Cartilage Proteoglycan Research Articles

The senolytic drug fisetin mitigates age‐related bone density loss in the progeroid mouse model Zmpste24−/−

Senescence is a cell state defined by loss of proliferative capacity, increased metabolic activity, and importantly, resistance to apoptosis. Senescent cells can release pro‐inflammatory cytokines/chemokines, proteases, and other factors, otherwise known as the senescence‐associated secretory phenotype (SASP). The SASP can adversely affect not only neighboring cells, but also likely contributes to driving systemic aging. Senolytic compounds such as dasatinib (D), quercetin (Q), and fisetin (FIS) were recently found to target anti‐apoptotic pathways known to be upregulated in senescent cells. Several reports have found significant improvement in healthspan indices including decreased frailty, neurologic dysfunction, and bone loss in vivo following intermittent treatment with senolytic agents. Our lab routinely uses the accelerated aging model Zmpste24−/− (Z24−/−) mice to investigate age‐related pathologies as they have a maximum lifespan of ~6 months. For the first time here, we examined the effects of another significantly safer senolytic compound, the flavonoid FIS, on spontaneous bone density loss associated with age using the Z24−/− model.Z24−/− mice begin to exhibit significant musculoskeletal decline associated with increased senescent cell burden as early as 2 months including weight loss and reduced cartilage proteoglycan and bone levels in skeletal preparations (Fig. 1). Importantly, we previously found that senolytic drug treatment restored cartilage in Z24−/− mice in a dose dependent manner. These data demonstrated for the first time the therapeutic potential for senotherapuetic drugs for the treatment of age‐associated knee OA. Fisetin, a newly characterized senolytic drug was recently demonstrated to significantly extend lifespan and healthspan, including musculoskeletal function, in progeroid mice. We thus next evaluated if FIS, a less toxic alternative to dasatinib that targets several senescence associated pathways, might better prevent bone loss in rapidly aging Z24−/− mice. Indeed, we found that weekly dosing of FIS for weeks starting at 3 months of age could significantly attenuate bone density loss in Z24−/− mice as evidenced by micro‐CT analysis (Fig. 2). Future studies will examine if more chronic dosing of FIS at younger ages.Aging is associated with sever musculoskeletal decline including OA and osteoporosis for which there are few treatment options none of which that target shared fundamental mechanistic drivers. We previously found that the senolytic drug cocktail DQ could prevent articular cartilage degeneration. The main objective of these studies was to investigate the efficacy of senolytic drugs, principally FIS, to attenuate age‐associated loss of bone density in progeroid Z24−/− mice. In agreement to previous reports, we found senolytic drug treatment could mitigate bone density loss in aged/progeroid mice. However, we report this for the first time using FIS, a much safer alternative to chemotherapeutic agents with similar efficacy. FIS may thus be a more clinically viable option for senotherapeutic treatment.Support or Funding InformationNIA (5P01AG043376‐05).Musculoskeletal pathology in Z24−/− mice is improved with DQ treatmentFigure 1Effects of senolytic drugs on trabecular bone in Z24−/− miceFigure 2

The relationship between synovial inflammation, structural pathology, and pain in post-traumatic osteoarthritis: differential effect of stem cell and hyaluronan treatment

BackgroundSynovitis is implicated in the severity and progression of pain and structural pathology of osteoarthritis (OA). Increases in inflammatory or immune cell subpopulations including macrophages and lymphocytes have been reported in OA synovium, but how the particular subpopulations influence symptomatic or structural OA disease progression is unclear. Two therapies, hyaluronan (HA) and mesenchymal stem cells (MSCs), have demonstrated efficacy in some clinical settings: HA acting as device to improve joint function and provide pain relief, while MSCs may have immunomodulatory and disease-modifying effects. We used these agents to investigate whether changes in pain sensitization or structural damage were linked to modulation of the synovial inflammatory response in post-traumatic OA.MethodsSkeletally mature C57BL6 male mice underwent medial-meniscal destabilisation (DMM) surgery followed by intra-articular injection of saline, a hyaluronan hexadecylamide derivative (Hymovis), bone marrow-derived stem cells (MSCs), or MSC + Hymovis. We quantified the progression of OA-related cartilage, subchondral bone and synovial histopathology, and associated pain sensitization (tactile allodynia). Synovial lymphocytes, monocyte/macrophages and their subpopulations were quantified by fluorescent-activated cell sorting (FACS), and the expression of key inflammatory mediators and catabolic enzyme genes quantified by real-time polymerase chain reaction (PCR).ResultsMSC but not Hymovis significantly reduced late-stage (12-week post-DMM) cartilage proteoglycan loss and structural damage. Allodynia was initially reduced by both treatments but significantly better at 8 and 12 weeks by Hymovis. Chondroprotection by MSCs was not associated with specific changes in synovial inflammatory cell populations but rather regulation of post-injury synovial Adamts4, Adamts5, Mmp3, and Mmp9 expression. Reduced acute post-injury allodynia with all treatments coincided with decreased synovial macrophage and T cell numbers, while longer-term effect on pain sensitization with Hymovis was associated with increased M2c macrophages.ConclusionsThis therapeutic study in mice demonstrated a poor correlation between cartilage, bone or synovium (histo)pathology, and pain sensitization. Changes in the specific synovial inflammatory cell subpopulations may be associated with chronic OA pain sensitization, and a novel target for symptomatic treatment.

ADAMTS-5: A difficult teenager turning 20.

A Disintegrin And Metalloproteinase with ThromboSpondin motif (ADAMTS)-5 was identified in 1999 as one of the enzymes responsible for cleaving aggrecan, the major proteoglycan in articular cartilage. Studies in vitro, ex vivo and in vivo have validated ADAMTS-5 as a target in osteoarthritis (OA), a disease characterized by extensive degradation of aggrecan. For this reason, it attracted the interest of many research groups aiming to develop a therapeutic treatment for OA patients. However, ADAMTS-5 proteoglycanase activity is not only involved in the dysregulated aggrecan proteolysis, which occurs in OA, but also in the physiological turnover of other related proteoglycans. In particular, versican, a major ADAMTS-5 substrate, plays an important structural role in heart and blood vessels and its proteolytic processing by ADAMTS-5 must be tightly regulated. On the occasion of the 20th anniversary of the discovery of ADAMTS-5, this review looks at the evidence for its detrimental role in OA, as well as its physiological turnover of cardiovascular proteoglycans. Moreover, the other potential functions of this enzyme are highlighted. Finally, challenges and emerging trends in ADAMTS-5 research are discussed.

Age-related changes in the cartilage of the temporomandibular joint.

Osteoarthritis (OA) of the knee is closely associated with aging; however, little is known about the age-related degeneration in the mandibular condylar cartilage (MCC) of the TMJ. Our objective was to examine whether a correlation exists between aging and degeneration of the MCC of the TMJ. Thirty-two male C57BL/6J wild-type mice were aged to 2, 12, 18, and 25months old. The mice were euthanized by CO2 inhalation and were dissected and examined by micro-CT and histology. Sagittal sections of the condyles were stained for tartrate-resistant alkaline phosphatase, alkaline phosphatase, safranin O, picrosirius red, and toluidine blue. In addition, immunostaining for BMP2, BMP4, BMP7, PRG4, and MMP13 was performed. Bone volume fraction and tissue density significantly increased with the age of the animals. There was a significant increase in the Osteoarthritis Research Society International histopathological score and mineralization of the noncalcified cartilage in the aged animals. There was a decrease in cartilage thickness, proteoglycan distribution, and cellularity in the aged animals. Additionally, we noted increased picrosirius red staining with the increase in the age of the animals. Our protein expression showed increased BMP2, BMP4, BMP7, and MMP13, whereas there was a decrease in PRG4 expression in the aged animals. As the animal ages, there is decreased proteoglycan secretion, decreased cellularity, decreased cartilage thickness, increased fibrillation, and increased proteolytic activity. A better understanding of the basic mechanisms underlying the degeneration of the MCC in the older animals could provide novel ways to slow the development of OA.

Link N suppresses interleukin-1β-induced biological effects on human osteoarthritic cartilage.

Osteoarthritis (OA) is a disease of diarthrodial joints associated with extracellular matrix proteolytic degradation under inflammatory conditions, pain and disability. Currently, there is no therapy to prevent, reverse or modulate the disease course. The present study aimed at evaluating the regenerative potential of Link N (LN) in human OA cartilage in an inflammatory milieu and determining if LN could affect pain-related behaviour in a knee OA mouse injury model. Osteo-chondro OA explants and OA chondrocytes were treated with LN in the presence of interleukin-1β (IL-1β) to simulate an osteoarthritic environment. Quantitative von Frey polymerase chain reaction and Western blotting were performed to determine the effect of LN on matrix protein synthesis, catabolic enzymes, cytokines and nerve growth factor expression. Partial medial meniscectomy (PMM) was performed on the knee of C57BL/6 mice and, 12 weeks post-surgery, mice were given a 5 µg intra-articular injection of LN or phosphate-buffered saline. A von Frey test was conducted over 24 h to measure the mechanical allodynia in the hind paw. LN modulated proteoglycan and collagen synthesis in human OA cartilage through inhibition of IL-1β-induced biological effects. LN also supressed IL-1β-induced upregulation of cartilage-degrading enzymes and inflammatory molecules in OA chondrocytes. Upon investigation of the canonical signalling pathways IL-1β and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), LN resulted to significantly inhibit NF-κB activation in a dose-dependent manner. In addition, LN suppressed mechanical allodynia in an OA PMM mouse model. Results supported the concept that LN administration could provide therapeutic potential in OA.

Conditional deletion of Adrb2 in mesenchymal stem cells attenuates osteoarthritis-like defects in temporomandibular joint.

β2-adrenergic signal transduction in mesenchymal stem cells (MSCs) induces subchondral bone loss in osteoarthritis (OA) of temporomandibular joints (TMJs). However, whether conditional deletion of β2-adrenergic receptor (Adrb2) in nestin+ MSCs can alleviate TMJ-OA development remains unknown. In this study, nestin-Cre mice were crossed with Adrb2 flox mice to generate mice lacking Adrb2 expression specifically in the nestin+ MSCs (Adrb2-/-), and TMJ-OA development in such mice was investigated. Adrb2 flox mice (Adrb2+/+) and Adrb2-/- mice were subjected to unilateral anterior crossbite (UAC), while mice in the control group were subjected to sham operation. Adrb2+/+ and Adrb2-/- mice in the control group showed no distinguishable phenotypic changes in body weight and length, mandibular condylar size, and other histomorphological parameters of the condylar subchondral bone. A significant increase in subchondral bone loss and cartilage degradation was observed in Adrb2+/+ UAC mice; the former was characterized by decreased bone mineral density, bone volume fraction, and trabecular plate thickness, and increased trabecular separation, osteoclast number and osteoclast surface, and pro-osteoclastic factor expression; the latter was characterized by decreased cartilage thickness, chondrocyte density, proteoglycan area, and collagen II and aggrecan expression, but increased matrix metalloproteinase and alkaline phosphatase expression and percentage area of calcified cartilage. Adrb2 deletion in nestin+ MSCs largely attenuated UAC-induced increase in condylar subchondral bone loss, cartilage degradation, and aberrant calcification at the osteochondral interface. Thus, Adrb2-expressing MSCs in the condylar subchondral bone play an important role in TMJ-OA progression and may serve as novel therapeutic targets for TMJ-OA.

Differential expression of Sox9 protein and proteoglycans in the epiphyseal cartilage of bromocriptine-treated pregnant and lactating rats.

Several investigations have shown that pregnancy and lactation are able to induce elongation of long bone by altering epiphyseal cartilage function in a prolactin-dependent manner. Since the transcription factor Sox9 is of utmost importance for chondrocyte proliferation and differentiation and since bromocriptine, a dopaminergic D2 agonist widely used to suppress milk production, is known to disrupt the production and release of prolactin, we herein aimed to investigate whether pregnancy and lactation as well as bromocriptine could alter the expression of Sox9. Our immunohistochemical analysis showed that the Sox9 expression levels were markedly upregulated in the tibial proliferative zone of day 21 pregnant rats. In day 8 (early) and day 14 (mid) lactating rats, the Sox9 expression was enhanced only in the proliferative zone, but not in the resting and hypertrophic zones. There was no change in Sox9 expression in day 21 (late) lactating rats. Postweaning rats manifested a decreased Sox9 expression in the hypertrophic zone. Bromocriptine had no effect on Sox9 expression in the proliferative zone of day 21 pregnant rats; however, it completely prevented the Sox9 upregulation in those of early and mid-lactating rats. A differential response was observed in the proliferative and hypertrophic zones of late lactating rats, in which bromocriptine enhanced Sox9 expression. Further investigation of cartilaginous matrix revealed no change in proteoglycans accumulation in lactating rats. In conclusion, the upregulated Sox9 expression predominantly occurred in the proliferative zone during late pregnancy and early and mid-lactation, while the bromocriptine effects depended on the periods and epiphyseal zones.

A 24-Month Follow-Up Study of the Effect of Intra-Articular Injection of Autologous Microfragmented Fat Tissue on Proteoglycan Synthesis in Patients with Knee Osteoarthritis.

Osteoarthritis (OA) is a widely prevalent disease worldwide, and with an increasingly ageing society, it has become a challenge for the field of regenerative medicine. OA is a disease process involving multiple joint tissues, including those not visible on radiography, and is a complex disease process with multiple phenotypes that require evaluation by a multimodality imaging assessment. The purpose of this study was to evaluate the effect of micro-fragmented fat tissue intra-articular injection 24 months after application in two ways: Indirectly using functional magnetic resonance imaging (MRI) assessment analyzing the glycosaminoglycans (GAG) content in cartilage by means of delayed gadolinium (Gd)-enhanced magnetic resonance imaging of cartilage (dGEMRIC), as well as clinical outcome on observed level of GAG using standard orthopedic physical examination including VAS assessment. In our previous study assessing comprehensive results after 12 months, the dGEMRIC results have drawn attention. The present study explores the long-term effect of intra-articular injection of autologous microfragmented adipose tissue to host chondrocytes and cartilage proteoglycans in patients with knee OA. A prospective, non-randomized, interventional, single-center, open-label clinical trial was conducted from January 2016 to April 2018. A total of 17 patients were enrolled in the study, and 32 knees were assessed in a 12-month follow-up, but only 10 patients of them with 18 knees are included in a 24-month follow-up. The rest of the seven patients dropped out of the study 12 months after follow-up: three patients underwent knee arthroplasty, and the remaining four did not fulfil the basic criteria of 24 months involvement in the study. Surgical intervention (lipoaspiration), followed by tissue processing and intra-articular injection of the final microfragmented adipose tissue product into the affected knee(s), was performed in all patients. Patients were assessed for a visual analog scale (VAS), dGEMRIC at the baseline, three, six, 12 and 24 months after the treatment. A magnetic resonance sequence in dGEMRIC due to infiltration of the anionic, negatively-charged contrast gadopentetate dimeglumine (Gd-DTPA2) into the cartilage indicated that the contents of cartilage glycosaminoglycans significantly increased in specific areas of the treated knee joint. Our results suggest that this method of single intra-articular injection of autologous microfragmented adipose tissue improves GAG content on a significant scale, with over half of the measurements suggesting relevant improvement 24 months after intra-articular injection opposed to the expected GAG decrease over the natural course of the disease.

Photobiostimulation activity of different low-level laser dosage on masticatory muscles and temporomandibular joint in an induced arthritis rat model.

This study aimed to investigate the anti-inflammatory effects of different dosage of low-level laser therapy (LLLT) in an experimental model of temporomandibular joint (TMJ) arthritis. One hundred male Wistar rats were used and divided into the following groups: CG, control group; AG, animals group with left TMJ arthritis induced by intra-articular injection of Complete Freund's adjuvant - CFA; LG5, LG10 and LG20 - animals with arthritis and treated with LLLT at doses 5, 10, and 20J/cm2, respectively. Morphological analysis was performed by TMJ histological sections stained with hematoxylin-eosin (HE), picrosirius (PSR), and toluidine blue (TB), as well as histomorphometric evaluation of cartilage, articular disc, and masticatory muscles. The amount of feed consumed within 3weeks was evaluated, and biochemical analysis of TMJ tissues included measurement of sulfated glycosaminoglycans (GAGs), matrix metalloproteinases (MMPs) 2 and 9 zymography, and ELISA for cytokines IL-6, TNF-α, and IL-1β. Only the 20J/cm2 dose promoted higher feed intake compared to AG. On the other hand, all LLLT doses promoted better organization of articular disc collagen fibers, greater number of proteoglycans in articular cartilage, increased area and diameter of left lateral pterygoid fibers, reduced latent and active MMP 9 and 2 activity, and lower IL-1β concentration compared to AG. Considering the study limitations, it was observed that LLLT treatments were effective in protecting and tissue cleansing joint structures, accelerating tissue repair, especially at lower doses.

Osteocyte dysfunction promotes osteoarthritis through MMP13-dependent suppression of subchondral bone homeostasis

Osteoarthritis (OA), long considered a primary disorder of articular cartilage, is commonly associated with subchondral bone sclerosis. However, the cellular mechanisms responsible for changes to subchondral bone in OA, and the extent to which these changes are drivers of or a secondary reaction to cartilage degeneration, remain unclear. In knee joints from human patients with end-stage OA, we found evidence of profound defects in osteocyte function. Suppression of osteocyte perilacunar/canalicular remodeling (PLR) was most severe in the medial compartment of OA subchondral bone, with lower protease expression, diminished canalicular networks, and disorganized and hypermineralized extracellular matrix. As a step toward evaluating the causality of PLR suppression in OA, we ablated the PLR enzyme MMP13 in osteocytes while leaving chondrocytic MMP13 intact, using Cre recombinase driven by the 9.6-kb DMP1 promoter. Not only did osteocytic MMP13 deficiency suppress PLR in cortical and subchondral bone, but it also compromised cartilage. Even in the absence of injury, osteocytic MMP13 deficiency was sufficient to reduce cartilage proteoglycan content, change chondrocyte production of collagen II, aggrecan, and MMP13, and increase the incidence of cartilage lesions, consistent with early OA. Thus, in humans and mice, defects in PLR coincide with cartilage defects. Osteocyte-derived MMP13 emerges as a critical regulator of cartilage homeostasis, likely via its effects on PLR. Together, these findings implicate osteocytes in bone-cartilage crosstalk in the joint and suggest a causal role for suppressed perilacunar/canalicular remodeling in osteoarthritis.

Synchrotron MicroCT Reveals the Potential of the Dual Contrast Technique for Quantitative Assessment of Human Articular Cartilage Composition.

ABSTRACTDual contrast micro computed tomography (CT) shows potential for detecting articular cartilage degeneration. However, the performance of conventional CT systems is limited by beam hardening, low image resolution (full‐body CT), and long acquisition times (conventional microCT). Therefore, to reveal the full potential of the dual contrast technique for imaging cartilage composition we employ the technique using synchrotron microCT. We hypothesize that the above‐mentioned limitations are overcome with synchrotron microCT utilizing monochromatic X‐ray beam and fast image acquisition. Human osteochondral samples (n = 41, four cadavers) were immersed in a contrast agent solution containing two agents (cationic CA4+ and non‐ionic gadoteridol) and imaged with synchrotron microCT at an early diffusion time point (2 h) and at diffusion equilibrium (72 h) using two monochromatic X‐ray energies (32 and 34 keV). The dual contrast technique enabled simultaneous determination of CA4+ (i.e., proteoglycan content) and gadoteridol (i.e., water content) partitions within cartilage. Cartilage proteoglycan content and biomechanical properties correlated significantly (0.327 < r < 0.736, p < 0.05) with CA4+ partition in superficial and middle zones at both diffusion time points. Normalization of the CA4+ partition with gadoteridol partition within the cartilage significantly (p < 0.05) improved the detection sensitivity for human osteoarthritic cartilage proteoglycan content, biomechanical properties, and overall condition (Mankin, Osteoarthritis Research Society International, and International Cartilage Repair Society grading systems). The dual energy technique combined with the dual contrast agent enables assessment of human articular cartilage proteoglycan content and biomechanical properties based on CA4+ partition determined using synchrotron microCT. Additionally, the dual contrast technique is not limited by the beam hardening artifact of conventional CT systems. © 2019 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals, Inc. on behalf of Orthopaedic Research Society. J Orthop Res 38:563–573, 2020

T1ρ, T2 mapping, and EPIC-µCT Imaging in a Canine Model of Knee Osteochondral Injury.

The dog is the most commonly used large animal model for the study of osteoarthritis. Optimizing methods for assessing cartilage health would prove useful in reducing the number of dogs needed for a valid study of osteoarthritis and cartilage repair. Twelve beagles had critical-sized osteochondral defects created in the medial femoral condyle of both knees. Eight dogs had T1ρ and T2 magnetic resonance imaging (MRI) performed approximately 6 months after defect creation. Following MRI evaluations, all 12 dogs were humanely euthanatized and cartilage samples were obtained from the medial and lateral femoral condyles, medial and lateral tibial plateaus, trochlear groove, and patella for proteoglycan and collagen quantification. Equilibrium partitioning of an ionic contrast (EPIC)-µCT was then performed followed by the histologic assessment of the knees. Correlations between T1ρ, T2, EPIC-µCT and proteoglycan, collagen, and histology scores were assessed using a multivariate analysis accounting for correlations from samples within the same knee and in the same dog. Pearson's correlation coefficients were calculated to assess the strength of significant relationships. Correlations between µCT values and biochemical or histologic assessment were weak to moderately strong (0.09-0.41; p < 0.0001-0.66). There was a weak correlation between the T2 values and cartilage proteoglycan (-0.32; p = 0.04). The correlation between T1ρ values and cartilage proteoglycan were moderately strong (-0.38; p < 0.05) while the strongest correlation was between the T1ρ values and histological assessment of cartilage with a correlation coefficient of 0.58 (p < 0.0001). These data suggest that T1ρ shows promise for possible utility in the translational study of cartilage health and warrants further development in this species. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:368-377, 2020.

MiR-146b accelerates osteoarthritis progression by targeting alpha-2-macroglobulin.

Osteoarthritis (OA) is an aging-related chronic degenerative disease characterized by the degradation of chondrocyte extracellular matrix (ECM). Previous studies have suggested that microRNAs (miRNAs) are associated with OA, but the role of miR-146b in OA remains unclear. The aim of this study was to determine the role of miR-146b in OA progression. The effect of miR-146b on ECM degradation were studied in mouse chondrocytes transfected with miRNA and treated with IL-1β. Cell viability and the expression levels of proteolytic enzymes in the transfected cells were assessed by real-time RT-PCR, ELISA and Western blots. We found downregulation of miR-146b expression in chondrocytes dramatically inhibited IL-1β-induced caspase activation and proteolytic enzyme expression via influencing its targeted Alpha-2-macroglobulin (A2M). Luciferase reporter assays confirmed that A2M mRNA was negatively regulated by miR-146b in chondrocytes. Intra-articular injection of antago-miR-146b against miR-146b effectively protected mice from the progression of DMM-induced osteoarthritis by inhibiting cartilage proteoglycan degradation. Our study indicates that miR-146b plays a critical role in the progression of injury-induced osteoarthritis by directly targeting A2M expression to elevate the proteolytic enzyme production and stimulate chondrocytes apoptosis, and miR-146b as well as A2M could be therapeutic targets.

Extracellular matrix composition of connective tissues: a systematic review and meta-analysis

The function of connective tissues depends on the physical and biochemical properties of their extracellular matrix (ECM), which are in turn dictated by ECM protein composition. With the primary objective of obtaining quantitative estimates for absolute and relative amounts of ECM proteins, we performed a systematic review of papers reporting protein composition of human connective tissues. Articles were included in meta-analysis if they contained absolute or relative quantification of proteins found in the ECM of human bone, adipose tissue, tendon, ligament, cartilage and skeletal muscle. We generated absolute quantitative estimates for collagen in articular cartilage, intervertebral disk (IVD), skeletal muscle, tendon, and adipose tissue. In addition, sulfated glycosaminoglycans were quantified in articular cartilage, tendon and skeletal muscle; total proteoglycans in IVD and articular cartilage, fibronectin in tendon, ligament and articular cartilage, and elastin in tendon and IVD cartilage. We identified significant increases in collagen content in the annulus fibrosus of degenerating IVD and osteoarthritic articular cartilage, and in elastin content in degenerating disc. In contrast, collagen content was decreased in the scoliotic IVD. Finally, we built quantitative whole-tissue component breakdowns. Quantitative estimates improve our understanding of composition of human connective tissues, providing insights into their function in physiology and pathology.

Type II collagen peptide Coll2-1 is an actor of synovitis

We evaluated the ability of Coll2-1, a type II collagen peptide, to activate pro-inflammatory pathways in synovial cells and to induce arthritis in Lewis rats. Human synoviocytes and chondrocytes from knee OA patients were cultured for 24h with/without Coll2-1 and/or purified immunoglobulin G (AS0619) binding specifically this peptide, and/or CLI-095, a TLR-4 signaling inhibitor and/or apocynin and diphenyleneiodonium, Reactive oxygen species (ROS) production inhibitors. The Interleukin (IL)-8 and Vascular Endothelium Growth Factor (VEGF) expression, the IL-8 production, the IκB-α and p65 phosphorylation and ROS were evaluated. Coll2-1 peptide, bovine type II collagen (CIA), streptococcal cell wall (SCW) or saline solution were injected into Lewis rats. The Coll2-1 peptide was injected subcutaneously (SC; 20-200μg/100μl/animal) or intra-articularly (IA; 0.5-5μg/50μl/animal) and compared to CIA injected in SC (200μg/100μl/animal) and SCW in IA (5μg/50μl/animal). The animals were injected on day 0 and monitored for 28 days. Histological lesions assessment was performed using an arthritis score. Coll2-1 peptide significantly increased IL-8 gene expression and production by synoviocytes. AS0619 and CLI-095 significantly decreased IL-8 expression. Coll2-1 induced p65 and IκBα phosphorylation and oxidative stress inhibitors decreased it. In human chondrocytes culture, Coll2-1 significantly increased MMP-3 and VEGF gene expression. In Lewis rats, CIA, SCW or Coll2-1 injection triggered arthritis. Like CIA or SCW, Coll2-1 induced synovitis, loss of cartilage proteoglycans, cartilage structure lesion and subchondral bone remodeling. Coll2-1 activates synoviocytes to produce IL-8 and induces arthritis in rat. These findings suggest that neutralizing Coll2-1 could be a therapeutic approach of arthritis.

Canine IL4-10 fusion protein provides disease modifying activity in a canine model of OA; an exploratory study.

ObjectiveAn ideal disease modifying osteoarthritis drug (DMOAD) has chondroprotective, anti-inflammatory, and analgesic effects. This study describes the production and characterization of a canine IL4-10 fusion protein (IL4-10 FP) and evaluates its in vivo DMOAD activity in a canine model of osteoarthritis (OA).DesignThe canine Groove model was used as an in vivo model of degenerative knee OA. Six weeks after OA induction dogs were intra-articularly injected weekly, for ten weeks, with either IL4-10 FP or phosphate buffered saline (PBS). In addition to the use of human IL4-10 FP, canine IL4-10 FP was developed and characterized in vitro, and tested in vivo. Force plate analysis (FPA) was performed to analyze joint loading as a proxy measure for pain. After ten weeks dogs were euthanized and cartilage and synovial tissue samples were analyzed by histochemistry (OARSI scores) and biochemistry (cartilage proteoglycan turnover).ResultsRepetitive intra-articular injections with human IL4-10 FP led to antibody formation, that blocked its functional activity. Therefore, a canine IL4-10 FP was developed, which completely inhibited LPS-induced TNFα production by canine blood cells, and increased proteoglycan synthesis of canine cartilage in vitro (p = 0.043). In vivo, canine IL4-10 FP restored the, by OA impaired, joint loading (p = 0.002) and increased cartilage proteoglycan content (p = 0.029).ConclusionsThis first study on the potential DMOAD activity upon prolonged repeated treatment with IL4-10 FP demonstrates that a species-specific variant has anti-inflammatory and chondroprotective effects in vitro and chondroprotective and analgesic effects in vivo. These data warrant further research on the DMOAD potential of the IL4-10 FP.

Arthroscopic Determination of Cartilage Proteoglycan Content and Collagen Network Structure with Near-Infrared Spectroscopy

Conventional arthroscopic evaluation of articular cartilage is subjective and insufficient for assessing early compositional and structural changes during the progression of post-traumatic osteoarthritis. Therefore, in this study, arthroscopic near-infrared (NIR) spectroscopy is introduced, for the first time, for in vivo evaluation of articular cartilage thickness, proteoglycan (PG) content, and collagen orientation angle. NIR spectra were acquired in vivo and in vitro from equine cartilage adjacent to experimental cartilage repair sites. As reference, digital densitometry and polarized light microscopy were used to evaluate superficial and full-thickness PG content and collagen orientation angle. To relate NIR spectra and cartilage properties, ensemble neural networks, each with two different architectures, were trained and evaluated by using Spearman’s correlation analysis (ρ). The ensemble networks enabled accurate predictions for full-thickness reference properties (PG content: ρin vitro, Val= 0.691, ρin vivo= 0.676; collagen orientation angle: ρin vitro, Val= 0.626, ρin vivo= 0.574) from NIR spectral data. In addition, the networks enabled reliable prediction of PG content in superficial (25%) cartilage (ρin vitro, Val= 0.650, ρin vivo= 0.613) and cartilage thickness (ρin vitro, Val= 0.797, ρin vivo= 0.596). To conclude, NIR spectroscopy could enhance the detection of initial cartilage degeneration and thus enable demarcation of the boundary between healthy and compromised cartilage tissue during arthroscopic surgery.

The expression of adamts4, a major aggrecanase in osteoarthritic synovium, is synergistically up-regulated by IL-1ALPHA, TNF-ALPHA and TGF-BETA

Purpose: ADAMTS 1, 4, 5, 8, 9, 15, 16, 18 and 20 show the ability to degrade aggrecan, a major proteoglycan in articular cartilage. However, limited information is available for which species play a major role in osteoarthritis (OA) and how the expression of the ADAMTS species is regulated. Methods: Synovial tissue obtained from OA patients was used for expression analyses and primary synovial fibroblasts were cultured from the tissue. Screening of the expression for aggrecanase-type ADAMTS species was done by RT-PCR and real-time PCR. Effect of IL-1α, IL-1β, TNF-α, TGF-β, VEGF or HB-EGF on the ADAMTS4 expression was analyzed by real-time PCR and immunoblotting. The signaling pathways for downstream molecules of these cytokines were examined by using their inhibitors and effect of anti-arthritic drugs including high-molecular-weight hyaluronan (Suvenyl), Adalimumab (Humira) and Tocilizumab (Actemra) on the ADAMTS4 expression was also examined. Results: Among the ADAMTS species examined, ADAMTS1, 4, 5, 9 and 16 were expressed in OA synovium and synovial fibroblasts. IL-1α, TNF-α and TGF-β, but not VEGF or HB-EGF, up-regulated the ADAMTS4 expression, but the effects of these factors were minimal for ADAMTS1, 9 and 16. In contrast, ADAMTS5 expression was constitutive, and no expression of ADAMTS8, 15, 18 and 20 was observed. The ADAMTS4 expression was synergistically up-regulated by IL-1α and TNF-α, IL-1α and TGF-β, or IL-1α, TNF-α and TGF-β. Inhibition studies showed that the IL-1α-stimulated ADAMTS4 expression is predominantly through TAK1, and the TNF-α-stimulated expression is via TAK1 and partially by NF-κB. The TGF-β-stimulated expression was through the ALK5/Smad2/3 and TAK1 pathways. Adalimumab abolished the TNF-α-stimulated expression. Under the co-stimulation with IL-1α, TNF-α and TGF-β, the ADAMTS4 expression was completely inhibited by combination of Adalimumab and TAK1 inhibitor or ALK5/Smad2/3 inhibitor. Conclusions: Our data demonstrate that ADAMTS4 is a major aggrecanase in OA synovium and synergistically up-regulated by IL-1α, TNF-α and TGF-β in OA synovial fibroblasts, and suggest that combined therapy with anti-TNF-α drug and signaling pathway inhibitor(s) may be a useful remedy for OA.

Novel model for age-related OA: ER stress in articular cartilage induces joint degeneration in mice

Purpose: The lifetime risk of osteoarthritis (OA) to an individual is 45% and arthritis is the most common form of disability in the United States, making burden to the individual and society extensive. Age is the most important risk factor for adult-onset OA and ER stress response declines with age. Multiple lines of evidence indicates that pathological ER stress contributes to OA progression. In this work, tested the hypothesis that ER stress in articular chondrocytes alone is sufficient to drive joint degeneration in adult mice. In addition to ER stress, one group of mice was subjected to intense exercise to determine if mechanical stress would hasten joint degeneration. Methods: In the inducible-ER-stress mouse (I-ERS), ER stress was induced by expressing a mis-folded protein, mutant cartilage oligomeric matrix protein, in adult articular chondrocytes (from 16 to 20 weeks). There were three treatment groups: 1) control, 2) ER stress and 3) ER stress with treadmill exercise. Results: Four weeks of ER stress in healthy articular cartilage stimulated joint degeneration including increases matrix metalloproteinase (MMP) activity, inflammation, chondrocyte death, decreases in articular cartilage thickness and proteoglycan content and gait dysfunction, all of which are outcomes associated with OA. Intense exercise increased OARSI score, loss of proteoglycans, articular cartilage thinning and gait dysfunction suggesting that some aspects of OA are exacerbated by mechanical stress. Conclusions: OA is a multifactorial disease involving many risk factors including genetic factors, age, BMI, sex, joint injury and repetitive mechanical stress. Many models recapitulate post-traumatic OA and fewer models address age-related cellular stress. In these studies, physiology relevant ER chondrocyte stress was used to induce joint degeneration in previously healthy joints. This unique model of non-trauma adult-onset OA is useful for 1) defining the role of ER stress in the molecular pathology of OA, 2) for studying age-related OA and 3) testing prevention/treatment strategies and complements other OA models. Defining the role that ER stress plays in OA will lead to a better understand of this complex pathology and may offer new therapeutic strategies.

GagCEST MRI at 3T can detect cartilage differences between healthy and osteoarthritic subjects

Purpose: Evaluation of osteoarthritis (OA) is hampered by a lack of non-invasive tools to effectively detect early and reversible changes associated with the disease. Early OA is characterized by cartilage proteoglycan depletion related to an increase in enzymatic degradation. GagCEST is a promising quantitative MR technique for assessing content of Glycosaminoglycan (GAG) side chains attached to proteoglycans at 7T and is of particular interest due to its specificity to GAG content without the use of exogenous contrast agents or specialized hardware. While gagCEST has been shown to be a useful biomarker for cartilage composition at 7T, there is limited evidence of its utility at 3T. In this study, we assess the utility of an optimized gagCEST protocol at 3T by comparing gagCEST asymmetry in subjects with established OA to healthy controls. Methods: Ten healthy subjects (5 female and 5 male, ages 20-30) and twenty-four subjects with medial compartment OA were scanned on a 3T MRI system. The OA cohort (ages 60-70) was grouped by Kellgren-Lawrence (KL) grade (assessed using radiography) with five subjects with a KL grade of 1 (4 female and 1 male), twelve with a KL grade of 2 (8 female and 4 male), and five with a KL grade of 3 (4 female and 3 male). Other inclusion criteria included no previous ACL reconstruction surgery and BMI < 35. GagCEST images were acquired with a magnetization prepared 3D spoiled gradient-echo sequence (imaging parameters in Table 1). After correcting for magnetic field inhomogeneities, gagCEST asymmetry (%) was calculated using the B0-field corrected signal intensity at ±1.0 ppm, and the chemical shift of GAG hydroxyl protons, using the equation: gagCESTasym= [S(-1.0 ppm)-S(+1.0 ppm)]/ S0]. Femoral cartilage was manually segmented and subdivided into medial and lateral subregions. Statistical comparisons between cartilage compartments and healthy vs OA subjects were made using an ANOVA 2-way test with a Tukey HSD Test for multiple comparisons. Results: Subjects with OA showed a reduced gagCEST asymmetry compared to healthy controls. Further, there was a trend of an inverse relationship between GagCEST asymmetry and KL grade. There was a statistically significant difference in gagCEST asymmetry among KL grade values (p = 0.019). Further analysis comparing healthy subjects to the different OA KL grade subjects, showed a significant difference between healthy and OA KL-2 subjects and OA KL-3 subjects (p = 0.022 and p = 0.046 respectively). The comparison between healthy and KL-1 subjects did not show a significant difference (p = 0.536), which may be due to insufficient power in this cohort. There was no statistically significant difference between medial and lateral compartments in the femoral cartilage (p = 0.977). Additionally, a negative correlation of GagCEST with KL grade was observed (r= -0.404, p=0.01). The results show that optimized gagCEST methods at 3T were able to detect a statistically significant reduction in gagCEST asymmetry in osteoarthritic subjects, known to have cartilage degeneration and lower biochemical GAG composition, compared to healthy controls. Further analysis showed a significant difference in gagCEST asymmetry between the healthy and OA KL-2 and KL-3 subjects. This decrease can be seen in the unrolled gagCEST asymmetry maps, especially in the medial compartment of the knee, which corresponds well with the diagnosis in our cohort of medial compartment OA. Further, at a total acquisition time of 8:76 minutes for whole joint coverage, these methods offer translational potential. Conclusions: Our results demonstrate promise for the application of gagCEST at 3T to detect differences between healthy cartilage and cartilage in subjects with OA. Taken together, our results show that GagCEST could be a viable tool to assess early degenerative changes in cartilage in clinical trials. A strength of MRI over X-ray is that it is more sensitive to early changes in cartilage composition that occur due to OA. GagCEST has the potential for distinguishing these changes that are unseen in X-rays because it may be sensitive to signs of changes in GAG content that radiographs are not able to visualize.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)