The Effect of Preoperative Intra-Articular Methylprednisolone on Pain After TKA: A Randomized Double-Blinded Placebo Controlled Trial in Patients With High-Pain Knee Osteoarthritis and Sensitization.

In a randomized, double-blind, placebo controlled trial, we investigated the postoperative analgesic effect of a single intra-articular injection of 40 mg methylprednisolone acetate (MP) administered 1 week before total knee arthroplasty (TKA). Forty-eight patients with high pain osteoarthritis (≥5 on a numeric rating scale during walk) and sensitization (pressure pain threshold <250 kPa), aged 50 to 80 years and scheduled for primary unilateral TKA under spinal anaesthesia were included. The primary outcome was the proportion of patients with moderate/severe pain during a 5-m walk test 24 hours postoperatively. Secondary outcomes included pain at 48 hours, during the first 14 days, sensitization (quantitative sensory testing with pressure pain threshold and wind-up from temporal summation), and inflammatory changes (systemic C-reactive protein, intra-articular interleukin [IL]-6). No difference in the proportion of patients with moderate/severe pain was found between MP/placebo groups at 24 hours (67% and 74%, χ2 = .2, P = .63, odds ratio = .7, 95% confidence interval = .2-2.8) or at 48 hours (57% and 68%, χ2 = .5, P = .46, odds ratio = .6, 95% confidence interval = .2-2.3), and no difference between groups in postoperative sensitization was found (P > .4) despite reduced preoperative intra-articular inflammation (IL-6) in the MP group versus placebo (median change in IL-6 = -70 pg/mL, interquartile range = -466 to 0 vs. 32 pg/mL, interquartile range = -26 to 75, P = .029). Alternative central or peripheral analgesic interventions in this high-risk group are required. PERSPECTIVE: Peripherally driven inflammatory pain and nociceptive changes before TKA has been suggested to be a cause for increased acute postoperative pain. However, preoperative intra-articular MP in patients with high pain osteoarthritis and sensitization did not reduce acute post-TKA pain or sensitization despite a preoperative reduction of intra-articular inflammatory markers.

The effect of protease inhibitors on the induction of osteoarthritis-related biomarkers in bovine full-depth cartilage explants.

OBJECTIVE: The specific degradation of type II collagen and aggrecan by matrix metalloproteinase (MMP)-9, -13 and ADAMTS-4 and -5 (aggrecanase-1 and -2) in the cartilage matrix is a critical step in pathology of osteoarthritis (OA). The aims of this study were: i) To investigate the relative contribution of ADAMTS-4 and ADAMTS-5 to cartilage degradation upon catabolic stimulation; ii) To investigate the effect of regulating the activities of key enzymes by mean of broad-spectrum inhibitors. METHODS: Bovine full-depth cartilage explants stimulated with tumor necrosis factor alpha (TNF-α) and Oncostatin M (OSM) were cultured for 21 days with or without a number of inhibitors targeting different types of proteases. Monoclonal antibodies were raised against the active sites of ADAMTS-4, -5, MMP-9 and -13, and 4 ELISAs were developed and technically validated. In addition, the established AGNxI (ADAMTS-degraded aggrecan), AGNxII (MMP-degraded aggrecan), and CTX-II (MMP-derived type II collagen) were quantified in the explants-conditioned media. RESULTS: We found that: i) Active ADAMTS-4, MMP-9, -13 were released in the late stage of TNF-α/ OSM stimulation, whereas no significant active ADAMTS-5 was detected in either extracts or supernatants; ii) Active ADAMTS-4 was primarily responsible for E373-374A bond cleavage in aggrecan in this setting; and iii) The compensatory mechanism could be triggered following the blockage of the enzyme caused by inhibitors. CONCLUSIONS: ADAMTS-4 appeared to be the major protease for the generation of 374ARGS aggrecan fragment in the TNF-α/OSM stimulated bovine cartilage explants. This study addresses the need to determine the roles of ADAMTS-4 and ADAMTS-5 in human articular degradation in OA and hence identify the attractive target for slowing down human cartilage breakdown.

Cartilage turnover reflected by metabolic processing of type II collagen: a novel marker of anabolic function in chondrocytes.

The aim of this study was to enable measurement of cartilage formation by a novel biomarker of type II collagen formation. The competitive enzyme-linked immunosorbent assay (ELISA) Pro-C2 was developed and characterized for assessment of the beta splice variant of type II procollagen (PIIBNP). This is expected to originate primarily from remodeling of hyaline cartilage. A mouse monoclonal antibody (Mab) was raised in mouse, targeting specifically PIIBNP (QDVRQPG) and used in development of the assay. The specificity, sensitivity, 4-parameter fit and stability of the assay were tested. Levels of PIIBNP were quantified in human serum (0.6-2.2 nM), human amniotic fluid (163-188 nM) and sera from different animal species, e.g., fetal bovine serum (851-901 nM) with general good linearity (100% (SD 7.6) recovery) and good intra- and inter-assay variation (CV% < 10). Dose (0.1 to 100 ng/mL) and time (7, 14 and 21 days) dependent release of PIIBNP were evaluated in the conditioned medium from bovine cartilage explants (BEX) and human cartilage explants (HEX) upon stimulation with insulin-like growth factor (IGF-1), transforming growth factor (TGF)-ß1 and fibroblastic growth factor-2 (FGF-2). TGF-ß1 and IGF-1 in concentrations of 10-100 ng/mL significantly (p < 0.05) induced release of PIIBNP in BEX compared to conditions without treatment (WO). In HEX, IGF-1 100 ng/mL was able to induce a significant increase of PIIBNP after one week compared to WO. FGF-2 did not induce a PIIBNP release in our models. To our knowledge this is the first assay, which is able to specifically evaluate PIIBNP excretion. The Pro-C2 assay seems to provide a promising and novel marker of type II collagen formation.

The active form of MMP-3 is a marker of synovial inflammation and cartilage turnover in inflammatory joint diseases.

BACKGROUND: Matrix metalloproteinase-3 (MMP-3) plays an important role in the pathology of rheumatoid arthritis (RA) and ankylosing spondylitis (AS). Measurement of active MMP-3 in clinical samples could provide information about progression of rheumatoid diseases, and potentially response to treatment. Hence, we aimed to develop a sensitive assay specifically measuring the active form of MMP-3 (act-MMP-3) both in ex vivo models and in human sera. METHODS: A monoclonal antibody against the first 6 amino acids of act-MMP-3 was developed, and the specificity was carefully tested by comparing total and active MMP-3. A technically robust act-MMP-3 ELISA was produced. For biological validation, human synovial membrane and human cartilage explant (HEX) culture models were measured and compared by ELISA and immunoblots. For clinical relevance, the serum levels of act-MMP-3 in AS and RA patients before and after anti-TNF-α treatment were evaluated. RESULTS: A highly specific and technically robust ELISA detecting act-MMP-3 in serum was developed. The lower limit of detection was 33.7 pg/mL. The dilution and spiking recovery of human serum was within 100 ± 20%. The average intra- and inter-assay variations were 3.1% and 13.5% respectively.High levels of act-MMP-3 expression were observed in human synovial membrane culture and oncostatin M and TNF-α stimulated human cartilage. In a cross-sectional study of both AS and RA patients, serum act-MMP-3 level was correlated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). In addition, in patients receiving anti-TNF-α treatment, the serum level of act-MMP-3 was significantly reduced compared to baseline level reflecting the anti-inflammatory effects of the treatment. CONCLUSION: We have successfully developed an assay measuring act-MMP-3 in human serum showing correlation to inflammatory markers. Further studies are required to clarify, whether act-MMP-3 can serve as a predictive marker for outcome in chronic rheumatoid disorders.

The development and characterization of a competitive ELISA for measuring active ADAMTS-4 in a bovine cartilage ex vivo model.

ADAMTS-4 (aggrecanase1) is believed to play an important role in the degradation of aggrecan during the progression of joint diseases. ADAMTS-4 is synthesized as a latent pro-enzyme that requires the removal of the pro-domain, exposing the N-terminal neoepitope, to achieve activity. We developed a monoclonal antibody against this neoepitope of active ADAMTS-4. Furthermore, we established and characterized a competitive ELISA for measuring active ADAMTS-4 form applying the specific antibody. We used this assay to profile the presence of active ADAMTS-4 and its aggrecan degradation product (NITEGE(373)) in a bovine cartilage ex vivo model. We found that after stimulation with catabolic factors, the cartilage initially released high levels of aggrecanase-derived aggrecan fragments into supernatant but subsequently decreased to background levels. The level of active ADAMTS-4 released into the supernatant and retained in the cartilage matrix increased continuously throughout the 21days of the study. The activity of ADAMTS-4 on the last day of catabolic stimulation was verified in vitro by adding deglycosylated or native aggrecan to the conditioned medium. Samples of human cartilage affected by varying degrees of osteoarthritis stained strongly for active ADAMTS-4 where surface fibrillation and clustered chondrocytes were observed. This assay could be an effective tool for studying ADAMTS-4 activity and for screening drugs regulating ADAMTS-4 activation. Moreover, it could be a potential biomarker for degenerative joint disease.