81.9 ± 10.1 MPa with a time-to-peak load of 2.4 ± 0.5 ms. Articular cartilage from impacted medial femoral condyles (MFCs) had higher rates of apoptotic cells (p = 0.0058) and possessed higher Osteoarthritis Research Society International (OARSI) scores of 3.38 ± 1.43 compared to the non-impacted contralateral MFCs (0.56 ± 0.42), and other cartilage surfaces of the impacted knee (p < 0.0001). No differences in OARSI scores were detected among the non-impacted articular surfaces (p > 0.05).

Exosomes from osteoarthritic fibroblast-like synoviocytes promote cartilage ferroptosis and damage via delivering microRNA-19b-3p to target SLC7A11 in osteoarthritis.

Our previous studies revealed that normal synovial exosomes promoted chondrogenesis, and microRNA (miR)-19b-3p independently related to osteoarthritis (OA) risk. Subsequently, this study intended to further explore the effect of OA fibroblast-like synoviocyte (OA-FLS) exosomal miR-19b-3p on OA ferroptosis and its potential mechanisms. Interleukin (IL)-1β-stimulated chondrocytes and medial meniscus surgery were used to construct the OA cellular model and the OA rat model, respectively. OA-FLS exosomes with/without miR-19b-3p modification were added to the IL-1β-stimulated chondrocytes and OA rat models, followed by direct miR-19b-3p mimic/inhibitor transfection with/without SLC7A11 overexpression plasmids. miR-19b-3p, ferroptosis-related markers (malondialdehyde (MDA), glutathione (GSH)/oxidized glutathione (GSSG), ferrous ion (Fe2+), glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11), and acyl-CoA synthetase long-chain family member 4 (ACSL4)), mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) levels were detected. Enhanced ferroptosis reflected by dysregulated ferroptosis-related markers, a reduced MMP, and an increased ROS was observed in cartilage tissues from OA patients vs. controls, IL-1β-stimulated chondrocytes vs. normal ones, and OA rat models vs. sham, so did miR-19b-3p. OA-FLS exosomes promoted MDA, Fe2+, ACSL4, and ROS but reduced cell viability, GSH/GSSG, GPX4, SLC7A11, and MMP in IL-1β-stimulated chondrocytes, whose effect was enhanced by miR-19b-3p mimics and attenuated by miR-19b-3p inhibitors. miR-19b-3p negatively regulated SLC7A11 and directly bound to SLC7A11 via luciferase reporter gene assay. Furthermore, SLC7A11 overexpression weakened miR-19b-3p mimics' effect on ferroptosis-related markers, MMP, or ROS in IL-1β-stimulated chondrocytes. OA-FLS exosomes also induced cartilage damage and ferroptosis in OA rats whose influence was tempered by miR-19b-3p inhibitors. OA-FLS exosomal miR-19b-3p enhances cartilage ferroptosis and damage by sponging SLC7A11 in OA, indicating a potential linkage among synovium, cartilage, and ferroptosis during the OA process.

N-TELOPEPTIDE DERIVED FROM TYPE II COLLAGEN UPREGULATES EXPRESSION OF BETA1 INTEGRIN AND MMPS IN CARTILAGE OF PATIENTS RECEIVING HIP OR KNEE ARTHROPLASTY

Previous studies showed that telo-peptides degraded from type II collagen, a type of collagen fragments, could induce cartilage damage in bovine stifle joints. We aim to investigate the role of integrins (ITGs) and matrix metalloproteinases (MMPs) in collagen fragment-induced human cartilage damage that is usually observed in osteoarthritis (OA). We hypothesized that N-telopeptide (NT) derived from type II collagen could up-regulate the expression of β1 integrin (ITGB1) and then MMPs that may lead to osteoarthritic cartilage damage.Human chondrocytes were isolated from femoral head or tibial plateau of patients receiving arthroplasty (N = 24). Primary chondrocyte cultures were either treated with 30 µM NT, or 30 µM scrambled NT (SN), or PBS, or left untreated for 24 hrs. Total proteins and RNAs were extracted for examination of expression of ITGB1 and MMPs-3&amp;13 with Western blotting and quantitative real-time PCR.Compared to untreated or PBS treated chondrocytes, NT-treated chondrocytes expressed significantly higher levels of ITGB1 and MMPs-3&amp;-13. However, SN also up-regulated expression of ITGB1 and MMP-13.ITGB1 and MMPs-3&amp;-13 might mediate the catalytic effect of NT, a type of collagen fragments, on human cartilage damage that is a hallmark of OA.

A human in vitro 3D neo-cartilage model to explore the response of OA risk genes to hyper-physiological mechanical stress

ObjectiveDue to the complexity and heterogeneity of osteoarthritis (OA) pathophysiology, studying the interaction between intrinsic molecular changes in chondrocytes after hyper-physiological mechanical stress (MS) and aberrant signalling of OA risk genes remains a challenge. In this study we set out to set up an in vitro 3D neo cartilage pellet model that enables us to explore the responses of OA risk genes to hyper-physiological MS. DesignHuman primary chondrocyte neo-cartilage pellets were exposed for 2 days to 2 ​× ​10 ​min of hyper-physiological dynamic MS attained by a 20% strain and a frequency of 5 ​Hz. In order to assess cartilage damage, sulphated glycosaminoglycan (sGAG) content in the neo-cartilage was quantified using Alcian blue staining and a dimethyl methylene blue (DMMB) assay, while cleavage of aggrecan was visualized by immunohistochemical staining of aggrecan neo-epitope NITEGE. In addition, changes in expression levels of catabolic, anabolic and hypertrophic genes, and of three OA risk genes; IL11, MGP and TGFA were determined. ResultsHyper-physiological MS induced cartilage damage, as reflected by decreased sGAG content. mRNA levels of aggrecanase ADAMTS5 were increased, while hypertrophic gene RUNX2 was downregulated. MS increased expression of pro-apoptotic marker NOXA. Furthermore, 20% MS led to increased expression of all three OA risk genes IL11, MGP and TGFA. ConclusionsWe established a human in vitro model in which hyper-physiological MS induced cartilage damage and catabolic signalling. Next, we demonstrated its usage to study OA risk genes and their response to the mechanical aspects of OA pathophysiology.

Selonsertib Alleviates the Progression of Rat Osteoarthritis: An in vitro and in vivo Study.

Osteoarthritis (OA) is a prevalent degenerative joint disease. Its development is highly associated with inflammatory response and apoptosis in chondrocytes. Selonsertib (Ser), the inhibitor of Apoptosis Signal-regulated kinase-1 (ASK1), has exhibited multiple therapeutic effects in several diseases. However, the exact role of Ser in OA remains unclear. Herein, we investigated the anti-arthritic effects as well as the potential mechanism of Ser on rat OA. Our results showed that Ser could markedly prevent the IL-1β-induced inflammatory reaction, cartilage degradation and cell apoptosis in rat chondrocytes. Meanwhile, the ASK1/P38/JNK and NFκB pathways were involved in the protective roles of Ser. Furthermore, intra-articular injection of Ser could significantly alleviate the surgery induced cartilage damage in rat OA model. In conclusion, our work provided insights into the therapeutic potential of Ser in OA, indicating that Ser might serve as a new avenue in OA treatment.

The Beneficial Effect of an Intra-articular Injection of Losartan on Microfracture-Mediated Cartilage Repair Is Dose Dependent

Background: A previous publication demonstrated that the oral intake of losartan promoted microfracture-mediated hyaline-like cartilage repair in osteochondral defects of a rabbit knee model. However, an intra-articular (IA) injection of losartan may have direct beneficial effects on cartilage repair and has not been studied. Purpose: To determine the dosage and beneficial effects of an IA injection of losartan on microfracture-mediated cartilage repair and normal cartilage homeostasis. Study Design: Controlled laboratory study. Methods: Rabbits were divided into 5 groups (n = 6 each): a microfracture group (MFX group) and 4 different losartan treatment groups that received varying doses of IA losartan (0.1, 1, 10, and 100 mg per knee). An osteochondral defect (5 mm) was created in the trochlear groove cartilage of 1 limb in each rabbit, and 5 microfracture perforations were made in the osteochondral defect. Both the injured and the contralateral knee joints were injected with IA losartan immediately after microfracture and at 2 and 4 weeks after surgery. Rabbits were sacrificed at 6 weeks after surgery for analysis including gross observation, micro–computed tomography, histology, and reverse transcription quantitative polymerase chain reaction. Results: Micro–computed tomography and gross observation demonstrated comparable subchondral bone healing and hyaline-like cartilage morphology in the 0.1-, 1-, and 10-mg losartan groups relative to the MFX group. Conversely, the 100-mg losartan group showed neither bony defect healing nor cartilage repair. Histology revealed higher O’Driscoll scores and hyaline-like cartilage regeneration in the 1-mg losartan group compared with the MFX group. In contrast, the 100-mg losartan group showed the lowest histology score and no cartilage repair. An IA injection of losartan at the doses of 0.1, 1, and 10 mg did not cause adverse effects on uninjured cartilage, while the 100-mg dose induced cartilage damage. Quantitative polymerase chain reaction results showed downregulation of the transforming growth factor β (TGF-β) signaling pathway after IA losartan injection. Conclusion: An IA injection of losartan at the dose of 1 mg was most effective for the enhancement of microfracture-mediated cartilage repair without adversely affecting uninjured cartilage. Conversely, a high dose (100 mg) IA injection of losartan inhibited cartilage repair in the osteochondral defect and was chondrotoxic to normal articular cartilage. Clinical Relevance: An IA injection of losartan at an optimal dosage represents a novel microfracture enhancement therapy and warrants a clinical trial for future clinical applications.

The beneficial effect of intra-articular injection of losartan on the microfracture mediated cartilage repair is dose dependent

Objectives:1. To determine the dosage and beneficial effects of intra-articular injection of losartan on microfracture-mediated cartilage repair and normal cartilage homeostasis.Methods:Rabbits were divided into 5 groups (n=6):a microfracture group (MFX) and 4 different losartan treatment cohorts received varying dosages of IA losartan (0.1,1,10 and 100 mg/knee). An osteochondral defect (5mm) was created in the trochlear groove cartilage and 5 microfracture perforations were performed in the osteochondral defect. Both injured and contralateral knee joints were injected with losartan IA at days 0,14 and 28 after surgery. Rabbits were sacrificed at 6 weeks after surgery for analysis including gross observation, micro computed tomography, histology analysis and reverse transcription quantitative PCR.Results:Micro computed tomography analysis and gross observation demonstrated comparable subchondral bone healing and hyaline-like appearing cartilage morphology in the 0.1, 1 and 10mg/knee losartan IA injection groups relative to the MFX group. Conversely, IA injection of losartan at 100mg/knee dosage showed neither bony defect healing nor cartilage repair. Histology revealed higher O’Driscoll scores and hyaline cartilage regeneration in the 1mg/knee cohort when compared to the MFX group. In contrast,100mg/knee losartan showed the lowest histology score and no cartilage repair. IA injection of losartan at the doses of 0.1,1 and 10mg/knee did not cause adverse effects on uninjured cartilage while 100mg/knee dose induced cartilage damage. Q-PCR results showed down-regulation of the TGFβ signaling pathway after losartan injection.Conclusions:Intra-articular injection of losartan at the dose 1mg/knee was most effective for enhancement of microfracture-mediated cartilage repair without adversely affecting uninjured cartilage. Conversely, high dose (100mg/knee) IA injection of losartan inhibited cartilage repair in osteochondral defect and was chondrotoxic to normal articular cartilage.

Anti-inflammatory Activity of Nanoemulgel formulated from Ageratum conyzoides (L.) L. and Oldenlandia corymbosa L. Extracts in Rats

The use of traditional medicine in the treatment of disease has increased globally due to its safety and efficacy. Ageratum conyzoides (L.) L. and Oldenlandia corymbosa L. have been used traditionally as a topical preparation for joint disease in Indonesia. Hence, the study was planned to scientifically study the existing empirical data. A nanoemulgel of combined Ageratum conyzoides (L.) L. (ACE) and Oldenlandia corymbosa L. Extract (OCE) as a new drug focused on plant-based natural products with a good physical characteristic that inhibits inflammatory process in managing osteoarthritis (OA) was formulated. Thirty animals were randomly designated to the 6 groups (n=5) as follows: (1) The normal control group (Normal), (2) negative control groups of Monosodium Iodoacetate (MIA), (3) combination ACE-OCE, (4) single ACE, (5) single OCE, (6) positive control group (Diclofenac). Rats received intraarticular MIA injection dose 3mg/0.05 mL on day zero excluding normal control group. All groups were administered topical preparations allotted to each dose group on day 29. Knee edema profile (every 7 days) and serum cytokine level (on day 57) was evaluated with Enzyme-Linked Immunoabsorbent Assay (ELISA). Till day 42, knee edema profile of all group treatment have been similar with normal control group (p>0.05). Serum cytokines level for some biomarkers, such as S100A8 Protein, Interleukin-1β, Inducible Nitric Oxide Synthase (iNOS), matrix metalloproteinase-13 (MMP-13), a disintegrin and metalloproteinase thrombospondin-like motifs-5 (ADAMTS-5), Collagen Type II and Aggrecan Core Protein were decreased. A significant difference compared with MIA group showed for all group treatment on measurement of S100A8 Protein, IL-1β, and iNOS as a biomarker of inflammatory process (#P<0.05). The developed nanoemulgel ACE-OCE either in single or in combination has good physical characteristic and promising effect of anti-inflammatory activity to enhance MIA induced cartilage damage as potential therapeutic agent for OA and encouraging to conduct further studies.

Clinical relevance of 3D gait analysis in patients with haemophilia.

Haemophilia is characterized by a congenital deficiency of clotting factor VIII or IX. One of the consequences of haemophilia is joint bleedings. Repetitive haemathroses induce cartilage damage and chronic synovitis leading to joint deterioration, and to definitive haemophilic arthropathy which is source of walking disability. Three-dimension gait analysis (3DGA) appears particularly relevant in the case of haemophilia because it allows an evaluation of several joints in weight-bearing situations. The purpose of this study was to review the interest and the contribution of 3DGA in the management of patients with haemophilia. The greatest interest of gait analysis would be to detect early walking changes with a non-invasive and well-tolerated examination, especially in paediatric population. In adulthood, this technic may be also useful to help detect walking worsening in patients known to have already arthropathy. However, it takes time to realize and needs expensive equipment, which limits its possibility of routine use. Although generalizations of these results remain difficult, especially to compare patients with haemophilia to normal population. Indeed, in the studies, patient groups are small and usually heterogeneous in terms of age and target joints. It certainly results of the rarity of the disease. So, it could be interesting to perform a study with a larger cohort in order to allow subgroup analysis, helping to define clearly the place of 3DGA in the strategy of haemophilia evaluation.

Metabolic dysregulation accelerates injury-induced joint degeneration, driven by local inflammation; an in vivo rat study.

Evidence is growing for the existence of an obesity-related phenotype of osteoarthritis in which low-grade inflammation and a disturbed metabolic profile play a role. The contribution of an obesity-induced metabolic dysbalance to the progression of the features of osteoarthritis upon mechanically induced cartilage damage was studied in a rat in vivo model. Forty Wistar rats were randomly allocated 1:1 to a standard diet or a high-fat diet. After 12 weeks, in 14 out of 20 rats in each group, cartilage was mechanically damaged in the right knee joint. The remaining six animals in each group served as controls. After a subsequent 12 weeks, serum was collected for metabolic state, subchondral bone changes assessed by μCT imaging, osteoarthritis severity determined by histology, and macrophage presence assessed by CD68 staining. The high-fat diet increased statistically all relevant metabolic parameters, resulting in a dysmetabolic state and subsequent synovial inflammation, whereas cartilage degeneration was hardly influenced. The high-fat condition in combination with mechanical cartilage damage resulted in a clear statistically significant progression of the osteoarthritic features, with increased synovitis and multiple large osteophytes. Both the synovium and osteophytes contained numerous CD68 positive cells. It is concluded that a metabolic dysbalance due to a high-fat diet increases joint inflammation without cartilage degeneration. The dysmetabolic state clearly accelerates progression of osteoarthritis upon surgically induced cartilage damage supported by inflammatory responses as demonstrated by histology and increased CD68 expressing cells localized on the synovial membrane and osteophytes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:881-890, 2018.

Cellular responses to T-2 toxin and/or deoxynivalenol that induce cartilage damage are not specific to chondrocytes

The relationship between T-2 toxin and deoxynivalenol (DON) and the risk of Kashin-Beck disease is still controversial since it is poorly known about their selectivity in cartilage damage. We aimed to compare the cytotoxicity of T-2 toxin and DON on cell lines representative of cell types encountered in vivo, including human chondrocytes (C28/I2), human hepatic epithelial cells (L-02) and human tubular epithelial cells (HK-2). In addition, we determined the distribution of T-2 toxin and DON in Sprague-Dawley (SD) rats after a single dose exposure. T-2 toxin or DON decreased proliferation in a time- and concentration-dependent manner and their combination showed a similar antagonistic effect in C28/I2, L-02 and HK-2 cells. Moreover, we observed cell cycle arrest and apoptosis, associated with increased oxidative stress and decline in mitochondrial membrane potential induced by T-2 toxin and/or DON. In vivo study showed that T-2 toxin and DON did not accumulate preferentially in the knee joint compared to liver and kidney after an acute exposure in SD rats. These results suggest that T-2 toxin and/or DON inhibit proliferation and induce apoptosis through a possible mechanism involving reactive oxygen species-mediated mitochondrial pathway that is not specific for chondrocytes in vitro or joint tissues in vivo.

Intra-articular implantation of collagen scaffold carriers is safe in both native and arthrofibrotic rabbit knee joints.

ObjectivesSustained intra-articular delivery of pharmacological agents is an attractive modality but requires use of a safe carrier that would not induce cartilage damage or fibrosis. Collagen scaffolds are widely available and could be used intra-articularly, but no investigation has looked at the safety of collagen scaffolds within synovial joints. The aim of this study was to determine the safety of collagen scaffold implantation in a validated in vivo animal model of knee arthrofibrosis.Materials and MethodsA total of 96 rabbits were randomly and equally assigned to four different groups: arthrotomy alone; arthrotomy and collagen scaffold placement; contracture surgery; and contracture surgery and collagen scaffold placement. Animals were killed in equal numbers at 72 hours, two weeks, eight weeks, and 24 weeks. Joint contracture was measured, and cartilage and synovial samples underwent histological analysis.ResultsAnimals that underwent arthrotomy had equivalent joint contractures regardless of scaffold implantation (-13.9° versus -10.9°, equivalence limit 15°). Animals that underwent surgery to induce contracture did not demonstrate equivalent joint contractures with (41.8°) or without (53.9°) collagen scaffold implantation. Chondral damage occurred in similar rates with (11 of 48) and without (nine of 48) scaffold implantation. No significant difference in synovitis was noted between groups. Absorption of the collagen scaffold occurred within eight weeks in all animalsConclusionOur data suggest that intra-articular implantation of a collagen sponge does not induce synovitis or cartilage damage. Implantation in a native joint does not seem to induce contracture. Implantation of the collagen sponge in a rabbit knee model of contracture may decrease the severity of the contracture.Cite this article: J. A. Walker, T. J. Ewald, E. Lewallen, A. Van Wijnen, A. D. Hanssen, B. F. Morrey, M. E. Morrey, M. P. Abdel, J. Sanchez-Sotelo. Intra-articular implantation of collagen scaffold carriers is safe in both native and arthrofibrotic rabbit knee joints. Bone Joint Res 2016;6:162–171. DOI: 10.1302/2046-3758.63.BJR-2016-0193.

Groove model of tibia-femoral osteoarthritis in the rat.

ABSTRACTSeveral experimental models of osteoarthritis in rats are used to study the pathophysiology of osteoarthritis. Many mechanically induced models have the limitation that permanent joint instability is induced by, for example, ligament transection or meniscal damage. This permanent instability will counteract the potential beneficial effects of therapy. The groove model of osteoarthritis uses a one‐time trigger, surgically induced cartilage damage on the femoral condyles, and has been validated for the canine tibia‐femoral compartment. The present study evaluates this model for the rat knee joint. The articular cartilage of the weight bearing surface of both femoral condyles and trochlea were damaged (grooved) without damaging the underlying subchondral bone. Severity of joint degeneration was histologically assessed, in addition to patella cartilage damage, and subchondral bone characteristics by means of (contrast‐enhanced) micro‐CT. Mild histological degeneration of the surgically untouched tibial plateau cartilage was observed in addition to damage of the femoral condyles, without clear synovial tissue inflammation. Contrast enhanced micro‐CT demonstrated proteoglycan loss of the surgically untouched patella cartilage. Besides, a more sclerotic structure of the subchondral bone was observed. The tibia‐femoral groove model in a rat results in mild knee joint degeneration, without permanent joint instability and joint inflammation. This makes the rat groove model a useful model to study the onset and progression of post‐traumatic non‐inflammatory osteoarthritis, creating a relatively sensitive model to study disease modifying osteoarthritic drugs. © 2016 The Authors. Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. J Orthop Res 35:496–505, 2017.

Why Synergism between Researches and Orthopaedics is still not Enough? Role of IL-1 Beta in Blood Induced Cartilage Damage

Why Synergism between Researches and Orthopaedics is still not Enough? Role of IL-1 Beta in Blood Induced Cartilage Damage

Joint shear load determination using sensate scaffolds that support cartilage regeneration in the knee

Joint shear load determination using sensate scaffolds that support cartilage regeneration in the knee

Induction of Canonical Wnt Signaling by Synovial Overexpression of Selected Wnts Leads to Protease Activity and Early Osteoarthritis-Like Cartilage Damage

Proteins from the Wnt signaling pathway are very important for joint development. Curiously, osteoarthritis (OA) is thought to be a recapitulation of developmental processes. Various members of the Wnt signaling pathway are overexpressed in the synovium during experimental OA. Here, we investigated the potency of specific Wnt proteins, when expressed in the synovium, to induce OA pathology. We overexpressed Wnt5a, Wnt8a, Wnt16, and WISP1 in the synovium using adenoviral vectors. We determined whether overexpression resulted in OA pathology by histology, and we measured whether Wnt signaling led to increased protease activity in the joint. Synovial overexpression of Wnt8a and Wnt16 led to canonical Wnt signaling in the cartilage, whereas overexpression of Wnt5a did not. Canonical Wnt signaling increased protease activity and induced cartilage damage shortly after overexpression. Specific blocking of the canonical Wnt signaling pathway with Dickkopf-1 reduced the Wnt-signaling-induced cartilage damage. By contrast, the noncanonical signaling Wnt5a did not cause cartilage lesions. Overexpression of WISP1, a downstream protein of canonical Wnt signaling, resulted in increased cartilage damage. In conclusion, our data show that canonical Wnts and WISP1, which we found overexpressed in the synovium during experimental OA, may conduce to OA pathology.

Establishment of a rat model of lumbar facet joint osteoarthritis using intraarticular injection of urinary plasminogen activator

Lumbar facet joint (LFJ) osteoarthritis (OA) is an important etiology of low back pain. Several animal models of LFJ OA have been established using intraarticular injection of various chemicals. This study aimed to establish a rat model of LFJ OA using urinary plasminogen activator (uPA). Sprague-Dawley rats were treated with intraarticular injection in the L5-L6 facet joints with uPA (OA group, n = 40) or normal saline (vehicle group, n = 40). Mechanical and thermal hyperalgesia in the ipsilateral hind paws were evaluated using von Frey hairs and a thermoalgesia instrument, respectively. Toluidine blue staining, hematoxylin-eosin staining, and immunohistochemical examination of the LFJ was performed. Treatment with uPA induced cartilage damage, synovitis, and proliferation of synovial cells in the fact joints. The OA group showed significantly higher hyperalgesia in the hind paws in comparison with the vehicle group and normal controls (P < 0.05). Expression of IL-1β, TNF-α, and iNOS in the LFJ cartilage in the OA group was significantly increased (P < 0.05). A rat model of LFJ OA was successfully established using intraarticular injection of uPA. This animal model is convenient and shows good resemblance to human OA pathology.

Palmitate Has Proapoptotic and Proinflammatory Effects on Articular Cartilage and Synergizes With Interleukin‐1

Obesity is a major risk factor for the development of osteoarthritis (OA) that is associated with a state of low-grade inflammation and increased circulating levels of adipokines and free fatty acids (FFAs). The aim of this study was to analyze the effects of saturated (palmitate) and monounsaturated (oleate) FFAs on articular chondrocytes, synoviocytes, and cartilage. Human articular chondrocytes and fibroblast-like synoviocytes obtained from young healthy donors and OA chondrocytes from patients undergoing total knee replacement surgery were treated with palmitate or oleate alone or in combination with interleukin-1β (IL-1β). Cell viability, caspase activation, and gene expression of proinflammatory factors, extracellular matrix (ECM) proteins, and proteases were studied. In addition, chondrocyte viability, IL-6 production, and matrix damage were assessed in bovine and human articular cartilage explants cultured with FFAs in the presence or absence of IL-1β. Palmitate, but not oleate, induced caspase activation and cell death in IL-1β-stimulated normal chondrocytes, and up-regulated the expression of IL-6 and cyclooxygenase 2 in chondrocytes and fibroblast-like synoviocytes through Toll-like receptor 4 (TLR-4) signaling. In cartilage explants, palmitate induced chondrocyte death, IL-6 release, and ECM degradation. Palmitate synergized with IL-1β in stimulating proapoptotic and proinflammatory cellular responses. Pharmacologic inhibition of caspases or TLR-4 signaling reduced palmitate and IL-1β induced cartilage damage. Palmitate acts as a proinflammatory and catabolic factor that, in synergy with IL-1β, induces chondrocyte apoptosis and articular cartilage breakdown. Collectively, our data suggest that elevated levels of saturated FFAs that are often found in patients who are obese may contribute to the pathogenesis of OA.

SAT0567 Wnt and WISP1 Expression in the Synovium Induces Production of Cartilage-Degrading Metalloproteinases by Synovial Cells

BackgroundPreviously, we found strong upregulation of various members of the Wnt signaling pathway in knee joints in two osteoarthritis (OA) models. Wnt signaling has been implicated in OA through activation...

Palmitate has proapoptotic and proinflammatory effects on articular cartilage and synergizes with interleukin-1.

Objective Obesity is a major risk factor for the development of osteoarthritis (OA) that is associated with a state of low-grade inflammation and increased circulating levels of adipokines and free fatty acids (FFAs). The aim of this study was to analyze the effects of saturated (palmitate) and monounsaturated (oleate) FFAs on articular chondrocytes, synoviocytes, and cartilage. Methods Human articular chondrocytes and fibroblast-like synoviocytes obtained from young healthy donors and OA chondrocytes from patients undergoing total knee replacement surgery were treated with palmitate or oleate alone or in combination with interleukin-1β (IL-1β). Cell viability, caspase activation, and gene expression of proinflammatory factors, extracellular matrix (ECM) proteins, and proteases were studied. In addition, chondrocyte viability, IL-6 production, and matrix damage were assessed in bovine and human articular cartilage explants cultured with FFAs in the presence or absence of IL-1β. Results Palmitate, but not oleate, induced caspase activation and cell death in IL-1β–stimulated normal chondrocytes, and up-regulated the expression of IL-6 and cyclooxygenase 2 in chondrocytes and fibroblast-like synoviocytes through Toll-like receptor 4 (TLR-4) signaling. In cartilage explants, palmitate induced chondrocyte death, IL-6 release, and ECM degradation. Palmitate synergized with IL-1β in stimulating proapoptotic and proinflammatory cellular responses. Pharmacologic inhibition of caspases or TLR-4 signaling reduced palmitate and IL-1β induced cartilage damage. Conclusion Palmitate acts as a proinflammatory and catabolic factor that, in synergy with IL-1β, induces chondrocyte apoptosis and articular cartilage breakdown. Collectively, our data suggest that elevated levels of saturated FFAs that are often found in patients who are obese may contribute to the pathogenesis of OA.