In vivo suppression of early experimental osteoarthritis by interleukin-1 receptor antagonist using gene therapy

IL37 dampens the IL1β-induced catabolic status of human OA chondrocytes

Objective

A crucial feature of OA is cartilage degradation. This process is mediated by pro-inflammatory cytokines, among other factors, via induction of matrix-degrading enzymes. Interleukin 37 (IL37) is an anti-inflammatory cytokine and is efficient in blocking the production of pro-inflammatory cytokines during innate immune responses. We hypothesize that IL37 is therapeutic in treating the inflammatory cytokine cascade in human OA chondrocytes and can act as a counter-regulatory cytokine to reduce cartilage degradation in OA.

Methods

Human OA cartilage was obtained from patients undergoing total knee or hip arthroplasty. Immunohistochemistry was applied to study IL37 protein expression in cartilage biopsies from OA patients. Induction of IL37 expression by IL1β, OA synovium-conditioned medium and TNFα was investigated in human OA chondrocytes. Adenoviral overexpression of IL37 followed by IL1β stimulation was performed to investigate the anti-inflammatory potential of IL37.

Results

IL37 expression was detected in cartilage biopsies of OA patients and induced by IL1β. After IL1β stimulation, increased IL1β, IL6 and IL8 expression was observed in OA chondrocytes. Elevated IL37 levels diminished the IL1β-induced IL1β , IL6 and IL8 gene levels and IL1β and IL8 protein levels. In addition to the reduction in pro-inflammatory cytokine expression, IL37 reduced MMP1 , MMP3 , MMP13 and disintegrin and metalloproteinase with thrombospondin motifs 5 gene levels and MMP3 and MMP13 protein levels.

Conclusion

IL37 is induced by IL1β, and IL37 itself reduced IL1β, IL6 and IL8 production, indicating that IL37 is able to induce a counter-regulatory anti-inflammatory feedback loop in chondrocytes. In addition, IL37 dampens catabolic enzyme expression. This supports IL37 as a potential therapeutic target in OA.

Revisiting the Role of Interleukin-1 Pathway in Osteoarthritis: Interleukin-1α and -1β, and NLRP3 Inflammasome Are Not Involved in the Pathological Features of the Murine Menisectomy Model of Osteoarthritis

Background: Innate immune response components such as toll-like receptors (TLRs) and NLRP3-inflammasome act in concert to increase IL-1α/β secretion by synovial macrophages. Previous results suggest that IL-1α/β could be an important mediator involved in the pathogenesis of osteoarthritis (OA). Objectives: The aim of our study was to evaluate the role of NLRP3, IL-1β, and IL-1α in the menisectomy (MNX) model of murine OA. Methods: Murine chondrocytes (CHs) and bone marrow-derived machrophages (BMDM) were stimulated with hydroxyapatite (HA) crystals, a form of calcium-containing crystal found in human OA, and IL-1β and IL-6 secretion assayed by ELISA.Conversely, the ability of IL-1β and IL-6 to induce CHs calcification was assessed in vitro by Alizarin red staining. Knees from 8 to 10 weeks old C57Bl/6J wild-type (WT) (n = 7), NLRP3^-/- (n = 9), IL-1α^-/- (n = 5), and IL-1β^-/- (n = 5) mice were menisectomized, using the sham-operated contralateral knee as control. 8 weeks later, knee cartilage degradation and synovial inflammation were evaluated by histology. In addition, apoptotic chondrocytes, metalloproteases activity, and collagen-type 2 expression were evaluated in all mice. Joint calcification and subchondral bone parameters were quantified by CT-scan in WT and IL-1β^-/- menisectomized knees. Results:In vitro, HA crystals induced significant increased IL-6 secretion by CHs, while IL-1β remained undetectable.Conversely, both IL-6 and IL-1β were able to increase chondrocytes mineralization. In vivo, operated knees exhibited OA features compared to sham-operated knees as evidenced by increased cartilage degradation and synovial inflammation. In menisectomized KO mice, severity and extent of cartilage lesions were similar (IL-1α^-/- mice) or exacerbated (IL-1β^-/- and NLRP3^-/- mice) compared to that of menisectomized WT mice. Metalloproteases activity, collagen-type 2 expression, chondrocytes apoptosis, and synovial inflammation were similar between KO and WT mice menisectomized knees. Moreover, the extent of joint calcification in osteoarthritic knees was comparable between IL-1β^-/- and WT mice. Conclusions: MNX knees recapitulated features of OA, i.e, cartilage destruction, synovial inflammation, cell death, and joint calcification. Deficiency of IL-1α did not impact on the severity of these features, whereas deficiency of IL-1β or of NLRP3 led to increased cartilage erosion. Our results suggest that IL-1α and IL-1β are not key mediators in this murine OA model and may explain the inefficiency of IL-1 targeted therapies in OA.

Concise Review: Mesenchymal Stem Cells for Functional Cartilage Tissue Engineering: Taking Cues from Chondrocyte-Based Constructs

Osteoarthritis, the most prevalent form of joint disease, afflicts 9% of the U.S. population over the age of 30 and costs the economy nearly $100 billion annually in healthcare and socioeconomic costs. It is characterized by joint pain and dysfunction, though the pathophysiology remains largely unknown. Due to its avascular nature and limited cellularity, articular cartilage exhibits a poor intrinsic healing response following injury. As such, significant research efforts are aimed at producing engineered cartilage as a cell-based approach for articular cartilage repair. However, the knee joint is mechanically demanding, and during injury, also a milieu of harsh inflammatory agents. The unforgiving mechano-chemical environment requires tissue replacements that are capable of bearing such burdens. The use of mesenchymal stem cells (MSCs) for cartilage tissue engineering has emerged as a promising cell source due to their ease of isolation, capacity to readily expand in culture, and ability to undergo lineage-specific differentiation into chondrocytes. However, to date, very few studies utilizing MSCs have successfully recapitulated the structural and functional properties of native cartilage, exposing the difficult process of uniformly differentiating stem cells into desired cell fates and maintaining the phenotype during in vitro culture and after in vivo implantation. To address these shortcomings, here, we present a concise review on modulating stem cell behavior, tissue development and function using well-developed techniques from chondrocyte-based cartilage tissue engineering. Stem Cells Translational Medicine 2017;6:1295-1303.

Peculiarities in Ankle Cartilage

Posttraumatic osteoarthritis (PTOA) is the most common form of osteoarthritis (OA) of the ankle joint. PTOA occurs as a result of several factors, including the poor regenerative capacity of hyaline articular cartilage as well as increased contact stresses following trauma. The purpose of this article is to review the epidemiology, pathogenesis, and potential targets for treatment of PTOA in the ankle joint. Previous reviews primarily addressed clinical approaches to ankle PTOA, while the focus of the current article will be specifically on the newly acquired knowledge of the cellular mechanisms that drive PTOA in the ankle joint and means for potential targeted therapeutics that might halt the progression of cartilage degeneration and/or improve the outcome of surgical interventions. Three experimental treatment strategies are discussed in this review: (1) increasing the anabolic potential of chondrocytes through treatment with growth factors such as bone morphogenetic protein-7; (2) limiting chondrocyte cell death either through the protection of cell membrane with poloxamer 188 or inhibiting activity of intracellular proteases, caspases, which are responsible for cell death by apoptosis; and (3) inhibiting catabolic/inflammatory responses of chondrocytes by treating them with anti-inflammatory agents such as tumor necrosis factor-α antagonists. Future studies should focus on identifying the appropriate timing for treatment and an appropriate combination of anti-inflammatory, chondro- and matrix-protective biologics to limit the progression of trauma-induced cartilage degeneration and prevent the development of PTOA in the ankle joint.

rAAV-mediated combined gene transfer and overexpression of TGF-β and SOX9 remodels human osteoarthritic articular cartilage

Direct administration of therapeutic candidate gene sequences using the safe and effective recombinant adeno-associated virus (rAAV) vectors is a promising strategy to stimulate the biologic activities of articular chondrocytes as an adapted tool to treat human osteoarthritic (OA) cartilage. In the present study, we developed a combined gene transfer approach based on the co-delivery of the pleiotropic transformation growth factor beta (TGF-β) with the specific transcription factor SOX9 via rAAV to human normal and OA chondrocytes in vitro and cartilage explants in situ in light of the mitogenic and pro-anabolic properties of these factors. Effective, durable co-overexpression of TGF-β and SOX9 significantly enhanced the levels of cell proliferation both in human normal and OA chondrocytes and cartilage explants over an extended period of time (21 days), while stimulating the biosynthesis of key matrix components (proteoglycans, type-II collagen) compared with control conditions (reporter lacZ gene transfer, absence of vector treatment). Of further note, expression of hypertrophic type-X collagen significantly decreased following co-treatment by the candidate vectors. The present findings show the value of combining the transfer and expression of potent candidate factors in human OA cartilage as a means to re-establish essential features of normal cartilage and counteract the pathological shift of homeostasis. These observations support the concept of developing dual therapeutic rAAV gene transfer strategies as future, adapted tools for the direct treatment of human OA. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2181-2190, 2016.

The Basic Science of Bone Marrow Aspirate Concentrate in Chondral Injuries

There has been great interest in bone marrow aspirate concentrate (BMAC) as a cost effective method in delivering mesenchymal stem cells (MSCs) to aid in the repair and regeneration of cartilage defects. Alongside MSCs, BMAC contains a range of growth factors and cytokines to support cell growth following injury. However, there is paucity of information relating to the basic science underlying BMAC and its exact biological role in supporting the growth and regeneration of chondrocytes. The focus of this review is the basic science underlying BMAC in relation to chondral damage and regeneration.

PEO-PPO-PEO Carriers for rAAV-Mediated Transduction of Human Articular Chondrocytes in Vitro and in a Human Osteochondral Defect Model

Gene therapy is an attractive strategy for the durable treatment of human osteoarthritis (OA), a gradual, irreversible joint disease. Gene carriers based on the small human adeno-associated virus (AAV) exhibit major efficacy in modifying damaged human articular cartilage in situ over extended periods of time. Yet, clinical application of recombinant AAV (rAAV) vectors remains complicated by the presence of neutralizing antibodies against viral capsid elements in a majority of patients. The goal of this study was to evaluate the feasibility of delivering rAAV vectors to human OA chondrocytes in vitro and in an experimental model of osteochondral defect via polymeric micelles to protect gene transfer from experimental neutralization. Interaction of rAAV with micelles of linear (poloxamer PF68) or X-shaped (poloxamine T908) poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) copolymers (PEO-PPO-PEO micelles) was characterized by means of isothermal titration calorimetry. Micelle encapsulation allowed an increase in both the stability and bioactivity of rAAV vectors and promoted higher levels of safe transgene (lacZ) expression both in vitro and in experimental osteochondral defects compared with that of free vector treatment without detrimental effects on the biological activity of the cells or their phenotype. Remarkably, protection against antibody neutralization was also afforded when delivering rAAV via PEO-PPO-PEO micelles in all systems evaluated, especially when using T908. Altogether, these findings show the potential of PEO-PPO-PEO micelles as effective tools to improve current gene-based treatments for human OA.

Evaluation of a Single Intra-Articular Injection of Autologous Protein Solution for Treatment of Osteoarthritis in a Canine Population

OBJECTIVE

To evaluate the safety and efficacy of an intra-articular injection of autologous protein solution (APS) for treatment of canine osteoarthritis (OA).

STUDY DESIGN

Prospective, randomized, blinded, placebo-controlled pilot clinical trial.

ANIMALS

Client-owned dogs with single limb lameness because of OA in a stifle or elbow joint (n=21).

METHODS

Lame dogs, confirmed with OA by physical and lameness examination and imaging, were randomly assigned to control or treatment groups. Owners, blinded to treatment, scored pain (University of Pennsylvania Canine Brief Pain Inventory) and lameness severity (Hudson Visual Analogue Scale [HVAS]). Weight-bearing was assessed by kinetic gait analysis. Dogs were injected intra-articularly with APS (treatment group) or saline solution (control group). Evaluations were performed before injection, and 2 and 12 weeks post-injection.

RESULTS

Compared to pretreatment values, APS treatment data showed a significant improvement in week 12 pain scores (improved 25.6% over baseline), lameness scores (improved 15% over baseline) and peak vertical force (PVF; N/kg; increased 14.9% of baseline), as well as vertical impulse (Ns/kg) and PVF normalized to stance time (N/kg/s). Control group dogs improved at week 2 in owner assigned indices, but not force plate values and had no significant improvement in scores or force plate values from pretreatment values at 12 weeks.

CONCLUSION

APS injection reduced pain and lameness scores and increased weight-bearing associated with the OA-affected joint in dogs at 12 weeks providing preliminary evidence that APS therapy may be beneficial in the treatment of OA in dogs and supporting pursuit of additional studies.

Interleukin-6 and chondrocyte mineralisation act in tandem to promote experimental osteoarthritis

OBJECTIVES

Basic calcium phosphate (BCP) crystal and interleukin 6 (IL-6) have been implicated in osteoarthritis (OA). We hypothesise that these two factors may be linked in a reciprocal amplification loop which leads to OA.

METHODS

Primary murine chondrocytes and human cartilage explants were incubated with hydroxyapatite (HA) crystals, a form of BCP, and the modulation of cytokines and matrix-degrading enzymes assayed. The ability of IL-6 to stimulate chondrocyte calcification was assessed in vitro. The mechanisms underlying the effects of HA on chondrocytes were investigated using chemical inhibitors, and the pathways mediating IL-6-induced calcification characterised by quantifying the expression of genes involved in chondrocyte mineralisation. The role of calcification in vivo was studied in the meniscectomy model of murine OA (MNX), and the link between IL-6 and cartilage degradation investigated by histology.

RESULTS

In chondrocytes, BCP crystals stimulated IL-6 secretion, further amplified in an autocrine loop, through signalling pathways involving Syk and PI3 kinases, Jak2 and Stat3 molecules. Exogenous IL-6 promoted calcium-containing crystal formation and upregulation of genes involved in calcification: the pyrophosphate channel Ank, the calcium channel Annexin5 and the sodium/phosphate cotransporter Pit-1. Treatment of chondrocytes with IL-6 inhibitors significantly inhibited IL-6-induced crystal formation. In meniscectomised mice, increasing deposits of BCP crystals were observed around the joint and correlated with cartilage degradation and IL-6 expression. Finally, BCP crystals induced proteoglycan loss and IL-6 expression in human cartilage explants, which were reduced by an IL-6 inhibitor.

CONCLUSIONS

BCP crystals and IL-6 form a positive feedback loop leading to OA. Targeting calcium-containing crystal formation and/or IL-6 are promising therapeutic strategies in OA.

Osteoarthritis: Pathology, Mouse Models, and Nanoparticle Injectable Systems for Targeted Treatment

Osteoarthritis (OA) is a progressive, degenerative disease of articulating joints that not only affects the elderly, but also involves younger, more active individuals with prolonged participation in high physical-demand activities. Thus, effective therapies that are easy to adopt clinically are critical in limiting the societal burden associated with OA. This review is focused on intra-articular injectable regimens and provides a comprehensive look at existing in vivo models of OA that might be suitable for developing, testing, and finding a cure for OA by intra-articular injections. We first discuss the pathology, molecular mechanisms responsible for the initiation and progression of OA, and challenges associated with disease-specific targeting of OA. We proceed to discuss available animal models of OA and provide a detailed perspective on the use of mouse models in studies of experimental OA. We finally provide a closer look at intra-articular injectable treatments for OA, focusing on biomaterials-based nanoparticles, and provide a comprehensive overview of the various nanometer-size ranges studied.

Safety and biodistribution assessment of sc-rAAV2.5IL-1Ra administered via intra-articular injection in a mono-iodoacetate-induced osteoarthritis rat model

Interleukin-1 (IL-1) plays an important role in the pathophysiology of osteoarthritis (OA), and gene transfer of IL-1 receptor antagonist (IL-1Ra) holds promise for OA treatment. A preclinical safety and biodistribution study evaluated a self-complementary adeno-associated viral vector carrying rat IL-1Ra transgene (sc-rAAV2.5rIL-1Ra) at 5 × 10⁸, 5 × 10⁹, or 5 × 10¹⁰ vg/knee, or human IL-1Ra transgene (sc-rAAV2.5hIL-1Ra) at 5 × 10¹⁰ vg/knee, in Wistar rats with mono-iodoacetate (MIA)–induced OA at days 7, 26, 91, 180, and 364 following intra-articular injection. The MIA-induced OA lesions were consistent with the published data on this model. The vector genomes persisted in the injected knees for up to a year with only limited vector leakage to systemic circulation and uptake in tissues outside the knee. Low levels of IL-1Ra expression and mitigation of OA lesions were observed in the vector-injected knees, albeit inconsistently. Neutralizing antibodies against the vector capsid developed in a dose-dependent manner, but only the human vector induced a small splenic T-cell immune response to the vector capsid. No local or systemic toxicity attributable to vector administration was identified in the rats as indicated by clinical signs, body weight, feed consumption, clinical pathology, and gross and microscopic pathology through day 364. Taken together, the gene therapy vector demonstrated a favorable safety profile.

Humoral and cell-mediated immune response, and growth factor synthesis after direct intraarticular injection of rAAV2-IGF-I and rAAV5-IGF-I in the equine middle carpal joint

Intraarticular (IA) administration of viral vectors expressing a therapeutic transgene is an attractive treatment modality for osteoarthritis (OA) as the joint can be treated as a contained unit. Humoral and cell-mediated immune responses in vivo can limit vector effectiveness. Transduction of articular tissues has been investigated; however, the immune response to IA vectors remains largely unknown. We hypothesized that IA rAAV2 and rAAV5 overexpressing insulin-like growth factor-I (IGF-I) would result in long-term IGF-I formation but would also induce neutralizing antibodies (NAb) and anti-capsid effector T cells. Twelve healthy horses were assigned to treatment (rAAV2 or rAAV5) or control (saline) groups. Middle carpal joints were injected with 5×10(11) vector genomes/joint. Synovial fluid was analyzed for changes in composition, NAb titers, immunoglobulin isotypes, proinflammatory cytokines, and IGF-I. Serum was analyzed for antibody titers and cytokines. A T cell restimulation assay was used to assess T cell responses. Injection of rAAV2- or rAAV5-IGF-I did not induce greater inflammation compared with saline. Synovial fluid IGF-I was significantly increased in both rAAV2- and rAAV5-IGF-I joints by day 14 and remained elevated until day 56; however, rAAV5 achieved the highest concentrations. A capsid-specific T cell response was not noted although all virus-treated horses had increased NAbs in serum and synovial fluid after treatment. Taken together, our data show that IA injection of rAAV2- or rAAV5-IGF-I does not incite a clinically detectable inflammatory or cell-mediated immune response and that IA gene therapy using minimally immunogenic vectors represents a clinically relevant tool for treating articular disorders including OA.

Gene therapy for human osteoarthritis: principles and clinical translation

INTRODUCTION

Osteoarthritis (OA) is the most prevalent chronic joint disease. Its key feature is a progressive articular cartilage loss. Gene therapy for OA aims at delivering gene-based therapeutic agents to the osteoarthritic cartilage, resulting in a controlled, site-specific, long-term presence to rebuild the damaged cartilage.

AREAS COVERED

An overview is provided of the principles of gene therapy for OA based on a PubMed literature search. Gene transfer to normal and osteoarthritic cartilage in vitro and in animal models in vivo is reviewed. Results from recent clinical gene therapy trials for OA are discussed and placed into perspective.

EXPERT OPINION

Recombinant adeno-associated viral (rAAV) vectors enable to directly transfer candidate sequences in human articular chondrocytes in situ, providing a potent tool to modulate the structure of osteoarthritic cartilage. However, few preclinical animal studies in OA models have been performed thus far. Noteworthy, several gene therapy clinical trials have been carried out in patients with end-stage knee OA based on the intraarticular injection of human juvenile allogeneic chondrocytes overexpressing a cDNA encoding transforming growth factor-beta-1 via retroviral vectors. In a recent placebo-controlled randomized trial, clinical scores were improved compared with placebo. These translational results provide sufficient reason to proceed with further clinical testing of gene transfer protocols for the treatment of OA.

Effects of diacerein on cartilage and subchondral bone in early stages of osteoarthritis in a rabbit model

Background

Osteoarthritis is thought to be the most prevalent chronic and disabling joint disease in animals and humans. At present, there is no ideal treatment option. The aim of this study was to assess the effects of the treatment with oral diacerein on articular cartilage, synovial membrane and subchondral bone in an experimental rabbit model of osteoarthritis by micro-CT evaluation and histological analysis. To this purpose, osteoarthritis was surgically induced on one knee of 16 rabbits using the contralateral knee as healthy controls. Treatment was started three weeks later and lasted eight weeks. Animals were divided into two groups for treatment: Placebo (treated daily with oral saline) and diacerein (treated orally with 1.5 mg/kg/day of diacerein).

Results

Sample analysis revealed that this model induced osteoarthritis in the operated knee joint. Osteoarthritis placebo group showed a significant increase in non-calcified cartilage thickness and volume with respect to the control placebo group and important changes in the synovial membrane; whereas the parameters measured in subchondral bone remained unchanged. In the osteoarthritis diacerein-treated group the results showed an improvement with respect to the OA placebo group in all parameters, although the results were not statistically significant.

Conclusion

The results of this animal study suggested that the diacerein treatment for OA may be able to ameliorate the swelling and surface alterations of the cartilage and exert an anti-inflammatory effect on the synovial membrane, which might contribute to OA improvement, as well as an anabolic effect on subchondral trabecular bone.

Serum concentrations of canine interleukin-1 receptor antagonist protein in healthy dogs after incubation using an autologous serum processing system

The objectives of this study were to optimize and validate a canine IL-1RA ELISA using commercially available reagents and to determine the effect of an autologous serum processing system (IRAP II) on IL-1RA concentrations in canine serum. The clinical detection limit of the optimized ELISA was 188.8 to 39,965.6 pg/mL. The observed-to-expected ratio (O:E) for three serial dilutions for four serum samples ranged from 109.6 to 132.2%. The O:E for four serum samples spiked with four concentrations of canine IL-1 RA ranged from 98.7 to 114.3%. Coefficients of variances for intra- and interassay variability ranged from 1.4 to 3.0 and 6.3 to 9.8, respectively. The ELISA was sensitive, linear, accurate, precise, and reproducible. Mean±SD serum concentration of IL-1RA in 12 healthy dogs was 396.6±208.0 pg/mL. There was a significant increase in IL-1RA when blood was incubated in the IRAP II system (15,955.0±6421.0 pg/mL, P<0.0001).

Pullulan: a new cytoadhesive for cell-mediated cartilage repair

Introduction

Local delivery of mesenchymal stem cells (MSCs) to the acutely injured or osteoarthritic joint retards cartilage destruction. However, in the absence of assistive materials the efficiency of engraftment of MSCs to either intact or fibrillated cartilage is low and localization is further reduced by natural movement of the joint surfaces. It is hypothesised that enhanced engraftment of the delivered MSCs at the cartilage surface will increase their reparative effect and that the application of a bioadhesive to the degraded cartilage surface will provide improved cell retention. Pullulan is a structurally flexible, non-immunogenic exopolysaccharide with wet-stick adhesive properties and has previously been used for drug delivery via the wet surfaces of the buccal cavity. In this study, the adhesive character of pullulan was exploited to enhance MSC retention on the damaged cartilage surface.

Methods

MSCs labeled with PKH26 were applied to pullulan-coated osteoarthritic cartilage explants to measure cell retention. Cytocompatability was assessed by measuring the effects of prolonged exposure to the bioadhesive on MSC viability and proliferation. The surface phenotype of the cells was assessed by flow cytometry and their multipotent nature by measuring osteogenic, adipogenic and chrondrogenic differentiation. Experiments were also carried out to determine expression of the C-type lectin Dectin-2 receptor.

Results

MSCs maintained a stable phenotype following exposure to pullulan in terms of metabolic activity, proliferation, differentiation and surface antigen expression. An increase in osteogenic activity and Dectin-2 receptor expression was seen in MSCs treated with pullulan. Markedly enhanced retention of MSCs was observed in explant culture of osteoarthritic cartilage.

Conclusions

Pullulan is a biocompatible and effective cytoadhesive material for tissue engraftment of MSCs. Prolonged exposure to pullulan has no negative impact on the phenotype, viability and differentiation potential of the cells. Pullulan dramatically improves the retention of MSCs at the fibrillated surface of osteoarthritic articular cartilage. Pullulan causes an upregulation in expression of the Dectin-2 C-type lectin transmembrane complex.

Inflammatory cytokine response following acute tibial plateau fracture

BACKGROUND

The objective of the present study was to evaluate human synovial fluid for inflammatory cytokine concentrations following acute tibial plateau fracture. Our hypothesis was that there would be an elevated inflammatory response following intra-articular fracture, and that the inflammatory response would be greater after high-energy compared with low-energy injuries.

METHODS

Between December 2011 and June 2013, we prospectively enrolled forty-five patients with an acute tibial plateau fracture. Synovial fluid aspirations were performed on the injured and uninjured knees. Twenty patients who required an external fixator followed by delayed fixation underwent aspiration at both surgical procedures. The concentrations of interferon-gamma (IFN-γ), interleukin-1 beta (IL-1β), interleukin-1 receptor antagonist (IL-1RA), IL-2, IL-4, IL-6, IL-7, IL-8, IL-10, IL-12(p70), IL-13, IL-17A, tumor necrosis factor-alpha (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-1 beta (MIP-1β) were quantified with use of multiplex assays.

RESULTS

The forty-five patients had an average age of forty-two years (range, twenty to sixty years). There were twenty-four low-energy and twenty-one high-energy tibial plateau injuries. There was a significant difference between injured and uninjured knees (p < 0.001) with regard to concentrations of IL-1β, IL-6, IL-8, IL-10, IL-1RA, and MCP-1. There was not a detectable difference in synovial fluid cytokine concentrations between high and low-energy injuries. The concentrations of IL-10 (p < 0.001), IL-1RA (p = 0.002), IL-6 (p < 0.001), IL-8 (p < 0.001), and MCP-1 (p = 0.002) were significantly greater in the injured knee than in the uninjured knee at the second aspiration, at a mean of 9.5 days (range, three to twenty-one days) after the initial injury.

CONCLUSIONS

There was a significant local inflammatory response following acute tibial plateau fracture. There was not a detectable difference in inflammatory cytokine concentration between high and low-energy injuries. Synovial fluid concentrations of IL-10, IL-8, IL-6, IL-1RA, and MCP-1 remained elevated at the second aspiration.

Generation and characterization of ABT-981, a dual variable domain immunoglobulin (DVD-Ig(TM)) molecule that specifically and potently neutralizes both IL-1α and IL-1β

Interleukin-1 (IL-1) cytokines such as IL-1α, IL-1β, and IL-1Ra contribute to immune regulation and inflammatory processes by exerting a wide range of cellular responses, including expression of cytokines and chemokines, matrix metalloproteinases, and nitric oxide synthetase. IL-1α and IL-1β bind to IL-1R1 complexed to the IL-1 receptor accessory protein and induce similar physiological effects. Preclinical and clinical studies provide significant evidence for the role of IL-1 in the pathogenesis of osteoarthritis (OA), including cartilage degradation, bone sclerosis, and synovial proliferation. Here, we describe the generation and characterization of ABT-981, a dual variable domain immunoglobulin (DVD-Ig) of the IgG1/k subtype that specifically and potently neutralizes IL-1α and IL-1β. In ABT-981, the IL-1β variable domain resides in the outer domain of the DVD-Ig, whereas the IL-1α variable domain is located in the inner position. ABT-981 specifically binds to IL-1α and IL-1β, and is physically capable of binding 2 human IL-1α and 2 human IL-1β molecules simultaneously. Single-dose intravenous and subcutaneous pharmacokinetics studies indicate that ABT-981 has a half-life of 8.0 to 10.4 d in cynomolgus monkey and 10.0 to 20.3 d in rodents. ABT-981 exhibits suitable drug-like-properties including affinity, potency, specificity, half-life, and stability for evaluation in human clinical trials. ABT-981 offers an exciting new approach for the treatment of OA, potentially addressing both disease modification and symptom relief as a disease-modifying OA drug.

Possible chondroprotective effect of canakinumab: an in vitro study on human osteoarthritic chondrocytes

Canakinumab is a human IgGκ monoclonal antibody that neutralizes the activity of interleukin (IL)-1β blocking interaction with IL-1β receptors. Our study aimed to evaluate the in vitro effect of canakinumab on human osteoarthritic (OA) chondrocytes cultivated in the presence or absence of tumor necrosis factor (TNF)-α. Articular cartilage was obtained from the femoral heads of patients with osteoarthritis (OA). Chondrocytes were incubated with two concentrations (1μg/ml and 10μg/ml) of canakinumab alone or with TNF-α (10ng/ml) for 48h. We evaluated cell viability, release of proteoglycans (PG) and nitric oxide (NO) in culture medium, inducible nitric oxide synthase (iNOS) and metalloproteinanes (MMP)-1,3,13 gene expression, apoptosis, necrosis and morphological feature by transmission electron microscopy (TEM). Canakinumab alone did not have cytotoxic effect. Cell viability was reduced significantly (p<0.001) by TNF-α and restored by canakinumab at both concentrations used. TNF-α determined a significant decrease of PG (p<0.001) and an increase of NO (p<0.001) and MMP-1,3,13 gene expression. Canakinumab significantly increased the PG levels and decreased (1μg/ml, p<0.01; 10μg/ml, p<0.01) NO levels in cells cultured with TNF-α. The NO data were confirmed by the immunocytochemistry assay for iNOS. A significant reduction of MMP-1,3,13 gene expression was induced by canakinumab. Our experiments confirmed the pro-apoptotic effect of TNF-α and demonstrated a protective role of canakinumab. The results concerning biochemical data were further confirmed by the morphological findings obtained by TEM. We showed that canakinumab counteracts the negative effects of TNF-α on OA chondrocyte cultures and may have a potential chondroprotective role in OA.

Mesenchymal stem-cell potential in cartilage repair: an update

Articular cartilage damage and subsequent degeneration are a frequent occurrence in synovial joints. Treatment of these lesions is a challenge because this tissue is incapable of quality repair and/or regeneration to its native state. Non-operative treatments endeavour to control symptoms and include anti-inflammatory medications, viscosupplementation, bracing, orthotics and activity modification. Classical surgical techniques for articular cartilage lesions are frequently insufficient in restoring normal anatomy and function and in many cases, it has not been possible to achieve the desired results. Consequently, researchers and clinicians are focusing on alternative methods for cartilage preservation and repair. Recently, cell-based therapy has become a key focus of tissue engineering research to achieve functional replacement of articular cartilage. The present manuscript is a brief review of stem cells and their potential in the treatment of early OA (i.e. articular cartilage pathology) and recent progress in the field.

Immune modulation to improve tissue engineering outcomes for cartilage repair in the osteoarthritic joint

Osteoarthritis (OA), the most common form of arthritis, is a disabling degenerative joint disease affecting synovial joints and is associated with cartilage destruction, inflammation of the synovial membrane, and subchondral bone remodeling. Inflammation of the synovial membrane may arise secondary to degenerative processes in articular cartilage (AC), or may be a primary occurrence in OA pathogenesis. However, synovial inflammation plays a key role in the pathogenesis and disease progression of OA through the production of pro-inflammatory mediators, and is associated with cartilage destruction and pain. The triggers that initiate activation of the immune response in OA are unknown, but crosstalk between osteoarthritic chondrocytes, cartilage degradation products, and the synovium may act to perpetuate this response. Increasing evidence has emerged highlighting an important role for pro-inflammatory mediators and infiltrating inflammatory cell populations in the progression of the disease. Tissue engineering strategies hold great potential for the repair of damaged AC in an osteoarthritic joint. However, an in-depth understanding of how OA-associated inflammation impacts chondrocyte and progenitor cell behavior is required to achieve efficient cartilage regeneration in a catabolic osteoarthritic environment. In this review, we will discuss the role of inflammation in OA, and investigate novel immune modulation strategies that may prevent disease progression and facilitate successful cartilage regeneration for the treatment of OA.

Pathogenesis of post-traumatic OA with a view to intervention

Post-traumatic osteoarthritis (PTOA) subsequent to joint injury accounts for over 12% of the overall disease burden of OA, and higher in the most at-risk ankle and knee joints. Evidence suggests that the pathogenesis of PTOA may be related to inflammatory processes and alterations to the articular cartilage, menisci, muscle and subchondral bone that are initiated in the acute post-injury phase. Imaging of these early changes, as well as a number of biochemical markers, demonstrates the potential for use as predictors of future disease, and may help stratify patients on the likelihood of their developing clinical disease. This will be important in guiding future interventions, which will likely target elements of the inflammatory response within the joint, molecular abnormalities related to cartilage matrix degradation, chondrocyte function and subchondral bone remodelling. Until significant improvements are made, however, in identifying patients most at risk for developing PTOA--and therefore those who are candidates for therapy--primary prevention programmes will remain the most effective current management tools.

Advances and challenges in gene-based approaches for osteoarthritis

Osteoarthritis (OA), a paramount cause of physical disability for which there is no definitive cure, is mainly characterized by the gradual loss of the articular cartilage. Current nonsurgical and reconstructive surgical therapies have not met success in reversing the OA phenotype so far. Gene transfer approaches allow for a long-term and site-specific presence of a therapeutic agent to re-equilibrate the metabolic balance in OA cartilage and may consequently be suited to treat this slow and irreversible disorder. The distinct stages of OA need to be respected in individual gene therapy strategies. In this context, molecular therapy appears to be most effective for early OA. A critical step forward has been made by directly transferring candidate sequences into human articular chondrocytes embedded within their native extracellular matrix via recombinant adeno-associated viral vectors. Although extensive studies in vitro attest to a growing interest in this approach, data from animal models of OA are sparse. A phase I dose-escalating trial was recently performed in patients with advanced knee OA to examine the safety and activity of chondrocytes modified to produce the transforming growth factor β1 via intra-articular injection, showing a dose-dependent trend toward efficacy. Proof-of-concept studies in patients prior to undergoing total knee replacement may be privileged in the future to identify the best mode of translating this approach to clinical application, followed by randomized controlled trials.

The hallmarks of osteoarthritis and the potential to develop personalised disease-modifying pharmacological therapeutics

Osteoarthritis (OA) is an age-related condition and the leading cause of pain, disability and shortening of adult working life in the UK. The incidence of OA increases with age, with 25% of the over 50s population having OA of the knee. Despite promising preclinical data covering various molecule classes, there is regrettably at present no approved disease-modifying OA drugs (DMOADs). With the advent of next generation sequencing technologies, other therapeutic areas, in particular oncology, have experienced a paradigm shift towards defining disease by its molecular composition. This paradigm shift has enabled high resolution patient stratification and supported the emergence of personalised or precision medicines. In this review we evaluate the potential for the development of OA therapeutics to undergo a similar paradigm shift given that OA is increasingly being recognised as a heterogeneous disease affecting multiple joint tissues. We highlight the evidence for the role of these tissues in OA pathology as different "hallmarks" of OA biology and review the opportunities to identify and develop targeted disease-modifying pharmacological therapeutics. Finally, we consider whether it is feasible to expect the emergence of personalised disease-modifying medicines for patients with OA and how this might be achieved.

New and emerging treatments for osteoarthritis management: will the dream come true with personalized medicine?

INTRODUCTION

Osteoarthritis (OA) is a dynamic process involving the main tissues of the joint for which a global approach should be considered. No disease-modifying OA drug (DMOAD) has yet been approved. New therapeutic strategies are needed that would be cost effective by reducing the need for pharmacological interventions and surgical management while targeting specific pathways leading to OA. The treatment landscape of OA is about to change based on new agents having shown some structural effects and emerging therapies with DMOAD effects.

AREAS COVERED

In this review based on a Medline (via PubMed) search, promising new and emerging therapies with a potential structural effect (DMOAD) will be discussed including growth factors, platelet-rich plasma, autologous stem cells, bone remodeling modulators, cytokine inhibition, gene therapy, and RNA interference.

EXPERT OPINION

DMOAD development should focus on targeting some phenotypes of OA patients evidenced with sensitive techniques such as magnetic resonance imaging, as a single treatment will unlikely be appropriate for all OA patients. This will allow the development of DMOADs based on personalized medicine. An exciting new era in DMOAD development is within reach, provided future clinical trials are sufficiently powered, systematically designed, use the appropriate evaluation tools, and target the appropriate categories of OA patients.

Dispensable role of myeloid differentiation primary response gene 88 (MyD88) and MyD88-dependent toll-like receptors (TLRs) in a murine model of osteoarthritis

OBJECTIVES

The aim of our study was to evaluate the role of cell-membrane expressed TLRs and the signaling molecule MyD88 in a murine model of OA induced by knee menisectomy (surgical partial removal of the medial meniscus [MNX]).

METHODS

OA was induced in 8-10weeks old C57Bl/6 wild-type (WT) female (n=7) mice and in knockout (KO) TLR-1 (n=7), -2 (n=8), -4 (n=9) -6 (n=5), MyD88 (n=8) mice by medial menisectomy, using the sham-operated contralateral knee as a control. Cartilage destruction and synovial inflammation were evaluated by knee joint histology using the OARSI scoring method. Apoptotic chondrocytes and cartilage metabolism (collagen II synthesis and MMP-mediated aggrecan degradation) were analyzed using immunohistochemistry.

RESULTS

Operated knees exhibited OA features at 8weeks post-surgery compared to sham-operated ones. In menisectomized TLR-1, -2, -4, and -6 deficient mice, cartilage lesions, synovial inflammation and cartilage metabolism were similar to that in operated WT mice. Accordingly, using the same approach, we found no significant protection in MyD88-deficient mice in terms of OA progression as compared to WT littermates.

CONCLUSIONS

Deficiency of TLRs or their signalling molecule MyD88 did not impact on the severity of experimental OA. Our results demonstrate that MyD88-dependent TLRs are not involved in this murine OA model. Moreover, the dispensable role of MyD88, which is also an adaptor for IL-1 receptor signaling, suggests that IL-1 is not a key mediator in the development of OA. This latter hypothesis is strengthened by the lack of efficiency of IL-1β antagonist in the treatment of OA.

Cordycepin prevented IL-β-induced expression of inflammatory mediators in human osteoarthritis chondrocytes

PURPOSE

Cordycepin, a nucleoside derivative isolated from Cordyceps, has been reported to exert anti-inflammatory, antitumor, antidiabetic and renoprotective effects. Osteoarthritis (OA) is a degenerative joint disease with an inflammatory component that drives the degradation of cartilage extracellular matrix. This study aimed to assess the effects of cordycepin on human OA chondrocytes.

METHODS

In this study, human OA chondrocytes were pretreated with cordycepin at 10, 50 or 100 μM and subsequently stimulated with interleukin-1β (IL-1β) (5 ng/ml) for 24 h. Production of prostaglandin E2 (PGE2) and nitric oxide (NO) were evaluated by the Griess reaction and an enzyme-linked immunosorbent assay (ELISA). Gene expression of matrix metalloproteinase (MMP)-13, IL-6, inducible nitric oxide synthase (iNOS) and cyclo-oxygenase (COX-2) was measured by real-time polymerase chain reaction (PCR). MMP-13 and IL-6 proteins in culture medium were determined using cytokine-specific ELISA. Western immunoblotting was used to analyse the iNOS and COX-2 protein production in culture medium. Nuclear factor kappa-B (NF-κB) activity regulation was explored using Western immunoblotting.

RESULTS

Pretreatment with cordycepin significantly inhibited the production of PGE2 and NO induced by IL-1β. Cordycepin also significantly decreased the IL-1β-stimulated gene expression and production of MMP-13, IL-6, iNOS and COX-2 in OA chondrocytes. Pretreatment with cordycepin attenuated IL-1β-induced activation of NF-κB by suppressing degradation of its inhibitory protein nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκB-α) in the cytoplasm.

CONCLUSIONS

We show for the first time the anti-inflammatory activity of cordycepin in human OA chondrocytes. Thus, with this unique profile of actions, cordycepin may prove to be a potentially attractive and new therapeutic/preventive agent for OA.

Biologic agents in osteoarthritis: hopes and disappointments

New treatment options are needed for osteoarthritis (OA) to slow down the structural progression of the disease; current therapies mostly target pain and function with minimal effectiveness. OA results from an imbalance between catabolic and anabolic factors, and biologic agents either target specific catabolic proinflammatory mediators, such as cytokines, nitric oxide synthesis, or affect anabolism more generally. Biologic agents have dramatic effects in other rheumatic inflammatory diseases such as rheumatoid arthritis; they were hoped to have similar effects in the treatment of OA. In this Review, we will discuss the three main types of cytokine blockers used in knee and hand OA, which target β-nerve growth factor (β-NGF), IL-1β or TNF. We will also discuss inhibitors of nitrogen oxide production and the use of growth factors to treat OA. Among the targeted agents, anti-β-NGF therapy has shown promising results, although cases of rapid destructive arthropathy caution against its widespread use. The future of therapies targeting cytokines, nitrogen oxide synthesis and growth factors in OA is questionable, as results from clinical trials have been repeatedly negative. Strategies in OA therapy need to be reconsidered. New molecules emerging from preclinical data should focus on treating the early phase of the disease where damage may be reversible, and treatment should be modified to fit each patient.

Arthritis gene therapy and its tortuous path into the clinic

Arthritis is a disease of joints. The biology of joints makes them very difficult targets for drug delivery in a manner that is specific and selective. This is especially true for proteinaceous drugs ("biologics"). Gene transfer is the only technology that can solve the delivery problem in a clinically reasonable fashion. There is an abundance of preclinical data confirming that genes can be efficiently transferred to tissues within joints by intra-articular injection using a variety of different vectors in conjunction with ex vivo and in vivo strategies. Using the appropriate gene transfer technologies, long-term, intra-articular expression of anti-arthritic transgenes at therapeutic concentrations can be achieved. Numerous studies confirm that gene therapy is effective in treating experimental models of rheumatoid arthritis (RA) and osteoarthritis (OA) in the laboratory. A limited number of clinical trials have been completed, which confirm safety and feasibility but only 3 protocols have reached phase II; as yet, there is no unambiguous evidence of efficacy in human disease. Only 2 clinical trials are presently underway, both phase II studies using allogeneic chondrocytes expressing transforming growth factor-β1 for the treatment of OA. Phase I studies using adeno-associated virus to deliver interleukin-1Ra in OA and interferon-β in RA are going through the regulatory process. It is to be hoped that the recent successes in treating rare, Mendelian diseases by gene therapy will lead to accelerated development of genetic treatments for common, non-Mendelian diseases, such as arthritis.

Immunopathogenesis of osteoarthritis

Even though osteoarthritis (OA) is mainly considered as a degradative condition of the articular cartilage, there is increasing body of data demonstrating the involvement of all branches of the immune system. Genetic, metabolic or mechanical factors cause an initial injury to the cartilage resulting in release of several cartilage specific auto-antigens, which trigger the activation of immune response. Immune cells including T cells, B cells and macrophages infiltrate the joint tissues, cytokines and chemokines are released from different kinds of cells present in the joint, complement system is activated, and cartilage degrading factors such as matrix metalloproteinases (MMPs) and prostaglandin E2 (PGE2) are released, resulting in further damage to the articular cartilage. There is considerable success in the treatment of rheumatoid arthritis using anti-cytokine therapies. In OA, however, these therapies did not show much effect, highlighting more complex nature of pathogenesis of OA. This needs the development of more novel approaches to treat OA, which may include therapies that act on multiple targets. Plant natural products have this kind of property and may be considered for future drug development efforts. Here we reviewed the studies implicating different components of the immune system in the pathogenesis of OA.

Autologous conditioned serum for the treatment of osteoarthritis and other possible applications in musculoskeletal disorders

INTRODUCTION

The therapeutic use of interleukin 1 (IL-1) cytokine receptor antagonists (IL-1RA) has promoted the development of new biological therapies for osteoarthritis (OA). Autologous conditioned serum (ACS) is an alternative, safe and well-tolerated treatment in OA. Sources of data We performed a comprehensive search of PubMed, Medline, Cochrane, CINAHL, Embase, SportDiscus, Pedro and Google scholar databases using keywords such as 'interleukin 1', 'osteoarthritis' and 'autologous conditioned serum'.

AREAS OF AGREEMENT

ACS, containing endogenous anti-inflammatory cytokines including IL-1RA and several growth factors, could reduce pain and increase function and mobility in mild to moderate knee OA. AREA OF CONTROVERSY: Given the limited data available on the composition of ACS, the mechanisms through which ACS produces clinical improvement, the duration of its effect and the changes in cytokine levels after repeated injections are still unknown. Growing points Although previous clinical data are encouraging and confirm the safety of this modality, given the limitations of current studies, there should be additional, controlled trials to further confirm efficacy for the use of ACS in OA treatment. AREA TIMELY FOR DEVELOPING RESEARCH: ACS can lead to enhancement of tissue regeneration and to reduction of degenerative mechanisms.

Evaluation of the inflammatory response in experimentally induced synovitis in the horse: a comparison of recombinant equine interleukin 1 beta and lipopolysaccharide

OBJECTIVE

To compare two transient models of synovitis-osteoarthritis (OA) in horses by characterizing biological changes in synovial fluid and joint tissue.

METHOD

Twelve skeletally mature mares were utilized in a block design. Synovitis was induced by an intra-articular injection of 100 ng recombinant equine interleukin 1 beta (reIL-1β) or 0.5 ng lipopolysaccharide (LPS) into a middle carpal joint in 1 ml volumes. One ml of saline was injected into the contra-lateral control joint. Lameness evaluations were conducted through post-injection hour (PIH) 8 (at which time arthroscopic removal of synovium and articular biopsies was done), and at PIH 240. Arthrocentesis collection of synovial fluid occurred between PIH 0 and 48. An arthroscopic examination at PIH 8 included synovium and articular cartilage biopsies for gene expression analysis.

RESULTS

Synovial fluid analysis indicated that single injections of reIL-1β or LPS increased synovial white blood cell (WBC), neutrophil count, total protein, prostaglandin E(2) (PGE(2)) concentrations and general matrix metalloproteinase (MMP) activity relative to control joints through PIH 8. Injections of either reIL-1β or LPS increased mRNA expression for MMP-1 and a disintegrin and metalloprotease with thrombospondin motifs (ADAMTS)-4 in synovium and for MMP-1, ADAMTS-4, ADAMTS-5 in articular cartilage collected at PIH 8 compared to saline injections.

CONCLUSION

Injections of reIL-1β into equine carpal joints resulted in a transient inflammatory response that was similar in severity to the LPS injection, causing increased expression of certain deleterious mediators in joint tissues at 8 h. Given that IL-1β is a known critical mediator of traumatic arthritis and OA, this humane and temporary model may be useful in evaluating therapeutics that act against early stages of joint disease.

Does endotoxaemia contribute to osteoarthritis in obese patients?

OA (osteoarthritis) is a degenerative condition associated with obesity. A number of metabolic explanations have been proposed to explain the association between obesity and OA in non-weight-bearing joints; however, none of these hypotheses have been demonstrated empirically. In the present Hypothesis article, we recognize that obesity is associated with compromised gut mucosa, translocation of microbiota and raised serum LPS (lipopolysaccharide). The consequent activation of the innate immune response leads to increased serum titres of inflammatory mediators in obese patients, with both local and systemic markers of inflammation associated with onset and progression of OA. Furthermore, a number of workers have shown that articular cartilage repair is impaired by a range of inflammatory mediators, both in vitro and in vivo. We propose that metabolic endotoxaemia, caused by impaired gastric mucosa and low-grade chronic inflammation, may contribute to the onset and progression of OA in obese patients. This may account for the association between obesity and OA at non-weight-bearing joints which cannot be explained by biomechanical factors.

Benefits of recombinant adeno-associated virus (rAAV)-mediated insulinlike growth factor I (IGF-I) overexpression for the long-term reconstruction of human osteoarthritic cartilage by modulation of the IGF-I axis

Administration of therapeutic genes to human osteoarthritic (OA) cartilage is a potential approach to generate effective, durable treatments against this slow, progressive disorder. Here, we tested the ability of recombinant adeno-associated virus (rAAV)-mediated overexpression of human insulinlike growth factor (hIGF)-I to reproduce an original surface in human OA cartilage in light of the pleiotropic activities of the factor. We examined the proliferative, survival and anabolic effects of the rAAV-hIGF-I treatment in primary human normal and OA chondrocytes in vitro and in explant cultures in situ compared with control (reporter) vector delivery. Efficient, prolonged IGF-I secretion via rAAV stimulated the biological activities of OA chondrocytes in all the systems evaluated over extended periods of time, especially in situ, where it allowed for the long-term reconstruction of OA cartilage (at least for 90 d). Remarkably, production of high, stable amounts of IGF-I in OA cartilage using rAAV advantageously modulated the expression of central effectors of the IGF-I axis by downregulating IGF-I inhibitors (IGF binding protein [IGFBP]-3 and IGFBP4) while up-regulating key potentiators (IGFBP5, the IGF-I receptor and downstream mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 [MAPK/ERK-1/2] and phosphatidylinisitol-3/Akt [PI3K/Akt] signal transduction pathways), probably explaining the enhanced responsiveness of OA cartilage to IGF-I treatment. These findings show the benefits of directly providing an IGF-I sequence to articular cartilage via rAAV for the future treatment of human osteoarthritis.

Stem cells and other innovative intra-articular therapies for osteoarthritis: what does the future hold?

Osteoarthritis (OA), the most common type of arthritis in the world, is associated with suffering due to pain, productivity loss, decreased mobility and quality of life. Systemic therapies available for OA are mostly symptom modifying and have potential gastrointestinal, renal, hepatic, and cardiac side effects. BMC Musculoskeletal Disorders recently published a study showing evidence of reparative effects demonstrated by homing of intra-articularly injected autologous bone marrow stem cells in damaged cartilage in an animal model of OA, along with clinical and radiographic benefit. This finding adds to the growing literature showing the potential benefit of intra-articular (IA) bone marrow stem cells. Other emerging potential IA therapies include IL-1 receptor antagonists, conditioned autologous serum, botulinum toxin, and bone morphogenetic protein-7. For each of these therapies, trial data in humans have been published, but more studies are needed to establish that they are safe and effective. Several additional promising new OA treatments are on the horizon, but challenges remain to finding safe and effective local and systemic therapies for OA.Please see related article: http://www.biomedcentral.com/1471-2474/12/259.

Effects of intraarticular IL1-Ra for acute anterior cruciate ligament knee injury: a randomized controlled pilot trial (NCT00332254)

OBJECTIVE

To evaluate the clinical effectiveness of intraarticular IL-1 receptor antagonist (IL-1Ra) for anterior cruciate ligament (ACL) tear.

METHODS

Eleven patients with acute ACL tear confirmed by magnetic resonance imaging (MRI) were randomized to receive a single intraarticular injection of IL-1Ra (anakinra 150 mg, n = 6) or equal volume of saline placebo (1 ml, n = 5). The double-blinded treatment was administered a mean 2 weeks after injury. Synovial fluid (SF) (n = 9 patients) and sera (all patients) were available at baseline (prior to injection) and immediately prior to surgery (mean 35 days later) and analyzed for SF IL-1α, IL-1β, IL-1Ra and serum hyaluronan (HA), an indicator of synovial inflammation. The primary outcome, standardized Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire, was obtained at 0 (baseline), 4, and 14 days after injection.

RESULTS

Compared with placebo, the IL-1Ra group had substantially greater improvement in key outcomes over 14 days (KOOS pain P = 0.001; activities of daily living P = 0.0015; KOOS sports function P = 0.0026; KOOS quality of life (QOL) P = 0.0048; and total KOOS P < 0.0001). There were no adverse reactions in either group. SF IL-1α (P = 0.05) and serum HA (P = 0.03), but not IL-1β, or IL-1Ra, decreased significantly in the IL-1Ra but not the placebo treated patients. Compared with placebo, IL-1α was borderline significantly different in the IL-1Ra treated group (P = 0.06).

CONCLUSIONS

Administered within the first month following severe knee injury, IL-1Ra reduced knee pain and improved function over a 2-week interval. This promising proof of concept study provides a new paradigm for studies of acute joint injury and suggests that a larger follow-up study is warranted.

Clinical potential and challenges of using genetically modified cells for articular cartilage repair

Articular cartilage defects do not regenerate. Transplantation of autologous articular chondrocytes, which is clinically being performed since several decades, laid the foundation for the transplantation of genetically modified cells, which may serve the dual role of providing a cell population capable of chondrogenesis and an additional stimulus for targeted articular cartilage repair. Experimental data generated so far have shown that genetically modified articular chondrocytes and mesenchymal stem cells (MSC) allow for sustained transgene expression when transplanted into articular cartilage defects in vivo. Overexpression of therapeutic factors enhances the structural features of the cartilaginous repair tissue. Combined overexpression of genes with complementary mechanisms of action is also feasible, holding promises for further enhancement of articular cartilage repair. Significant benefits have been also observed in preclinical animal models that are, in principle, more appropriate to the clinical situation. Finally, there is convincing proof of concept based on a phase I clinical gene therapy study in which transduced fibroblasts were injected into the metacarpophalangeal joints of patients without adverse events. To realize the full clinical potential of this approach, issues that need to be addressed include its safety, the choice of the ideal gene vector system allowing for a long-term transgene expression, the identification of the optimal therapeutic gene(s), the transplantation without or with supportive biomaterials, and the establishment of the optimal dose of modified cells. As safe techniques for generating genetically engineered articular chondrocytes and MSCs are available, they may eventually represent new avenues for improved cell-based therapies for articular cartilage repair. This, in turn, may provide an important step toward the unanswered question of articular cartilage regeneration.

Anabolic/Catabolic balance in pathogenesis of osteoarthritis: identifying molecular targets

Osteoarthritis is the most common degenerative musculoskeletal disease. In healthy cartilage, a low turnover of extracellular matrix molecules occurs. Proper balance of anabolic and catabolic activities is thus crucial for the maintenance of cartilage tissue integrity and for the repair of molecular damages sustained during daily usage. In persons with degenerative diseases such as osteoarthritis, this balance of anabolic and catabolic activities is compromised, and the extent of tissue degradation predominates over the capacity of tissue repair. This mismatch eventually results in cartilage loss in persons with osteoarthritis. Tissue homeostasis is controlled by coordinated actions and crosstalk among a number of proanabolic and antianabolic and procatabolic and anticatabolic factors. In osteoarthritis, an elevation of antianabolic and catabolic factors occurs. Interestingly, anabolic activity is also increased, but this response fails to repair the tissue because of both quantitative and qualitative insufficiency. This review presents an overview of the anabolic and catabolic activities involved in cartilage degeneration and the interplay among different signaling and metabolic factors. Understanding the basic molecular mechanisms responsible for tissue degeneration is critical to identifying and developing means to efficiently block or reverse the pathobiological symptoms of osteoarthritis.

Intraarticular application of autologous conditioned serum (ACS) reduces bone tunnel widening after ACL reconstructive surgery in a randomized controlled trial

PURPOSE

Pro-inflammatory cytokines play a pivotal role in osteoarthritis, as well as in bone tunnel widening after ACL reconstructive surgery. A new treatment option is to administer autologous conditioned serum (ACS) containing endogenous anti-inflammatory cytokines including IL-1Ra and growth factors (IGF-1, PDGF, and TGF-β1, among others) in the liquid blood phase. The purpose of this trial was to establish whether the postoperative outcome could be affected by intraarticular application of ACS.

METHODS

In a prospective, randomized, double-blinded, placebo-controlled trial with two parallel groups, 62 patients were treated. Bone tunnel width was measured by CT scans, while clinical efficacy was assessed by patient-administered outcome instruments (WOMAC, IKDC 2000) up to 1 year following the ACL reconstruction in patients receiving either ACS (Group A) or placebo (Group B). We compared the levels and dynamics of IL-1β concentrations in the synovial liquid and examined the correlation between the levels of IL-1β at three different postoperative points.

RESULTS

Bone tunnel enlargement was significantly less (6 months: 8%, 12 months: 13%) in Group A than in Group B (6 months: 31%, 12 months: 38%). Clinical outcomes (WOMAC, IKDC 2000) were consistently better in patients treated with ACS at all data points and for all outcome parameters, and there were statistically significant differences in the WOMAC stiffness subscale after 1 year. The decrease in IL-1β synovial fluid concentration was more pronounced in the ACS group, and values were lower, to a statistically significant degree, in the ACS group at day 10.

CONCLUSION

The intraarticular administration/injection of ACS results in decreased bone tunnel widening after ACL reconstructive surgery.

Emerging ideas: prevention of posttraumatic arthritis through interleukin-1 and tumor necrosis factor-alpha inhibition

BACKGROUND

Despite surgical and mechanical stabilization of an acutely injured joint through ligament reconstruction, meniscus repair, or labral repair, the risk of posttraumatic arthritis remains high. Joint injury triggers three phases of pathogenic events: the early (acute) phase involves joint swelling, hemarthrosis, expression of inflammatory cytokines (especially interleukin-1 [IL-1] and tumor necrosis factor-α [TNF-α]), and biomarkers of cartilage catabolism; an intermediate phase is characterized by reduction of joint inflammation, ongoing joint catabolism, but no evidence yet for typical features of radiographic osteoarthritis (OA); and a late phase characterized by radiographic OA.

HYPOTHESES

We hypothesize that the early phase of acute knee injury represents a window of opportunity for providing biologic treatment to promote healing and to slow or prevent a subsequent cascade of destructive joint processes leading to OA.

PROPOSED PROGRAM

We propose a phase II, randomized, placebo-controlled, double-blinded, clinical trial to treat acute knee injuries with intraarticular injection of an IL-1 inhibitor. Patient-centered outcomes will include pain reduction and improvement of knee function. MR imaging and measurement of biochemical markers will be monitored during the subsequent 2 years to determine if the structural response to injury can be reversed.

SIGNIFICANCE

If this model is validated, modulation of the molecular pathways responsible for articular cartilage breakdown will augment current reconstructive procedures in the treatment of acute joint injuries and prevent the development of injury-related arthritis.

Effect of intra-articular administration of interleukin 1 receptor antagonist on cartilage repair in temporomandibular joint

Interleukin 1 (IL-1) plays a central role in cartilage deterioration in osteoarthritis (OA). Interleukin 1 receptor antagonist (IL-1Ra) is a natural receptor antagonist and blocks the effects of IL-1. In this study, partial disk perforation was performed bilaterally to induce an osteoarthritic joint in rabbit temporomandibular joint. Fifty micrograms of recombinant human IL-1Ra was injected into the right joint, and the contralateral joint received vehicle injection 4 weeks postoperatively. Animals were killed at different intervals. Histology and reverse transcription-polymerase chain reaction were performed for comparison. The vehicle-treated joint had typical OA-related cartilage degradation, whereas the lesions in cartilage of the IL-1Ra-treated joint were less severe than the control joint. At 12 weeks, a higher expression of aggrecan and collagen type II and a lower expression of aggrecanase were observed in the treated joint than in the control joint. At 24 weeks after injection, the expression of aggrecan and collagen type II was also higher in the treated joint than in the control joint. However, no difference in either aggrecanase or tumor necrosis factor α was found between 2 groups at 24 weeks. Our results suggest that intra-articular administration of IL-1Ra into the temporomandibular joint may be a good alternative for the treatment of cartilage degeneration in OA. There was also evidence confirming that supplemented IL-1Ra functions by modifying the signal transduction mechanisms specific to IL-1.

Effect of a Herbal-Leucine mix on the IL-1β-induced cartilage degradation and inflammatory gene expression in human chondrocytes

Background

Conventional treatments for the articular diseases are often effective for symptom relief, but can also cause significant side effects and do not slow the progression of the disease. Several natural substances have been shown to be effective at relieving the symptoms of osteoarthritis (OA), and preliminary evidence suggests that some of these compounds may exert a favorable influence on the course of the disease. The objective of this study was to investigate the anti-inflammatory/chondroprotective potential of a Herbal and amino acid mixture containing extract of the Uncaria tomentosa, Boswellia spp., Lepidium meyenii and L-Leucine on the IL-1β-induced production of nitric oxide (NO), glycosaminoglycan (GAG), matrix metalloproteinases (MMPs), aggrecan (ACAN) and type II collagen (COL2A1) in human OA chondrocytes and OA cartilage explants.

Methods

Primary OA chondrocytes or OA cartilage explants were pretreated with Herbal-Leucine mixture (HLM, 1-10 μg/ml) and then stimulated with IL-1β (5 ng/ml). Effect of HLM on IL-1β-induced gene expression of iNOS, MMP-9, MMP-13, ACAN and COL2A1 was verified by real time-PCR. Estimation of NO and GAG release in culture supernatant was done using commercially available kits.

Results

HLM tested in these in vitro studies was found to be an effective anti-inflammatory agent, as evidenced by strong inhibition of iNOS, MMP-9 and MMP-13 expression and NO production in IL-1β-stimulated OA chondrocytes (p < 0.05). Supporting these gene expression results, IL-1β-induced cartilage matrix breakdown, as evidenced by GAG release from cartilage explants, was also significantly blocked (p < 0.05). Moreover, in the presence of herbal-Leucine mixture (HLM) up-regulation of ACAN and COL2A1 expression in IL-1β-stimulated OA chondrocytes was also noted (p < 0.05). The inhibitory effects of HLM were mediated by inhibiting the activation of nuclear factor (NF)-kB in human OA chondrocytes in presence of IL-1β.

Conclusion

Our data suggests that HLM could be chondroprotective and anti-inflammatory agent in arthritis, switching chondrocyte gene expression from catabolic direction towards anabolic and regenerative, and consequently this approach may be potentially useful as a new adjunct therapeutic/preventive agent for OA or injury recovery.