Recent advances in biomarkers in osteoarthritis

A rapid VEGF-gene-sequence photoluminescence detector for osteoarthritis

Osteoarthritis (OA) has become a serious problem to the human society for years due to its high economic burden, disability, pain, and severe impact on the patient's lifestyle. The importance of current clinical imaging modalities in the assessment of the onset and progression of OA is well recognized by clinicians, but these modalities can only detect OA in the II stage with significant structural deterioration and clinical symptoms. Blood vessel formation induced by vascular endothelial growth factor (VEGF) occurs in the early stage and throughout the entire course of OA, enables VEGF relating gene sequence to act as a biomarker in the field of early diagnosis and monitoring of the disease. Here in, a facile rapid detection of VEGF relating ssDNA sequence was developed, in which manganese-based zeolitic imidazolate framework nanoparticles (Mn-ZIF-NPs) were synthesized by a simple coprecipitation strategy, followed by the introduction and surficial absorption of probe ssDNAs and the CRISPR/Cas12a system components. Furthermore, fluorescence experiments demonstrated that the biosensor displayed a low detection limit of 2.49 nM, a good linear response to the target ssDNA ranging from 10 nM to 500 nM, and the ability of distinguishing single nucleotide polymorphism. This finding opens a new window for the feasible and rapid detection of ssDNA molecules for the early diagnose of OA.

Matrix in Medicine: Health Consequences of Mutant Cartilage Oligomeric Matrix Protein and its relationship to abnormal growth and to joint degeneration

Cartilage oligomeric matrix protein (COMP), an extracellular matrix protein, has been shown to enhance proliferation and mechanical integrity in the matrix, supporting functions of the growth plate and articular cartilage. Mutations in COMP cause pseudoachondroplasia (PSACH), a severe dwarfing condition associated with premature joint degeneration and significant lifelong joint pain. The MT (mutant)-COMP mouse mimics PSACH with decreased limb growth, early joint degeneration and pain. Ablation of endoplasmic reticulum stress CHOP signaling eliminated pain and prevented joint degeneration. The health effects of mutant COMP are discussed in relation to cellular/chondrocyte stress in the growth plate, articular cartilage and nearby tissues, and the implications for therapeutic approaches. There are many similarities between osteoarthritis and mutant-COMP protein-induced joint degeneration, suggesting that the relevance of findings in the joints may extend beyond PSACH to idiopathic primary OA.

Prediction of diagnosis results of rheumatoid arthritis patients based on autoantibodies and cost-sensitive neural network

OBJECTIVES

To analyze and evaluate the effectiveness of the detection of single autoantibody and combined autoantibodies in patients with rheumatoid arthritis (RA) and related autoimmune diseases and establish a machine learning model to predict the disease of RA.

METHODS

A total of 309 patients with joint pain as the first symptom were retrieved from the database. The effectiveness of single and combined antibodies tests was analyzed and evaluated in patients with RA, a cost-sensitive neural network (CSNN) model was used to integrate multiple autoantibodies and patient symptoms to predict the diagnosis of RA, and the ROC curve was used to analyze the diagnosis performance and calculate the optimal cutoff value.

RESULTS

There are differences in the seropositive rate of autoimmune diseases, the sensitivity and specificity of single or multiple autoantibody tests were insufficient, and anti-CCP performed best in RA diagnosis and had high diagnostic value. The cost-sensitive neural network prediction model had a sensitivity of up to 0.90 and specificity of up to 0.86, which was better than a single antibody and combined multiple antibody detection.

CONCLUSION

In-depth analysis of autoantibodies and reliable early diagnosis based on the neural network could guide specialized physicians to develop different treatment plans to prevent deterioration and enable early treatment with antirheumatic drugs for remission. Key Points • There are differences in the seropositive rate of autoimmune diseases. • This is the first study to use a cost-sensitive neural network model to diagnose RA disease in patients. • The diagnosis effect of the cost-sensitive neural network model is better than a single antibody and combined multiple antibody detection.

Detection and Evaluation of Serological Biomarkers to Predict Osteoarthritis in Anterior Cruciate Ligament Transection Combined Medial Meniscectomy Rat Model

Biomarkers are essential tools in osteoarthritis (OA) research, clinical trials, and drug development. Detecting and evaluating biomarkers in OA research can open new avenues for researching and developing new therapeutics. In the present report, we have explored the serological detection of various osteoarthritis-related biomarkers in the preclinical model of OA. In this surgical OA model, we disrupted the medial tibial cartilage’s integrity via anterior cruciate ligament transection combined with medial meniscectomy (ACLT+MMx) of a single joint of Wistar rats. The progression of OA was verified, as shown by the microscopic deterioration of cartilage and the increasing cartilage degeneration scoring from 4 to 12 weeks postsurgery. The concentration of serological biomarkers was measured at two timepoints, along with the complete blood count and bone electrolytes, with biochemical analysis further conducted. The panel evaluated inflammatory biomarkers, bone/cartilage biomarkers, and lipid metabolic pathway biomarkers. In chronic OA rats, we found a significant reduction of total vitamin D3 and C-telopeptide fragments of type II (CTX-II) levels in the serum as compared to sham-operated rats. In contrast, the serological levels of adiponectin, leptin, and matrix metallopeptidase (MMP3) were significantly enhanced in chronic OA rats. The inflammatory markers, blood cell composition, and biochemical profile remained unchanged after surgery. In conclusion, we found that a preclinical model of single-joint OA with significant deterioration of the cartilage can lead to serological changes to the cartilage and metabolic-related biomarkers without alteration of the systemic blood and biochemical profile. Thus, this biomarker profile provides a new tool for diagnostic/therapeutic assessment in OA scientific research.

Data Integration Reveals the Potential Biomarkers of Circulating MicroRNAs in Osteoarthritis

The abnormal expression of circulating miRNAs (c-miRNAs) has become an emerging field in the development of miRNAs-based diagnostic and therapeutic tools for human diseases, including osteoarthritis (OA). OA is the most common form of arthritis leading to disability and a major socioeconomic burden. The abnormal expression of miRNAs plays important roles in the pathogenesis of OA. Unraveling the role of miRNAs in the pathogenesis of OA will throw light on the potential for the development of miRNAs-based diagnostic and therapeutic tools for OA. This article reviews and highlights recent advances in the study of miRNAs in OA, with specific demonstration of the functions of miRNA, especially c-miRNA, in OA pathogenesis as well as its potential implication in the treatment of OA. Based on a systematic literature search using online databases, we figured out the following main points: (1) the integrative systematic review of c-mRNAs and its target genes related to OA pathogenesis; (2) the potential use of c-miRNAs for OA diagnosis purposes as potential biomarkers; and (3) for therapeutic purposes, and we also highlight certain remedies that regulate microRNA expression based on its target genes.

Biomarkers and immunological parameters in haemophilia and rheumatoid arthritis patients: a comparative multiplexing laboratory study

INTRODUCTION

Haemophilia (HA) and rheumatoid arthritis (RA) patients may develop joint damage caused by recurrent joint bleedings in HA or by chronic inflammation in RA. Only few data exist for biomarker studies in these patients.

AIM

The objective of the present study is to assess a large array of biomarkers in peripheral blood samples obtained from HA patients without or with arthropathy and to compare pattern to RA patients and healthy controls.

METHODS

A panel of biomarkers was assessed in 129 men (40 HA patients without arthropathy, 23 HA patients with arthropathy, 23 RA patients and 43 control subjects). 37 different biomarkers (cytokines, angiogenesis-related proteins) were analysed using a multiple analyte profiling technology and supplemented by acute phase proteins, coagulation and immunological parameters.

RESULTS

Evidence for systemic inflammation was obtained by increased acute phase reactants in all patient groups. 13 or 14 from 42 soluble parameters demonstrated significant differences (p < .05) between HA patients without arthropathy and healthy controls, or between HA patients with arthropathy and healthy controls, respectively. Largely overlapping patterns were obtained except for interleukin-7 being increased in HA patients without arthropathy and being decreased in HA in the presence of arthropathy.

CONCLUSIONS

In addition to data supporting systemic inflammation, we provide evidence for a common biomarker profile in HA patients and RA patients compared to healthy controls. A distinctive biomarker profile for HA patients with arthropathy did not appear except for interleukin-7 demonstrating specific changes depending on the absence or presence of arthropathy in HA patients.

The emerging landscape of nanotheranostic-based diagnosis and therapy for osteoarthritis

Osteoarthritis (OA) is a common degenerative disease involving numerous joint tissues and cells, with a growing rate in prevalence that ultimately results in a negative social impact. Early diagnosis, OA progression monitoring and effective treatment are of significant importance in halting OA process. However, traditional imaging techniques lack sensitivity and specificity, which lead to a delay in timely clinical intervention. Additionally, current treatments only slow the progression of OA but have not meet the largely medical need for disease-modifying therapy. In order to overcome the above-mentioned problems and improve clinical efficacy, nanotheranostics has been proposed on OA remedy, which has confirmed success in animal models. In this review, different imaging targets-based nanoprobe for early and timely OA diagnosis is first discussed. Second, therapeutic strategies delivered by nanosystem are summarized as much as possible. Their advantages and the potential for clinical translation are detailed discussed. Third, nanomedicine simultaneously combined with the imaging for OA treatment is introduced. Nanotheranostics dynamically tracked the OA treatment outcomes to timely and individually adjust therapy. Finally, future prospects and challenges of nanotechnology-based OA diagnosis, imaging and treatment are concluded and predicted. It is believed that nanoprobe and nanomedicine will become prospective in OA therapeutic revolution.

Mechanically stimulated biomarkers signal cartilage changes over 5 years consistent with disease progression in medial knee osteoarthritis patients

Using serum biomarkers to assess osteoarthritis (OA) disease state and risks of progression remain challenging. This study tested the hypothesis that changes to serum biomarkers in response to a mechanical stimulus in patients with medial knee OA signal cartilage thickness changes 5 years later. Specifically, serum concentrations of a collagen degradation marker (C1,2C) and a chondroitin sulfate synthesis marker (CS846) were measured 0.5 and 5.5 hours after a 30-min walk in 16 patients. Regional cartilage thickness changes measured from magnetic resonance images obtained at study entry and at 5-year follow-up were tested for correlations with baseline biomarker changes after mechanical stimulus, and for differences between groups stratified based on whether biomarker levels increased or decreased. Results showed that an increase in the degradation biomarker C1,2C correlated with cartilage thinning of the lateral tibia (R = -0.63, p = 0.009), whereas an increase in the synthesis marker CS846 correlated with cartilage thickening of the lateral femur (R = 0.76, p = 0.001). Changes in C1,2C and CS846 were correlated (R²  = 0.28, p = 0.037). Subjects with increased C1,2C had greater (p = 0.05) medial tibial cartilage thinning than those with decreased C1,2C. In conclusion, the mechanical stimulus appeared to metabolically link the biomarker responses where biomarker increases signaled more active OA disease states. The findings of medial cartilage thinning for patients with increases in the degradation marker and correlation of cartilage thickening in the less involved lateral femur with increases in the synthetic marker were consistent with progression of medial compartment OA. Thus, the mechanical stimulus facilitated assessing OA disease states using serum biomarkers. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:891-897, 2018.

Effectiveness of NEM® brand eggshell membrane in the treatment of suboptimal joint function in dogs: a multicenter, randomized, double-blind, placebo-controlled study

Introduction

Sub-optimal joint function is extremely prevalent in dogs. Therefore, a 6-week, prospective, randomized, double-blind, placebo-controlled study was conducted at eight different veterinary clinics to evaluate the efficacy, safety, and tolerability of NEM^® brand eggshell membrane (EM), a novel dietary supplement shown in other species to help maintain healthy joints and connective tissues.

Subjects and methods

Fifty-one dogs received oral EM ~13.5 mg/kg (6 mg/lb) or placebo (excipients) once daily for 6 weeks. The primary outcome measure of this study was to evaluate the change in mean joint function following 1 week and 6 weeks of supplementation as determined via the Canine Brief Pain Inventory (CBPI) questionnaire (Q#5-10) in the treatment group versus the placebo group. Secondary outcome measures were for changes in mean CBPI pain and CBPI quality of life, and mean joint pain, mobility and lameness via Veterinary Canine Scoring Assessments (VCSA). A final secondary outcome measure was for a change in serum levels of the cartilage degradation biomarker, c-terminal cross-linked telopeptide of type-II collagen (CTX-II).

Results

Supplementation with EM produced a significant treatment response versus placebo at 1 week (20.5% improvement, P=0.028), but fell shy of significance at 6 weeks post-treatment (22.5% improvement) for the primary outcome measure (CBPI Function), despite a sizeable treatment effect. Similarly, there was also a significant treatment response versus placebo at 1 week for CBPI Pain (19.4% improvement, P=0.010), but fell just shy of significance at 6 weeks (22.5% improvement), again despite a sizeable treatment effect. Results were not significant versus placebo at 1 week for CBPI quality of life (14.0% improvement), but produced a significant treatment response by the end of the 6-week study (26.8% improvement, P=0.033). Additionally, EM produced a significant treatment response versus placebo at 6 weeks for VCSA pain (23.6% improvement, P=0.012), but fell shy of significance for VCSA mobility and VCSA lameness (walking & trotting). Serum CTX-II levels in EM-supplemented dogs was significantly improved versus placebo at 6 weeks (47.9% improvement, P=0.018). There were no serious adverse events reported during the study and subject dog owners reported that EM was well tolerated by their pets.

Conclusion

Supplementation with EM, ~13.5 mg/kg (6 mg/lb) taken once daily, significantly reduced joint pain and improved joint function rapidly (CBPI 1 week) and demonstrated a lasting improvement in joint pain (VCSA 6 weeks) leading to an improved quality of life (CBPI 6 weeks). Moreover, a profound chondroprotective effect was demonstrated following 6 weeks of supplementation with EM (CTX-II).

Synovial Fluid Macrophage Migration Inhibitory Factor Levels Correlate with Severity of Self-Reported Pain in Knee Osteoarthritis Patients

BACKGROUND Inflammation is considered as one of the main pathogeneses in OA-induced pain. Macrophage migration inhibitory factor (MIF) is a well known pro-inflammatory cytokine. We aimed to determine whether MIF levels in serum and synovial fluid (SF) are associated with severity of OA-induced pain. MATERIAL AND METHODS We recruited 226 patients with knee OA and 106 controls. Self-reported pain severity of OA patients was evaluated using the Western Ontario McMaster University Osteoarthritis (WOMAC) pain scores. MIF levels were detected using enzyme-linked immunosorbent assay (ELISA). RESULTS OA patients had similar serum MIF levels compared to controls (11.93 [5.68-18.10] vs. 10.06 [6.60-14.61] ng/ml, P>0.05). In OA patients, MIF levels in SF were dramatically lower compared to paired serum samples (3.39 [1.87-5.89] vs. 11.93 [5.68-18.10] ng/ml, P<0.01). MIF levels in SF were significantly correlated with WOMAC pain scores (r=0.237, P<0.001), but MIF levels in serum had no significant correlation with WOMAC pain scores (r=0.009, P=0.898). CONCLUSIONS MIF levels in SF, but not in serum, were independently associated with the severity of self-reported pain in OA patients. The inhibition of MIF signaling pathways may be a novel therapeutic approach for ameliorating OA-induced pain.

Fractalkine (CX3CL1): a biomarker reflecting symptomatic severity in patients with knee osteoarthritis

BACKGROUND

Elevated serum and synovial fluid (SF) fractalkine (CX3CL1) levels have been detected in patients with knee osteoarthritis (OA). The current study was carried out to investigate the association between serum and SF fractalkine levels with symptomatic severity in patients with knee OA.

METHOD

One hundred ninety-three patients with OA and 182 healthy controls were enrolled in this study. The symptomatic severity was assessed by the Western Ontario McMaster University Osteoarthritis scores.

RESULTS

Fractalkine levels in SF and serum were both positively associated with self-reported greater pain and physical disability.

CONCLUSIONS

Fractalkine in SF and serum may serve as a biomarker for reflecting symptomatic severity. Therapeutic interventions that target fractalkine signaling pathways to delay OA-related symptoms deserve further study.

Correlation of Synovial Fluid Biomarkers With Cartilage Pathology and Associated Outcomes in Knee Arthroscopy

PURPOSE

To correlate the intraoperative concentrations of 20 synovial fluid biomarkers with preoperative symptoms, intraoperative findings, and postoperative outcomes in patients undergoing knee arthroscopy, with comparisons made to samples obtained from asymptomatic knees.

METHODS

Synovial fluid samples were obtained from 81 patients undergoing knee arthroscopy meeting the inclusion criteria, which included 70 samples from operative knees and 32 samples from contralateral knees. Preoperatively, baseline data obtained from clinical questionnaires including a visual analog scale (VAS) score, the Lysholm score, and the Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form were recorded. Synovial fluid was collected from both the operative knee and asymptomatic contralateral knee. Synovial fluid was stored with a protease inhibitor at -80°C until analysis. Intraoperative findings, procedures performed, and International Cartilage Repair Society (ICRS) cartilage status scores in all operative knees were documented. The concentrations of the following 20 biomarkers were measured using a multiplex magnetic bead immunoassay: matrix metalloproteinase (MMP) 3; MMP-13; tissue inhibitor of metalloproteinase (TIMP) 1; TIMP-2; TIMP-3; TIMP-4; fibroblast growth factor 2; eotaxin; interferon γ; interleukin (IL) 10; platelet-derived growth factor BB; IL-1 receptor antagonist; IL-1β; IL-6; monocyte chemotactic protein 1 (MCP-1); macrophage inflammatory protein 1α; macrophage inflammatory protein 1β; RANTES (regulated upon activation, normal T cell expressed and secreted); tumor necrosis factor α; and vascular endothelial growth factor. Clinical outcome scores were obtained in 83% of patients at a mean of 17 months' follow-up postoperatively. Analysis of variance and Pearson correlation analysis were performed to determine statistical significance between preoperative data, intraoperative findings, postoperative outcomes, and synovial fluid biomarker concentrations compared with asymptomatic contralateral knees.

RESULTS

Analysis was performed on 70 operative and 32 contralateral samples. There were strong positive correlations between ICRS score and age, symptom duration, VAS score, and Knee Injury and Osteoarthritis Outcome Score-Physical Function Short Form. A strong positive correlation was found between MCP-1 and IL-6 concentrations, intraoperative ICRS score, and continued pain at the time of final follow-up. MCP-1 and IL-6 were the strongest predictors of severe cartilage lesions, whereas IL-1 receptor antagonist was inversely related. MMP-3 levels were consistently elevated in all operative samples and directly correlated to increased preoperative VAS scores. RANTES, vascular endothelial growth factor, and platelet-derived growth factor BB were the strongest predictors of postoperative improvement at final follow-up regardless of injury and cartilage status.

CONCLUSIONS

Synovial fluid biomarkers have the capacity to reflect the intra-articular environment before surgery and potentially predict postoperative clinical outcomes. Recognition of key molecular players may yield future therapeutic targets, and large clinical trials exploring these discoveries are anticipated.

LEVEL OF EVIDENCE

Level III, therapeutic case-control study.

Magnetic Capture of a Molecular Biomarker from Synovial Fluid in a Rat Model of Knee Osteoarthritis

Biomarker development for osteoarthritis (OA) often begins in rodent models, but can be limited by an inability to aspirate synovial fluid from a rodent stifle (similar to the human knee). To address this limitation, we have developed a magnetic nanoparticle-based technology to collect biomarkers from a rodent stifle, termed magnetic capture. Using a common OA biomarker--the c-terminus telopeptide of type II collagen (CTXII)--magnetic capture was optimized in vitro using bovine synovial fluid and then tested in a rat model of knee OA. Anti-CTXII antibodies were conjugated to the surface of superparamagnetic iron oxide-containing polymeric particles. Using these anti-CTXII particles, magnetic capture was able to estimate the level of CTXII in 25 μL aliquots of bovine synovial fluid; and under controlled conditions, this estimate was unaffected by synovial fluid viscosity. Following in vitro testing, anti-CTXII particles were tested in a rat monoiodoacetate model of knee OA. CTXII could be magnetically captured from a rodent stifle without the need to aspirate fluid and showed tenfold changes in CTXII levels from OA-affected joints relative to contralateral control joints. Combined, these data demonstrate the ability and sensitivity of magnetic capture for post-mortem analysis of OA biomarkers in the rat.

Analysis on the serum levels of the biomarker CTX-II in professional indoor soccer players over the course of one season

Objective

The aim of this study was to analyze the blood serum levels of CTX-II in professional indoor soccer players, at three different times during one season: at the start of the pre-season, four months later (a time that marks the middle of the season) and at the end of the season.

Methods

Fourteen male soccer players of mean age 19 years were included. Blood samples of 3 mL were collected from each individual. The samples were analyzed by means of Elisa tests.

Results

There was a significant increase in the serum level of CTX-II in the indoor soccer players, from the beginning to the end of the season (p < 0.01).

Conclusion

These data suggest that joint degradation had occurred in these soccer players, by the end of this period. It is evident that further studies are needed, with methodological rigor, so as to make an effective contribution toward precise elucidation of the etiology of this osteoarthritis and its relationship with the biomarkers, as a tool for early diagnosis.

Cartilage oligomeric matrix protein in monitoring and prognostication of osteoarthritis and its utility in drug development

Osteoarthritis (OA) is a major public concern as it is one of the leading causes of morbidity and lays a huge medical and economic burden on health resources. Early detection of OA has been a clinical challenge as early signs of joint inflammation are often not evidently identifiable on routine radiographic images. This presents a dire unmet medical need for a biomarker, which could detect early signs of joint inflammation much before irreversible joint damage and radiographic changes set in. Besides, the treatment of OA has remained mainly symptomatic. A disease modifying OA drug (DMOAD), which can act as targeted anti-OA therapy has not been able to receive regulatory approval yet. The clinical development of a DMAOD too warrants the need of a biomarker; which can act as a surrogate clinical endpoint used to monitor therapeutic efficacy and to validate a clinically meaningful change within the restricted time frame of a clinical study. In this regard, the current review focuses on cartilage oligomeric matrix protein (COMP), a potential OA biomarker which has shown significant clinical promise as a tool for early detection, therapeutic monitoring, prognostication and drug development for OA. This brief review is pivoted around the findings of selected relevant publications from PubMed indexed journals.

A systems view of risk factors for knee osteoarthritis reveals insights into the pathogenesis of the disease

Early detection of osteoarthritis (OA) remains a critical yet unsolved multifaceted problem. To address the multifaceted nature of OA a systems model was developed to consolidate a number of observations on the biological, mechanical and structural components of OA and identify features common to the primary risk factors for OA (aging, obesity and joint trauma) that are present prior to the development of clinical OA. This analysis supports a unified view of the pathogenesis of OA such that the risk for developing OA emerges when one of the components of the disease (e.g., mechanical) becomes abnormal, and it is the interaction with the other components (e.g., biological and/or structural) that influences the ultimate convergence to cartilage breakdown and progression to clinical OA. The model, applied in a stimulus-response format, demonstrated that a mechanical stimulus at baseline can enhance the sensitivity of a biomarker to predict cartilage thinning in a 5 year follow-up in patients with knee OA. The systems approach provides new insight into the pathogenesis of the disease and offers the basis for developing multidisciplinary studies to address early detection and treatment at a stage in the disease where disease modification has the greatest potential for a successful outcome.

Influence of model and matrix on cytokine profile in rat and human

OBJECTIVE

Emerging evidence indicates that low-grade inflammation is part of the clinical picture of OA and that there is a need to identify soluble biomarkers of ongoing inflammation in the joint from a translational aspect. The aim of this study was to compare levels of pro-inflammatory biomarkers in SF, serum and/or EDTA plasma.

METHODS

SF and blood from rats subjected to Freund's complete adjuvant (FCA; n = 48) or monoiodoacetate (MIA; n = 88) monoarthritis and from control rats were collected over time. SF, EDTA plasma and serum were obtained from six individuals with OA of the knee and healthy controls. Levels of IL-6, KC/GRO, IL-8, monocyte chemoattractant protein 1 (MCP-1), macrophage inflammatory protein 3α (MIP-3α), IL-1β, TNF and l(+)-lactate were assessed either by immune assay or by a colorimetric method.

RESULTS

Elevated levels of biomarkers were shown in monoarthritic animals in SF compared with the control groups, although with considerably lower magnitude in the MIA groups, which also indicated a biphasic pattern. Levels of KC/GRO and MIP-3α in serum from the FCA model and IL-6 in the MIA model followed the pattern of SF. In serum samples from OA individuals, MIP-3α correlated significantly with levels in SF.

CONCLUSION

While we found increased levels of markers in joint fluid and blood, no single systemic biochemical biomarkers that were a common denominator between the animal models and the patient material could be identified. Our data indicate that it is critical to delineate the temporal profile of multiple local and systemic factors in order to pinpoint soluble biomarkers for OA.

The forward problem of electroarthrography: modeling load-induced electrical potentials at the surface of the knee

Electroarthrography (EAG) is a novel technology recently proposed to detect cartilage degradation. EAG consists of recording electrical potentials on the knee surface while the joint is undergoing compressive loading. Previous results show that these signals originating from streaming potentials in the cartilage reflect joint cartilage health. The aim of this study is to contribute to the understanding of the generation of the EAG signals and to the development of interpretation criteria using computer models of the human knee. The knee is modeled as a volume conductor composed of different regions characterized by specific electrical conductivities. The source of the EAG signal is the load-induced interstitial fluid flow that transports ions within the compressed cartilage. It is modeled as an impressed current density in different sections of the articular cartilage. The finite-element method is used to compute the potential distribution in two knee models with a realistic geometry. The simulated potential distributions correlate very well with previously measured potential values, which further supports the hypothesis that the EAG signals originate from compressed cartilage. Also, different localized cartilage defects simulated as a reduced impressed current density produce specific potential distributions that may be used to detect and localize cartilage degradation. In conclusion, given the structural and electrophysiological complexity of the knee, computer modeling constitutes an important tool to improve our understanding of the generation of EAG signals and of the various factors that affect the EAG signals so as to help develop the EAG technology as a useful clinical tool.

Early intra-articular complement activation in ankle fractures

Cytokine regulation possibly influences long term outcome following ankle fractures, but little is known about synovial fracture biochemistry. Eight patients with an ankle dislocation fracture were included in a prospective case series and matched with patients suffering from grade 2 osteochondritis dissecans (OCD) of the ankle. All fractures needed external fixation during which joint effusions were collected. Fluid analysis was done by ELISA measuring aggrecan, bFGF, IL-1β, IGF-1, and the complement components C3a, C5a, and C5b-9. The time periods between occurrence of fracture and collection of effusion were only significantly associated with synovial aggrecan and C5b-9 levels (P < 0.001). Furthermore, synovial expressions of both proteins correlated with each other (P < 0.001). Although IL-1β expression was relatively low, intra-articular levels correlated with C5a (P < 0.01) and serological C-reactive protein concentrations 2 days after surgery (P < 0.05). Joint effusions were initially dominated by neutrophils, but the portion of monocytes constantly increased reaching 50% at day 6 after fracture (P < 0.02). Whereas aggrecan and IL-1β concentrations were not different in fracture and OCD patients, bFGF, IGF-1, and all complement components were significantly higher concentrated in ankle joints with fractures (P < 0.01). Complement activation and inflammatory cell infiltration characterize the joint biology following acute ankle fractures.

Analysis of mass spectrometry data from the secretome of an explant model of articular cartilage exposed to pro-inflammatory and anti-inflammatory stimuli using machine learning

BACKGROUND

Osteoarthritis (OA) is an inflammatory disease of synovial joints involving the loss and degeneration of articular cartilage. The gold standard for evaluating cartilage loss in OA is the measurement of joint space width on standard radiographs. However, in most cases the diagnosis is made well after the onset of the disease, when the symptoms are well established. Identification of early biomarkers of OA can facilitate earlier diagnosis, improve disease monitoring and predict responses to therapeutic interventions.

METHODS

This study describes the bioinformatic analysis of data generated from high throughput proteomics for identification of potential biomarkers of OA. The mass spectrometry data was generated using a canine explant model of articular cartilage treated with the pro-inflammatory cytokine interleukin 1 β (IL-1β). The bioinformatics analysis involved the application of machine learning and network analysis to the proteomic mass spectrometry data. A rule based machine learning technique, BioHEL, was used to create a model that classified the samples into their relevant treatment groups by identifying those proteins that separated samples into their respective groups. The proteins identified were considered to be potential biomarkers. Protein networks were also generated; from these networks, proteins pivotal to the classification were identified.

RESULTS

BioHEL correctly classified eighteen out of twenty-three samples, giving a classification accuracy of 78.3% for the dataset. The dataset included the four classes of control, IL-1β, carprofen, and IL-1β and carprofen together. This exceeded the other machine learners that were used for a comparison, on the same dataset, with the exception of another rule-based method, JRip, which performed equally well. The proteins that were most frequently used in rules generated by BioHEL were found to include a number of relevant proteins including matrix metalloproteinase 3, interleukin 8 and matrix gla protein.

CONCLUSIONS

Using this protocol, combining an in vitro model of OA with bioinformatics analysis, a number of relevant extracellular matrix proteins were identified, thereby supporting the application of these bioinformatics tools for analysis of proteomic data from in vitro models of cartilage degradation.

Association of Cross Linked C-Telopeptide II Collagen and Hyaluronic Acid with Knee Osteoarthritis Severity

BACKGROUND: This study was carried out to investigate the association of Cross Linked C-Telopeptide Type I & II Collagen (CTX-I and II) and hyaluronic acid (HA) with knee osteoarthritis (OA) severity.METHODS: Sixty menopause women with primary knee OA were enrolled in this study during their visits to the Outpatient Department. Patients with knee pain during weight bearing, active or passive range of motion, or tenderness with Kellgren-Lawrence (KL) grade of more than I were included. Patients with injury, inflammatory and metabolic diseases were excluded. Patients were put in a 10-hour fasting prior to withdrawal of morning blood samples for examinations of HA, CTX-I, interleukin 1 beta (IL-1β), and high sensitivity C reactive protein (hs-CRP) level. Second void morning urine specimens were taken for CTXII assessment. HA, CTX-I and II levels were measured by enzyme-linked immunosorbent assay.RESULTS: Sixty menopausal female patients were included in this study, 35 with KL grade II, 17 grade III, and 8 grade IV. Means of CTX-II were significantly different between subjects KL grade IV and III (p=0.021). Correlation of KL grade was significant with CTX-II (p=0.001, r=0.412) and HA (p=0.0411, r=0.269). KL grades were not significantly associated with CTX-I (p=0.8364, r=-0.0272); IL-1β (p=0.5773, r=0.0853) and hs-CRP (p=0.2625, r=0.1470).CONCLUSION: CTX-II and HA were associated with severity of knee OA, suggesting that CTX-II and HA can be used as marker for knee OA severity.KEYWORDS: CTX-II, hyaluronic acid, otestoarthritis, knee

Osteoarthritis: detection, pathophysiology, and current/future treatment strategies

Osteoarthritis (OA) is a disease of the joint, and age is the major risk factor for its development. Clinical manifestation of OA includes joint pain, stiffness, and loss of mobility. Currently, no pharmacological treatments are available to treat this specific joint disease; only symptom-modifying drugs are available. Improvement in imaging technology, identification of biomarkers, and increased understanding of the molecular basis of OA will aid in detecting the early stages of disease. Yet the development of interventional strategies remains elusive and will be critical for effective prevention of OA-associated joint destruction. The potential of cell-based therapies may be applicable in improving joint function in mild to more advanced cases of OA. Ongoing studies to understand the basis of this disease will eventually lead to prevention and treatment strategies and will also be a key in reducing the social and economic burden of this disease. Nurses are advised to provide an integrative approach of disease assessment and management in OA patients' care with a focus on education and implementation. Knowledge and understanding of OA and how this affects the individual patient form the basis for such an integrative approach to all-round patient care and disease management.

Enhanced expression of the central survival of motor neuron (SMN) protein during the pathogenesis of osteoarthritis

The identification of new components implicated in the pathogenesis of osteoarthritis (OA) might improve our understanding of the disease process. Here, we investigated the levels of the survival of motor neuron (SMN) expression in OA cartilage considering the fundamental role of the SMN protein in cell survival and its involvement in other stress-associated pathologies. We report that SMN expression is up-regulated in human OA compared with normal cartilage, showing a strong correlation with the disease severity, a result confirmed in vivo in an experimental model of the disease. We further show that the prominent inflammatory cytokines (IL-1β, TNF-α) are critical inducers of SMN expression. This is in marked contrast with the reported impaired levels of SMN in spinal muscular atrophy, a single inherited neuromuscular disorder characterized by mutations in the smn gene whereas OA is a complex disease with multiple aetiologies. While the precise functions of SMN during OA remain to be elucidated, the conclusions of this study shed light on a novel pathophysiological pathway involved in the progression of OA, potentially offering new targets for therapy.

Molecular characterization of articular cartilage from young adults with femoroacetabular impingement

BACKGROUND

Femoroacetabular impingement is a frequent cause of hip pain and may lead to secondary osteoarthritis, yet little is known about the molecular events linking mechanical hip impingement and articular cartilage degeneration. The first goal of this study was to quantify the expression of inflammatory cytokine and chemokine, matrix-degrading, and extracellular matrix genes in articular cartilage harvested from control hips and hips with femoroacetabular impingement and end-stage osteoarthritis. The second goal was to analyze the relative expression of these genes in articular cartilage harvested at various stages of osteoarthritis.

METHODS

Cartilage samples were obtained from thirty-two hips undergoing hip preservation surgery for femoroacetabular impingement or hip arthroplasty. Three control cartilage samples were also analyzed. Specimens were graded intraoperatively with regard to the severity of cartilage damage, the radiographic osteoarthritis grade was recorded, and quantitative RT-PCR (real-time polymerase chain reaction) was performed to determine relative gene expression.

RESULTS

Except for interleukin-1β (IL-1β) and CXCL2, the mRNA (messenger RNA) expression of all other chemokine (IL-8, CXCL1, CXCL3, CXCL6, CCL3, and CCL3L1), matrix-degrading (matrix metalloproteinase [MMP]-13 and ADAMTS-4), and structural matrix (COL2A1 [collagen, type II, alpha] and ACAN [aggregan]) genes was higher overall in cartilage from hips with femoroacetabular impingement compared with hips with osteoarthritis and normal controls. The differences reached significance (p ≤ 0.05) for seven of these ten quantified genes, with CXCL3, CXCL6, and COL2A1 being elevated in the femoroacetabular impingement group compared with only the control group and IL-8, CCL3L1, ADAMTS-4, and ACAN being elevated compared with both the osteoarthritis and control groups. When samples were grouped according to the stage of the degenerative cascade, mRNA expression was relatively higher in one of the two middle stages of femoroacetabular impingement (chondromalacia or cleavage/thinning), with the difference reaching significance for IL-8, CXCL2, CXCL3, CCL3L1, and ACAN. ACAN expression was diminished in hips with osteoarthritis compared with femoroacetabular impingement but elevated compared with the control articular cartilage.

CONCLUSIONS

Articular cartilage from the impingement zone of hips with femoroacetabular impingement (and particularly those hips in the cleavage/thinning stage) expressed higher levels of certain inflammatory, anabolic, and catabolic genes, representing a heightened metabolic state.

CLINICAL RELEVANCE

The articular cartilage from the impingement zone of hips with femoroacetabular impingement was metabolically hyperactive, supporting the concept that such impingement is a structural precursor to hip osteoarthritis.

Prognostic biomarkers in osteoarthritis

PURPOSE OF REVIEW

Identification of patients at risk for incident disease or disease progression in osteoarthritis remains challenging, as radiography is an insensitive reflection of molecular changes that presage cartilage and bone abnormalities. Thus there is a widely appreciated need for biochemical and imaging biomarkers. We describe recent developments with such biomarkers to identify osteoarthritis patients who are at risk for disease progression.

RECENT FINDINGS

The biochemical markers currently under evaluation include anabolic, catabolic, and inflammatory molecules representing diverse biological pathways. A few promising cartilage and bone degradation and synthesis biomarkers are in various stages of development, awaiting further validation in larger populations. A number of studies have shown elevated expression levels of inflammatory biomarkers, both locally (synovial fluid) and systemically (serum and plasma). These chemical biomarkers are under evaluation in combination with imaging biomarkers to predict early onset and the burden of disease.

SUMMARY

Prognostic biomarkers may be used in clinical knee osteoarthritis to identify subgroups in whom the disease progresses at different rates. This could facilitate our understanding of the pathogenesis and allow us to differentiate phenotypes within a heterogeneous knee osteoarthritis population. Ultimately, such findings may help facilitate the development of disease-modifying osteoarthritis drugs (DMOADs).

Neopterin concentrations in synovial fluid may reflect disease severity in patients with osteoarthritis

We aimed to detect neopterin concentrations in serum and synovial fluid (SF) of knee osteoarthritis (OA) patients and to clarify their relationship with clinical severity of the disease. We cross-sectionally enrolled 176 knee OA patients and 63 age- and sex-matched controls. We measured neopterin concentrations by enzyme-linked immunosorbent assay (ELISA) and investigated the correlation between serum/SF neopterin concentrations and Kellgren-Lawrence (KL) grades as well as Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores in OA patients. Our results demonstrated that increased SF neopterin concentrations were independently correlated with greater symptomatic and radiographic severity in OA patients. These results suggested a crucial role of neopterin activation in the development and progression of knee OA. Assessment of neopterin levels in SF is a potential biomarker to evaluate disease severity in OA patients.

Osteoarthritis year 2012 in review: biomarkers

PURPOSE

Biomarkers provide useful diagnostic information by detecting cartilage degradation in osteoarthritis (OA), reflecting disease-relevant biological activity and predicting the course of disease progression. They also serve as surrogate endpoints in the drug discovery process. The aim of this narrative review was to focus on OA biomarker-related papers published between the osteoarthritis research society international (OARSI) 2011 meeting in San Diego and the OARSI 2012 meeting in Barcelona.

METHODS

The PubMed/MEDLINE and SciVerse Scopus bibliographic databases were searched using the keywords: 'biomarker' and 'osteoarthritis' and/or 'biomarker' and 'proteomics'.

RESULTS

Ninety-eight papers were found with the keywords 'biomarker' and 'osteoarthritis'. Fifteen papers were found with the keywords 'biomarker' and 'proteomics'. Review articles were also included. The most relevant published studies focused on extracellular matrix (ECM) molecules in body fluids. Enrichment of the deamidated epitope of cartilage oligomeric matrix protein (D-COMP) suggests that OA disease progression is associated with post-translational modifications that may show specificity for particular joint sites. Fibulin-3 peptides (Fib3-1 and Fib3-2) have been proposed as potential biomarkers of OA along with follistatin-like protein 1 (FSTL1), a new serum biomarker with the capacity to reflect the severity of joint damage. The 'membrane attack complex' (MAC) component of complement has also been implicated in OA.

CONCLUSION

Novel OA biomarkers are needed for sub-clinical disease diagnosis. Proteomic techniques are beginning to yield useful data and deliver new OA biomarkers in serum and urine. Combining biochemical markers with tissue and cell imaging techniques and bioinformatics (i.e., machine learning, clustering, data visualization) may facilitate the development of biomarker combinations enabling earlier detection of OA.

Increased Femoral Cartilage Thickness in Patients With Klinefelter Syndrome

The objective of this study was to determine femoral cartilage thickness (FCT) in patients with Klinefelter syndrome (KS), which is the most common sex chromosome disorder in men with varying degrees of androgen deficiency. This cross-sectional controlled study was conducted in a tertiary care center. Participants were 33 male patients (mean age = 36.2 years) with KS and 35 aged-matched healthy male controls (mean age = 32.9 years). Femoral condyle cartilage was measured by ultrasonography at three locations in each knee. Total testosterone, estradiol, sex hormone binding globulin, free androgen index, bioavailable testosterone, and albumin levels were measured. Femoral cartilage of patients at right and left knee lateral (3.03 and 2.99 mm), mid (3.81 and 3.74 mm), and medial (3.01 and 3.20 mm) were statistically thicker than in controls (right and left knee lateral 2.29 and 2.36 mm, mid 2.64 and 2.53 mm, medial 2.39 and 2.32 mm, respectively, p < .001). There was no significant correlation between FCT and sex hormones. In conclusion, patients with KS had thicker femoral cartilage. Relatively low testosterone levels in these patients and altered estrogen metabolism may hypothetically explain increased cartilage thickness in these patients.

Chondrogenesis, chondrocyte differentiation, and articular cartilage metabolism in health and osteoarthritis

Chondrogenesis occurs as a result of mesenchymal cell condensation and chondroprogenitor cell differentiation. Following chondrogenesis, the chondrocytes remain as resting cells to form the articular cartilage or undergo proliferation, terminal differentiation to chondrocyte hypertrophy, and apoptosis in a process termed endochondral ossification, whereby the hypertrophic cartilage is replaced by bone. Human adult articular cartilage is a complex tissue of matrix proteins that varies from superficial to deep layers and from loaded to unloaded zones. A major challenge to efforts to repair cartilage by stem cell-based and other tissue-engineering strategies is the inability of the resident chondrocytes to lay down a new matrix with the same properties as it had when it was formed during development. Thus, understanding and comparing the mechanisms of cartilage remodeling during development, osteoarthritis (OA), and aging may lead to more effective strategies for preventing cartilage damage and promoting repair. The pivotal proteinase that marks OA progression is matrix metalloproteinase 13 (MMP-13), the major type II collagen-degrading collagenase, which is regulated by both stress and inflammatory signals. We and other investigators have found that there are common mediators of these processes in human OA cartilage. We also observe temporal and spatial expression of these mediators in early through late stages of OA in mouse models and are analyzing the consequences of knockout or transgenic overexpression of critical genes. Since the chondrocytes in adult human cartilage are normally quiescent and maintain the matrix in a low turnover state, understanding how they undergo phenotypic modulation and promote matrix destruction and abnormal repair in OA may to lead to identification of critical targets for therapy to block cartilage damage and promote effective cartilage repair.

Early diagnosis to enable early treatment of pre-osteoarthritis

Osteoarthritis is a prevalent and disabling disease affecting an increasingly large swathe of the world population. While clinical osteoarthritis is a late-stage condition for which disease-modifying opportunities are limited, osteoarthritis typically develops over decades, offering a long window of time to potentially alter its course. The etiology of osteoarthritis is multifactorial, showing strong associations with highly modifiable risk factors of mechanical overload, obesity and joint injury. As such, characterization of pre-osteoarthritic disease states will be critical to support a paradigm shift from palliation of late disease towards prevention, through early diagnosis and early treatment of joint injury and degeneration to reduce osteoarthritis risk. Joint trauma accelerates development of osteoarthritis from a known point in time. Human joint injury cohorts therefore provide a unique opportunity for evaluation of pre-osteoarthritic conditions and potential interventions from the earliest stages of degeneration. This review focuses on recent advances in imaging and biochemical biomarkers suitable for characterization of the pre-osteoarthritic joint as well as implications for development of effective early treatment strategies.

Nanomedicines for chronic non-infectious arthritis: the clinician's perspective

Rheumatoid arthritis (RA) and osteoarthritis (OA) are prevalent chronic health conditions. However, despite recent advances in medical therapeutics, their treatment still represents an unmet medical need because of safety and efficacy concerns with currently prescribed drugs. Accordingly, there is an urgent need to develop and test new drugs for RA and OA that selectively target inflamed joints thereby mitigating damage to healthy tissues. Conceivably, biocompatible, biodegradable, disease-modifying antirheumatic nanomedicines (DMARNs) could represent a promising therapeutic approach for RA and OA. To this end, the unique physicochemical properties of drug-loaded nanocarriers coupled with pathophysiological characteristics of inflamed joints amplify bioavailability and bioactivity of DMARNs and promote their selective targeting to inflamed joints. This, in turn, minimizes the amount of drug required to control articular inflammation and circumvents collateral damage to healthy tissues. Thus, nanomedicine could provide selective control both in space and time of the inflammatory process in affected joints. However, bringing safe and efficacious DMARNs for RA and OA to the marketplace is challenging because regulatory agencies have no official definition of nanotechnology, and rules and definitions for nanomedicines are still being developed. Although existing toxicology tests may be adequate for most DMARNs, as new toxicity risks and adverse health effects derived from novel nanomaterials with intended use in humans are identified, additional toxicology tests would be required. Hence, we propose that detailed pre-clinical in vivo safety assessment of promising DMARNs leads for RA and OA, including risks to the general population, must be conducted before clinical trials begin.

Association of MIF in serum and synovial fluid with severity of knee osteoarthritis

OBJECTIVE

Recent evidences suggest that inflammation contributes to the development and progression of osteoarthritis (OA). This study aims to determine macrophage migration inhibitory factor (MIF) levels in serum and synovial fluid (SF) of patients with knee OA and to analyze the association of MIF levels with the radiographic severity of OA.

DESIGN AND METHODS

224 patients with knee OA and 186 healthy controls were enrolled in this study.

RESULTS

Higher levels of serum MIF were found in knee OA patients compared with healthy controls. Knee OA patients with Kellgren and Lawrence (KL) grade 4 showed significantly elevated MIF levels in serum and SF compared with those with KL grade 2 and 3. MIF levels in serum and SF of knee OA patients were significantly related to disease severity evaluated by KL grading criteria.

CONCLUSION

MIF levels in serum and SF were closely related to the radiographic severity of OA.

Biological aspects of early osteoarthritis

PURPOSE

Early OA primarily affects articular cartilage and involves the entire joint, including the subchondral bone, synovial membrane, menisci and periarticular structures. The aim of this review is to highlight the molecular basis and histopathological features of early OA.

METHODS

Selective review of literature.

RESULTS

Risk factors for developing early OA include, but are not limited to, a genetic predisposition, mechanical factors such as axial malalignment, and aging. In early OA, the articular cartilage surface is progressively becoming discontinuous, showing fibrillation and vertical fissures that extend not deeper than into the mid-zone of the articular cartilage, reflective of OARSI grades 1.0-3.0. Early changes in the subchondral bone comprise a progressive increase in subchondral plate and subarticular spongiosa thickness. Early OA affects not only the articular cartilage and the subchondral bone but also other structures of the joint, such as the menisci, the synovial membrane, the joint capsule, ligaments, muscles and the infrapatellar fat pad. Genetic markers or marker combinations may become useful in the future to identify early OA and patients at risk.

CONCLUSION

The high socioeconomic impact of OA suggests that a better insight into the mechanisms of early OA may be a key to develop more targeted reconstructive therapies at this first stage of the disease.

LEVEL OF EVIDENCE

Systematic review, Level II.

Computed tomography of subchondral bone and osteophytes in hip osteoarthritis: the shape of things to come?

Bone is a fundamental component of the disordered joint homeostasis seen in osteoarthritis, a disease that has been primarily characterized by the breakdown of articular cartilage accompanied by local bone changes and a limited degree of joint inflammation. In this review we consider the role of computed tomography imaging and computational analysis in osteoarthritis research, focusing on subchondral bone and osteophytes in the hip. We relate what is already known in this area to what could be explored through this approach in the future in relation to both clinical research trials and the underlying cellular and molecular science of osteoarthritis. We also consider how this area of research could impact on our understanding of the genetics of osteoarthritis.