Hyaluronic acid in synovial fluid. I. Molecular parameters of hyaluronic acid in normal and arthritis human fluids

Genotoxicity, acute and subchronic toxicity studies in rats of a rooster comb extract rich in sodium hyaluronate

The toxicity of a rooster comb extract (IB0004) that contains mainly sodium hyaluronate was assessed in acute and subchronic studies and in a bacterial reverse mutation assay. In a single dose acute study, male and female rats were administered 2000 mg/kg body weight (bw) of the product and observed for 14 days. No mortality was recorded, thus it was considered that the minimum lethal dose for rats by oral route was greater than 2000 mg/kg bw. A 90-day subchronic study (5, 55 and 600 mg/kg bw/day, oral gavage) with 50 male and 50 female Wistar-Hannover rats produced no significant adverse effects on food consumption, body weight, mortality, clinical biochemistry, hematology, gross pathology, and histopathology. Although some differences were observed between the treated and control animals in body weight gain (%) and some hematological parameters, these changes were generally minor in nature and, are considered to be of no toxicological significance. The no-observable-adverse-effects level was established at 600 mg/kg bw/day. There was no evidence of mutagenic activity in Salmonella typhimurium TA98, TA100, TA1535 and TA1537 or in Escherichia coli WP2 uvra pkM101. In conclusion, the results from these safety studies support the safety of rooster comb extract IB0004 in food.

The effect of molecular weight on hyaluronan's cartilage boundary lubricating ability--alone and in combination with proteoglycan 4

OBJECTIVES

(1) assess the molecular weight dependence of hyaluronan's (HA) cartilage boundary lubricating ability, alone and in combination with proteoglycan 4 (PRG4), at physiological concentrations; (2) determine if HA and PRG4 interact in solution via electrophoretic mobility shift assay (EMSA).

METHODS

The cartilage boundary lubricating ability of a broad range of MW HA (20 kDa, 132 kDa, 780 kDa, 1.5 MDa, and 5 MDa) at 3.33 mg/ml, both alone and in combination with PRG4 at 450 μg/ml, was assessed using a previously described cartilage-on-cartilage friction test. Static, μ(static, Neq), and kinetic, <μ(kinetic, Neq)>, were calculated. An EMSA was conducted with PRG4 and monodisperse 150 kDa and 1,000 kDa HA.

RESULTS

Friction coefficients were reduced by HA, in a MW-dependent manner. Values of <μ(kinetic, Neq)> in 20 kDa HA, 0.098 (0.089, 0.108), were significantly greater compared to both 780 kDa, 0.080 (0.072, 0.088), and 5 MDa, 0.079 (0.070, 0.089). Linear regression showed a significant correlation between both μ(static, Neq) and <μ(kinetic, Neq)>, and log HA MW. Friction coefficients were also reduced by PRG4, and with subsequent addition of HA; however the synergistic effect was not dependent on HA MW. Values of <μ(kinetic, Neq)> in PRG4, 0.080 (0.047, 0.113), were significantly greater than values of PRG4+various MW HA (similar in value, averaging 0.040 (0.033, 0.047)). EMSA indicated that migration of 150 kDa and 1,000 kDa HA was retarded when combined with PRG4 at high PRG4:HA ratios.

CONCLUSIONS

These results suggest alterations in HA MW could significantly affect synovial fluid's cartilage boundary lubricating ability, yet this diminishment in function could be circumvented by physiological levels of PRG4 forming a complex, potentially in solution, with HA.

Efficacy evaluation of highly purified intra-articular hyaluronic acid (Sinovial(®)) vs hylan G-F20 (Synvisc(®)) in the treatment of symptomatic knee osteoarthritis. A double-blind, controlled, randomized, parallel-group non-inferiority study

OBJECTIVE

Knee osteoarthritis is a major cause of disability and pain. This phase III, double-blind (patient and observer blinded,) multicenter, randomized, non-inferiority study was conducted to demonstrate the non-inferiority of the highly purified intra-articular injection of hyaluronic acid (Sinovial(®)) in comparison to Hylan G-F20 (Synvisc(®)) in the treatment of knee osteoarthritis.

METHODS

A total of 381 patients were randomly assigned to receive either the test drug, 16 mg/2 ml (0.8%) highly purified ia hyaluronic acid of biofermentative origin (Sinovial(®)), or the comparative drug, 16 mg/2 ml of 0.8% hylan G-F20 (Synvisc(®)). The duration of the treatment was 2 weeks (three injections at 1-week interval), followed by an observation period of 6 months. The primary efficacy variable was the improvement in mean Western Ontario and McMaster Universities (WOMAC) pain subscore from baseline to the final visit (week 26), compared between the two treatment groups. The acceptable margin for non-inferiority was chosen to be 8 mm.

RESULTS

At week 26, WOMAC pain subscores decreased by a mean of 32.5 for both Sinovial(®) and Synvisc(®). These results met prespecified criteria for non-inferiority for both the Intent-to-Treat and Per-Protocol populations. There were no statistically significant differences between groups at 26 weeks, although Sinovial(®)-treated patients tended to have a slightly better outcome for select variables, as they did at earlier time-points, some of which reached statistical significance. Both hyaluronic acid preparations were well-tolerated, with no statistically significant differences in tolerability profile between groups.

CONCLUSION

Sinovial(®) and Synvisc(®) treatments were found to be equivalent, both in terms of efficacy and safety.

CLINICAL TRIAL NUMBER

NCT00556608 (ClinicalTrials.gov Identifier).

Intra-articular Duration of Durolane™ after Single Injection into the Rabbit Knee

OBJECTIVE

The aim of the present study was to investigate the intra-articular duration of Durolane™ in a rabbit model to allow comparison between Durolane™ residence time and data reported for other hyaluronic acid products as well as native hyaluronic acid.

DESIGN

(14)C-labeled Durolane™ was manufactured by labeling the cross-linker used for stabilization. A single injection of approximately 0.3 mL (14)C-labeled Durolane™ was administered intra-articularly in both knee joints of male New Zealand White rabbits. At days 1, 2, 3, 7, 28, 60, 96, and 120 after injection, the knee joints of 4 animals were collected, and the radioactivity of the remaining gel was measured. The obtained data were fitted by exponential models to calculate the half-life of the gel. Two additional rabbits were used for histology of the joint 127 days after the injection.

RESULTS

The elimination of (14)C-labeled Durolane™ followed first-order kinetics with an apparent half-life of approximately 32 days. Histology showed no morphological changes in the knee joints.

CONCLUSIONS

This study shows that Durolane™ has a half-life of 32 days in the rabbit knee joint, which is much longer compared to literature data on hyaluronic acid and other modified hyaluronic acid products.

Challenges associated with using bovine serum in wear testing orthopaedic biopolymers

For appropriate in vitro wear testing of prostheses and their biomaterials, the choice of lubricant is critical. Bovine serum is the lubricant recommended by several international standards for wear testing artificial joints and their biomaterials because the wear rate and wear mechanisms closely match clinical results of polyethylene bearings. The main problem with the use of bovine serum as a lubricant is protein degradation and precipitation formation, effects that are recognized as having a direct impact on wear processes. Hence, some researchers have questioned the validity of using bovine serum in simulator testing. This paper reviews the various lubricants used in laboratory wear studies and also the properties of the synovial fluid that the lubricant is trying to replicate. It is clear from the literature survey that the composition of bovine-serum-based lubricants does not match that of synovial fluid. In view of this conclusion, it is suggested that there is a need to develop an alternative lubricant that can replace bovine serum.

Evaluation of long-term antinociceptive properties of stabilized hyaluronic acid preparation (NASHA) in an animal model of repetitive joint pain

Introduction

Clinical trials provided controversial results on whether the injection of hyaluronan preparations into osteoarthritic joints reduces pain. Problems of clinical studies may be the substantial placebo effects of intra-articular injections, different severity and rate of progression of the disease and others. We hypothesize that the use of preclinical pain models may help to clarify whether a certain hyaluronan exerts antinociceptive effects upon intra-articular injection. In the present study we tested in the bradykinin/prostaglandin E₂ (PGE₂) model primarily the putative antinociceptive effect of stabilized hyaluronic acid from a non animal source (NASHA), a stabilized hyaluronic acid based gel for intra-articular treatment of OA. We established a dose-response relationship for NASHA and we compared NASHA to other hyaluronans with different formulations that are in clinical use.

Methods

To induce transient joint pain episodes bradykinin and PGE₂ were repetitively administered intra-articularly and unilaterally into rat knee joints during short anaesthesia. After establishment of the predrug nociceptive responses, a single intra-articular injection of saline or NASHA at different concentrations was administered and pain responses to further bradykinin/PGE₂ injections were monitored up to 56 days after NASHA. Furthermore, the obtained effective dose was compared to clinically defined concentrations of Hylan GF20 and sodium hyaluronate. The primary outcome measures were primary mechanical hyperalgesia at the knee joint and pain-induced weight bearing.

Results

On day 1 after injection, all tested hyaluronan preparations showed an antinociceptive effect >50% compared to saline. Single injections of higher doses of NASHA (50, 75 and 100 μl) were antinociceptive up to 56 days. When injection volumes in rat knee joints were adapted to clinical injection volumes in humans, the antinociceptive effects of the cross-linked NASHA and Hylan GF20 had a longer duration than that of the non cross-linked sodium hyaluronate (with a slightly better effect of NASHA than Hylan GF20).

Conclusions

In the bradykinin/PGE₂ model of joint pain a single injection of all hyaluronan preparations provided significant antinociceptive effects compared to saline. It appeared that the duration of the antinociceptive effect of the cross-linked hyaluronan preparations NASHA and Hylan GF20 was more prolonged. In addition, the gel beads structure allowing only a slow release of hyaluronic acid (NASHA) may even enhance this prolonged antinociceptive effect.

Free-radical degradation of high-molecular-weight hyaluronan induced by ascorbate plus cupric ions. Testing of bucillamine and its SA981-metabolite as antioxidants

High-molecular-weight hyaluronan (HA) samples were exposed to free-radical chain-degradation reactions induced by ascorbate in the presence of Cu(II) ions - the so-called Weissberger's oxidative system. The concentrations of both reactants [ascorbate, Cu(II)] were comparable to those that may occur during an early stage of the acute phase of joint inflammation. The time-dependent changes of the viscosity of the HA solution in the absence of the substance tested were monitored by rotational viscometry. However, when the anti- or pro-oxidative effects of the antioxidants/drugs were investigated, their dose-dependency was also examined. Additionally, the anti-oxidative activities of these substances were screened by the well-established ABTS and DPPH decolorization assays. The actions of the disease-modifying anti-rheumatic drugs, namely bucillamine and D-penicillamine, were compared to those of L-cysteine and of SA981, the oxidized metabolite of bucillamine. The results indicated that bucillamine was the most efficient scavenger of hydroxyl- and/or peroxyl-type radicals, even at the lowest drug concentration. In contrast, SA981 demonstrated no scavenging activity against the aforementioned free radicals. D-Penicillamine and L-cysteine showed a dual effect, i.e. a pronounced anti-oxidative effect was, after a given time period, followed by a significant pro-oxidative effect.

Agarose and polyacrylamide gel electrophoresis methods for molecular mass analysis of 5- to 500-kDa hyaluronan

Agarose and polyacrylamide gel electrophoresis systems for the molecular mass-dependent separation of hyaluronan (HA) in the size range of approximately 5-500 kDa were investigated. For agarose-based systems, the suitability of different agarose types, agarose concentrations, and buffer systems was determined. Using chemoenzymatically synthesized HA standards of low polydispersity, the molecular mass range was determined for each gel composition over which the relationship between HA mobility and logarithm of the molecular mass was linear. Excellent linear calibration was obtained for HA molecular mass as low as approximately 9 kDa in agarose gels. For higher resolution separation, and for extension to molecular masses as low as approximately 5 kDa, gradient polyacrylamide gels were superior. Densitometric scanning of stained gels allowed analysis of the range of molecular masses present in a sample as well as calculation of weight-average and number-average values. The methods were validated for polydisperse HA samples with viscosity-average molecular masses of 112, 59, 37, and 22 kDa at sample loads of 0.5 μg (for polyacrylamide) to 2.5 μg (for agarose). Use of the methods for electrophoretic mobility shift assays was demonstrated for binding of the HA-binding region of aggrecan (recombinant human aggrecan G1-IGD-G2 domains) to a 150-kDa HA standard.

Hyaluronan inhibits matrix metalloproteinase-13 in human arthritic chondrocytes via CD44 and P38

We investigated the effects of hyaluronan (HA) on interleukin-1β (IL-1β)-stimulated matrix metalloproteinase (MMP)-13 production in human chondrocytes from patients with osteoarthritis (OA) or rheumatoid arthritis (RA). Secreted levels of MMP-13 in conditioned media were detected by immunoblotting, while intracellular MMP-13 synthesis in articular cartilage was evaluated by immunofluorescence microscopic analysis. Mitogen-activated protein kinases (MAPKs), p38, extracellular signal-regulated kinases (ERK), and c-jun NH2-terminal kinase (JNK) were assessed by Western blotting. IL-1β (2 ng/ml) stimulates the secretion of MMP-13 in both OA and RA chondrocytes. Inhibition studies using specific MAPK inhibitors revealed that IL-1β induced MMP-13 via p38 in both OA and RA chondrocytes. HA down-regulates IL-1β-stimulated MMP-13 and phosphorylated p38 (p-p38) in a dose-dependent manner (0.1, 1, 2, and 4 mg/ml). When used at 4 mg/ml, HA inhibits p-p38 phosphorylation by more than 60%. In response to IL-1β, RA chondrocytes express a higher level of p-p38 than that of OA chondrocytes. Inhibition of CD44, using a blocking antibody, significantly reversed the inhibitory effect of HA on both MMP-13 and p-p38. Our study clearly shows that HA inhibits IL-1β-induced MMP-13 via its principal receptor, CD44, and subsequent intracellular p38 MAPK signaling in OA and RA chondrocytes.

Effects of supplemental intra-articular lubricin and hyaluronic acid on the progression of posttraumatic arthritis in the anterior cruciate ligament-deficient rat knee

BACKGROUND

Lubricin and hyaluronic acid lubricate articular cartilage and prevent wear. Because lubricin loss occurs after anterior cruciate ligament injury, intra-articular lubricin injections may reduce cartilage damage in the anterior cruciate ligament-deficient knee.

PURPOSE

This study was conducted to determine if lubricin and/or hyaluronic acid supplementation will reduce cartilage damage in the anterior cruciate ligament-deficient knee.

STUDY DESIGN

Controlled laboratory study.

METHODS

Thirty-six male rats, 3 months old, underwent unilateral anterior cruciate ligament transection. They were randomized to 4 treatments: (1) saline (phosphate-buffered saline [PBS]), (2) hyaluronic acid (HA), (3) purified human lubricin (LUB), and (4) LUB and HA (LUB+HA). Intra-articular injections were given twice weekly for 4 weeks starting 1 week after surgery. Knees were harvested 1 week after the final injection. Radiographs of each limb and synovial fluid lavages were obtained at harvest. Histologic analysis was performed to assess cartilage damage using safranin O/fast green staining. Radiographs were scored for the severity of joint degeneration using the modified Kellgren-Lawrence scale. Synovial fluid levels of sulfated glycosaminoglycan, collagen II breakdown, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and lubricin were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Treatment with LUB or LUB+HA significantly decreased radiographic and histologic scores of cartilage damage (P = .039 and P = .015, respectively) when compared with the PBS and HA conditions. There was no evidence of an effect of HA nor was the LUB effect HA-dependent, suggesting that the addition of HA did not further reduce damage. The synovial fluid of knees treated with LUB had significantly more lubricin in the synovial fluid at euthanasia, although there were no differences in the other cartilage metabolism biomarkers.

CONCLUSION

Supplemental intra-articular LUB reduced cartilage damage in the anterior cruciate ligament-transected rat knee 6 weeks after injury, while treatment with HA did not.

CLINICAL RELEVANCE

Although longer term studies are needed, intra-articular supplementation (tribosupplementation) with lubricin after anterior cruciate ligament injury may protect the articular cartilage in the anterior cruciate ligament-injured knee.

Viscosupplementation in the management of ankle osteoarthritis: a review

INTRODUCTION

Osteoarthritis (OA) is a disease of synovial joints and is the most common cause of chronic pain. Viscosupplementation (VS) with hyaluronic acid (HA) is largely used for knee osteoarthritis therapy but the evidence for its usefulness in ankle osteoarthritis is limited. The objective of this review is to assess the efficacy of viscosupplementation treatment of ankle osteoarthritis in the current literature.

METHODS

The following databases were searched: Medline (period 2006-2008), Database of Abstract on Reviews and Effectiveness and Cochrane Database of Systematic Reviews. Reference lists of relevant articles were controlled for additional references. The search terms Review, Viscosupplementation (VS), Osteoarthritis (OA), Hyaluronic acid (HA), Hyaluronan, Sodium hyaluronate, Ankle OA, Ankle joint were used to identify all studies relating to the use of VS therapy for the ankle OA. Methodological quality of included studies was assessed by assigning level of evidence as previously defined by the Centre for Evidence Based Medicine (CEBM).

RESULT

Seven articles concerning the efficacy of a total of 275 patients undergoing VS treatment for ankle OA were included. One European study, one Taiwanese study, one Italian study, one Turkish study and three American studies with level of evidence ranging from I to IV evaluated the following products: Hyalgan, Synvisc, Supartz, Adant.

CONCLUSION

Viscosupplementation is used widely in knee OA and is included in the professional guidelines for treatment of the disease in this joint. The potential for treating osteoarthritis of the ankle joint by viscosupplementation has been suggested in the literature, however, no dosing studies have been published to date, and dosing in the ankle joint remains an area for discussion. Viscosupplementation could potentially provide an useful alternative in treating such patients with painful ankle OA.

Hylan g-f 20: review of its safety and efficacy in the management of joint pain in osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a chronic degenerative joint disease that is a clinically and economically important disease. The increased prevalence of OA with aging, coupled to the demographics of aging populations, make OA a high priority health care problem. Viscosupplementation (VS) is a well-established treatment option in knee OA that is included in the professional guidelines for treatment of this joint disease, and could potentially provide a useful alternative in treating such patients with painful OA. Theoretically VS is an approach that should apply to all synovial joints.

OBJECTIVES

The aim of this review is to assess the efficacy and safety of viscosupplementation with Hylan GF-20 (Synvisc(®)) in the management of joint pain in osteoarthritis.

METHODS

THE FOLLOWING DATABASES WERE SEARCHED: Medline, Database of Abstract on Reviews and Effectiveness, Cochrane Database of Systematic Reviews. Furthermore, the lists of references of retrieved publications were manually checked for additional references. The search terms Review, Viscosupplementation, Osteoarthritis, Hyaluronic acid, Hyaluronan, Sodium Hyaluronate, Hylan GF-20, Synvisc, intra-articular injection were used to identify all studies relating to the use of Synvisc(®) viscosupplementation therapy in OA.

RESULTS

Hylan GF-20 is a safe and effective treatment for decreasing pain and improving function in patients suffering from knee and hip OA but new evidences are emerging for its use in other joints.

Effects of low-intensity pulsed ultrasound on the expression and activity of hyaluronan synthase and hyaluronidase in IL-1β-stimulated synovial cells

The purpose of this study is to examine effects of low-intensity pulsed ultrasound (LIPUS) on metabolism of hyaluronan (HA) in synovial membrane cells stimulated by IL-1β. Rabbit knee synovial membrane cell line, HIG-82, was cultured in medium with the presence or absence of 1 ng/mL IL-1β, and after 4 h the cell was exposed to LIPUS for 15 min. The mRNA levels of HA synthase (HAS) 2,3, hyaluronidase (HYAL) 2, and cyclooxygenase (COX)-2 were examined by real-time PCR analysis. Concentrations of HA and PGE₂ were quantified by use of enzyme linked immunosorbent assay (ELISA). The COX-2 level was analyzed by western blotting. Gene levels of HAS2 and HAS3 in IL-1β-stimulated cells were up-regulated significantly (p < 0.01) by LIPUS. HYAL2 mRNA was up-regulated by the treatment with IL-1β, whereas down-regulated significantly (p < 0.01) by the following LIPUS exposure. Furthermore, IL-1β stimulation enhanced COX-2 and PGE₂ expression as compared to the untreated control, and IL-1β-induced COX-2 and PGE₂ expression was inhibited by LIPUS. These results suggest that LIPUS enhanced HA synthesis and inhibited HYAL2 expression, leading to the accumulation of high-molecular weight HA. Therefore, LIPUS stimulation may be a better candidate as medical remedy to treat inflammatory joint diseases accompanied with HA degradation in synovial fluid.

Conservative treatment modalities and outcomes for osteoarthritis: the concomitant pyramid of treatment

This article reviews current treatment algorithms for the conservative treatment of hip and knee osteoarthritis. The available treatment options for osteoarthritis (physical therapy, medical therapeutics, steroid injections, nutraceuticals, hyaluronic acid injections, acupuncture, pulsed electrical stimulation, and topical ointments) are compared to determine efficacy in the treatment of pain and return of function in the osteoarthritic joint. A literature review was conducted to determine combinations of appropriate concomitant therapy. Based on the available literature, we conclude that an early transition to multimodal and concomitant therapy is the most efficacious approach to decrease pain and improve joint function in the osteoarthritic hip and knee.

Intra-articular hyaluronans: the treatment of knee pain in osteoarthritis

The etiology of pain in osteoarthritis is multifactoral, and includes mechanical and inflammatory processes. Intra-articular injections of hyaluronans (HAs) are indicated when non-pharmacological and simple analgesics have failed to relieve symptoms. The HAs appear to reduce pain by restoring both mechanical and biomechanical homeostasis in the joint. There are five FDA-approved injectable preparations of HAs: Hyalgan^®, Synvisc^®, Supartz^®, Orthovisc^® and Euflexxa^®. They all appear to relieve pain from 4 to 14 weeks after injection and may have disease-modification properties. Although several randomized controlled trials have established the efficacy of this treatment modality, additional high quality randomized control studies with appropriate comparison are still required to clearly define the role of intra-articular HA injections in the treatment of osteoarthritis.

A versatile pH sensitive chondroitin sulfate-PEG tissue adhesive and hydrogel

We developed a chondroitin sulfate-polyethylene glycol (CS-PEG) adhesive hydrogel with numerous potential biomedical applications. The carboxyl groups on chondroitin sulfate (CS) chains were functionalized with N-hydroxysuccinimide (NHS) to yield chondroitin sulfate succinimidyl succinate (CS-NHS). Following purification, the CS-NHS molecule can react with primary amines to form amide bonds. Hence, using six arm polyethylene glycol amine PEG-(NH2)6 as a crosslinker we formed a hydrogel which was covalently bound to proteins in tissue via amide bonds. By varying the initial pH of the precursor solutions, the hydrogel stiffness, swelling properties, and kinetics of gelation could be controlled. The sealing/adhesive strength could also be modified by varying the damping and storage modulus properties of the material. The adhesive strength of the material with cartilage tissue was shown to be ten times higher than that of fibrin glue. Cells encapsulated or in direct contact with the material remained viable and metabolically active. Furthermore, CS-PEG material produced minimal inflammatory response when implanted subcutaneously in a rat model and enzymatic degradation was demonstrated in vitro. This work establishes an adhesive hydrogel derived from biological and synthetic components with potential application in wound healing and regenerative medicine.

Hylan G-F 20 has better pain relief and cost-effectiveness than sodium hyaluronate in treating early osteoarthritic knees in Taiwan

BACKGROUND/PURPOSE

Intra-articular injection of hyaluronan (hyaluronic acid; HA) products is available to treat early osteoarthritis (OA) of the knee in Taiwan. We tested whether HA products with different molecular weights have significantly different effects on clinical efficacy and cost-effectiveness.

METHODS

Thirty-seven patients with mild to moderate OA of both knees underwent five weekly intra-articular injections of sodium hyaluronate (Artz) in one knee and three weekly intra-articular injections of chemically cross-linked Hylan G-F 20 (Synvisc) in the other. Visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Lequesne's index, and Hospital for Special Surgery (HSS) knee scores were compared initially and at the last injection, and at 8, 12, 16, 20, and 26 weeks after the first injection.

RESULTS

VAS, WOMAC, WOMAC-A1 (pain when walking on a flat surface) scores before week 16, HSS scores before week 12, and Lequesne's index scores except at week 26 all showed that HA significantly improved the scores time-dependently. In VAS scores, Synvisc showed better improvement before week 20, while this effect appeared at week 12 for the WOMAC-A1 scores. The incremental cost-effectiveness ratio of the Taiwan National Health Insurance Program, of the patient, and both of these was lower for Synvisc, which also reduced the number of additional hospital visits for injections by two.

CONCLUSION

Synvisc possesses better symptom-modifying ability and cost-utility in treating early OA of the knee in Taiwan.

Serum hyaluronic acid as a potential marker with a predictive value for further radiographic progression of hand osteoarthritis

OBJECTIVE

To compare serum levels of hyaluronic acid (HA) between patients with erosive and non-erosive hand osteoarthritis (HOA), and investigate its association with morphological changes and radiographic progression over 2 years.

METHODS

Fifty-five women with erosive and 33 women with non-erosive HOA were included in this study. All underwent clinical examination, which included assessment of pain, swelling, deformity and deviation of small hand joints and completed health assessment questionnaires. Serum levels of HA were measured by ELISA. Three-phase bone scintigraphy was performed at baseline. Radiographs of both hands were performed at baseline and after 2 years and scored according Kallman grading scale.

RESULTS

Serum levels of HA were significantly higher in patients with erosive than with non-erosive HOA (P<0.01). It correlated significantly with the number of hand joints with deviations and deformities. HA adjusted for age and disease duration significantly correlated with radiographs at baseline and after 2 years in all patients with HOA (r=0.560 and r=0.542, P<0.01 for both correlations). Although there was an association between HA and radiographic score in erosive disease, after adjustment for confounders it remained no longer significant. HA adjusted for confounders correlated significantly with the late phase in all patients with HOA (r=0.412, P<0.01) and in patients with erosive disease (r=0.320, P<0.05).

CONCLUSION

HA is increased in patients with erosive HOA and could be proposed as a surrogate marker with a predictive value for further radiographic progression of HOA in general. Further investigation is necessary to confirm these results.

Etanercept overcomes P-glycoprotein-induced drug resistance in lymphocytes of patients with intractable rheumatoid arthritis

P-glycoprotein (P-gp) on activated lymphocytes is an adenosine triphosphate (ATP)-binding cassette transporter that causes drug resistance by exclusion of intracellular drugs in patients with active rheumatoid arthritis (RA). However, infliximab with methotrexate (MTX) can overcome P-gp-mediated drug resistance. We encounter patients who cannot continue infliximab or MTX. Here we tested how etanercept affected P-gp-mediated drug resistance in such intractable RA patients. Peripheral lymphocytes of 11 RA patients (3 switched from infliximab and 8 who could not be treated with MTX) were analyzed for P-gp expression by flow cytometry and for drug exclusion using radioisotope-labeled dexamethasone. Activated lymphocytes of RA patients overexpressed P-gp and coexpressed CD69. Incubation of these lymphocytes with dexamethasone in vitro reduced intracellular dexamethasone levels. Two-week etanercept therapy significantly reduced P-gp expression and eliminated such P-gp- and CD69-high-expressing subgroup. The reduction in P-gp resulted in recovery of intracellular dexamethasone levels in lymphocytes and improvement of disease activity, thus allowing tapering of corticosteroids. None of the patients experienced any severe adverse effects. Etanercept is useful for overcoming P-gp-mediated treatment resistance in intractable RA patients who have to discontinue infliximab or are intolerant to MTX.

Desirable effect of combination therapy with high molecular weight hyaluronate and NSAIDs on MMP production

OBJECTIVE

We previously reported that nonsteroidal anti-inflammatory drugs (NSAIDs) aggravated cartilage degeneration and that hyaluronate (HA) reversed the cartilage destruction accelerated by NSAIDs in a rabbit osteoarthritis (OA) model. In the present study, we analyzed the mechanisms of these effects of NSAIDs and HA.

METHOD

An experimental rabbit model of OA was induced by partial meniscectomy and treated with NSAIDs, HA and the combination of NSAIDs and HA over 2 weeks. After sacrifice, cartilage degeneration and the levels of matrix metalloproteases (MMP)-1, MMP-3 and MMP-13 in synovial lavage fluid were measured. In an in vitro study, human articular chondrocytes were cultured with NSAIDs and HA in the presence of interleukin (IL)-1beta or IL-6+sIL-6 for 24 h. After culture, the production of MMPs, IL-1beta, and IL-6 was measured.

RESULTS

The levels of MMP-1, MMP-3 and MMP-13 in synovial fluid from the NSAID-treated group were significantly higher than in controls. The increased production of MMPs induced by NSAIDs was counteracted by the concomitant administration of HA. In vitro studies showed that NSAIDs augmented IL-1beta- and IL-6-induced production of MMPs from human chondrocytes, while completely inhibiting the IL-1beta- and IL-6/sIL-6R-induced production of prostaglandin E(2) (PGE(2)). The addition of PGE(2) did not reduce the augmentation of MMP production. HA inhibited the promotion of cytokine-induced MMP and cytokine production by NSAIDs.

CONCLUSIONS

Our data clearly showed that HA inhibited NSAID-accelerated MMP production which was followed by inflammatory cytokine production from cytokine-activated chondrocytes. The results warrant further evaluation of the potential chondroprotective effects of co-administration of HA with NSAIDs.

Rheologic behavior of osteoarthritic synovial fluid after addition of hyaluronic acid: a pilot study

Viscosupplementation is a symptomatic treatment of osteoarthritis (OA) intended to restore rheologic homeostasis of the synovial fluid by injecting hyaluronic acid intraarticularly. Despite the long history of this therapy, little is known about its mechanisms of action and differences between commercial preparations. We investigated the rheologic behavior of OA synovial fluid with time, when stored at 4 degrees C, before and after the addition of two hyaluronic acid commercial preparations (linear and cross-linked). Thirteen OA synovial fluids were stored at 4 degrees C and assayed using steric exclusion chromatography, which allows hyaluronic acid to be separated from the remaining pool of proteins and its molecular weight and concentration to be determined without any pretreatment and calibration. The synovial fluid rheology also was studied in vitro, before and after addition of two viscosupplements, over 6 weeks. The non-Newtonian behavior of synovial fluid throughout followup appears to be the result of loose interactions between proteins and hyaluronic acid. When mixed with the linear hyaluronic acid, synovial fluid becomes less non-Newtonian whereas the non-Newtonian behavior was reinforced when mixed with the cross-linked hyaluronic acid. The rheology was nearly unchanged for all synovial fluids over 6 weeks. Our preliminary trial shows it is possible to study synovial fluid, stored at 4 degrees C, over a long time and suggests the enzymatic degradation of hyaluronic acid is negligible under these experimental conditions.

Low-energy laser irradiation promotes synovial fibroblast proliferation by modulating p15 subcellular localization

BACKGROUND AND OBJECTIVE

Low-energy laser irradiation (low-level laser therapy) (LELI/LLLT/photobiomodulation) has been found to modulate various biological effects, especially those involved in promoting cell proliferation. Synovial fibroblasts are important in maintaining the homeostasis of articular joints and have strong chondrogenetic capacity. Here, we investigated the effect and molecular basis of LELI on synovial fibroblast proliferation.

STUDY DESIGN/MATERIALS AND METHODS

HIG-82 rabbit synovial fibroblasts were cultured, and laser irradiation (660 nm) was applied at the power density of 40 mW/cm(2) for 2 minutes, corresponding to laser fluence of 4.8 J/cm(2). The effect of LELI on cell proliferation, cell cycle progression, and expression of cyclin-dependent kinase inhibitors (CKIs) were investigated. We also examined whether the effects of LELI on HIG-82 cell proliferation were affected by cAMP content, which is known to influence the cell cycle via inducing CKIs.

RESULTS

LELI promoted HIG-82 synovial fibroblast proliferation and induced cytoplasmic localization of cyclin-dependent kinase inhibitor p15 (INK4B/CDKN2B). Moreover, the proliferation of HIG-82 synovial fibroblasts was reduced by cAMP, while cAMP inhibitor, SQ22536, induced p15 cytoplasmic localization and as a result, elevated synovial fibroblast proliferation was observed. In addition, the promotive effect of LELI-induced HIG-82 synovial fibroblast proliferation was abolished by cAMP treatment. Our findings suggest that cAMP may be involved in the effect of LELI on synovial fibroblast proliferation.

CONCLUSION

We revealed the effect and molecular link involved in synovial fibroblast proliferation induced by 660-nm LELI. Our study provides new insights into the mechanisms by which LELI has biological effects on synovial fibroblast proliferation. These insights may contribute to further investigation on biological effects and application of LELI in regenerative medicine.

Joint aspiration and injection and synovial fluid analysis

Joint aspiration/injection and synovial fluid (SF) analysis are both invaluable procedures for the diagnosis and treatment of joint disease. This chapter addresses: (1) the indications, the technical principles and the expected benefits and risks of aspiration and injection of intra-articular corticosteroid; and (2) practical aspects relating to SF analysis, especially in relation to crystal identification. Intra-articular injection of long-acting insoluble corticosteroids is a well-established procedure that produces rapid pain relief and resolution of inflammation in most injected joints. The knee is the most common site to require aspiration, although any non-axial joint is accessible for obtaining SF. The technique requires a knowledge of basic anatomy and should not be unduly painful for the patient. Provided sterile equipment and a sensible, aseptic approach are used, it is very safe. Analysis of aspirated SF is helpful in the differential diagnosis of arthritis and is the definitive method for diagnosis of septic arthritis and crystal arthritis. The gross appearance of SF can provide useful diagnostic information in terms of the degree of joint inflammation and presence of haemarthrosis. Microbiological studies of SF are the key to the confirmation of infectious conditions. Increasing joint inflammation is associated with increased SF volume, reduced viscosity, increasing turbidity and cell count, and increasing ratio of polymorphonuclear: mononuclear cells, but such changes are non-specific and must be interpreted in the clinical setting. However, detection of SF monosodium urate and calcium pyrophosphate dihydrate crystals, even from un-inflamed joints during intercritical periods, allow a precise diagnosis of gout and of calcium pyrophosphate crystal-related arthritis.

Temporomandibular joint osteoarthritis: an open label trial of 76 patients treated with arthrocentesis plus hyaluronic acid injections

This study is an open-label trial on a sample of 76 consecutive patients with temporomandibular joint (TMJ) osteoarthritis treated with a cycle of five weekly arthrocenteses plus hyaluronic acid injections. Patients had a diagnosis of osteoarthritis according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD Axis I Group IIIb). They underwent a cycle of five arthrocenteses with injections (1 per week) of 1ml hyaluronic acid and four follow-up assessments after the end of the treatment (at 1 week, 1 month, 3 months, 6 months). At each appointment, several subjective and objective outcome variables were assessed to test the efficacy of the treatment protocol. Marked improvements were reported for all variables during the treatment phase. The improvements were maintained over the 6-month follow-up period. The p-value of the multivariate permutation test for the efficacy of the treatment over time (with Tippett's combination) was 0.001, and significant changes at the end of the follow-up period were detected for almost all the outcome variables. Data from this study lend further support to the usefulness of serial hyaluronic acid injections performed after arthrocentesis for the treatment of TMJ osteoarthritis and for the maintenance of improvements over a 6-month follow-up period.

Hyaluronan-binding receptors: possible involvement in osteoarthritis

Our objectives were to compare the expression of the hyaluronan receptors CD44 and RHAMM in knee synovial tissue of patients with and without advanced osteoarthritis (OA). Both receptors were detected immunohistochemically; the staining appeared more intense in the tissues from the patients with advanced OA. Expression of CD44 and RHAMM were each significantly increased (p < 0.05) in synovial tissue from patients with OA, as determined by means of Western-blot analysis. The findings suggested that changes in levels of the HA-binding proteins might be implicated in the development or progression of OA.

Intra-articular injection of hyaluronan diminishes loss of chondrocytes in a rat immobilized-knee model

Joint immobilization is a useful and common treatment modality in orthopedics. However, it also causes unfavorable outcome such as articular cartilage degeneration. Intra-articular injection of hyaluronan has been accepted as a treatment of osteoarthritis, but its effects on immobilized joint remain to be clarified. Hyaluronan is a polysaccharide, distributed ubiquitously in various tissues. In this study, we examined the effect of hyaluronan on the articular cartilage in immobilized joints. The unilateral knee joints of adult male rats were immobilized at 150 degrees in flexion with an internal plate and screws for 1, 2, 4, 6, 8, 12, or 16 weeks (n = 84). Hyaluronan or saline (50 microl/each injection) was administered intra-articularly on the day of surgery and once a week. The articular cartilage from the medial midcondylar region of the knee was obtained, and divided into non-contact, contact and transitional areas (between the non-contact and the contact areas). In each area, a degree of degeneration was evaluated by histomorphometric grading, and measurements of thickness and number of chondrocytes. Histological grading scores in the hyaluronan group were smaller at 12 and 16 weeks compared with those in the saline group. The thickness of the articular cartilage increased in the transitional area in both groups. The number of chondrocytes in the contact and transitional areas gradually decreased, but their number in the hyaluronan group was greater at 12 and 16 weeks compared with that in the saline group. Hyaluronan showed chondroprotective effects on the articular cartilage in a rat immobilized-knee model.

The role of viscosupplementation in the ankle using hylan G-F 20

The use of intra-articular injections of high molecular weight elastoviscous solutions of hyaluronan or hylans (cross-linked derivatives of hyaluronan) to treat arthritis is termed viscosupplementation. The function of viscosupplementation is to restore the rheologic properties of synovial fluid. Although anecdotal data exist, no long-term studies regarding the use of viscosupplementation in the ankle have been published to date. The goal of this clinical trial was to compare pain reduction following ankle arthroscopy versus that following ankle arthroscopy combined with weekly intra-articular instillation of hylan G-F 20 during the first 3 postoperative weeks. In the series of patients described in this report, we found that both treatment groups experienced statistically significantly decreased pain following the intervention (P = .002 and P = .0009 for the arthroscopy alone and arthroscopy plus hylan groups, respectively), and that those who received 3 intra-articular injections of hylan G-F 20 following ankle arthroscopy improved statistically significantly (P = .0014) more than did those who underwent arthroscopy as a sole therapy. These preliminary results suggest that viscosupplementation combined with arthroscopy may be more beneficial than arthroscopy alone, and provide further insight into the role of viscosupplementation in the treatment of ankle osteoarthritis.

LEVEL OF CLINICAL EVIDENCE

4.

Efficacy of Hylan G-F 20 and Sodium Hyaluronate in the treatment of osteoarthritis of the knee -- a prospective randomized clinical trial

In this independent prospective randomized trial, we compared the clinical effectiveness, functional outcome and patient satisfaction following intra articular injection with two viscosupplementation agents - Hylan G-F-20 (n=199) and Sodium Hyaluronate (n=193) in patients with osteoarthritis (OA) of the knee. All patients were prospectively reviewed by blinded independent assessors at pre injection, 6 weeks, 3, 6, 12 months. Knee pain and patient satisfaction were measured on a visual analogue scale. Functional outcome was assessed using WOMAC, Oxford knee score and EuroQol EQ-5D scores. Knee pain on VAS improved from 6.7 to 3.2 by 6 weeks (p=0.02) and was sustained until 12 months (3.7, p=0.04) with Hylan G-F 20. In the Sodium Hyaluronate group, pain improved from 6.6 to 5.7 at 6 weeks (p>0.05) and to 4.1 at 3 months (p=0.04) but was sustained only until 6 months (5.9, p>0.05). Improvement in the WOMAC pain subscale was significantly superior in the Hylan G-F 20 group at 3 months (p=0.02), 6 months (p=0.01) and 12 months (p=0.007). There was no significant difference in the EQ-5D scores at 6 weeks and 3 months between the two groups. The numbers of treatment related adverse events were higher (39 vs. 30) in the Hylan G-F 20 group. One patient in the Hylan G-F 20 group who had a serious adverse event was also included in the final analysis. Although both treatments offered significant pain reduction, it was achieved earlier and sustained for a longer period with Hylan G-F 20. From this study, it appeared that the clinical effectiveness and general patient satisfaction are better amongst patients who received Hylan G-F 20.

Effects of different molecular weight hyaluronan products on the expression of urokinase plasminogen activator and inhibitor and gelatinases during the early stage of osteoarthritis

Hyaluronan or hyaluronic acid (HA) has been used to treat osteoarthritic knees for more than 30 years. Here, we tested the hypothesis that HA with high molecular weight (MW) would have greater effects than HA with low MW on the expression of the plasminogen activator (PA)/plasmin system and gelatinases [matrix metalloproteinase (MMP)-2 and MMP-9] during early development of osteoarthritis (OA). We compared the levels of MMP-2, MMP-9, urokinase-type PA (u-PA), and PA inhibitor-1 (PAI-1) in a series of chondral, meniscal, and synovial cultures of early OA after treatment with or without three different MW HA products (Hyalgan and Artz with low MW, and Synvisc with high MW). Gelatin zymography revealed that three different HA products could decrease the secretion of MMP-2 in all tissue cultures and MMP-9 in meniscal and synovial cultures time-dependently. Enzyme-linked immunosorbent assay showed that Artz and Synvisc had significant inhibition on u-PA and PAI-1 levels after 24 h, but Hyalgan did at 96 h. Compared with Hyalgan and Artz, Synvisc provided the greatest ability to inhibit MMP-2, MMP-9, u-PA, and PAI-1 expression. Our studies clearly demonstrate that the therapeutic effects of using HA to treat early OA may be partially dependant on downregulation of the PA/plasmin system and gelatinases expression, which delay the structural progression of the disease. HA with high MW might have a greater ability than that with low MW to offer effective protection for articular cartilage.

Lubrication of the temporomandibular joint

Although tissue engineering of the temporomandibular joint (TMJ) structures is in its infancy, tissue engineering provides the revolutionary possibility for treatment of temporomandibular disorders (TMDs). Recently, several reviews have provided a summary of knowledge of TMJ structure and function at the biochemical, cellular, or mechanical level for tissue engineering of mandibular cartilage, bone and the TMJ disc. As the TMJ enables large relative movements, joint lubrication can be considered of great importance for an understanding of the dynamics of the TMJ. The tribological characteristics of the TMJ are essential for reconstruction and tissue engineering of the joint. The purpose of this review is to provide a summary of advances relevant to the tribological characteristics of the TMJ and to serve as a reference for future research in this field. This review consists of four parts. Part 1 is a brief review of the anatomy and function of the TMJ articular components. In Part 2, the biomechanical and biochemical factors associated with joint lubrication are described: the articular surface topology with microscopic surface roughness and the biomechanical loading during jaw movements. Part 3 includes lubrication theories and possible mechanisms for breakdown of joint lubrication. Finally, in Part 4, the requirement and possibility of tissue engineering for treatment of TMDs with degenerative changes as a future treatment regimen will be discussed in a tribological context.

Exercise and injury increase chondroitin sulfate chain length and decrease hyaluronan chain length in synovial fluid

OBJECTIVES

(1) To investigate the effects of exercise and osteochondral (OC) injury on synovial fluid (SF) chondroitin sulfate (CS) and hyaluronan (HA) concentration and chain length, (2) to compare SF and cartilage CS data from joints with OC fragmentation, and (3) to compare SF CS and HA profiles with those seen in serum from the same horses.

METHODS

Serum and SF were obtained from (1) normal horses after 8 weeks rest, (2) the same horses after 9 months treadmill training, and (3) horses with OC injury from racing. Articular cartilage was also collected from group 3 horses. Concentrations and chain lengths of CS and HA were determined by gel chromatography and fluorophore-assisted carbohydrate electrophoresis.

RESULTS

SF CS peak chain length in the OC injury group increased significantly (18.7kDa) when compared to rested horses (11.6kDa), with exercise producing an intermediate chain length (15.6kDa). Cartilage and serum from the OC injury group had the abnormally long CS chains seen in SF from these horses. Total SF HA was significantly lower in the OC injury group compared to the rested group. Both the OC injury group and the exercised group had significant decreases in SF HA chain length compared to the rested group.

CONCLUSIONS

Chain length of SF CS was increased by exercise and OC injury. Exercise resulted in a modest increase, whereas OC injury caused a marked increase. In contrast to CS, SF HA chain length was decreased by OC injury, and to a lesser extent by exercise. Chain length analysis of SF CS and HA may provide a useful tool for evaluation of joint health.

Viscosupplementation with hyaluronans for osteoarthritis of the knee: clinical efficacy and economic implications

Treatment with intra-articular viscosupplementation with hyaluronan (hyaluronic acid) and its derivatives is an important component of the management of osteoarthritis (OA) of the knee. Several intra-articular hyaluronan formulations are now available that vary in their physical properties, duration of effect and treatment schedules. Although aspects regarding their mechanism of action are not completely understood, numerous clinical trials, systematic reviews and meta-analyses have confirmed the efficacy of intra-articular hyaluronan therapies for relieving OA-related pain and improving joint function. Data indicate that intra-articular hyaluronan preparations provide OA pain relief that is comparable to or greater than that observed with conventional treatment, NSAID medications, intra-articular corticosteroids, arthroscopic lavage, physical therapy and exercise. Other studies indicate that multiple courses of hyaluronan are effective. Intra-articular hyaluronan formulations are well tolerated and are associated with a low incidence of adverse effects, usually localised to the injected joint. Local adverse events associated with intra-articular hyaluronan products are typically mild to moderate in severity, benign and transient, although their aetiology is unknown. The cost effectiveness of intra-articular hyaluronan has been demonstrated, but only in a limited number of studies. Cost savings with intra-articular hyaluronan can also be realised with reduction of NSAID medication use and the possibility of delaying total knee replacement, which can reduce the need for costly revision procedures. Because different intra-articular hyaluronan formulations require different numbers of injections and office visits, are associated with variable treatment costs, and provide varying degrees of efficacy, not all intra-articular hyaluronan formulations may be equally cost effective over time.

Degradation of high-molar-mass hyaluronan by an oxidative system comprising ascorbate, Cu(II), and hydrogen peroxide: Inhibitory action of antiinflammatory drugs—Naproxen and acetylsalicylic acid

Changes in dynamic viscosity of the solutions of a high-molar-mass hyaluronan (HA) were monitored using a rotational viscometer. The degradative conditions generated in the HA solutions by a system comprising ascorbate plus Cu(II) plus H(2)O(2) were studied either in the presence or absence of a drug--naproxen or acetylsalicylic acid. Continual decrease of the dynamic viscosity of HA solution was indicative of the polymer degradation. Addition of the drug retarded/inhibited the HA degradation in a concentration-dependent manner. The characteristics of the fragmented polymers were investigated by FT-IR spectroscopy and by two different liquid chromatographic techniques, namely by size-exclusion chromatography equipped with a multi-angle light scattering photometric detector and by high-performance liquid chromatography connected on-line to a spectrofluorometer.

Nociceptive nerve activity in an experimental model of knee joint osteoarthritis of the guinea pig: Effect of intra-articular hyaluronan application

Nociceptive impulse activity was recorded extracellularly from single A delta and C primary afferents of the guinea pig's medial articular nerve after induction of an experimental osteoarthritis in the knee joint by partial medial menisectomy and transection of the anterior cruciate ligament (PMM+TACL). Also, the analgesic effects of intra-articular hyaluronan solutions were evaluated. Healthy, PMM+TACL operated, sham-operated (opening of the joint capsule without PMM and TACL surgery) and acutely inflamed (intra-articular kaolin-carrageenan, K-C) animals were used. The stimulus protocol consisted of torque meter-controlled, standardized innocuous and noxious inward and outward rotations of the joint. This stimulus protocol of 50 s duration was repeated every 5 min for 70 min. One day, one week and three weeks after PMM+TACL, the movement-evoked discharges of A delta articular afferents were increased significantly over values found in sham-operated animals. The discharges of C fibers were significantly augmented only one week after PMM+TACL surgery. Filling of the joint cavity with a high viscosity hyaluronan solution (hylan G-F 20, Synvisc) immediately and three days after surgery reduced significantly the enhanced nerve activity observed in joint afferent fibers one day and one week after surgery. Augmentation of movement-evoked discharges in K-C acutely inflamed knee joints was similar to that observed one week after PMM+TACL. Our results indicate that in the PMM+TACL model of osteoarthritis in guinea pigs, enhancement of nociceptive responses to joint movement was primarily associated to post-surgical inflammation. Intra-articular injection of an elastoviscous hyaluronan solution reduced the augmented nerve activity.

Solution properties of high-molar-mass hyaluronans: the biopolymer degradation by ascorbate

An accurate molecular characterization, molar mass and size distributions, of 10 hyaluronan (HA) samples was performed by using a multi-angle light scattering detector connected on-line to a size exclusion chromatographic system. The dynamic viscosity eta of the HA solutions was investigated using a rotational viscometer. On monitoring the sample dynamic viscosity for up to 5h, a small however constant increase of the eta value was observed, indicating rheopectic behavior of all 10 HA solutions. Addition of ascorbic acid to the HA solutions caused significant changes in the rheological properties of the samples investigated. The change of eta values in the course of time was explained by the redox reactions (caused by the added ascorbate) that occur during the dynamic viscosity monitoring.

Degradation of matrix glycosaminoglycans by peroxynitrite/peroxynitrous acid: evidence for a hydroxyl-radical-like mechanism

The oxidant peroxynitrite/peroxynitrous acid (ONOO-/ONOOH) is generated at sites of inflammation via reaction of O2.- with .NO. Previous studies have shown that these species can oxidize cellular targets, but few data are available on damage to extracellular matrix and its components, despite evidence for matrix modification in a number of pathologies. In the current study we show that reaction of ONOO-/ONOOH with glycosaminoglycans results in extensive polymer fragmentation. Bolus authentic ONOO-/ONOOH modifies hyaluronan, heparin, and chondroitin, dermatan, and heparan sulfates, in a concentration-dependent, but O2-independent, manner. The ONOO-/ONOOH generator 3-(4-morpholinyl)sydnoneimine produces similar time- and concentration-dependent damage. These reactions generate specific polymer fragments via cleavage at disaccharide intervals. Studies at different pH values, and in the presence of bicarbonate, are consistent with ONOOH, rather than the carbonate adduct, CO3.- or ONOO-, being the source of damage. EPR spin trapping experiments have provided evidence for the formation of carbon-centered radicals on glycosaminoglycans and related monosaccharides; the similarity of these spectra to those obtained with authentic HO. is consistent with fragmentation being induced by this oxidant. These data suggest that extracellular matrix fragmentation at sites of inflammation may be due, in part, to the formation and reactions of ONOOH.