The potential of multiple synovial-fluid protein-concentration analyses in the assessment of knee osteoarthritis

Correlation of synovial tissue protein abundance with menopause in osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a common articular disorder. Epidemiologic surveys show a higher prevalence of OA in women than men and that morbidity is higher during menopause. We aimed to explore whether menopause influences the clinical recovery of a knee joint following OA and injury, and identify associated mechanisms by analyzing the proteomic profile of synovial tissue (ST) samples.

METHODS

Routine blood examination and hormone level tests were conducted before surgery. ST samples from eight participants were collected intraoperatively for proteomic analysis. One day before and one month after the surgery, we assessed various aspects of function in the affected knee including the with Visual Analog Score (VAS), Lysholm, The Western Ontario, and McMaster Universities Osteoarthritis Index (WOMAC) scores. The relationships between proteomic data, estrogen levels, and affected knee function were compared and analyzed. This was a retrospective study.

RESULT

Menopause was associated with the clinical outcomes of knee OA and knee injuries. ST proteomic data identified that 80 proteins in premenopausal OA females were significantly different from menopausal OA females. In addition, 100 proteins were significantly different between premenopausal OA females and premenopausal injured females.

CONCLUSIONS

Age and menopause showed a positive correlation with the protein profile of ST from OA or knee injury female patients, indicating that the protein components might be affected by menopause. Postoperative clinical outcomes were affected by menopause. We conclude that menopause may, in part, regulate knee joint function by altering ST protein expression.

Randomized, Placebo-Controlled Analysis of the Knee Synovial Environment Following Platelet-Rich Plasma Treatment for Knee Osteoarthritis

BACKGROUND

Platelet-rich-plasma (PRP) is used to treat knee osteoarthritis; however, mechanistic evidence of PRP effectiveness for pain relief is limited.

OBJECTIVE

To assess molecular biomarkers and mesenchymal stem cells (MSCs) in synovial fluid during PRP treatment of the osteoarthritic knee joint.

DESIGN

Single blinded, randomized, placebo controlled pilot study.

SETTING

Veterans Affairs Medical Center.

PARTICIPANTS

Seventeen participants with mild to moderate knee osteoarthritis were randomized in a 2:1 placebo-controlled ratio, receiving PRP or saline (placebo) intra-articular injection into the knee joint.

METHODS

Knee synovial fluid was analyzed before the respective injections and again 10 days following injection. Participants were followed up to 12 months completing visual analog scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires at intervals over that period.

MAIN OUTCOME MEASURES

The effects of PRP on synovial protein and MSC gene expression levels were measured by multiplex enzyme-linked immunosorbent assay and quantitative polymerase chain reaction.

RESULTS

Novel biomarkers including levels of interleukin (IL)-5, IL-6, IL-10, and tumor necrosis factor-α were measured in synovial fluid 10 days after PRP treatment. Altered gene expression profiles in MSCs from patients treated with PRP were observed for matrix metalloproteinases and inflammatory markers (IL-6, IL-8, CCL2, TNF-α). A2M protease was significantly increased following PRP treatment (P = .005). WOMAC scores declined for up to 3 months from baseline levels and remained low at 6 and 12 months in the PRP group. In contrast, WOMAC scores for patients receiving the saline injection were relatively unchanged for up to 12 months.

CONCLUSIONS

We report significant changes for the biomarker A2M (P = .005) as well as differences in expression of cellular markers and postulate that PRP modulates the local knee synovial environment by altering the inflammatory milieu, matrix degradation, and angiogenic growth factors. The PRP treatment group had less pain and stiffness and improved function scores.

Common Musculoskeletal Disorders in the Elderly: The Star Triad

Musculoskeletal disorders are debilitating conditions that significantly impair the state of health, especially in elderly subjects. A pathological triad of inter-related disorders that are highly prevalent in the elderly consists of the following main “components”: sarcopenia, tendinopathies, and arthritis. The aim of this review is to critically appraise the literature relative to the different disorders of this triad, in order to highlight the pathophysiological common denominator and propose strategies for personalized clinical management of patients presenting with this combination of musculoskeletal disorders. Their pathophysiological common denominator is represented by progressive loss of (focal or generalized) neuromuscular performance with a risk of adverse outcomes such as pain, mobility disorders, increased risk of falls and fractures, and impaired ability or disability to perform activities of daily living. The precise management of these disorders requires not only the use of available tools and recently proposed operational definitions, but also the development of new tools and approaches for prediction, diagnosis, monitoring, and prognosis of the three disorders and their combination.

Cartilage oligomeric matrix protein, C-terminal cross-linking telopeptide of type II collagen, and matrix metalloproteinase-3 as biomarkers for knee and hip osteoarthritis (OA) diagnosis: a systematic review and meta-analysis

OBJECTIVE

This study was design to examine the diagnostic performance of cartilage oligomeric matrix protein (COMP), C-terminal cross-linking telopeptide of type II collagen (CTX-II), and matrix metalloproteinase-3 (MMP-3) as biomarker for knee and hip OA.

METHODS

Systematic search on multiple databases was completed in January 2018 using certain keywords. COMP, CTX-II, MMP-3 levels in knee and hip OA patients and healthy individuals were collected and calculated. Differences between subgroups were expressed as standardized mean differences (SMD). Subgroup analyses were performed to compare COMP, CTX-II, and MMP-3 performance between measuring sources, genders, large and small sample size and diagnostic criteria for OA patients.

RESULTS

A moderate performance of COMP in distinguishing between knee (SMD: 0.68; 95% confidence intervals (CI): 0.43-0.93; P < 0.0001) or hip (SMD: 0.25; 95% CI, 0.10, 0.40; P = 0.0008) OA patients and controls were found. CTX-II showed a moderated standardised mean differences (SMD) of 0.48 (95% CI, 0.32, 0.64; P < 0.0001) in the detection of knee OA and a large SMD of 0.76 (95% CI, 0.09, 1.42; P = 0.03) in diagnosing hip OA. A small SMD of 0.32 (95% CI, -0.03, 0.67; P = 0.07) was found for MMP-3 performance and the results did not reach statistic significance. Progression study revealed potential effectiveness of serum COMP in predicting OA progression. Subgroup analysis showed that serum COMP and urinary CTX-II performed better in male than female. Study size and diagnostic criteria did not significantly influence the pooled SMD, but they might be the sources of heterogeneity among studies.

CONCLUSION

The overall results indicates that serum COMP and urinary CTX-II can distinguish between knee or hip OA patients and control subjects. Serum COMP is effective in predicting OA progression.Further researches with rigorous study design and a larger sample size are required to validate our findings.

Can we identify patients with high risk of osteoarthritis progression who will respond to treatment? A focus on epidemiology and phenotype of osteoarthritis

Osteoarthritis is a syndrome affecting a variety of patient profiles. A European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis and the European Union Geriatric Medicine Society working meeting explored the possibility of identifying different patient profiles in osteoarthritis. The risk factors for the development of osteoarthritis include systemic factors (e.g., age, sex, obesity, genetics, race, and bone density) and local biomechanical factors (e.g., obesity, sport, joint injury, and muscle weakness); most also predict disease progression, particularly joint injury, malalignment, and synovitis/effusion. The characterization of patient profiles should help to better orientate research, facilitate trial design, and define which patients are the most likely to benefit from treatment. There are a number of profile candidates. Generalized, polyarticular osteoarthritis and local, monoarticular osteoarthritis appear to be two different profiles; the former is a feature of osteoarthritis co-morbid with inflammation or the metabolic syndrome, while the latter is more typical of post-trauma osteoarthritis, especially in cases with severe malalignment. Other biomechanical factors may also define profiles, such as joint malalignment, loss of meniscal function, and ligament injury. Early- and late-stage osteoarthritis appear as separate profiles, notably in terms of treatment response. Finally, there is evidence that there are two separate profiles related to lesions in the subchondral bone, which may determine benefit from bone-active treatments. Decisions on appropriate therapy should be made considering clinical presentation, underlying pathophysiology, and stage of disease. Identification of patient profiles may lead to more personalized healthcare, with more targeted treatment for osteoarthritis.

Delineating the synovial fluid proteome: recent advancements and ongoing challenges in biomarker research

There is an urgent need for identifying novel serum biomarkers that can be used to improve diagnosis, predict disease progression or response to therapy, or serve as therapeutic targets for rheumatic diseases. Synovial fluid (SF) is secreted by and remains in direct contact with the synovial membrane, and can reflect the biochemical state of the joint under different physiological and pathological conditions. Therefore, SF is regarded as an excellent source for identifying biomarkers of rheumatologic diseases. The use of high-throughput and/or quantitative proteomics and sophisticated computational software applied to analyze the protein content of SF has been well-adopted as an approach to finding novel arthritis biomarkers. This review will focus on some of the potential pitfalls of biomarker studies using SF, summarize the status of the field of SF proteomics in general, as well as discuss some of the most promising biomarker study approaches using proteomics. A brief status of the biomarker discovery efforts in rheumatoid arthritis, osteoarthritis and juvenile idiopathic arthritis is also provided.

Matrix metalloproteinase protein expression profiles cannot distinguish between normal and early osteoarthritic synovial fluid

Background

Osteoarthritis (OA) and Rheumatoid arthritis (RA) are diseases which result in the degeneration of the joint surface articular cartilage. Matrix Metalloproteinases (MMPs) are enzymes that aid in the natural remodelling of tissues throughout the body including cartilage. However, some MMPs have been implicated in the progression of OA and RA as their expression levels and activation states can change dramatically with the onset of disease. Yet, it remains unknown if normal and arthritic joints demonstrate unique MMPs expression profiles, and if so, can the MMP expression profile be used to identify patients with early OA. In this study, the synovial fluid protein expression levels for MMPs 1, 2, 3, 7, 8, 9, 12 & 13, as well as those for the Tissue Inhibitors of MMPs (TIMPs) 1, 2, 3, & 4 were examined in highly characterized normal knee joints, and knee joints with clinically diagnosed OA (early and advanced) or RA. The purpose of this study was to determine if normal, OA, and RA patients exhibit unique expression profiles for a sub-set of MMPs, and if early OA patients have a unique MMP expression profile that could be used as an early diagnostic marker.

Methods

Synovial fluid was aspirated from stringently characterized normal knee joints, and in joints diagnosed with either OA (early and advanced) or RA. Multiplexing technology was employed to quantify protein expression levels for 8 MMPs and 4 TIMPs in the synovial fluid of 12 patients with early OA, 17 patients diagnosed with advanced OA, 15 with RA and 25 normal knee joints. Principle component analysis (PCA) was used to reveal which MMPs were most influential in the distinction between treatment groups. K – means clustering was used to verify the visual grouping of subjects via PCA.

Results

Significant differences in the expression levels of MMPs and TIMPs were observed between normal and arthritic synovial fluids (with the exception of MMP 12). PCA demonstrated that MMPs 2, 8 & 9 can be used to effectively separate individuals diagnosed with advanced arthritis from early osteoarthritic and normal individuals, however, these MMP profiles do not separate early OA from normal synovial fluid. An apparent separation between advanced OA and RA subjects was also revealed through PCA. K-means clustering verified the presence of 3 clusters: normal joints clustered with early OA, and separate clusters of advanced OA or RA.

Conclusions

This study demonstrates that unique MMP and TIMP expression profiles are present within normal, advanced OA and RA synovial fluid. These MMP profiles can be used to distinguish advanced OA & RA synovial fluid from early OA & normal synovial fluid, and even between synovial fluid samples from OA and RA joints. Although this methodology cannot be used for the diagnosis of early OA, high throughput multiplex technology of MMPs and TIMPs in synovial fluid may prove useful in determining the severity of the disease state, and/or quantifying the response of individuals to disease interventions.

Biochemical comparison of osteoarthritic knees with and without effusion

BACKGROUND

Several symptom-relieving interventions have been shown to be efficacious among osteoarthritis (OA) patients with knee effusion; however, not every symptomatic knee OA patient has clinical effusion. Results may be over-generalized since it is unclear if effused knees represent a unique pathological condition or subset compared to knees without effusion. The primary purpose of this study was to determine if biochemical differences existed between OA knees with and without effusion.

METHODS

The present cross-sectional study consisted of 22 volunteers (11 with knee effusion, 11 without knee effusion) with confirmed late-stage radiographic knee OA (Kellgren-Lawrence score ≥ 3). Synovial fluid samples were collected and analyzed using a custom multiplex enzyme-linked immunosorbent assay to determine eight specific biomarker concentrations (e.g., catabolic, anabolic).

RESULTS

Matrix metalloproteinase (MMP)-3, tissue inhibitor of MMPs (TIMP)-1, TIMP-2, and interleukin-10 were significantly higher in the knees with effusion than in the knees without effusion.

CONCLUSIONS

The biochemical differences that existed between knees with and without effusion provide support that OA subsets may exist, characterized by distinct biochemical characteristics and clinical findings (e.g., effusion).