Recent progress toward biomarker identification in osteoarthritis

Potential therapeutic strategies for osteoarthritis via CRISPR/Cas9 mediated gene editing

Osteoarthritis (OA) is an incapacitating and one of the most common physically degenerative conditions with an assorted etiology and a highly complicated molecular mechanism that to date lacks an efficient treatment. The capacity to design biological networks and accurately modify existing genomic sites holds an apt potential for applications across medical and biotechnological sciences. One of these highly specific genomes editing technologies is the CRISPR/Cas9 mechanism, referred to as the clustered regularly interspaced short palindromic repeats, which is a defense mechanism constituted by CRISPR associated protein 9 (Cas9) directed by small non-coding RNAs (sncRNA) that bind to target DNA through Watson-Crick base pairing rules where subsequent repair of the target DNA is initiated. Up-to-date research has established the effectiveness of the CRISPR/Cas9 mechanism in targeting the genetic and epigenetic alterations in OA by suppressing or deleting gene expressions and eventually distributing distinctive anti-arthritic properties in both in vitro and in vivo osteoarthritic models. This review aims to epitomize the role of this high-throughput and multiplexed gene editing method as an analogous therapeutic strategy that could greatly facilitate the clinical development of OA-related treatments since it's reportedly an easy, minimally invasive technique, and a comparatively less painful method for osteoarthritic patients.

Biomarkers for Osteoarthritis Diseases

Growing evidence has revealed the pivotal role of inflammatory biomarkers in the pathogenesis of osteoarthritis. There is significant interest in the prognostic value of select biomarkers, given the potential for early identification and treatment of patients at risk of osteoarthritis prior to the development of irreversible clinical disease. Clinical trials of novel therapeutics that disrupt the inflammatory pathways of osteoarthritis are also ongoing. The purpose of this review is to summarize the current literature on key biomarkers within the context of osteoarthritis pathogenesis, clinical symptom development, and treatment capabilities. Multiple recent studies have established biomarkers that signal the existence of osteoarthritis pathology and the development of clinical symptomology. However, prior to implementation in clinical practice, additional research is required to precisely define the prognostic value for numerous biomarkers and standardize their measurement. Biomarker-driven investigations represent a promising avenue for the early diagnosis and treatment of osteoarthritis.

Emerging role of lncRNAs in osteoarthritis: An updated review

Osteoarthritis (OA) is a prevalent joint disease, which is associated with progressive articular cartilage loss, synovial inflammation, subchondral sclerosis and meniscus injury. The molecular mechanism underlying OA pathogenesis is multifactorial. Long non-coding RNAs (lncRNAs) are non-protein coding RNAs with length more than 200 nucleotides. They have various functions such as modulating transcription and protein activity, as well as forming endogenous small interfering RNAs (siRNAs) and microRNA (miRNA) sponges. Emerging evidence suggests that lncRNAs might be involved in the pathogenesis of OA which opens up a new avenue for the development of new biomarkers and therapeutic strategies. The purpose of this review is to summarize the current clinical and basic experiments related to lncRNAs and OA with a focus on the extensively studied H19, GAS5, MALAT1, XIST and HOTAIR. The potential translational value of these lncRNAs as therapeutic targets for OA is also discussed.

Metabolic signatures of osteoarthritis in urine using liquid chromatography-high resolution tandem mass spectrometry

INTRODUCTION

Osteoarthritis (OA) is a common cause of disability in older people, but its aetiology is not yet fully understood. Biomarkers of OA from metabolomics studies have shown potential use in understanding the progression and pathophysiology of OA.

OBJECTIVES

To investigate possible surrogate biomarkers of knee OA in urine using metabolomics to contribute towards a better understanding of OA progression and possible targeted treatment.

METHOD

Liquid chromatography-high resolution mass spectrometry (LC-HRMS) was applied in a case-control approach to explore the possible metabolic differences between the urinary profiles of symptomatic knee OA patients (n = 74) (subclassified into inflammatory OA, n = 22 and non-inflammatory OA, n = 52) and non-OA controls (n = 68). Univariate, multivariate and pathway analyses were performed with a rigorous validation including cross-validation, permutation test, prediction and receiver operating characteristic curve to identify significantly altered metabolites and pathways in OA.

RESULTS

OA datasets generated 7405 variables and multivariate analysis showed clear separation of inflammatory OA, but not non-inflammatory OA, from non-OA controls. Adequate cross-validation (R²Y = 0.874, Q² = 0.465) was obtained. The prediction model and the ROC curve showed satisfactory results with a sensitivity of 88%, specificity of 71% and accuracy of 77%. 26 metabolites were identified as potential biomarkers of inflammatory OA using HMDB, authentic standards and/or MS/MS database.

CONCLUSION

Urinary metabolic profiles were altered in inflammatory knee OA subjects compared to those with non-inflammatory OA and non-OA controls. These altered profiles associated with perturbed activity of the TCA cycle, pyruvate and amino acid metabolism linked to inflammation, oxidative stress and collagen destruction. Of note, 2-keto-glutaramic acid level was > eightfold higher in the inflammatory OA patients compared to non-OA control, signalling a possible perturbation in glutamine metabolism related to OA progression.

Serum Biomarkers of Inflammation and Turnover of Joint Cartilage Can Help Differentiate Psoriatic Arthritis (PsA) Patients from Osteoarthritis (OA) Patients

The aim of this study was to find characteristic biomarkers in the serum of patients with osteoarthritis (OA) and psoriatic arthritis (PsA) responsible for inflammation and destruction of joint cartilage, which could differentiate these two diseases. The study included 67 people: 22 patients with knee OA, 22 patients with PsA, and 23 individuals who were the control group of healthy individuals (HC). The concentration of IL-18, IL-20, IL-6, MMP-1, MMP-3, COMP, PG-AG, and YKL-40 in serum were determined. Among the OA and PsA patients group, the radiological assessment and clinical assessment were also performed. The concentration of 7 out of 8 of examined biomarkers (except MMP-1) was statistically significantly higher in the serum of patients with OA and PsA than in the control group. Compering OA and PsA groups only, the serum PG-AG level in OA patients was statistically significantly higher than in PsA patients (p < 0.001). The results of univariate and multivariate logistic regression analysis comparing OA and PsA biomarker serum levels identified PG-AG and COMP as markers that are significantly different between patients with OA and PsA (odds ratio 0.995 and 1.003, respectively). The ROC curve constructed using the model with age showed PG-AG and COMP had an AUC of 0.907. The results of this study show that COMP and PG-AG may be sensitive markers differentiating patients with osteoarthiritis from psoriatic arthritis.

Locomotion replacement exercise cannot counteract cartilage biomarker response to 5 days of immobilization in healthy adults

Biomarkers of cartilage metabolism are sensitive to changes in the biological and mechanical environment and can indicate early changes in cartilage homeostasis. The purpose of this study was to determine if a daily locomotion replacement program can serve as a countermeasure for changes in cartilage biomarker serum concentration caused by immobilization. Ten healthy male subjects (mean ± 1 standard deviation; age: 29.4 ± 5.9 years; body mass: 77.7 ± 4.1 kg) participated in the crossover 5-day bed rest study with three interventions: control (CON), standing (STA), and locomotion replacement training (LRT). Serum samples were taken before, during, and after bed rest. Biomarker concentrations were measured using commercial enzyme-linked immunosorbent assays. Cartilage oligomeric matrix protein (COMP) levels after 24 hours of bed rest decreased independently of the intervention (-16.8% to -9.8%) and continued to decrease until 72 hours of bed rest (minimum, -23.2% to -20.6%). LRT and STA did not affect COMP during bed rests (P = .056) but there was a strong tendency for a slower decrease with LRT (-9.4%) and STA (-11.7%) compared with CON (-16.8%). MMP-3 levels decreased within the first 24 hours of bed rest (CON: -22.3%; STA: -14.7%; LRT: -17%) without intervention effect. Both COMP and MMP-3 levels recovered to baseline levels during the 6-day recovery period. MMP-1, MMP-9, and TNF-α levels were not affected by immobilization or intervention. COMP and MMP-3 are mechano-sensitive cartilage biomarkers affected by immobilization, and simple interventions such as standing upright or LRT during bed rest cannot prevent these changes. Clinical significance: simple locomotion interventions cannot prevent cartilage biomarker change during bed rest.

L-Theanine Reduced the Development of Knee Osteoarthritis in Rats via Its Anti-Inflammation and Anti-Matrix Degradation Actions: In Vivo and In Vitro Study

The etiology of osteoarthritis (OA) is multifactorial, with no effective disease-modifying-drugs. L-theanine has been reported to inhibit inflammatory responses in some diseases and this study aimed to investigate the effect of L-theanine on Interleukin-1(IL-1)β-stimulated chondrocytes, and in an injury-induced OA rat model. Primary chondrocytes were stimulated by IL-1β (10 ng/mL) for 24 h and then co-cultured with L-theanine for 24 h. The effects of L-theanine on IL-1β-stimulated expression of pro-inflammatory cytokines and hydrolytic enzyme were analyzed using Western blotting, quantitative polymerase chain reaction (q-PCR) and enzyme-linked immunosorbent assay (ELISA) kits. An immunofluorescence assay was used to detect nuclear factor kappa B (NF-κB) phosphorylation. OA was induced by anterior cruciate ligament transection (ACLT) surgery in rats and celecoxib was used as a positive control. OA severity was measured using the Osteoarthritis Research Society International (OARSI) grading system to describe histological changes. The results showed that L-theanine decreased the expression of pro-inflammatory mediators, including cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE-2), inducible nitric oxide synthase (iNOS), and nitric oxide (NO), both in vivo and in vitro. L-theanine treatment inhibited IL-1β-induced upregulation of matrix metalloproteinases (MMP)-3 and MMP-13, as well as inhibited NF-κB p65 activation. In vivo animal model showed that L-theanine administration (200 mg/kg) significantly alleviated OA lesions and decreased OARSI score. Our data indicated that L-theanine decreased inflammatory cytokines and protected extracellular matrix degradation through inhibition of the NF-κB pathway, and L-theanine may be considered a promising therapeutic strategy in OA prevention.

Circulating glucuronic acid predicts healthspan and longevity in humans and mice

Glucuronic acid is a metabolite of glucose that is involved in the detoxification of xenobiotic compounds and the structure/remodeling of the extracellular matrix. We report for the first time that circulating glucuronic acid is a robust biomarker of mortality that is conserved across species. We find that glucuronic acid levels are significant predictors of all-cause mortality in three population-based cohorts from different countries with 4-20 years of follow-up (HR=1.44, p=2.9×10^-6 in the discovery cohort; HR=1.13, p=0.032 and HR=1.25, p=0.017, respectively in the replication cohorts), as well as in a longitudinal study of genetically heterogenous mice (HR=1.29, p=0.018). Additionally, we find that glucuronic acid levels increase with age and predict future healthspan-related outcomes. Together, these results demonstrate glucuronic acid as a robust biomarker of longevity and healthspan.

Correlation between synovial fluid cytokine concentrations and limb function in normal dogs and in dogs with lameness from spontaneous osteoarthritis

OBJECTIVE

To determine the relationship between synovial biomarker concentrations and severity of lameness and to assess the ability to differentiate normal from osteoarthritic joints with synovial biomarker concentrations.

STUDY DESIGN

Prospective clinical study.

SAMPLE POPULATION

Twelve hounds with no evidence of osteoarthritis (OA) and 27 client-owned dogs with unilateral lameness and joint pain in a single joint from naturally occurring OA.

METHODS

Enrollment in the OA group required a history of lameness, radiographic evidence of OA on orthogonal joint radiographs, and ≥6% gait asymmetry between contralateral limbs. The concentrations of 14 synovial OA biomarkers in synovial samples obtained after gait analysis were measured with enzyme-linked immunosorbent assays and compared between normal and OA joints.

RESULTS

Concentrations of monocyte chemoattractant protein (MCP)-1, substance P, interleukin (IL)-6, IL-8, KC-like, matrix metalloproteinase (MMP)-1, and MMP-3 were greater (P ≤ .05) in OA than in normal joints. The concentrations of bradykinin and tissue inhibitors of metalloproteinase-4 were decreased in OA compared with normal joints. Monocyte chemoattractant protein 1 was identified as the most accurate marker to distinguish OA from normal joints. No correlation was detected between any OA biomarker concentration, individually or in combination, and severity of gait asymmetry at the walk.

CONCLUSION

Differences in proinflammatory and anti-inflammatory biomarkers were detected between OA and normal joints, but no relationship was identified between biomarker concentrations and gait asymmetry in dogs with OA.

CLINICAL IMPACT

This information will help guide future studies to elucidate how factors such as disease chronicity, severity, and etiology affect these relationships.

Amino Acid Profile of Synovial Fluid Following Intra-articular Ankle Fracture

BACKGROUND

Post-traumatic osteoarthritis (PTOA) is a frequent complication in patients with a previous traumatic joint injury, and the pathophysiology is not well understood. The goal of this study was to characterize the biochemical signature of amino acids, peptides, and amino acid metabolites in ankle synovial fluid following intra-articular fracture.

METHODS

Synovial fluid from both the injured and contralateral ankles of 19 patients with an intra-articular ankle fracture was obtained and analyzed via metabolic profiling. Follow-up analysis was performed after 6 months in 7 of these patients.

RESULTS

Statistical comparisons between injured and contralateral ankles revealed that 19 of the 66 measured amino acids, peptides, and amino acid metabolites were significantly elevated at time of fracture. Metabolites associated with glutathione metabolism exhibited the most elevated mean-fold changes, indicating a possible role for oxidative stress in fractured ankles. None of the metabolites elevated at baseline were significantly elevated after 6 months, but 6 metabolites had mean-fold changes greater than 2.1 at this time point. Multiple metabolites also exhibited significant correlations ( r > 0.575) with matrix metalloproteinase-1 and -9.

CONCLUSION

These results indicate the presence of amino acid metabolic products in the setting of ankle fracture and suggest that these changes in amino acid metabolism may be chronic and indicate a role for inflammation and collagen degradation in disease progression.

CLINICAL RELEVANCE

Changes in amino acid metabolism following intra-articular fracture may contribute to the progression to PTOA. This knowledge may allow for the identification and early treatment of patients at risk of developing PTOA.

LEVEL OF EVIDENCE

Level III, comparative series.

Developing a toolkit for the assessment and monitoring of musculoskeletal ageing

The complexities and heterogeneity of the ageing process have slowed the development of consensus on appropriate biomarkers of healthy ageing. The Medical Research Council–Arthritis Research UK Centre for Integrated research into Musculoskeletal Ageing (CIMA) is a collaboration between researchers and clinicians at the Universities of Liverpool, Sheffield and Newcastle. One of CIMA’s objectives is to ‘Identify and share optimal techniques and approaches to monitor age-related changes in all musculoskeletal tissues, and to provide an integrated assessment of musculoskeletal function’—in other words to develop a toolkit for assessing musculoskeletal ageing. This toolkit is envisaged as an instrument that can be used to characterise and quantify musculoskeletal function during ‘normal’ ageing, lend itself to use in large-scale, internationally important cohorts, and provide a set of biomarker outcome measures for epidemiological and intervention studies designed to enhance healthy musculoskeletal ageing. Such potential biomarkers include: biochemical measurements in biofluids or tissue samples, in vivo measurements of body composition, imaging of structural and physical properties, and functional tests. This review assesses candidate biomarkers of musculoskeletal ageing under these four headings, details their biological bases, strengths and limitations, and makes practical recommendations for their use. In addition, we identify gaps in the evidence base and priorities for further research on biomarkers of musculoskeletal ageing.

New insights into the natural course of knee osteoarthritis: early regulation of cytokines and growth factors, with emphasis on sex-dependent angiogenesis and tissue remodeling. A pilot study

OBJECTIVE

This study was conducted to identify cytokine profiles associated with radiographic phenotypes of knee osteoarthritis (rKOA) with a focus on early stage of the disease.

METHODS

The pilot population study involved 60 middle-aged patients (mean age 50 ± 7.3y.). Standardized weight-bearing anteroposterior and axial radiographs were used to assess rKOA severity in tibiofemoral (TFJ) of patellofemoral joint (PFJ) by grading system (grades 0-3). Luminex (xMAP^®) technology was used to simultaneously assess 60 biomarkers (BMs).

RESULTS

Several pathways of angiogenic (CXCL10/IP-10, FGF1/2, PDGF-AA/BB, ANG1, RANTES), tissue remodeling/fibrosis (MMP1/3, TIMP2/3/4, TGFβ), and fat tissue (leptin) BMs associated with rKOA severity already in very early phase (grade 1). We identified several sets of cytokines as key markers of early knee osteoarthritis (KOA) predicting radiographic features in logistic-regression models (AUC = 0.80-0.97). Marked sex-specificity of rKOA course was detected: upregulation of angiogenesis dominated in females, whereas the activation of tissue remodeling was dominant in males. Several of these shifts, e.g., decrease of CXCL10/IP-10, took place only in grade 1 KOA and disappeared or reversed in later stages. OA of different knee-joint compartments has distinct profiles of cytokines. A broad list of BMs (TIMP2/3/4, MMP1/3, TGFβ1/2, vWF-A2, sE-selectin and leptin) associated with OA in the PFJ.

CONCLUSION

Our results demonstrate that substantial and time-limited shifts in the angiogenic and TIMP/MMP systems occur in the early stage of KOA. Our study findings highlight the sex-, grade- and compartment-dependent shifts in above processes. The data may contribute to the individualized prevention of KOA in the future.

Sensitivity of serum concentration of cartilage biomarkers to 21-days of bed rest

The objective of the study was to test the hypothesis that serum levels of cartilage oligomeric matrix protein (COMP) would decrease and serum levels of tumor-necrosis factor alpha (TNF-α) and selected matrix metalloproteinases (MMPs) would increase in response to bed rest (BR) and that these changes are unaffected by the intake of potassium bicarbonate or whey protein. Seven and nine healthy male subjects participated in two 21-day 6° head down tilt crossover BR-studies with nutrition interventions. Serum samples were taken before, during, and after BR and biomarker concentrations were measured using commercial enzyme-linked immunosorbent assays. MMP-3 during BR was significantly lower than at baseline (reduction greater 20%; p < 0.001). MMP-3 increased significantly from 14 to 21 days of BR (+7%; p = 0.049). COMP during BR was significantly lower than at baseline (reduction greater 20%; p < 0.001). MMP-3 and COMP returned to baseline within 1 day after BR. MMP-9 on day 3 of BR was significantly lower than at baseline (-31%; p < 0.033) and on days 3, 5, and 14 of BR significantly lower than at the end of and after BR (reduction greater 35%; p < 0.030). The nutritional countermeasures did not affect these results. The observed changes in cartilage biomarkers may be caused by altered cartilage metabolism in response to the lack of mechanical stimulus during BR and inflammatory biomarkers may play a role in changes in biomarker levels.

CLINICAL RELEVANCE

Immobilization independently from injury can cause altered cartilage biomarker concentration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1465-1471, 2018.

Changes in Cartilage Biomarker Levels During a Transcontinental Multistage Footrace Over 4486 km

BACKGROUND

Cartilage turnover and load-induced tissue changes are frequently assessed by quantifying concentrations of cartilage biomarkers in serum. To date, information on the effects of ultramarathon running on articular cartilage is scarce.

HYPOTHESIS

Serum concentrations of cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP)-1, MMP-3, MMP-9, COL2-3/4C long mono (C2C), procollagen type II C-terminal propeptide (CPII), and C2C:CPII will increase throughout a multistage ultramarathon.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Blood samples were collected from 36 runners (4 female; mean age, 49.0 ± 10.7 years; mean body mass index, 23.1 ± 2.3 kg/m² [start] and 21.4 ± 1.9 kg/m² [finish]) before (t₀) and during (t₁: 1002 km; t₂: 2132 km; t₃: 3234 km; t₄: 4039 km) a 4486-km multistage ultramarathon. Serum COMP, MMP-1, MMP-3, MMP-9, C2C, and CPII levels were assessed using commercial enzyme-linked immunosorbent assays. Linear mixed models were used to detect significant changes in serum biomarker levels over time with the time-varying covariates of body weight, running speed, and daily running time.

RESULTS

Serum concentrations of COMP, MMP-9, and MMP-3 changed significantly throughout the multistage ultramarathon. On average, concentrations increased during the first measurement interval (MI1: t₁-t₀) by 22.5% for COMP (95% CI, 0.29-0.71 ng/mL), 22.3% for MMP-3 (95% CI, 0.24-15.37 ng/mL), and 95.6% for MMP-9 (95% CI, 81.7-414.5 ng/mL) and remained stable throughout MI2, MI3, and MI4. Serum concentrations of MMP-1, C2C, CPII, and C2C:CPII did not change significantly throughout the multistage ultramarathon. Changes in MMP-3 were statistically associated with changes in COMP throughout the ultramarathon race (MMP-3: Wald Z = 3.476, P = .001).

CONCLUSION

Elevated COMP levels indicate increased COMP turnover in response to extreme running, and the association between load-induced changes in MMP-3 and changes in COMP suggests the possibility that MMP-3 may be involved in the degradation of COMP.

CLINICAL RELEVANCE

These results suggest that articular cartilage is able to adapt even to extreme physical activity, possibly explaining why the risk of degenerative joint disease is not elevated in the running population.

Evaluation of serum cytokines in cats with and without degenerative joint disease and associated pain

Degenerative joint disease is common in cats, with signs of pain frequently found on orthopedic examination and radiographs often showing evidence of disease. However, understanding of the pathophysiology of degenerative joint disease and associated pain remains limited. Several cytokines have been identified as having a role in pain in humans, but this has not been investigated in cats. The present study was performed to use a multiplex platform to evaluate the concentration of 19 cytokines and chemokines in serum samples obtained from cats with and without degenerative joint disease and associated pain. Samples from a total of 186 cats were analyzed, with cats representing a range of severity on radiographic and orthopedic evaluations and categorized by degenerative joint disease scores and pain scores. Results showed that cats with higher radiographic degenerative joint disease scores have higher serum concentrations of IL-4 and IL-8, while cats with higher orthopedic exam pain scores have higher concentrations of IL-8, IL-2, and TNF-α; increased concentration of IL-8 in degenerative joint disease and pain may be confounded by the association with age. Discriminant analysis was unable to identify one or more cytokines that distinguish between groups of cats classified based on degenerative joint disease score category or pain score category. Finally, cluster analysis driven by analyte concentrations shows separation of groups of cats, but features defining the groups remain unknown. Further studies are warranted to investigate any changes in cytokine concentrations in response to analgesic therapies, and further evaluate the elevations in cytokine concentrations found here, particularly focused on studies of local cytokines present in synovial fluid.

Meniscal biology in health and disease

The knee is a fascinating yet complex joint. Researchers and clinicians agree that the joint is an organ comprised of highly specialized intrinsic and extrinsic tissues contributing to both health and disease. Key to the function and movement of the knee are the menisci, exquisite fibrocartilage structures that are critical structures for maintaining biological and biomechanical integrity of the joint. The biological/physiological functions of the menisci must be understood at the tissue, cellular and even molecular levels in order to determine clinically relevant methods for assessing it and influencing it. By investigating normal and pathological functions at the basic science level, we can begin to translate data to patients. The objective of this article is to provide an overview of this translational pathway so that progression toward improved diagnostic, preventative, and therapeutic strategies can be effectively pursued. We have thoroughly examined the pathobiological, biomarker, and imaging aspects of meniscus research. This translational approach can be effective toward optimal diagnosis, prevention, and treatment for the millions of patients who suffer from meniscal disorders each year.

Low- Versus High-Intensity Plyometric Exercise During Rehabilitation After Anterior Cruciate Ligament Reconstruction

BACKGROUND

Plyometric exercise is used during rehabilitation after anterior cruciate ligament (ACL) reconstruction to facilitate the return to sports participation. However, clinical outcomes have not been examined, and high loads on the lower extremity could be detrimental to knee articular cartilage.

PURPOSE

To compare the immediate effect of low- and high-intensity plyometric exercise during rehabilitation after ACL reconstruction on knee function, articular cartilage metabolism, and other clinically relevant measures.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Twenty-four patients who underwent unilateral ACL reconstruction (mean, 14.3 weeks after surgery; range, 12.1-17.7 weeks) were assigned to 8 weeks (16 visits) of low- or high-intensity plyometric exercise consisting of running, jumping, and agility activities. Groups were distinguished by the expected magnitude of vertical ground-reaction forces. Testing was conducted before and after the intervention. Primary outcomes were self-reported knee function (International Knee Documentation Committee [IKDC] subjective knee form) and a biomarker of articular cartilage degradation (urine concentrations of crosslinked C-telopeptide fragments of type II collagen [uCTX-II]). Secondary outcomes included additional biomarkers of articular cartilage metabolism (urinary concentrations of the neoepitope of type II collagen cleavage at the C-terminal three-quarter-length fragment [uC2C], serum concentrations of the C-terminal propeptide of newly formed type II collagen [sCPII]) and inflammation (tumor necrosis factor-α), functional performance (maximal vertical jump and single-legged hop), knee impairments (anterior knee laxity, average knee pain intensity, normalized quadriceps strength, quadriceps symmetry index), and psychosocial status (kinesiophobia, knee activity self-efficacy, pain catastrophizing). The change in each measure was compared between groups. Values before and after the intervention were compared with the groups combined.

RESULTS

The groups did not significantly differ in the change of any primary or secondary outcome measure. Of interest, sCPII concentrations tended to change in opposite directions (mean ± SD: low-intensity group, 28.7 ± 185.5 ng/mL; high-intensity group, -200.6 ± 255.0 ng/mL; P = .097; Cohen d = 1.03). Across groups, significant changes after the intervention were increased the IKDC score, vertical jump height, normalized quadriceps strength, quadriceps symmetry index, and knee activity self-efficacy and decreased average knee pain intensity.

CONCLUSION

No significant differences were detected between the low- and high-intensity plyometric exercise groups. Across both groups, plyometric exercise induced positive changes in knee function, knee impairments, and psychosocial status that would support the return to sports participation after ACL reconstruction. The effect of plyometric exercise intensity on articular cartilage requires further evaluation.

REGISTRATION NUMBER

Clinicaltrials.gov NCT01851655.

Evidence of changes to skeletal muscle contractile properties during the initiation of disease in the ageing guinea pig model of osteoarthritis

Background

Osteoarthritis (OA) is the most common joint disorder in the world and represents the leading cause of pain and disability in the elderly population. Advancing age remains the single greatest risk factor for OA. Several studies have characterised disease development in the guinea pig ageing model of OA in terms of its joint histopathology and inflammatory cytokine profile. However, the quadriceps muscle has yet to be studied in relation to age-related disease onset or early disease progression. Therefore, we examined whether the initiation of OA in the Dunkin Hartley guinea pig is associated with changes in the quadriceps skeletal muscle. Male Dunkin Hartley guinea pigs (N = 24) were group housed with free access to standard guinea pig chow and water. At 2, 3, 5 and 7 months of age, six animals were selected based on their proximity to the median weight of the cohort. OA severity was graded at each time point by the assessment of toluidine blue stained step coronal sections of the total knee joint. Serum CTX II was measured as a potential biomarker of OA severity. Myosin Heavy Chain (MHC) isoforms were determined by a validated real-time PCR assay. Oxidative and glycolytic potential was determined in quadriceps homogenates via the measurement of ICDH and LDH activity.

Results

Initiation of OA in the DH strain guinea pig occurred between 2 and 3 months of age and progressed until 7 months when the final analyses were conducted. Serum CTX II significantly decreased during this early period of OA initiation and levels were unrelated to the histopathological severity of knee OA at any of the time points assessed. MHC mRNA measurements revealed a significant elevation in MHC IIX mRNA (associated with fast-twitch skeletal muscle fibres) coincident with the initiation of OA at 3 months of age, with preliminary findings suggestive of a positive correlation to OA severity at this time point.

Conclusions

These preliminary findings suggest that disease initiation in the ageing guinea pig model of OA is not associated with overt quadriceps muscle atrophy but instead is coincident with altered expression of mRNAs associated with quadriceps skeletal muscle contractile properties (specifically fast-twitch MHC IIX).

Synovial fluid levels of bradykinin correlate with biochemical markers for cartilage degradation and inflammation in knee osteoarthritis

OBJECTIVE

To determine the content of bradykinin (BK) and markers of cartilage degradation and inflammation in the synovial fluid (SF) of patients with knee osteoarthritis (OA), and to evaluate correlations with biomarkers or clinical parameters.

METHODS

SFs were obtained from 30 patients with knee OA. Levels of basal and generated BK, cartilage oligomeric matrix protein (COMP), interleukin (IL) 1, IL-6, IL-8 and matrix metalloprotease (MMP) 1, MMP-3, MMP-13 and sulfated glycosaminoglycans (GAGs) were measured by enzyme-linked immunosorbent assay (ELISA) or colorimetric assays.

RESULTS

The mean concentration of basal BK (in the presence of peptidase and protease inhibitors to avoid degradation and de novo formation of BK) was 422 pg/ml (95% confidence interval, CI, 281-563) whereas that of in vitro generated BK (in the presence of peptidase inhibitors SFs were incubated 60 min at 37°C to measure the potential capability to generate BK) was 3427 pg/ml (2591-4264). The content of MMP-13, IL-1α, and IL-1β was under assay sensitivity. Basal BK levels positively correlated (Spearman's rank correlation) with GAGs (40 μg/ml, 26-54, r = 0.4834, P = 0.0308) and IL-6 (553 pg/ml, 171-935, r = 0.3946, P = 0.0377) similarly to the generated BK (GAGs, r = 0.4563, P = 0.0431; IL-6, r = 0.5605, P = 0.0019). Statistical analysis of basal BK and biomarkers was significant (P = 0.0483). When applying a stepwise logistic regression analysis considering biomarkers together with clinical parameters, results indicated that K/L radiographic OA grade and COMP improved the model (P = 0.0032).

CONCLUSION

The presence of BK in the knee OA SF and its correlations with cartilage degradation and inflammation markers of OA support its participation in OA pathology.

Bearing arms against osteoarthritis and sarcopenia: when cartilage and skeletal muscle find common interest in talking together

Osteoarthritis, a disease characterized by cartilage degradation, abnormal subchondral bone remodelling and some grade of inflammation, and sarcopenia, a condition of pathological muscle weakness associated with altered muscle mass, strength, and function, are prevalent disorders in elderly people. There is increasing evidence that decline in lower limb muscle strength is associated with knee or hip osteoarthritis in a context of pain, altered joint stability, maladapted postures and defective neuromuscular communication. At the cellular and molecular levels, chondrocytes and myoblasts share common pathological targets and pathways, and the close anatomical location of both cell types suggest a possibility of paracrine communication. In this review, we examine the relationship between osteoarthritis and sarcopenia in the musculoskeletal field, and discuss the potential advantage of concomitant therapies, or how each disorder may benefit from treatment of the other.

Low dose native type II collagen prevents pain in a rat osteoarthritis model

Background

Osteoarthritis is the most widespread joint-affecting disease. Patients with osteoarthritis experience pain and impaired mobility resulting in marked reduction of quality of life. A progressive cartilage loss is responsible of an evolving disease difficult to treat. The characteristic of chronicity determines the need of new active disease modifying drugs. Aim of the present research is to evaluate the role of low doses of native type II collagen in the rat model of osteoarthritis induced by sodium monoiodoacetate (MIA).

Methods

1, 3 and 10 mg kg^-1 porcine native type II collagen were daily per os administered for 13 days starting from the day of MIA intra-articular injection.

Results

On day 14, collagen-treated rats showed a significant prevention of pain threshold alterations induced by MIA. Evaluation were performed on paws using mechanical noxious (Paw pressure test) or non-noxious (Electronic Von Frey test) stimuli, and a decrease of articular pain was directly measured on the damaged joint (PAM test). The efficacy of collagen in reducing pain was as higher as the dose was lowered. Moreover, a reduced postural unbalance, measured as hind limb weight bearing alterations (Incapacitance test), and a general improvement of motor activity (Animex test) were observed. Finally, the decrease of plasma and urine levels of CTX-II (Cross Linked C-Telopeptide of Type II Collagen), a biomarker of cartilage degradation, suggests a collagen-dependent decrease of structural joint damage.

Conclusions

These results describe the preclinical efficacy of low dosages of native type II collagen as pain reliever by a mechanism that involves a protective effect on cartilage.

Association between cartilage and bone biomarkers and incidence of radiographic knee osteoarthritis (RKOA) in UK females: a prospective study

OBJECTIVE

There is a need to find biochemical markers that would identify people with increased risk of developing radiographic knee osteoarthritis (RKOA). The aim of this study was to evaluate the ability of cartilage and bone biomarkers (cartilage oligomeric matrix protein (COMP), aggrecan, cellular inhibitor of apoptosis protein (cIAP), N-telopeptide-to-helix (NTx)) to predict RKOA incidence in a 10-year follow-up of UK females from the Chingford community study.

METHOD

Joint space narrowing (JSN), osteophytes (OSP) and Kellgren-Lawrence (K/L) grades were scored from radiographs of both knees at study baseline and 10 years later in 1,003 women aged 45-64. Circulating levels of biomarkers and demographic variables were measured at baseline. Statistical association analysis was conducted between the potential predictor factors measured at baseline and documentation of RKOA at 10-year follow-up.

RESULTS

Age and body mass index (BMI), were significant predictors of incidence of RKOA as assessed by K/L and OSP. Considering biomarkers, independent significant association was found between COMP circulating levels and K/L scores (Odd Ratio (OR) = 2.87, 95% Confidence Interval (CI) = 1.19-6.89, P = 0.018). Significant negative association was detected between aggrecan plasma concentrations and JSN, with OR = 0.37 (95% CI 0.15-0.89), P = 0.026.

CONCLUSIONS

Aggrecan and COMP circulating levels contribute to identification of phenotype-specific RKOA incidence. These data suggest potentially protective role of aggrecan in cartilage loss, as measured by JSN. High COMP levels are risk factors for development of RKOA, as assessed by K/L scores.

Efficacy and tolerability of celecoxib versus naproxen in patients with osteoarthritis of the knee: a randomized, double-blind, double-dummy trial

OBJECTIVE

To assess the efficacy and tolerability of celecoxib versus naproxen in patients with osteoarthritis (OA) of the knee.

METHODS

This 6-month, randomized, double-blind, double-dummy trial was conducted at 47 centres in the USA. Patients with OA of the knee were randomized to receive 200 mg celecoxib orally once daily or 500 mg naproxen orally twice daily. The primary endpoint was defined as a 20% improvement from baseline to 6 months in Western Ontario and McMaster Universities (WOMAC) OA total score.

RESULTS

A total of 586 out of 589 randomized patients received at least one dose of celecoxib (n=294) or naproxen (n=292). The primary endpoint (6-month response rate) was achieved by 52.7% and 49.7% of patients in the celecoxib and naproxen treatment groups, respectively. Significantly fewer discontinuations due to gastrointestinal adverse events occurred in patients receiving celecoxib than in those receiving naproxen (4.1% versus 15.1%, respectively).

CONCLUSIONS

Over the 6month study period, celecoxib provided similar improvements in OA symptoms to naproxen. In addition, celecoxib provided better upper gastrointestinal tolerability than naproxen.

An intra-articular salmon calcitonin-based nanocomplex reduces experimental inflammatory arthritis

Prolonged inappropriate inflammatory responses contribute to the pathogenesis of rheumatoid arthritis (RA) and to aspects of osteoarthritis (OA). The orphan nuclear receptor, NR4A2, is a key regulator and potential biomarker for inflammation and represents a potentially valuable therapeutic target. Both salmon calcitonin (sCT) and hyaluronic acid (HA) attenuated activated mRNA expression of NR4A1, NR4A2, NR4A3, and matrix metalloproteinases (MMPs) 1, 3 and 13 in three human cell lines: SW1353 chondrocytes, U937 and THP-1 monocytes. Ad-mixtures of sCT and HA further down-regulated expression of NR4A2 compared to either agent alone at specific concentrations, hence the rationale for their formulation in nanocomplexes (NPs) using chitosan. The sCT released from NP stimulated cAMP production in human T47D breast cancer cells expressing sCT receptors. When NP were injected by the intra-articular (I.A.) route to the mouse knee during on-going inflammatory arthritis of the K/BxN serum transfer model, joint inflammation was reduced together with NR4A2 expression, and local bone architecture was preserved. These data highlight remarkable anti-inflammatory effects of sCT and HA at the level of reducing NR4A2 mRNA expression in vitro. Combining them in NP elicits anti-arthritic effects in vivo following I.A. delivery.

Evaluation of the chondroprotective effects of glucosamine and fish collagen peptide on a rabbit ACLT model using serum biomarkers

The aim of this study was to investigate the correlations of severity of osteoarthritis (OA) and serum biomarkers including keratan sulfate (KS), hyaluronic acid (HA) and chondroitin sulfate (CS) 846 epitope. We also investigated the effect of glucosamine and fish collagen peptide (FCP) on OA. OA was induced in 12 rabbits (12 weeks of age) by anterior cruciate ligament transection (ACLT). After the surgery, the rabbits were orally administered FCP (F group), glucosamine (G group) or FCP and glucosamine (FG group) for 4 weeks. The control group was provided water ad libitum (C group). Blood was collected before surgery (pre-ACLT) and before euthanasia (post-ACLT) for serum marker measurement. Biomarker levels were measured by using commercial kits. We evaluated OA severity both macroscopically and histologically. Macroscopic evaluation showed mildly eroded condylar surfaces in the C group. Histological findings were significantly different from the FG and other groups. There were no significant differences between each group at post-ACLT in terms of serum KS, HA and CS 846. Histological assessment and serum biomarker measurements performed at post-ACLT showed a significant correlation between HA concentration and OA severity. Variations in the CS 846 concentration at pre-ACLT and post-ACLT were significantly correlated with OA severity. Administration of glucosamine and FCP had chondroprotective effects in the ACLT model. Serum biomarker concentrations were significantly correlated with cartilage injury. Serum biomarker measurement would be useful for monitoring articular cartilage damage in the clinical setting.

Urinary CTX-II concentrations are elevated and associated with knee pain and function in subjects with ACL reconstruction

OBJECTIVE

Post-traumatic knee osteoarthritis (OA) is prevalent after anterior cruciate ligament reconstruction (ACLR). Biomarkers that identify individuals likely to develop OA, especially symptomatic OA, can help target preventative and therapeutic strategies. This study examined the magnitude and change over time in urinary CTX-II (uCTX-II) concentrations shortly after ACL reconstruction, and, secondarily, the associations with knee pain and function.

DESIGN

Subjects were 28 patients with ACLR and 28 age- and sex-matched controls (CNTRL). Testing was conducted at four time points spaced 4 weeks apart (4, 8, 12 and 16 weeks post-operative in ACLR). Measures included demographics, urine samples, Numeric Pain Rating Scale (NPRS) and International Knee Documentation Committee Subjective Knee Form (IKDC-SKF). uCTX-II concentrations were determined with competitive enzyme-linked immunosorbent assay (ELISA). uCTX-II concentrations at each time point in ACLR were compared to the mean concentration over time in CNTRL, with and without adjustment for body mass index (BMI). Changes over time in each measure and correlations between the slopes of change were examined.

RESULTS

uCTX-II concentrations were significantly higher in ACLR than CNTRL through 16 weeks post-operative when adjusted for BMI. In ACLR, uCTX-II concentrations significantly decreased over time, and the slope was associated with NPRS (r = 0.406, P = 0.039) and IKDC-SKF (r = -0.402, P = 0.034) slopes.

CONCLUSION

uCTX-II concentrations shortly after ACLR were elevated compared to CNTRL and declined over time. Decreasing uCTX-II concentrations were associated with decreasing knee pain and improving function. uCTX-II may have a role as a prognostic marker following ACLR and warrants further investigation.

Correlation of plasma amino acid concentrations and chondroprotective effects of glucosamine and fish collagen peptide on the development of osteoarthritis

We investigated the correlation of plasma amino acid concentrations and the effects of glucosamine and fish collagen peptide (FCP) on osteoarthritis (OA). OA was induced according to the rabbit anterior cruciate ligament transection (ACLT) model. After surgery, the rabbits were orally administered FCP (F group), glucosamine (G group) or both (FG group) for 4 weeks. The control group (C group) was not administered anything. Blood was collected before surgery (pre-ACLT) and before euthanasia (post-ACLT). Changes in the alanine, threonine and methionine concentrations were significant between pre- and post-ACLT. The correlation between the histological assessment and arginine concentration post-ACLT was significant. These findings indicate that measurement of plasma amino acids is useful for evaluation of the efficacy of intervention for OA.

Recent findings on the role of gelatinases (matrix metalloproteinase-2 and -9) in osteoarthritis

Several studies dealing with the pathomechanisms of OA refer to MMP-1, -3, -7, -8, and -13 whereas a smaller number of investigations have pointed out the pathogenic role of gelatinases in OA. These gelatinases are best known for their involvement in pulmonary, myocardial, and neoplastic disease but they are emerging as important proteases implicated in the OA progression. This paper highlights the role of the gelatinases as emerging factors in OA pathogenesis through the regulation of subchondral bone resorption and microvascular invasion. The most significant new findings over the last year that add to our knowledge of the activity of these proteins in OA have been reported.

Recent advances in biomarkers in osteoarthritis

PURPOSE OF REVIEW

Osteoarthritis is a joint disease characterized by a nonsymptomatic, preradiographical phase that if distinguished would allow earlier osteoarthritis diagnosis. Biochemical biomarkers offer a potential nonradiographical alternative to detect early, nonsymptomatic osteoarthritis.

RECENT FINDINGS

Biomarker development for osteoarthritis diagnosis is still in the forefront of the research repertoire in osteoarthritis. A number of previously identified biomarkers derived from cartilage breakdown or enzymes that cause cartilage degeneration still have prominence and are now better characterized with increasing use in identifying disease severity, progression, and testing treatment options. Combinations of cartilage-derived and bone-derived biomarkers have been used to subgroup osteoarthritis patients that could impact treatment and address the importance of bone turnover in cartilage integrity. Increasingly, inflammation markers have been used to profile osteoarthritis progression attesting to the inflammatory nature of osteoarthritis. The application of proteomic technologies has generated several new, nonconventional biomarkers that could allow better profiling of osteoarthritis.

SUMMARY

Biomarker combinations have the ability to subgroup the heterogenous osteoarthritis population to allow a better scrutiny of diagnosis and treatment options. The application of different technological platforms to osteoarthritis would allow a better understanding of its pathology and could provide for appropriate candidates for earlier detection of osteoarthritis.

Autophagy and cartilage homeostasis mechanisms in joint health, aging and OA

Osteoarthritis (OA) is the most prevalent joint disease, but neither preventive measures nor disease-modifying drugs are available and a continuing need exists for safe and effective symptom-modifying therapies. Clinical trials of candidate disease-modifying OA drugs in patients with established or advanced disease have not demonstrated their efficacy, but these failed trials have motivated investigation into the mechanisms that maintain joint health. The enhancement of such mechanisms could be a novel approach to reducing the risk of OA. Aging is one of the most important risk factors for OA; however, aging of joint cartilage is a process that is distinct from the subsequent cartilage changes that develop following the onset of OA. This Review focuses on the mechanisms that maintain cell and tissue homeostasis, and how these mechanisms fail during the aging process. Autophagy is a cellular homeostasis mechanism for the removal of dysfunctional organelles and macromolecules. Defective autophagy is involved in the pathogenesis of aging-related diseases and recent observations indicate that this process is compromised in aging cartilage. Augmentation of homeostasis mechanisms is discussed as a novel avenue to delay joint aging and reduce OA risk.

Biokinetic Mechanisms Linked With Musculoskeletal Health Disparities: Stochastic Models Applying Tikhonov's Theorem to Biomolecule Homeostasis

Multiscale technology and advanced mathematical models have been developed to control and characterize physicochemical interactions, respectively, enhancing cellular and molecular engineering progress. Ongoing tissue engineering development studies have provided experimental input for biokinetic models examining the influence of static or dynamic mechanical stimuli (Saha, A. K., and Kohles, S. S., 2010, "A Distinct Catabolic to Anabolic Threshold Due to Single-Cell Nanomechanical Stimulation in a Cartilage Biokinetics Model," J. Nanotechnol. Eng. Med., 1(3) p. 031005; 2010, "Periodic Nanomechanical Stimulation in a Biokinetics Model Identifying Anabolic and Catabolic Pathways Associated With Cartilage Matrix Homeostasis," J. Nanotechnol. Eng. Med., 1(4), p. 041001). In the current study, molecular regulatory thresholds associated with specific disease disparities are further examined through applications of stochastic mechanical stimuli. The results indicate that chondrocyte bioregulation initiates the catabolic pathway as a secondary response to control anabolic processes. In addition, high magnitude loading produced as a result of stochastic input creates a destabilized balance in homeostasis. This latter modeled result may be reflective of an injurious state or disease progression. These mathematical constructs provide a framework for single-cell mechanotransduction and may characterize transitions between healthy and disease states.