Articular Cartilage Degradation Research Articles

Pathogenesis of Osteoarthritis: Risk Factors, Regulatory Pathways in Chondrocytes, and Experimental Models.

As the most common chronic degenerative joint disease, osteoarthritis (OA) is the leading cause of pain and physical disability, affecting millions of people worldwide. Mainly characterized by articular cartilage degradation, osteophyte formation, subchondral bone remodeling, and synovial inflammation, OA is a heterogeneous disease that impacts all component tissues of the articular joint organ. Pathological changes, and thus symptoms, vary from person to person, underscoring the critical need of personalized therapies. However, there has only been limited progress towards the prevention and treatment of OA, and there are no approved effective disease-modifying osteoarthritis drugs (DMOADs). Conventional treatments, including non-steroidal anti-inflammatory drugs (NSAIDs) and physical therapy, are still the major remedies to manage the symptoms until the need for total joint replacement. In this review, we provide an update of the known OA risk factors and relevant mechanisms of action. In addition, given that the lack of biologically relevant models to recapitulate human OA pathogenesis represents one of the major roadblocks in developing DMOADs, we discuss current in vivo and in vitro experimental OA models, with special emphasis on recent development and application potential of human cell-derived microphysiological tissue chip platforms.

Meniscal and ligament modifications in spontaneous and post-traumatic mouse models of osteoarthritis

BackgroundOsteoarthritis (OA) is a whole joint disease that affects all joint tissues, with changes in the articular cartilage (AC), subchondral bone and synovium. Pathologies in menisci and ligaments, however, are rarely analysed, although both are known to play vital roles in the mechanical stability of the joint. The aim of our study was to describe the pathological changes in menisci and ligament during disease development in murine spontaneous and post-traumatic surgically induced OA and to quantify tissue mineralisation in the joint space using micro-computed tomography (μCT) imaging during OA progression.MethodsKnees of Str/ort mice (spontaneous OA model; 26–40 weeks) and C57CBA F1 mice following destabilisation of medial meniscus (DMM) surgery (post-traumatic OA model; 8 weeks after DMM), were used to assess histological meniscal and ligament pathologies. Joint space mineralised tissue volume was quantified by μCT.ResultsMeniscal pathological changes in Str/ort mouse knees were associated with articular cartilage lesion severity. These meniscal changes included ossification, hyperplasia, cell hypertrophy, collagen type II deposition and Sox9 expression in the fibrous region near the attachment to the knee joint capsule. Anterior cruciate ligaments exhibited extracellular matrix changes and chondrogenesis particularly at the tibial attachment site, and ossification was seen in collateral ligaments. Similar changes were confirmed in the post-traumatic DMM model. μCT analysis showed increased joint space mineralised tissue volume with OA progression in both the post-traumatic and spontaneous OA models.ConclusionsModifications in meniscal and ligament mineralisation and chondrogenesis are seen with overt AC degeneration in murine OA. Although the aetiology and the consequences of such changes remain unknown, they will influence stability and load transmission of the joint and may therefore contribute to OA progression. In addition, these changes may have important roles in movement restriction and pain, which represent major human clinical symptoms of OA. Description of such soft tissue changes, in addition to AC degradation, should be an important aspect of future studies in mouse models in order to furnish a more complete understanding of OA pathogenesis.

STUDY ON THE DEVELOPMENT OF THERAPEUTIC PROTOCOL IN KNEE ARTHROSIS

Arthrosis is an irreversible slow degenerative disease, which involves progressive degradation of articular cartilage, associated with progressive remodeling and possibly with minimal or medium synovial inflammation. Regarding the increase in the number of patients with osteoarthritis, the work is based on the detection of new ways of early and systematic application of the procedures and means of recovery by which patients can restore their functional capacity faster, ensuring social and sometimes professional reintegration. The purpose of this work is to present a therapeutic protocol for osteoarthritis of the knee that includes information on patient recovery.

Baicalin Protects Human OA Chondrocytes Against IL-1β-Induced Apoptosis and ECM Degradation by Activating Autophagy via MiR-766-3p/AIFM1 Axis.

BackgroundOsteoarthritis (OA) is one of the most prevalent and degenerative diseases with complicated pathology including articular cartilage degradation, subchondral sclerosis and synovitis. Chondrocytes play a crucial role in maintaining cartilage integrity.MethodsPrimary chondrocytes were treated with 10 ng/mL IL-1β alone, or pre-treated with 20 μM baicalin for 5 h followed by co-treatment with 20 μM baicalin and 10 ng/mL IL-1β. CCK-8 assay was used to assess cell viability, and cell apoptosis was analyzed by both PI/FITC-Annexin V staining and quantitating apoptosis-related Bcl-2, Bax and cleaved-caspase-3 expression at both protein and mRNA level by Western blotting and qRT-PCR, respectively. Chondrocytes were transfected with miRNA-766-3p mimic and autophagy flux was examined by LC3, Beclin and p62 Western blotting and by Cyto-ID assay to quantify autophagic vacuoles.ResultsBaicalin treatment decreased the apoptosis rate and the expressions of pro-apoptotic proteins induced by IL-1β, up-regulated anti-apoptotic Bcl-2 expression, and inhibited the degradation of ECM. Baicalin increased autophagy through up-regulating the autophagy markers Beclin-1 expression and LC3 Ⅱ/LC3 Ⅰ ratio and promoting autophagic flux. Contrarily, autophagy inhibition partially alleviated the beneficial effects of baicalin on ECM synthesis and anti-apoptosis in the chondrocytes treated with L-1β. Furthermore, the differential expressional profiles of miR-766-3p and apoptosis-inducing factor mitochondria-associated 1 (AIFM1) were determined in IL-1β and IL-1β + baicalin-treated chondrocytes, and we confirmed AIFM1 was a target of miR-766-3p. MiR-766-3p overexpression suppressed apoptosis and facilitated autophagy and ECM synthesis in the chondrocytes through decreasing AIFM1. Contrarily, silencing of miR-766-3p inhibited chondrocyte autophagy and promoted apoptosis, and this effect could be reversed by AIFM1 silence.ConclusionBaicalin protects human OA chondrocytes against IL-1β-induced apoptosis and the degradation of ECM through activating autophagy via miR-766-3p/AIFM1 axis and serves as a potential therapeutic candidate for OA treatment.

MiR-1207-5p/CX3CR1 axis regulates the progression of osteoarthritis via the modulation of the activity of NF-κB pathway.

Osteoarthritis (OA) is a prevalent chronic diseases characterized by formation of osteophytes and degradation of articular cartilage. Previous evidence has identified the regulatory effects of microRNAs (miRNAs) in OA. The goal of this study is to clearly explore the biological function of miR-1207-5p in OA. MiR-1207-5p and C-X3-C motif chemokine receptor 1 (CX3CR1) expression in OA cartilages were revealed by accessing to Gene Expression Omnibus database. In vitro OA model was established by lipopolysaccharide (LPS) stimulation. Western blot and quantitative real-time polymerase chain reaction were conducted to detect the expression level of genes. Cell counting kit-8 (CCK-8) and flow cytometric experiments were performed to investigate the proliferation and apoptosis capacities of CHON-001 cells. Bioinformatics analysis was applied to predict the binding site of miR-1207-5p and CX3CR1, the connections of which were ascertained using luciferase reporter assay. MiR-1207-5p expression was decreased while CX3CR1 was increased in OA cartilages. Up-regulation of miR-1207-5p alleviated the LPS-induced damage in the view of cell proliferation, apoptosis and extracellular matrix (ECM) degradation. A target of miR-1207-5p CX3CR1, its down-regulation intensified the impacts of miR-1207-5p mimic, promoted proliferation and mitigated apoptosis. LPS exposure increased the protein expression of the phosphorylated IκBα and P65, and this phenomena was reversed due to miR-1207-5p up-regulation and CX3CR1 knockdown. The treatment of Betulinic acid (BA; an activator of nuclear factor-κB pathway) reversed the miR-1207-5p mimic-induced inhibitory effect on apoptosis in LPS-treated CHON-001. Our results highlight that miR-1207-5p can prevent CHON-001 from LPS-stimulated injury, providing a novel biomarker for OA progression and further advancing treatment of OA.

Dioscin exhibits anti-inflammatory effects in IL-1β-stimulated human osteoarthritis chondrocytes by activating LXRα

Objective Osteoarthritis (OA) is the most common joint disease that characterized by the degradation of articular cartilage. In this study, we aimed to investigate the anti-inflammatory activity of dioscin on IL-1β-stimulated human osteoarthritis chondrocytes. Methods The production of PGE2 and NO was measured in this study. MMP1 and MMP3 were detected by ELISA. The expression of LXRα and NF-κB were tested by western blot analysis. Results Treatment of dioscin suppressed the production of PGE2 and NO, as well as the expression of COX-2 and iNOS (their key regulatory genes). Dioscin also attenuated the secretion of MMP1 and MMP3. Furthermore, dioscin inhibited the phosphorylation of NF-κB p65 and IκBα induced by IL-1β. The degradation of IκBα induced by IL-1β was also suppressed by dioscin. Dioscin increased the expression of LXRα and pretreatment of GGPP, the LXRα inhibitor, blocked the anti-inflammatory effects of dioscin. Conclusions In conclusion, this study indicated that dioscin-mediated anti-inflammatory effect may be involved in the activation of LXRα.

A multifunctional anti-inflammatory drug that can specifically target activated macrophages, massively deplete intracellular H2O2, and produce large amounts CO for a highly efficient treatment of osteoarthritis

Specifically inhibiting the proliferation of activated macrophages and clearing the high levels of reactive oxygen species (ROS) secreted by macrophages is crucial for osteoarthritis (OA) treatment. Moreover, if the clearance of these high levels of ROS can be simultaneously used to induce oxidation-responsive release of anti-inflammatory drugs, the therapeutic effect of OA may be further improved. Here, a multifunctional anti-inflammatory drug (CPHs) based on a peptide dendrimer nanogel was constructed by physically encapsulating CORM-401 and wrapping its surface with folic acid (FA)-modified hyaluronic acid (HA). CPHs is capable of efficiently entering activated macrophages via FA- and HA-mediated specific targeting effects and then rapidly release large amounts of CO by massive consumption of H2O2. The generated CO effectively suppresses the secretion of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α by inhibiting cell proliferation; inducing the activation of heme oxygenase (HO-1), and downregulating the expression of p38 MAPK, NF-kB (p50/p65) and TLR-2. In vivo experiments further confirmed that CPHs can massively deplete ROS in OA joints and effectively suppress the degradation of articular cartilage and their extracellular matrix. More importantly, CPHs is non-toxic to normal macrophages, and the high levels of CO generated in the joints do not result in notable changes in the HbCO levels in blood. Together, these results show that CPHs is an effective and safe anti-inflammatory drug and has essential application prospects in OA treatment.

4260 Hollow, Degradable poly(N-Isopropylacrylamide) Derived Nanoparticles for the Delivery of Anti-Inflammatory Peptides for the Treatment and Prevention of Post-Traumatic Osteoarthritis

OBJECTIVES/GOALS: Knocking down the inflammatory response following joint trauma may halt the cytokine cascade and prevent the resulting cyclic degradation of articular cartilage. MK2 inhibiting (MK2i) peptides are an emerging and promising class of pharmaceutical to treat post-traumatic osteoarthritis (PTOA); however, these peptides are susceptible to proteolytic degradation in the extracellular space. Our objective is to encapsulate MK2i in thermoresponsive hollow nanoparticles (hNPs) to knockdown the inflammatory cytokine IL-6 to prevent the cyclic degradation of articular cartilage. METHODS/STUDY POPULATION: NP Synthesis: N-isopropyl acrylamide (NIPAm) cores was initiated by potassium persulfate (KPS) in aqueous solution with sodium dodecylsulfate (SDS) at 70°C under a nitrogen for 2 hours. Then exposed to oxygen for 45 min, followed by a nitrogen purge. NIPAm, 2-acrylamindo-2-methyl-1-propanesulfonic acid (AMPS), N,N’-bis(acryoyl)cystamine (BAC), and Acrylic Acid (AAc), in fluorescent batches rhodamine b isothiocyanate (RBITC), were polymerized around the core to form the shell. NPs were purified using tangential flow filtration. The NPs were dialyzed at 4°C for 14 days to remove the core and form hNPs. Loading & Release: hNPs and MK2i were incubated at 1 mg/ml at 4°C for 24 h. MK2i released into 1x PBS and analyzed on HPLC. IL-6 Expression: Bovine chondrocytes seeded at 10,000 cell/cm2 were stimulated with 20 ng/ml IL-1b daily and treated once with 100 µg/ml MK2i loaded-NP or 100 µg/ml free MK2i treatment on day 2. Analyzed on bovine IL-6 ELISA. In Vivo Intra Articular Injections: 75 µl of 2 mg/ml hNPsRHB or a PBS control was injected into the right knee of 4-month old Fischer 344 (Envigo) rats. Rats were imaged daily for 7 days then euthanized, legs dissected, and imaged. RESULTS/ANTICIPATED RESULTS: Core removal facilitated increased MK2i release from hNPs, Fig 1A, allowing up to 63% after 5 days in PBS. The hNPs generated here offer a continual sustained release of MK2i and hNPs are non-cytotoxic (data not shown) up to 12 mg/ml. MK2i loaded-NPs significantly knocked down IL-6 production after a single treatment after 2 days, Figure 1B, and continued knockdown for up to 4 days. hNPsRBITC was successfully injected into rat joint space and was retained for at least 7-days compared to pre-injection and PBS control, Fig 1 B-C. DISCUSSION/SIGNIFICANCE OF IMPACT: hNPs protect MK2i from ECM degradation and offer continual sustained release into chondrocytes. Core removal allows for MK2i release in vitro with further sustained release compared to previous non-degradable model. The single MK2i treatment lead to a significant IL-6 knockdown bovine chondrocytes for up to 4 days in hNPs. We were able to successfully inject and retain fluorescently labeled hNPs within rat knees for 7 days. Our translational therapeutic shows the promise of delivering a degradable, non-cytotoxic hNP into the joint space to knockdown the inflammatory response to halt the cyclic progression of articular cartilage degradation and progression of PTOA. CONFLICT OF INTEREST DESCRIPTION: The authors declare the following competing financial interest(s): Moerae Matrix, Inc. has a worldwide exclusive license to the CPP (MK2 inhibitor peptide). A. Panitch owns greater than 5% of Moerae Matrix, Inc.

The gene expression of caspase 3, matrix metalloproteinase-9, tissue inhibitor of metalloproteinases-1, and cathepsins S and K in patients with osteoarthritis requiring large joint replacement

Osteoarthritis (OA) is a chronic rheumatic disease that is characterized by pain and articular cartilage degradation. Pain in OA is a main clinical symptom that limits working capacity and is one of the indications for joint replacement. However, 10-40% of patients with OA also continue to experience painful sensations after surgery.Objective: to develop a method for searching for biomarkers to predict the dynamics of pain in the postoperative period and to determine the feasibility of arthroplasty on the basis of a retrospective analysis of relative blood gene expression prior to surgery.Patients and methods. The investigators tested the blood taken from 53 OA patients (mean age, 56.5±8.9 years) before knee arthroplasty and from 26 healthy donors (mean age, 55±8.3 years). Total RNA was isolated from blood and after reverse transcription into complementary DNA was used to measure the level of relative gene expression in real-time polymerase chain reaction.Results and discussion. A retrospective analysis of the expression of genes associated with central sensitization in 53 patients with OA before arthroplasty showed that the data on the expression of tumor necrosis factor-α, interleukin-1β, cyclooxygenase-2, and transforming growth factor β1 were uninformative due to their high blood expression in all the patients. The high gene expression of cathepsin S (in 17% of the patients) and cathepsin K (in 21%) and the low gene expression of tissue inhibitor of metalloproteinases 1 (TIMP-1) (in 31%) may indicate that postoperative pain can be persistent. In contrast, no post-arthroplasty pain can be expected in 43% OA patients with low caspase 3 expression and in 23% of those with low MMP-9 one.Conclusion. Analysis of pre-arthroplasty blood gene expression in patients with OA seems to be a promising approach to predicting the dynamics of pain after surgical treatment.

Clinical, Diagnostic and Prognostic Significance of Farnesyl Diphosphate Synthase Gene Polymorphism in Patients with Osteoarthritis: Decreased Bone Density and Overweight

A comprehensive study of 96 patients with osteoarthritis (OA) revealed that AA homozygotes prevail, the frequency of which is significantly higher than heterozygotes or homozygotes with the SS genotype (53.1 ± 5.1 %, 41.7 ± 5.0 % and 5, 2 ± 2.3 %, respectively; p <0.05). The frequency of homozygotes with the AA genotype significantly (almost 8–10 times; p <0.001) prevails over the frequency of SS homozygotes. The generalized WOMAC index in the patient groups was 48.8 ± 1.8 % and was large in AA homozygotes with a tendency to prevail in the severity structure of the manifestations of stiffness. Among homozygotes, AA have an increased body mass (BM) or obesity of 83.3 ± 4.8 %, among heterozygotes - 75.0 ± 6.8 %, among homozygotes of SS - 80.0 ± 19.1 % of people. The apelin content in the blood plasma of patients with OA depending on the BM and the variant polymorphism of the FDPS gene is characterized by the fact that with homozygosity SS, in the case of an increase in BM, the apelin content decreases, while with AA homozygosity it does not change significantly. The relationship between the FDPS gene polymorphism and the OA stage is characterized by the prevalence of more severe radiological signs of articular cartilage degradation among homozygous AA alleles.

Asiatic acid attenuates hypertrophic and fibrotic differentiation of articular chondrocytes via AMPK/PI3K/AKT signaling pathway

BackgroundOsteoarthritis (OA), the most common joint disorder, is characterized by a progressive degradation of articular cartilage. Increasing evidence suggests that OA is closely associated with cartilage pathologies including chondrocyte hypertrophy and fibrosis.MethodsIn this study, we showed that asiatic acid (AA) treatment reduced chondrocyte hypertrophy and fibrosis. First, the cytotoxicity of AA (0, 5, 10, and 20 μM) to chondrocytes was evaluated, and 5 μM was selected for subsequent experiments. Then, we detected the gene and protein level of chondrocyte hypertrophic markers including type X collagen (COL-X), matrix metalloproteinase-13 (MMP-13), alkaline phosphatase (ALP), and runt-related transcription factor 2 (Runx2); chondrocyte fibrosis markers including type I collagen (COL-Ι) and alpha-smooth muscle actin (α-SMA); and chondrogenic markers including SRY-related HMG box 9 (SOX9), type II collagen (COL-II), and aggrecan (ACAN). Further, we tested the mechanism of AA on inhibiting chondrocyte hypertrophy and fibrosis. Finally, we verified the results in an anterior cruciate ligament transection (ACLT) rat OA model.ResultsWe found that AA treatment inhibited the hypertrophic and fibrotic phenotype of chondrocytes, without affecting the chondrogenic phenotype. Moreover, we found that AA treatment activated AMP-activated protein kinase (AMPK) and inhibited phosphoinositide-3 kinase/protein kinase B (PI3K/AKT) signaling pathway in vitro. The results in an ACLT rat OA model also indicated that AA significantly attenuated chondrocyte hypertrophy and fibrosis.ConclusionAA treatment could reduce hypertrophic and fibrotic differentiation and maintain the chondrogenic phenotype of articular chondrocytes by targeting the AMPK/PI3K/AKT signaling pathway. Our study suggested that AA might be a prospective drug component that targets hypertrophic and fibrotic chondrocytes for OA treatment.

Characterization of the interleukin-17 effect on articular cartilage in a translational model: an explorative study

BackgroundOsteoarthritis (OA) is a progressive, chronic disease characterized by articular cartilage destruction. The pro-inflammatory cytokine IL-17 levels have been reported elevated in serum and synovial fluid of OA patients and correlated with increased cartilage defects and bone remodeling. The aim of this study was to characterize an IL-17-mediated articular cartilage degradation ex-vivo model and to investigate IL-17 effect on cartilage extracellular matrix protein turnover.MethodsFull-depth bovine femoral condyle articular cartilage explants were cultured in serum-free medium for three weeks in the absence, or presence of cytokines: IL-17A (100 ng/ml or 25 ng/ml), or 10 ng OSM combined with 20 ng/ml TNFα (O + T). RNA isolation and PCR analysis were performed on tissue lysates to confirm IL-17 receptor expression. GAG and ECM-turnover biomarker release into conditioned media was assessed with dimethyl methylene blue and ELISA assays, respectively. Gelatin zymography was used for matrix metalloproteinase (MMP) 2 and MMP9 activity assessment in conditioned media, and shotgun LC-MS/MS for identification and label-free quantification of proteins and protein fragments in conditioned media. Western blotting was used to validate MS results.ResultsIL-17RA mRNA was expressed in bovine full-depth articular cartilage and the treatment with IL-17A did not interfere with metabolic activity of the model. IL-17A induced cartilage breakdown; conditioned media GAG levels were 3.6-fold-elevated compared to untreated. IL-17A [100 ng/ml] induced ADAMTS-mediated aggrecan degradation fragment release (14-fold increase compared to untreated) and MMP-mediated type II collagen fragment release (6-fold-change compared to untreated). MS data analysis revealed 16 differentially expressed proteins in IL-17A conditioned media compared to untreated, and CHI3L1 upregulation in conditioned media in response to IL-17 was confirmed by Western blotting.ConclusionsWe showed that IL-17A has cartilage modulating potential. It induces collagen and aggrecan degradation indicating an upregulation of MMPs. This was confirmed by zymography and mass spectrometry data. We also showed that the expression of other cytokines is induced by IL-17A, which provide further insight to the pathways that are active in response to IL-17A. This exploratory study confirms that IL-17A may play a role in cartilage pathology and that the applied model may be a good tool to further investigate it.

New developments in chondrocyte ER stress andrelated diseases.

Cartilage comprises a single cell type, the chondrocyte, embedded in a highly complex extracellular matrix. Disruption to the cartilage growth plate leads to reduced bone growth and results in a clinically diverse group of conditions known as genetic skeletal diseases (GSDs). Similarly, long-term degradation of articular cartilage can lead to osteoarthritis (OA), a disease characterised by joint pain and stiffness. As professionally secreting cells, chondrocytes are particularly susceptible to endoplasmic reticulum (ER) stress and this has been identified as a core disease mechanism in a group of clinically and pathologically related GSDs. If unresolved, ER stress can lead to chondrocyte cell death. Recent interest has focused on ER stress as a druggable target for GSDs and this has led to the first clinical trial for a GSD by repurposing an antiepileptic drug. Interestingly, ER stress markers have also been associated with OA in multiple cell and animal models and there is increasing interest in it as a possible therapeutic target for treatment. In summary, chondrocyte ER stress has been identified as a core disease mechanism in GSDs and as a contributory factor in OA. Thus, chondrocyte ER stress is a unifying factor for both common and rare cartilage-related diseases and holds promise as a novel therapeutic target.

Specific inhibition of FAK signaling attenuates subchondral bone deterioration and articular cartilage degeneration during osteoarthritis pathogenesis.

Osteoarthritis (OA), a disease of the entire joint, is characterized by abnormal bone remodeling and coalescent degradation of articular cartilage. We have previously found that elevated levels of H-type vessels in subchondral bone correlate with OA and that focal adhesion kinase (FAK) is critical for H-type vessel formation in osteoporosis. However, the potential role of FAK in OA remains unexplored. Here, we demonstrate that the p-FAK level was dramatically elevated in subchondral bone following anterior cruciate ligament transection (ACLT) in rats. Specific inhibition of FAK signaling with Y15 in subchondral bone resulted in the suppression of subchondral bone deterioration and this effect was mediated by H-type vessel-induced ectopic bone formation. Further, articular cartilage degeneration was also alleviated after Y15 treatment. In vitro, the p-FAK level was significantly elevated in mesenchymal stem cells (MSCs) from vehicle-treated ACLT rats as compared to that in MSCs from sham controls and Y15-treated ACLT rats. Elevated p-FAK level in MSCs promoted vascular endothelial growth factor (VEGF) expression, as demonstrated from the high VEGF level in the blood, subchondral bone, and conditioned medium (CM) of MSCs from vehicle-treated ACLT rats. The CM of MSCs from vehicle-treated ACLT rats might promote the angiogenesis of endothelial cells and the catabolic response of chondrocytes through the FAK-growth factor receptor-bound protein 2-mitogen-activated protein kinase-mediated expression of VEGF. The effect of the CM from MSCs of Y15-treated ACLT rats or that treated with a VEGF-neutralizing antibody on vessel formation and the catabolic response was lowered. Thus, the specific inhibition of FAK signaling may be a promising avenue for the prevention or early treatment of OA.

New Therapeutic Strategies for Osteoarthritis by Targeting Sialic Acid Receptors.

Osteoarthritis (OA) is the most common degenerative joint disease characterized by articular cartilage degradation and joint degeneration. The articular cartilage is mainly formed by chondrocytes and a collagen-proteoglycan extracellular matrix that contains high levels of glycosylated proteins. It was reported that the shift from glycoproteins containing α-2,6-linked sialic acids to those that contain α-2,3 was associated with the onset of common types of arthritis. However, the pathophysiology of α-2,3-sialylation in cartilage has not been yet elucidated. We show that cartilage from osteoarthritic patients expresses high levels of the α-2,3-sialylated transmembrane mucin receptor, known as podoplanin (PDPN). Additionally, the Maackia amurensis seed lectin (MASL), that can be utilized to target PDPN, attenuates the inflammatory response mediated by NF-kB activation in primary chondrocytes and protects human cartilage breakdown ex vivo and in an animal model of arthritis. These findings reveal that specific lectins targeting α-2,3-sialylated receptors on chondrocytes might effectively inhibit cartilage breakdown. We also present a computational 3D molecular model for this interaction. These findings provide mechanistic information on how a specific lectin could be used as a novel therapy to treat degenerative joint diseases such as osteoarthritis.

Comparison of early-stage changes of osteoarthritis in cartilage and subchondral bone between two different rat models.

Osteoarthritis (OA) is a chronic degenerative joint disease and the major cause of joint pain and disability in the elderly. It is mainly characterized by articular cartilage degradation and subchondral bone remodeling. There are two main types of OA: natural occurring OA and secondary OA, mainly associated with aging and trauma, respectively. In this study, we established two OA models in rat knee joints to simulate the two types of OA, using the type II collagenase injection (CI) and anterior cruciate ligament transection (ACLT), respectively. After intervention for 2–6 weeks, cartilage and subchondral bone changes were detected in histological staining, immunochemistry, and micro-CT. Results showed that both models with typical pathology changes of OA were successfully induced, while the development and severity of OA process in the models were different. In ACLT rats, the cartilage damage was milder, lasted for a shorter time, and subchondral bone reconstruction occurred earlier, compared with the changes in CI rats. The cartilage damage was secondary to subchondral bone change in ACLT rats, while subchondral bone change was secondary to cartilage degeneration in CI rats. In conclusion, the interaction between cartilage and subchondral bone is different between the natural-occurring and secondary OA models. These two models not only suggest potential different mechanisms of the two types of OA, but also provide new directions for OA treatment and prevention.

Characterization of OA development between sexes in the rat medial meniscal transection model

Osteoarthritis (OA) is a chronic degenerative disease of the joints characterized by articular cartilage degradation. While clear sex differences exist in human OA development, most pre-clinical research has been conducted solely in male animals, limiting generalizability of findings to both sexes. The objective of this study was to determine if sex impacts the progression and severity of OA in the rat medial meniscal tear (MMT) preclinical model used to surgically induce OA. It was hypothesized that differences would be observed between males and females following MMT surgery. An MMT model was employed in male and female Lewis rats to induce OA. Animals were euthanized 3 weeks post-surgery and EPIC-μCT was used to quantitatively evaluate articular cartilage structure and composition, osteophyte volumes and subchondral bone structure. Analysis of medial 1/3 articular cartilage, showed increased cartilage thickness and proteoglycan loss in the MMT of both sexes, when compared to sham. Both male and female MMT groups also saw increased subchondral bone mineral density and larger osteophyte volumes. Significant interactions between sex and OA development were seen in normalized cartilage volume (larger in females), and normalized total osteophyte volumes (larger in males). This study demonstrates the viability of both sexes in the rat MMT preclinical OA model. Though clear differences exist, this model can be used to model OA development and evaluate sex as a factor in the efficacy of OA therapeutics.

Caffeine, a Risk Factor for Osteoarthritis and Longitudinal Bone Growth Inhibition.

Osteoarthritis (OA), the most common chronic rheumatic disease, is mainly characterized by a progressive degradation of the hyaline articular cartilage, which is essential for correct joint function, lubrication, and resistance. Articular cartilage disturbances lead to joint failure, pain, and disability. Hyaline cartilage is also present in the growth plate and plays a key role in longitudinal bone growth. Alterations of this cartilage by diverse pathologies have been related to longitudinal bone growth inhibition (LBGI), which leads to growth retardation. Diet can play a crucial role in processes involved in the OA and LBGI’s onset and evolution. Specifically, there is ample evidence pointing to the negative impacts of caffeine consumption on hyaline cartilage. However, its effects on these tissues have not been reviewed. Accordingly, in this review, we summarize all current knowledge in the PubMed database about caffeine catabolic effects on articular and growth plate cartilage. Specifically, we focus on the correlation between OA and LBGI with caffeine prenatal or direct exposure. Overall, there is ample evidence indicating that caffeine intake negatively affects the physiology of both articular and growth plate cartilage, increasing consumers predisposition to suffer OA and LBGI. As a result, caffeine consumption should be avoided for these pathologies.

Low-Intensity Pulsed Ultrasound Alleviates Osteoarthritis Condition Through Focal Adhesion Kinase-Mediated Chondrocyte Proliferation and Differentiation.

Osteoarthritis (OA) is a prevalent chronic multifactorial degenerative disease characterized by joint tissue inflammation, osteophyte formation, subchondral bone sclerosis, and articular cartilage degradation. Low-intensity pulsed ultrasound (LIPUS), a noninvasive ultrasound technique, is widely used to attenuate diseases. The aim of this study was to investigate whether LIPUS can ameliorate OA, and to explore its underlying molecular mechanism. The OA model was established in a C57BL/6 mouse by the anterior cruciate ligament transaction method. OA was assessed using arthritis scoring and weightbearing parameters. Chondrocyte proliferation was detected by a CCK-8 assay. The levels of interleukin-6 (IL-6), IL-8 and tumor necrosis factor-α (TNF-α) in synovial fluid of the mice were measured by enzyme-linked immunosorbent assay. In OA mice, the arthritis score and weightbearing abilities were dramatically improved by LIPUS treatment. LIPUS also remarkably declined the levels of inflammatory cytokines IL-6, IL-8, and TNF-α in synovial fluid of OA mice. Moreover, LIPUS promoted chondrocyte proliferation and differentiation by activating focal adhesion kinase (FAK) signaling. Inhibition of FAK significantly blocked LIPUS-mediated cell proliferation and differentiation in vitro, as well as inflammation condition in OA mice. LIPUS alleviates OA through promoting chondrocytes proliferation and differentiation by activating FAK, which could act as an intervening target for OA treatment.

Assessment of Articular Cartilage Disorders After Distal Radius Fracture Using Biochemical and Morphological Nonenhanced Magnetic Resonance Imaging

To assess radiocarpal articular cartilage after distal radius fracture, with and without intra-articular extension, compared with healthy controls using multiparametric, nonenhanced magnetic resonance imaging (MRI). In this prospective study, multiparametric MRI of the radiocarpal articular cartilage was performed in 26 participants (16 males and 10 females; mean age, 39.5 ± 14.7 years; range, 20-70 years) using 3T MRI. The cohort consisted of 14 patients with a distal radius fracture and 12 healthy volunteers. The radiocarpal articular cartilage was assessed using morphological (Double Echo Steady-State [DESS] and True Fast Imaging With Steady-State Precession [TrueFISP]) and biochemical (T2∗) MRI sequences without an intravenous contrast agent. The modified Outerbridge classification system for morphological analyses and region-of-interest biochemical analysis were applied to assess the degree of articular cartilage damage in each patient. Morphological articular cartilage assessment showed no difference between the DESS sequence and the reference standard, TrueFISP. In the morphological (DESS and TrueFISP) and biochemical (T2∗) assessments, patients with intra-articular fractures did not show articular cartilage damage different from those with extra-articular fractures. Greater articular cartilage degradation was observed after distal radius fracture compared with controls. Posttraumatic radiocarpal articular cartilage damage did not differ between fractures with intra-articular and extra-articular extension, but patients with fractures had notably higher articular cartilage degradation compared with healthy controls. Magnetic resonance imaging using advanced multiparametric sequences may facilitate accurate, noninvasive assessment of articular cartilage changes after distal radius fracture without the need for a contrast agent. Diagnostic IV.