Synovitis biomarkers: ex vivo characterization of three biomarkers for identification of inflammatory osteoarthritis

Osteopontin inhibits autophagy via CD44 and avβ3 integrin and promotes cell proliferation in osteoarthritic fibroblast-like synoviocytes

OBJECTIVE

Osteoarthritis (OA) is closely related to aging, and autophagy is implicated in the retardation of aging. Activated synoviocytes play important roles in OA; the synoviocytes could produce osteopontin (OPN) and its main receptors CD44 and integrin, which are all involved in OA. The purpose of this study is to investigate whether OPN has an effect on autophagy in osteoarthritic synoviocytes.

METHODS

We cultured human OA fibroblast-like synoviocytes (FLS) and treated them with rhOPN and antibodies against CD44 and CD51/61 (αvβ3 integrin) or isotype IgG to block the interaction between receptors and ligands. Infection with lentivirus mRFP-GFP-LC3, laser confocal imaging and Western blotting were used to determine changes in the expression of autophagy markers, and cell proliferation of FLS was assessed with a CCK-8 assay.

RESULTS

Our results showed the expression level of autophagy marker protein LC3 II and the mRFP-GFP-LC3 puncta were significantly decreased after treatment with rhOPN when compared with the control group, when the FLS were incubated with antibodies against CD44 or CD51/61 (αvβ3 integrin) or with control isotype IgG for 1 h, followed by rhOPN treatment for 48 h, rhOPN could suppress the relative expression of LC3 II and Beclin1 via integrin and CD44 in the FLS, CCK-8 assay also showed that rhOPN significantly increased the cell proliferation and viability of FLS.

CONCLUSIONS

OPN could inhibit autophagy via CD44 and αvβ3 integrin and promote the proliferation of FLS, playing an important role in OA synovitis.

Association between type III collagen degradation and local tissue damage of a single joint

Objective

The development of disease-modifying drugs is limited by OA's heterogeneity and the challenge of defining clinical endpoints. Serological biomarkers are considered potential surrogate endpoints, but their contribution from single joints to systemic levels in OA patients is unclear. In this exploratory study we longitudinally assessed systemic biomarker levels' response to tissue damage and healing before and after surgery in patients undergoing knee or hip joint replacement revision for aseptic failure. Patients with chronic pain associated with a prior hip or knee arthroplasty, but not receiving revision surgery were included as control.

Method

The serological biomarker of MMP mediated type III collagen degradation C3M, associated with synovial tissue degradation, was measured at baseline before revision surgery, after revision surgery and at a 6-month follow-up in 48 patients with aseptic loosening of a knee or hip prosthesis and in 18 patients with chronic pain from a hip or knee prosthesis. Longitudinal changes in biomarkers were modeled using linear mixed models.

Results

No differences between the aseptic loosening and chronic pain groups were observed at baseline. Revision surgery in the aseptic loosening group led to a swift increase in C3M, which normalized within 2-3 months. No changes in biomarker level were observed in chronic pain patients over three months.

Conclusion

These findings suggest that tissue damage in a single joint significantly impacts systemic biomarker levels and underscores the relevance of systemic biomarkers in assessing local tissue remodeling.

Evaluation of collagen turnover biomarkers as an objective measure for efficacy of treatment with rurioctocog alfa pegol in patients with hemophilia A: a secondary analysis of a randomized controlled trial

BACKGROUND

Patients with hemophilia who have recurrent hemarthroses develop hemophilic arthropathy (HA). Regular prophylaxis with factor (F) VIII (FVIII) can reduce HA, but there is a need for objective outcome measures to evaluate treatment efficacy.

OBJECTIVES

Evaluate and assess collagen turnover biomarkers in patients with hemophilia A to determine the efficacy of rurioctocog alfa pegol treatment and understand their potential as tools for guiding treatment decisions and monitoring outcomes.

METHODS

Joint remodeling was assessed by analyzing serum levels of collagen remodeling products at baseline and months 3, 6, 9, and 12 in a 98 patient subset receiving pharmacokinetics-guided prophylaxis with rurioctocog alfa pegol, targeting FVIII trough levels of 1 to 3 International Units (IU)/dL or 8 to 12 IU/dL (PROPEL study, NCT0285960).

RESULTS

Basement membrane metabolism-related type 4 collagen remodeling products (C4M and PRO-C4) decreased after 3 months at all time points by up to 25% at 1 to 3 IU/dL (P = .049, P < .0001) and 8 to 12 IU/dL FVIII trough levels (P = .0002, P < .0001). Interstitial tissue metabolism-related type 3 (C3M) and 5 (PRO-C5) collagen remodeling products decreased after 3 months, by up to 19% at 1 to 3 IU/dL FVIII trough level (P = .0001, P = .009) and 23% at 8 to 12 IU/dL FVIII trough level (P = .0002, P = .001). An increase of up to 12% was seen for cartilage metabolism-related type 2 collagen product (PRO-C2, not C2M) after 6 months at both trough levels (P = .01, P = .005). When stratified by prior treatment, changes in C3M (P = .03) and C4M (P = .02) levels were observed between trough levels for prior on-demand treatment but not for prophylaxis prior to study entry.

CONCLUSION

Joint improvement measured by collagen remodeling biomarkers specific to the basement membrane, interstitial matrix, and cartilage was seen with pharmacokinetics-guided prophylaxis. These collagen remodeling biomarkers warrant further exploration as biomarkers to guide treatment toward improvement in HA.

Relevance of Biomarkers in Serum vs. Synovial Fluid in Patients with Knee Osteoarthritis

The association between structural changes and pain sensation in osteoarthritis (OA) remains unclear. Joint deterioration in OA leads to the release of protein fragments that can either systemically (serum) or locally (synovial fluid; SF) be targeted as biomarkers and describe structural changes and potentially pain. Biomarkers of collagen type I (C1M), type II (C2M), type III (C3M), type X (C10C), and aggrecan (ARGS) degradation were measured in the serum and SF of knee OA patients. Spearman's rank correlation was used to assess the correlation of the biomarkers' levels between serum and SF. Linear regression adjusted for confounders was used to evaluate the associations between the biomarkers' levels and clinical outcomes. The serum C1M levels were negatively associated with subchondral bone density. The serum C2M levels were negatively associated with KL grade and positively associated with minimum joint space width (minJSW). The C10C levels in SF were negatively associated with minJSW and positively associated with KL grade and osteophyte area. Lastly, the serum C2M and C3M levels were negatively associated with pain outcomes. Most of the biomarkers seemed to mainly be associated with structural outcomes. The overall biomarkers of extracellular matrix (ECM) remodeling in serum and SF may provide different information and reflect different pathogenic processes.

Assessment of joint pharmacokinetics and consequences for the intraarticular delivery of biologics

Intraarticular (IA) injections provide the opportunity to deliver biologics directly to their site of action for a local and efficient treatment of osteoarthritis. However, the synovial joint is a challenging site of administration since the drug is rapidly eliminated across the synovial membrane and has limited distribution into cartilage, resulting in unsatisfactory therapeutic efficacy. In order to rationally develop appropriate drug delivery systems, it is essential to thoroughly understand the unique biopharmaceutical environments and kinetics in the joint to adequately simulate them in relevant experimental models. This review presents a detailed view on articular kinetics and drug-tissue interplay of IA administered drugs and summarizes how these can be translated into reasonable formulation strategies by identification of key factors through which the joint residence time can be prolonged and specific structures can be targeted. In this way, pros and cons of the delivery approaches for biologics will be evaluated and the extent to which biorelevant models are applicable to gain mechanistic insights and ameliorate formulation design is discussed.

The activation fragment of PAR2 is elevated in serum from patients with rheumatoid arthritis and reduced in response to anti-IL6R treatment

Osteoarthritis (OA) and rheumatoid arthritis (RA) are serious and painful diseases. Protease-activated receptor 2 (PAR2) is involved in the pathology of both OA and RA including roles in synovial hyperplasia, cartilage destruction, osteophyogenesis and pain. PAR2 is activated via cleavage of its N-terminus by serine proteases. In this study a competitive ELISA assay was developed targeting the 36-amino acid peptide that is cleaved and released after PAR2 activation (PRO-PAR2). Technical assay parameters including antibody specificity, intra- and inter-assay variation (CV%), linearity, accuracy, analyte stability and interference were evaluated. PRO-PAR2 release was confirmed after in vitro cleavage of PAR2 recombinant protein and treatment of human synovial explants with matriptase. Serum levels of 22 healthy individuals, 23 OA patients and 15 RA patients as well as a subset of RA patients treated with tocilizumab were evaluated. The PRO-PAR2 antibody was specific for the neo-epitope and intra-inter assay CV% were 6.4% and 5.8% respectively. In vitro cleavage and matriptase treated explants showed increased PRO-PAR2 levels compared to controls. In serum, PRO-PAR2 levels were increased in RA patients and decreased in RA patients treated with tocilizumab. In conclusion, PRO-PAR2 may be a potential biomarker for monitoring RA disease and pharmacodynamics of treatment.

Soluble biological markers in osteoarthritis

In recent years, markers research has focused on the structural components of cartilage matrix. Specifically, a second generation of degradation markers has been developed against type II collagen neoepitopes generated by specific enzymes. A particular effort has been made to measure the degradation of minor collagens III and X of the cartilage matrix. However, because clinical data, including longitudinal controlled studies, are very scarce, it remains unclear whether they will be useful as an alternative to or in combination with current more established collagen biological markers to assess patients with osteoarthritis (OA). In addition, new approaches using high-throughput technologies allowed to detect new types of markers and improve the knowledge about the metabolic changes linked to OA. The relative advances coming from phenotype research are a first attempt to classify the heterogeneity of OA, and several markers could improve the phenotype characterization. These phenotypes could improve the selection of patients in clinical trials limiting the size of the studies by selecting patients with OA characteristics corresponding to the metabolic pathway targeted by the molecules evaluated. In addition, the inclusion of rapid progressors only in clinical trials would facilitate the demonstration of efficacy of the investigative drug to reduce joint degradation. The combination of selective biochemical markers appears as a promising and cost-effective approach to fulfill this unmet clinical need. Among the various potential roles of biomarkers in OA, their ability to monitor drug efficacy is probably one of the most important, in association with clinical and imaging parameters. Biochemical markers have the unique property to detect changes in joint tissue metabolism within a few weeks.

Osteoarthritis: Current Molecular Biomarkers and the Way Forward

The ultimate hope of researchers and patients is a pathway to development of treatments for osteoarthritis to modify the disease process in addition to the symptoms. However, development of disease modifying drugs requires objective endpoints such as measures of joint structure, joint tissue homeostasis and/or joint survival-measures such as provided by imaging biomarkers, molecular biomarkers and joint replacement frequency, respectively. Although biomarkers supporting investigational drug use and drug approval include surrogate endpoints that may not necessarily reflect or directly correlate with the clinical outcome of interest, a formal biomarker qualification process currently exists that is a rigorous three stage process that yields biomarker approvals (or denials) for specific contexts of use. From a cost perspective, biochemical biomarkers are the 'ones to beat'; however, even well-validated biomarkers may not cross the translation gaps for eventual use in healthcare unless they offer an advantage in terms of cost per quality adjusted life year. This review summarizes the case FOR and AGAINST biomarkers in drug development and highlights the current data for a subset of biomarkers in the osteoarthritis research field informing on cartilage homeostasis, joint inflammation and altered subchondral bone remodeling.

A matrix metalloproteinase-generated neoepitope of CRP can identify knee and multi-joint inflammation in osteoarthritis

OBJECTIVE

To compare C-reactive protein (CRP) and matrix metalloproteinase-generated neoepitope of CRP (CRPM) as biomarkers of inflammation and radiographic severity in patients with knee osteoarthritis.

METHODS

Participants with symptomatic osteoarthritis (n=25) of at least one knee underwent knee radiographic imaging and radionuclide etarfolatide imaging to quantify inflammation of the knees and other appendicular joints. For purposes of statistical analysis, semi-quantitative etarfolatide and radiographic imaging scores were summed across the knees; etarfolatide scores were also summed across all joints to provide a multi-joint synovitis measure. Multiple inflammation and collagen-related biomarkers were measured by ELISA including CRP, CRPM, MMP-generated neoepitopes of type I collagen and type III collagen in serum (n=25), and CD163 in serum (n=25) and synovial fluid (n=18).

RESULTS

BMI was associated with CRP (p=0.001), but not CRPM (p=0.753). Adjusting for BMI, CRP was associated with radiographic knee osteophyte score (p=0.002), while CRPM was associated with synovitis of the knee (p=0.017), synovitis of multiple joints (p=0.008), and macrophage marker CD163 in serum (p=0.009) and synovial fluid (p=0.03). CRP correlated with MMP-generated neoepitope of type I collagen in serum (p=0.045), and CRPM correlated with MMP-generated neoepitope of type III collagen in serum (p<0.0001). No biomarkers correlated with age, knee pain, or WOMAC pain.

CONCLUSIONS

To our knowledge, this is the first time that CRPM has been shown to be associated with knee and multi-joint inflammation based on objective imaging (etarfolatide) and biomarker (CD163) measures. These results demonstrate the capability of biomarker measurements to reflect complex biological processes and for neoepitope markers to more distinctly reflect acute processes than their precursor proteins. CRPM is a promising biomarker of local and systemic inflammation in knee OA that is associated with cartilage degradation and is independent of BMI. CRPM is a potential molecular biomarker alternative to etarfolatide imaging for quantitative assessment of joint inflammation.

Fibroblast-like synoviocytes: Role in synovial fibrosis associated with osteoarthritis

The synovial membrane undergoes a variety of structural changes throughout the pathogenesis of osteoarthritis (OA), including the development of fibrosis. Fibroblast-like synoviocytes (FLS) are a heterogenous cell population of the synovium that are suggested to drive the fibrotic response, but the exact mechanisms associated with their activation in OA remain unclear. Once activated, FLS are suggested to acquire a myofibroblast-like phenotype that drives fibrogenesis through excessive extracellular matrix (ECM) component deposition and an enhanced contractile function. In this review, we define FLS in the synovium, discuss how select extracellular or endogenous factors potentially induce their activation in OA, and describe how the activity of myofibroblast-like cells affects the structure of the synovial membrane.

An ex-vivo model for transsynovial drug permeation of intraarticular injectables in naive and arthritic synovium

Estimation of joint residence time of a drug is a key requirement for rational development of intraarticular therapeutics. There is a great need for a predictive model to reduce the high number of animal experiments in early stage development. Here, a Franz-cell based porcine ex-vivo permeation model is proposed, and transsynovial permeation of fluorescently-labeled dextrans in the range of potential drug candidates (10-150 kDa), as well as a small molecule (fluorescein sodium) and charged dextran derivates, have been determined. In addition, a lipopolysaccharide (LPS) -induced synovitis model was assessed for inflammatory biomarker levels and its effect on permeation of the solutes. Size-dependent permeability was observed for the analytes, which distinctly differed from findings with an artificial polycarbonate membrane, which is a widely used model. LPS was found to successfully stimulate an inflammatory response and led to a reduced size selectivity of the synovial membrane. 150 kDa dextran flux was accelerated approximately 2.5-fold in the inflamed state, whereas the permeation of smaller molecules was little affected. Moreover, by varying the LPS concentrations, the ex-vivo model was shown to produce varying degrees of synovitis-like inflammation. A simple and highly relevant ex-vivo tool for investigation of transsynovial permeation was developed, offering the further advantage of mimicking synovitis-induced permeability changes. Thus, this model provides a promising method for formulation screening, while reducing the need for animal experiments.

Recent advances of novel technologies for quality consistency assessment of natural herbal medicines and preparations

Quality consistency is one of the basic attributes of medicines, but it is also a difficult problem that natural medicines and their preparations must face. The complex chemical composition and comprehensive pharmacological action of natural medicines make it difficult to simply apply the commonly used evaluation methods in chemical drugs. It is thus urgent to explore the novel evaluation methods suitable for the characteristics of natural medicines. With the rapid development of analytical techniques and the deepening understanding of the quality of natural herbs, increasing numbers of researchers have proposed many new ideas and technologies. This review mainly focuses on the basic principles, technical characteristics and application examples of the chemical evaluation, biological evaluation methods and their combination in quality consistency evaluation of natural herbs. On the bases of chemical evaluation and clinical efficacy, new methods reflecting their pharmacodynamic mechanism and safety characteristics will be developed, and gradually towards accurate quality control, to achieve the goal of quality consistency. We hope that this manuscript can provide new ideas and technical references for the quality consistency of natural drugs and their preparations, thus better guarantee their clinical efficacy and safety, and better promote industrial development.

Inflammation and joint destruction may be linked to the generation of cartilage metabolites of ADAMTS-5 through activation of toll-like receptors

OBJECTIVE

Links between pain and joint degradation are poorly understood. We investigated the role of activation of Toll-like receptors (TLR) by cartilage metabolites in initiating and maintaining the inflammatory loop in OA causing joint destruction.

METHODS

Synovial membrane explants (SMEs) were prepared from OA patients' synovial biopsies. SMEs were cultured for 10 days under following conditions: culture medium alone, OSM + TNFα, TLR2 agonist - Pam2CSK4, Pam3CSK4 or synthetic aggrecan 32-mer, TLR4 agonist - Lipid A. Release of pro-inflammatory and degradation biomarkers (acMMP3 and C3M) were measured by ELISA in conditioned media along with IL-6. Additionally, human cartilage was digested with ADAMTS-5, with or without the ADAMTS-5 inhibiting nanobody - M6495. Digested cartilage solution (DCS) and synthetic 32-mer were tested for TLR activation in SEAP based TLR reporter assay.

RESULTS

Western blotting confirmed TLR2 and TLR4 in untreated OA synovial biopsies. TLR agonists showed an increase in release of biomarkers - acMMP3 and C3M in SME. Synthetic 32-mer showed no activation in the TLR reporter assay. ADAMTS-5 degraded cartilage fragments activated TLR2 in vitro. Adding M6495 - an anti-ADAMTS-5 inhibiting nanobody®, blocked ADAMTS-5-mediated DCS TLR2 activation.

CONCLUSION

TLR2 is expressed in synovium of OA patients and their activation by synthetic ligands causes increased tissue turnover. ADAMTS-5-mediated cartilage degradation leads to release of aggrecan fragments which activates the TLR2 receptor in vitro. M6495 suppressed cartilage degradation by ADAMTS-5, limiting the activation of TLR2. In conclusion, pain and joint destruction may be linked to generation of ADAMTS-5 cartilage metabolites.

Molecular taxonomy of osteoarthritis for patient stratification, disease management and drug development: biochemical markers associated with emerging clinical phenotypes and molecular endotypes

PURPOSE OF REVIEW

This review focuses on the molecular taxonomy of osteoarthritis from the perspective of molecular biomarkers. We discuss how wet biochemical markers may be used to understand disease pathogenesis and progression and define molecular endotypes of osteoarthritis and how these correspond to clinical phenotypes.

RECENT FINDINGS

Emerging evidence suggests that osteoarthritis is a heterogeneous and multifaceted disease with multiple causes, molecular endotypes and corresponding clinical phenotypes. Biomarkers may be employed as tools for patient stratification in clinical trials, enhanced disease management in the primary care centres of the future and for directing more rational and targeted osteoarthritis drug development. Proximal molecular biomarkers (e.g synovial fluid) are more likely to distinguish between molecular endotypes because there is less interference from systemic sources of biomarker noise, including comorbidities.

SUMMARY

In this review, we have focused on the molecular biomarkers of four distinct osteoarthritis subtypes including inflammatory, subchondral bone remodelling, metabolic syndrome and senescent age-related endotypes, which have corresponding phenotypes. Progress in the field of osteoarthritis endotype and phenotype research requires a better understanding of molecular biomarkers that may be used in conjunction with imaging, pain and functional assessments for the design of more effective, stratified and individualized osteoarthritis treatments.

Blood and urinary collagen markers in osteoarthritis: markers of tissue turnover and disease activity

Introduction: The need for diagnostic markers in osteoarthritis (OA) is acute and immediate, as sensitive and precise tools that monitor disease activity and treatment response are lacking. Collagens - types I, II, and III - are the skeleton of the extracellular matrix of joint tissues. Joint collagens are generally turned over at a low rate, but the balance between formation and degradation is disturbed, leading to the loss of, for example, cartilage.Areas covered: We discuss the markers reflecting collagen turnover and provide examples of how they have been applied in OA research, as well as how we believe these should be used in the future. We have searched PubMed for full-text articles written in English using different combinations of the following terms: OA, biomarker, and collagen. The result is a narrative review that gives examples from the literature.Expert opinion: Collagen markers show promise, as they are direct measures of tissue balance. Until now, collagen markers have mainly been tested in observational cohorts, which may provide insights into the association between the candidate marker and clinical variables; however, these do not advance the development of qualified markers that can be used for drug development or in clinical practice.

Metabolites of type I, II, III, and IV collagen may serve as markers of disease activity in axial spondyloarthritis

Local inflammation in axial spondyloarthritis (axSpA) leads to the release of collagen metabolites from the disease-affected tissue. We investigated whether collagen metabolites were associated with disease activity and could distinguish non-radiographic(nr)-axSpA from ankylosing spondylitis (AS). A total of 193 axSpA patients (nr-axSpA, n = 121 and AS, n = 72) and asymptomatic controls (n = 100) were included. Serum levels of metalloproteinase (MMP)-degraded collagen type I (C1M), type II (C2M), type III (C3M) and type IV (C4M2) were quantified by enzyme-linked immunosorbent assay (ELISA). All metabolites were higher in axSpA than in controls (all p < 0.001). Serum levels of C1M, C3M, and C4M2 were increased in AS compared to nr-axSpA (43.4 ng/mL vs. 34.6; p < 0.001, 15.4 vs. 12.8; p = 0.001, and 27.8 vs. 22.4; p < 0.001). The best metabolite to differentiate between axSpA and controls was C3M (AUC 0.95; specificity 92.0, sensitivity 83.4). C1M correlated with ASDAS-CRP in nr-axSpA (ρ = 0.37; p < 0.001) and AS (ρ = 0.57; p < 0.001). C1M, C3M, and C4M2 were associated with ASDAS-CRP in AS and nr-axSpA after adjustment for age, gender, and disease duration. Serum levels of collagen metabolites were significantly higher in AS and nr-axSpA than in controls. Moreover, the present study indicates that collagen metabolites reflect disease activity and are useful biomarkers of axSpA.

Novel Hybrid Gels Made of High and Low Molecular Weight Hyaluronic Acid Induce Proliferation and Reduce Inflammation in an Osteoarthritis In Vitro Model Based on Human Synoviocytes and Chondrocytes

High molecular weight hyaluronan (H-HA) has a pivotal role in the maintenance of normal functions of synovial fluid and structure of the articular joint, but it has been shown that its concentration is reduced in patients affected by degenerative cartilage diseases, such as osteoarthritis (OA). The aim of this study was to investigate the anti-inflammatory effects and properties of hybrid cooperative complexes based on high and low molecular weight hyaluronan (HCC) compared to H-HA on human primary cells derived by pathological joints. In addition, the rheological behavior of HCC was evaluated in order to define their potential as viscosupplement gel in degenerated joints. The experiments were performed using an in vitro model of OA based on human chondrocytes and synoviocytes isolated from degenerated joints of patients hospitalized for surgical replacement. In order to assess the anti-inflammatory effects of HCC, we evaluated NF-kB, COMP-2, IL-6, and IL-8 as specific markers at the transcriptional and/or protein level. Moreover, the proliferative properties of HCC were assessed using time lapse video microscopy. We showed that chondrocytes and synoviocytes clearly presented an altered cytokine profile compatible with a severe ongoing inflammation status. H-HA and, above all, HCC significantly reduced levels of the specific biomarkers evaluated and improved cartilage healing. The rheological profile indicated HCC suitability for intra-articular injection in joint diseases. HCC viscoelastic properties and the protective/anti-inflammatory effect on human chondrocytes and synoviocytes suggest the novel HCC-based gels as a valid support for OA management.

Serological biomarker profiles of rapidly progressive osteoarthritis in tanezumab-treated patients

There is a need for efficacious and safe pain treatments for OA (osteoarthritis). The nerve growth factor (NGF) antibody tanezumab is associated with high efficacy, but when combined with chronic NSAID treatment shows an increased risk of rapidly progressive osteoarthritis (RPOA) in a small group of patients.

AIM

The aim of this study was to phenotype with biochemical biomarkers of bone, cartilage, soft tissue, synovial metabolism OA patients who are at risk of developing RPOA type-2, for both limited and chronic NSAIDs users.

MATERIAL AND METHODS

The dataset consisted of OA patients participating in tanezumab trials who used NSAIDs <90 days (limited NSAID users) or chronic users (NSAIDs ≥90 days) over an average 10 month period. Biomarker data were available for 47 cases (RPOA type-2) and 92 controls. Non-linear and linear multivariable predictive models were developed.

RESULTS

By use of two biomarkers at baseline the receiver operating characteristic (ROC) curve area for RPOA type-2 in limited NSAID users was 71%, [CI] (60-83%). OA subjects with this biomarker phenotype had 8-fold higher confidence interval [CI][(2-33)] relative risk of developing RPOA type-2 as compared to OA patients without this phenotype. The AUC of the model in chronic NSAIDs users based on 5 biomarkers was 78%, [CI](69-88%), with 4-fold [CI (2-6)] relative risk of developing RPOA type-2.

CONCLUSION

In this hypothesis generating and exploratory study, we identified combinations of biomarkers associated with OA patients who develop RPOA type-2, which may be related to the pathology of the RPOA type-2 joint.

Tissue metabolite of type I collagen, C1M, and CRP predicts structural progression of rheumatoid arthritis

Background

Biomarkers of rheumatoid arthritis (RA) disease activity typically measure inflammation or autoimmunity (e.g. CRP, RF). C1M and C3M, metabolites of type I and III collagen, are markers reflecting tissue metabolism. These markers have been documented to provide additional prognostic and predictive value compared to commonly used biomarkers. We investigated the relationship of high serum levels of C1M or C3M to radiographic progression, and benchmarked them to CRP and RF.

Methods

Placebo treated patients of the OSK1, 2 and 3 studies (Phase III clinical trials testing efficacy of fostamatinib) with baseline serum biomarkers C1M, C3M, CRP and RF were included (n_BL = 474). Van der Heijde mTSS was calculated at baseline and 24-week (n₂₄ = 261). Progression was defined as moderate or rapid by ΔmTSS ≥0.5 or ≥ 5 units/year. Patients were divided into subgroups; low (L), high (H) or very high (V) C1M, C3M and CRP, or RF negative, positive and high positive. Difference in clinical parameters were analyzed by Mann-Whitney or χ²tests, and modelling for prediction of progression by logistic regression including covariates (age, gender, BMI, and clinical assessment scores).

Results

Levels of C1M, C3M, CRP and RF were significantly (p < 0.05) associated with measures of disease activity and mTSS at baseline. For prognostic measures, there were 2.5 and 4-fold as many rapid progressors in the C1M_H and CRP_H (p < 0.05), and in the C1M_V and CRP_V groups (p < 0.001) compared C1M_L and CRP_L, respectively. C1M and CRP performed similarly in the predictive analysis, where high levels predicted moderate and rapid progression with odds ratio of 2.1 to 3.8 and 3.7 to 13.1 after adjustment for covariates. C3M and RF did not provide prognostic value alone.

Discussion

Serum C1M and CRP showed prognostic value and may be tools for enrichment of clinical trials with structural progressor. The two markers reflect two different aspect of disease pathogenesis (tissue turnover vs. inflammation), thus may provide individual and supplementary information.

Electronic supplementary material

The online version of this article (10.1186/s41927-019-0052-0) contains supplementary material, which is available to authorized users.

Translational Biomarkers and Ex Vivo Models of Joint Tissues as a Tool for Drug Development in Rheumatoid Arthritis

Objective

Rheumatoid arthritis (RA) is a chronic and degenerative autoimmune joint disease that leads to disability, reduced quality of life, and increased mortality. Although several synthetic and biologic disease‐modifying antirheumatic drugs are available, there is still a medical need for novel drugs that control disease progression. As only 10% of experimental drug candidates for treatment of RA that enter phase I trials are eventually registered by the Food and Drug Administration, there is an immediate need for translational tools to facilitate early decision‐making in drug development. In this study, we aimed to determine if the inability of fostamatinib (a small molecule inhibitor of Syk) to demonstrate sufficient efficacy in phase III of a previous clinical study could have been predicted earlier in the development process.

Methods

Biomarkers of bone, cartilage, and interstitial matrix turnover (C‐telopeptide of type I collagen [CTX‐I], matrix metalloproteinase–derived types I, II, and III collagen neoepitopes [C1M, C2M, and C3M]) were measured in 450 serum samples from the Oral Syk Inhibition in Rheumatoid Arthritis 1 study (OSKIRA‐1, a phase III clinical study of the efficacy of fostamatinib in RA) at baseline and follow‐up. Additionally, the same biomarkers were subsequently measured in conditioned media from osteoclast, cartilage, and synovial membrane cultured with the active metabolite of fostamatinib, R406, to assess the level of suppression induced by the drug.

Results

In OSKIRA‐1 serum samples and osteoclast and cartilage cultures, fostamatinib suppressed the levels of CTX‐I and C2M. In OSKIRA‐1 serum samples and synovial membrane cultures, fostamatinib did not mediate any clinical or preclinical effect on either C1M or C3M, which have previously been associated with disease response and efficacy.

Conclusion

These data demonstrate that translational biomarkers are a potential tool for early assessment and decision‐making in drug development for RA treatment.

Differential involvement of synovial adipokines in pain and physical function in female patients with knee osteoarthritis. A cross-sectional study

OBJECTIVE

Adipokines have been reported to play a role in the development, progression and severity of knee osteoarthritis but the influence of the different adipokines are not well known. The aim of this study was to evaluate the association between different synovial fluid adipokines with pain and disability knee osteoarthritis patients.

METHODS

Cross-sectional study with systematic inclusion of 115 symptomatic primary knee osteoarthritis female patients with ultrasound-confirmed joint effusion. Age, physical exercise, symptoms duration and different anthropometric measurements were collected. Radiographic severity was evaluated according to Kellgren-Lawrence scale. Pain and disability were assessed by WOMAC-total, -pain, -function subscales and Knee injury and Osteoarthritis Outcome Score (KOOS) pain and function scales. Seven adipokines and three inflammatory markers were measured by ELISA in synovial fluid. Partial Correlation Coefficient (PCC) and corresponding 95% confidence interval were used as a measure of association.

RESULTS

Leptin, osteopontin and inflammatory factors, especially TNF-alpha, were associated to pain and function. After adjustment for potential confounders including inflammatory factors and all adipokines, an association was found for adiponectin with pain (PCC 0.240 [0.012, 0.444]) and for resistin and visfatin with function (PCC 0.336 [0.117, 0.524] and -0.262 [-0.463, -0.036]). No other adipokines or inflammatory markers were statistically and independently associated. An association between physical exercise and pain and disability remained after adjustment, whereas an attenuation of the influence of anthropometric measurements was observed.

CONCLUSIONS

Different patterns of association between synovial fluid adipokines were observed regarding pain and disability in knee osteoarthritis patients. Specifically, adiponectin was associated to pain while resistin and visfatin were mainly related to function.

Effects of dietary weight loss with and without exercise on interstitial matrix turnover and tissue inflammation biomarkers in adults with knee osteoarthritis: the Intensive Diet and Exercise for Arthritis trial (IDEA)

OBJECTIVE

To examine the effects of dietary weight loss, with and without exercise, on selected soluble biomarkers in overweight and obese older adults with symptomatic knee osteoarthritis (OA).

DESIGN

Blood samples were analyzed from 429 participants in the Intensive Diet and Exercise for Arthritis (IDEA) trial randomized to either an 18 month exercise control group (E), weight loss diet (D), or D + E. C1M, C2M, C3M and CRPM biomarkers and interleukin-6 (IL-6) were quantitated using ELISAs. Radiographic progression was defined as a decrease in joint space width of ≥0.7 mm. Statistical modeling of group means and associations used mixed models adjusted for visit, baseline body mass index (BMI), gender, and baseline values of the outcome.

RESULTS

Compared to the E control group, C1M was significantly lower in the D and D + E groups at both 6 and 18 months while C3M was significantly lower in D and D + E at 6 months and in D + E at 18 months. C2M did not change in any group. Using data from all groups, change in C1M (P < 0.0001), C3M (P < 0.0001), as well as CRPM (P = 0.0004) from baseline to 18 months was positively associated with change in weight. No marker was associated with change in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain or radiographic progression. C3M (P = 0.008) and CRPM (P = 0.028) were positively associated with change in WOMAC function. Change in IL-6 was positively associated with change in C1M, C3M, and CRPM.

CONCLUSION

Overweight and obese adults with knee OA who lost weight from diet and diet plus exercise reduced serum markers of interstitial matrix turnover and inflammation but not type II collagen degradation.

Matrix Metalloproteinases and Synovial Joint Pathology

Matrix metalloproteinases (MMPs) are zinc-dependent enzymes. These enzymes play a critical role in the destruction of articular cartilage in rheumatoid arthritis (RA), osteoarthritis (OA), psoriatic arthritis (PsA), and the spondyloarthropathies. MMP gene expression is upregulated in these synovial joint pathologies in response to elevated levels of proinflammatory cytokines and soluble mediators such as tumor necrosis factor-α, interleukin-1 (IL-1), IL-6, IL-17, and interferon-γ. These molecules are capable of activating the mitogen-activated protein kinase and Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathways by binding the cytokine to their respective receptors on immune cells, macrophages, chondrocytes, synoviocytes, and osteocytes leading to increased synthesis of MMPs. Biologic drugs and/or small-molecule inhibitors designed to block cytokine to cytokine receptor interactions or to selectively inhibit JAKs have clinical efficacy in RA, PsA, and ankylosing spondylitis which correlated with a reduction in MMPs. Although there are currently no OA-selective drugs, it is likely that such a drug would have to reduce MMP gene expression to have clinical efficacy.

Osteoarthritis Year in Review 2016: biomarkers (biochemical markers)

PURPOSE

The aim of this "Year in Review" article is to summarize and discuss the implications of biochemical marker related articles published between the Osteoarthritis Research Society International (OARSI) 2015 Congress in Seattle and the OARSI 2016 Congress in Amsterdam.

METHODS

The PubMed/MEDLINE bibliographic database was searched using the combined keywords: 'biomarker' and 'osteoarthritis'. The PubMed/MEDLINE literature search was conducted using the Advanced Search Builder function (http://www.ncbi.nlm.nih.gov/pubmed/advanced).

RESULTS

Over two hundred new biomarker-related papers were published during the literature search period. Some papers identified new biomarkers whereas others explored the biological properties and clinical utility of existing markers. There were specific references to several adipocytokines including leptin and adiponectin. ADAM Metallopeptidase with Thrombospondin Type 1 motif 4 (ADAMTS-4) and aggrecan ARGS neo-epitope fragment (ARGS) in synovial fluid (SF) and plasma chemokine (CeC motif) ligand 3 (CCL3) were reported as potential new knee biomarkers. New and refined proteomic technologies and novel assays including a fluoro-microbead guiding chip (FMGC) for measuring C-telopeptide of type II collagen (CTX-II) in serum and urine and a novel magnetic nanoparticle-based technology (termed magnetic capture) for collecting and concentrating CTX-II, were described this past year.

CONCLUSION

There has been steady progress in osteoarthritis (OA) biomarker research in 2016. Several novel biomarkers were identified and new technologies have been developed for measuring existing biomarkers. However, there has been no "quantum leap" this past year and identification of novel early OA biomarkers remains challenging. During the past year, OARSI published a set of recommendations for the use of soluble biomarkers in clinical trials, which is a major step forward in the clinical use of OA biomarkers and bodes well for future OA biomarker development.

Biomarkers of (osteo)arthritis

Arthritic diseases are a major cause of disability and morbidity, and cause an enormous burden for health and social care systems globally. Osteoarthritis (OA) is the most common form of arthritis. The key risk factors for the development of OA are age, obesity, joint trauma or instability. Metabolic and endocrine diseases can also contribute to the pathogenesis of OA. There is accumulating evidence to suggest that OA is a whole-organ disease that is influenced by systemic mediators, inflammaging, innate immunity and the low-grade inflammation induced by metabolic syndrome. Although all joint tissues are implicated in disease progression in OA, articular cartilage has received the most attention in the context of aging, injury and disease. There is increasing emphasis on the early detection of OA as it has the capacity to target and treat the disease more effectively. Indeed it has been suggested that this is the era of "personalized prevention" for OA. However, the development of strategies for the prevention of OA require new and sensitive biomarker tools that can detect the disease in its molecular and pre-radiographic stage, before structural and functional alterations in cartilage integrity have occurred. There is also evidence to support a role for biomarkers in OA drug discovery, specifically the development of disease modifying osteoarthritis drugs. This Special Issue of Biomarkers is dedicated to recent progress in the field of OA biomarkers. The papers in this Special Issue review the current state-of-the-art and discuss the utility of OA biomarkers as diagnostic and prognostic tools.