André Lussier

The role of viscosupplementation with hylan G-F 20 (Synvisc®) in the treatment of osteoarthritis of the knee: a Canadian multicenter trial comparing hylan G-F 20 alone, hylan G-F 20 with non-steroidal anti-inflammatory drugs (NSAIDs) and NSAIDs alone*

To determine the safety and efficacy of viscosupplementation with hylan G-F 20, a cross-linked hyaluronan preparation, used either alone or in combination with continuous non-steroidal anti-inflammatory drug (NSAID) therapy, a randomized, controlled, multicenter clinical trial, assessed by a blinded assessor, was conducted in 102 patients with osteoarthritis (OA) of the knee. All patients were on continuous NSAID therapy for at least 30 days prior to entering the study. Patients were randomized into three parallel groups: (1) NSAID continuation plus three control arthrocenteses at weekly intervals; (2) NSAID discontinuation but with three weekly intra-articular injections of hylan G-F 20; and (3) NSAID continuation plus three injections, one every week, intra-articular injections of hylan G-F 20. Outcome measures of pain and joint function were evaluated by both the patients and an evaluator at baseline and weeks 1, 2, 3, 7 and 12, with a follow-up telephone evaluation at 26 weeks. At 12 weeks all groups showed statistically significant improvements from baseline, but did not differ from each other. A statistical test for the equivalence, the q-statistic, demonstrated that viscosupplementation with hylan G-F 20 was at least as good or better than continuous NSAID therapy for all outcome measurements except activity restriction. At 26 weeks both groups receiving hylan G-F 20 were significantly better than the group receiving NSAIDs alone. A transient local reaction was observed in three patients after hylan G-F 20 injection; only one patient withdrew from the study as a result and all recovered without any sequela. Hylan G-F 20 is a safe and effective treatment for OA of the knee and can be used either as a replacement for or an adjunct to NSAID therapy.

A Risk-Benefit Assessment of Injections of Hyaluronan and its Derivatives in the Treatment of Osteoarthritis of the Knee

AbstractHyaluronan is critical for the homeostasis of the joint as an organ, in part, because it provides the rheological properties (viscosity and elasticity) of the synovial fluid. These properties depend upon both the concentration and the molecular weight of the hyaluronan in the synovial fluid. In osteoarthritis, the hyaluronan is both smaller in size and lower in concentration. Thus, it is rational and physiologically meaningful to treat osteoarthritis with viscosupplementation, i.e. injection of material designed to increase the rheological properties of the synovial fluid.It is important, though, to assess the risks and benefits of such a physiological treatment. There are various products on the market for viscosupplementation. These include hyaluronan preparations of relatively low molecular weight (Hyalgan® and ARTZ®), a hyaluronan preparation of intermediate molecular weight, but still lower molecular weight than that of the hyaluronan in normal healthy synovial fluid (Orthovisc®), and a cross-linked hyaluronan (a hylan) of high molecular weight (Synvisc®). The evidence from in vitro and in vivo models of osteoarthritis and from clinical trials to date suggests that efficacy, as would be expected by mechanistic reasoning, depends strongly upon molecular weight.The available evidence indicates that these products differ little in the incidence and severity of adverse events (about 2 to 4%, almost always local swelling, and with no adverse sequelae). All are very well tolerated in comparison to nonsteroidal anti-inflammatory drug therapy, although direct comparisons are few. The only potentially serious adverse event is joint infection, which is rare and directly dependent upon the number of injections, among other factors. No infection has been related to contamination of any of the products. In summary, treatment with low molecular weight preparations of hyaluronan seems to be effective. However, viscosupplementation with hyaluronan preparations may have slightly higher risk and less benefit than viscosupplementation with hylans, because the relatively lower molecular weight hyaluronan preparations require more injections which may incur higher costs and theoretically an increased chance of infection. Viscosupplementation with hylans is clearly effective, and the available evidence suggests that the benefits almost certainly outweigh the risks.

Monosodium urate monohydrate crystals induce the release of the proinflammatory protein S100A8/A9 from neutrophils.

The neutrophil cytoplasmic protein S100A8/A9 (along with S100A8 and S100A9) is chemotactic and stimulates neutrophil adhesion by activating the β2‐integrin CD11b/CD18. It is also essential to neutrophil migration in vivo in response to monosodium urate monohydrate (MSUM) crystals, the principal etiologic agent of gout. S100A8/A9 is present in the synovial fluid of patients with gout and arthritis and is secreted by activated monocytes; however, its mechanism of release by neutrophils remains unknown. The aim of this study was to identify the mechanism of stimulation of the release of S100A8/A9 by MSUM‐activated neutrophils. Here, we show that S100A8/A9 is released by neutrophils stimulated with MSUM crystals and that this release could be enhanced by preincubating neutrophils with granulocyte macrophage‐colony stimulating factor. Antibodies directed against CD11b and CD16 blocked the release induced by MSUM crystals, suggesting that Fc receptor for immunoglobulin G (FcγR)IIIB (CD16) and CD11b/CD18 were involved in the stimulation by MSUM crystals. Neutrophil preincubation with the Src kinase inhibitor 4‐amino‐5‐(4‐chlorophenyl)‐7‐(t‐butyl) pyrazolo[3,4‐d]pyrimidine and the Syk tyrosine kinase inhibitor trans‐3,3′,4,5′‐tetrahydrozystilbene significantly reduced the release of S100A8/A9, suggesting that the Src tyrosine kinase family and Syk were involved. In addition, wortmannin reduced neutrophil release of S100A8/A9, indicating a potential involvement of phosphatidylinolitol‐3 kinase in this release. Preincubation of neutrophils with the tubulin depolymerization promoters nocodazole and vincristine reduced MSUM‐induced release, suggesting a tubulin‐associated pathway of release. These results indicate that S100A8/A9 is released by MSUM crystal‐stimulated neutrophils following activation of CD11b, CD16, Src kinases, Syk, and tubulin polymerization.

Inflammatory Microcrystals Alter the Functional Phenotype of Human Osteoblast-Like Cells In Vitro: Synergism with IL-1 to Overexpress Cyclooxygenase-2

Chronic crystal-associated arthropathies such as gout and pseudogout can lead to local bone destruction. Because osteoblasts, which orchestrate bone remodeling via soluble factors and cell-to-cell interactions, have been described in contact with microcrystals, particularly in uratic foci of gout, we hypothesized that microcrystals of monosodium urate monohydrate (MSUM) and of calcium pyrophosphate dihydrate (CPPD) could alter osteoblastic functions. MSUM and CPPD adhered to human osteoblastic cells (hOB) in vitro and were partly phagocytized as shown by scanning electron microscopy. MSUM and CPPD dose-dependently stimulated the production of PGE2 in hOB as assessed by enzyme immunoassay, a response that was synergistically enhanced in the presence of IL-1. The mechanism of this synergism was, at least in part, at the level of the expression of cyclooxygenase-2 as evaluated by immunoblot analysis. MSUM and CPPD also stimulated the expression of IL-6 and IL-8 and reduced the 1,25-dihydroxyvitamin D3-induced activity of alkaline phosphatase and osteocalcin in hOB (with no synergism with IL-1). MSUM- or CPPD-stimulated expression of IL-6 in hOB pretreated with the selective cyclooxygenase-2 inhibitor NS-398 was increased, unlike that induced by IL-1 alone which was partially reduced. MSUM-, CPPD- or IL-1-induced expression of IL-8 was unchanged by pretreating hOB with NS-398. These results suggest that inflammatory microcrystals alter the normal phenotype of hOB, redirecting them toward reduced bone formation and amplified osteoblast-mediated bone resorption, abnormalities that could play a role in the bone destruction associated with chronic crystal-induced arthritis.

Crystal-induced neutrophil activation. IV. Specific inhibition of tyrosine phosphorylation by colchicine.

We recently demonstrated that pathologically relevant inflammatory microcrystals, namely triclinic monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals, potently stimulate a characteristic protein tyrosine phosphorylation pattern in human neutrophils that differed from that observed in response to other soluble or particulate agonists. In this study, the effects of colchicine on protein tyrosine phosphorylation induced by MSU and CPPD crystals in human blood neutrophils were investigated. Immunoblot analysis with antiphosphotyrosine antibodies demonstrated that colchicine dose-dependently inhibited the tyrosine phosphorylation of all the proteins phosphorylated in response to MSU and CPPD crystals. Other microtubule-disruptive agents such as vinblastine, nocodazole, and colcemid also inhibited crystal-induced protein tyrosine phosphorylation while lumicolchicine and trimethylcolchicinic acid were without effect. Indomethacin and phenylbutazone were similarly without effect on microcrystal-induced tyrosine phosphorylation. Colchicine, as well as the other active alkaloids, failed to inhibit the protein tyrosine phosphorylation elicited by FMLP, C5a, leukotriene B4, and unopsonized zymosan. Overall, these results demonstrate that colchicine specifically and significantly inhibits the protein tyrosine phosphorylation induced by MSU and CPPD crystals and suggest that its effects are associated, at least in part, with its interaction with microtubules. Furthermore, the use of microtubule-disrupting drugs demonstrate that the mechanisms implicated in the induction of protein tyrosine phosphorylation by microcrystals differed from those involved in response to other soluble or particulate agonists.

Crystal-induced neutrophil activation. III. Inflammatory microcrystals induce a distinct pattern of tyrosine phosphorylation in human neutrophils.

The activation of human neutrophils by monosodium urate and calcium pyrophosphate dihydrate crystals is believed to play a critical role in the pathogenesis of arthritides such as acute gout and pseudogout, respectively. In this study, we investigated the potential involvement of tyrosine phosphorylation in microcrystal-mediated activation of human neutrophils. Immunoblot analysis with antiphosphotyrosine antibodies demonstrated that triclinic monosodium urate and calcium pyrophosphate dihydrate crystals stimulated a time- and concentration-dependent tyrosine phosphorylation of at least five proteins (pp130, 118, 80, 70, and 60). While phosphoprotein (pp) 118 and pp70 were the major phosphorylated substrates, pp70 was the dominant one in reactivity with antiphosphotyrosine antibodies. When the temporal patterns, as well as the levels of tyrosine phosphorylation for both types of crystals were compared, monosodium urate crystals were found to be more potent activators than calcium pyrophosphate dihydrate crystals. The tyrosine phosphorylation patterns induced by microcrystals differed from those stimulated by other soluble (FMLP, C5a, or leukotriene B4) or particulate (unopsonized latex beads or zymosan) agonists which stimulated preferentially the tyrosine phosphorylation of pp118. The ratio of the intensities of pp118 and pp70 were specific of the stimulation with microcrystals when compared to those observed with the other soluble or particulate agonists. Colchicine, a drug used specifically in the treatment of gout and pseudogout, inhibited microcrystal-induced tyrosine phosphorylation, while beta- and gamma-lumicolchicine were without effect. On the other hand, colchicine failed to inhibit FMLP-induced tyrosine phosphorylation. Furthermore, while colchicine inhibited the activation of the NADPH oxidase by microcrystals, it, on the other hand, enhanced the production of superoxide anions by FMLP. Taken together, these results (a) demonstrate that tyrosine phosphorylation is involved in the mechanism of activation of human neutrophils induced by microcrystals; and (b) suggest, on the basis of the characteristics of the observed patterns of tyrosine phosphorylation, that this response may be specific to the microcrystals and relevant to their phlogistic properties.

Crystal-neutrophil interactions lead to interleukin-1 synthesis.

Normal human blood neutrophils were studied for their capacity to synthesize and release interleukin-1 (IL-1) species after phagocytosis of triclinic monosodium urate (MSU) and calcium pyrophosphate dihydrate crystals (CPPD). MSU crystals were more potent inducers of IL-1 generation than CPPD or unopsonized zymosan. Microcrystal-stimulated neutrophils characteristically secreted most of the newly synthesized IL-1. Colchicine partly inhibited the secretion of IL-1 by neutrophils during phagocytosis of solid particles. However, colchicine selectively inhibited IL-1 synthesis induced by microcrystals. These results suggest that neutrophil-derived IL-1 may contribute to the pathogenesis of crystal-induced arthritis.

Gastrointestinal microbleeding after aspirin and naproxen.

Gastrointestinal bleeding is the most serious side effect encountered with the anti‐inflammatory antirheumatic drugs. Using the 51Cr labeling technique, the comparative quantity of blood loss with aspirin or naproxen has been previously done on normal volunteers. With the present study, 12 rheumatoid arthritic patients were controlled in a double‐blind crossover study with the same radioactive technique. There is a difference in favor of naproxen. The difference between the baseline period and naproxen administration was not statistically significant.

Comparative Gastrointestinal Blood Loss Associated with Placebo, Aspirin, and Nabumetone as Assessed by Radiochromium (51Cr)

Nabumetone differs from most other nonsteroidal anti‐inflammatory drugs. It is presented to the gut as a nonacidic prodrug, and is metabolized to its active form after absorption. Studies in animals and humans suggest it is less irritating to the gastrointestinal mucosa. This study compared the gastrointestinal microbleeding induced by nabumetone to aspirin (acetylsalicylic acid, ASA), and placebo in a double blind parallel study using chromium 51Cr labelled red cells to quantitate fecal blood loss (FBL) in healthy volunteers. Thirty subjects were randomized to treatment with nabumetone (2000 mg), ASA (3.6 g) or placebo for 21 days following a 7 day placebo period. Six subjects served as untreated controls. FBL in nabumetone treated subjects was not significantly different to placebo or untreated subjects. In contrast, ASA‐treated subjects exhibited significantly increased FBL than the other 3 groups (P < .0001).

Paradoxical effects of colchicine on the activation of human neutrophils by chemotactic factors and inflammatory microcrystals

Neutrophil activation by chemotactic factors and by inflammatory microcrystals is accompanied by increases in protein tyrosine phosphorylation and by the activation of the NADPH oxidase. The addition of colchicine inhibited both responses induced by triclinic monosodium urate or calcium pyrophosphate crystals. On the other hand, colchicine enhanced the tyrosine phosphorylation of specific protein in neutrophils stimulated by chemotactic factor and augmented the production of superoxide anions induced by these same agonists. The effects of colchicine were shared by other anti‐microtubule agents (nocodazole and vinblastine) but not by its inactive analogue β‐lumicolchicine, trimethylcolchicinic acid, indomethacin, or phenyl‐butazone. Furthermore, the (enhancing as well as inhibitory) effects of colchicine on tyrosine phosphorylation and superoxide anion production were reversed by taxol. Finally, in human cytoplasts colchicine again inhibited microcrystal‐stimulated tyrosine phosphorylation but did not change chemotactic factor‐stimulated phosphorylation. These data strongly support the hypothesis that microtubule‐related mechanisms are involved in the modulation of the tyrosine phosphorylation response in human neutrophils, and suggest that a relationship may exist between the augmentation of tyrosine phosphorylation and of the stimulation of the NADPH oxidase induced by chemotactic factors.