Modulation of cartilage destruction by select nonsteroidal antiinflammatory drugs. In vitro effect on the synthesis and activity of catabolism-inducing cytokines produced by osteoarthritic and rheumatoid synovial tissue

Arthroscopic evaluation of potential structure-modifying drug in osteoarthritis of the knee. A multicenter, randomized, double-blind comparison of tenidap sodium vs piroxicam

OBJECTIVE

To test the hypothesis that tenidap has a structure-modifying effect in human knee osteoarthritis.

DESIGN

STUDY

multicenter, prospective, randomized, double blind, 1 year duration.

PATIENTS

primary painful knee osteoarthritis (ACR criteria) of the medial tibiofemoral compartment, medial joint space width > or =2mm, at least 10% of one cartilage surface of the medial compartment affected by superficial fibrillation or worse at baseline arthroscopy. STUDY MEDICATION: once daily dosage of either tenidap 40 mg, tenidap 120 mg or piroxicam 20mg. STUDY ENDPOINTS: bilateral extended weight-bearing X-rays and knee arthroscopy under local anaesthesia were done at entry and after 1 year. Joint space width was measured in millimeters at the narrowest point of the medial compartment. Chondropathy was scored by using reader's overall assessment (VAS score, 100mm) and Société Française d'Arthroscopie (SFA) score (0-100).

RESULTS

Patients (665) were randomized and 494 completed the study. After 1 year, intra-group radiological changes and radiological difference between both tenidap groups and the piroxicam group did not reach statistical significance. The intra-group arthroscopic deterioration of chondropathy was low, but statistically significant in the three study groups. However, there was no statistically significant difference between both tenidap groups and the piroxicam group.

CONCLUSIONS

This study failed to demonstrate any difference between the treatment arms with regard to the structural progression of medial knee osteoarthritis as measured by radiography and arthroscopy. Arthroscopy did, however, appears to be more sensitive in detecting disease progression than the weight-bearing radiographs with fully extended knees. This study shows that it is possible to complete a large international trial using arthroscopy as an outcome measure of articular cartilage.

Interleukin-1 beta regulation of fibroblast proteoglycan synthesis involves a decrease in versican steady-state mRNA levels

This study investigates the effects of interleukin (IL)-1 beta on proteoglycan metabolism by fibroblasts surrounded by endogenous extracellular matrix. In both three-dimensional matrix cultures and long-term monolayer cultures IL-1 beta caused a significant decrease in synthesis and deposition of sulphated proteoglycans, but had no effect on release of deposited material. The decrease in synthesis became successively more pronounced, and corresponded to 40-60% of the control after 72 h incubation. The reduction was almost totally accounted for by an effect on the chondroitin ABC-lyase-sensitive proteoglycans. Gel electrophoresis showed a significant decrease in a high-molecular-mass chondroitin ABC-lyase-sensitive proteoglycan after incubation with IL-1 beta. Northern-blot analyses of total RNA revealed a pronounced decrease in the steady-state mRNA levels of versican, the large chondroitin sulphate, with levels corresponding to 10-30% of controls. In comparison, the steady-state mRNA level for decorin, the major sulphated proteoglycan synthesized by the cells, was only slightly affected. The prominent decrease in synthesis of sulphated proteoglycans induced in long-term fibroblast cultures, including the pronounced decrease in versican steady-state mRNA levels, is likely to have a significant effect on the structure of the extracellular matrix. Induction of this type of change may constitute a significant mechanism whereby IL-1 beta can affect the properties of connective tissue during inflammation and wound healing.

In vitro effects of NSAIDs and corticosteroids on the synthesis and secretion of interleukin 1 by human osteoarthritic synovial membranes

The mechanism(s) of action of NSAIDs and corticosteroids in arthritic diseases has been the subject of intensive investigation in recent years. Although NSAIDs and corticosteroids have many effects, their possible ability to modify the disease course in patients has not been fully documented. In an attempt to characterize the mechanism(s) involved in the effect of some NSAIDs in joint diseases, we investigated the effect of three concentrations within the pharmacological (260 micrograms/ml) and therapeutic (26 and 2.6 micrograms/ml) ranges of tiaprofenic acid in the synthesis and release of interleukin (IL-1) alpha and beta in human OA synovial membranes. The effect of tiaprofenic acid was compared to the effect of two other NSAIDs, sodium salicylate (160 micrograms/ml) and indomethacin (1.5 micrograms/ml), and to a corticosteroid, hydrocortisone (0.725 and 7.25 micrograms/ml). This study was carried out using human OA synovium explants incubated in the presence or absence of LPS. In the absence of LPS and at therapeutic concentration, tiaprofenic acid decreased both the synthesis and release of IL-1 beta. A less marked effect of the drug was noted under LPS treatment, and inhibition of the production/secretion of IL-1 beta was found only at pharmacological concentration. Sodium salicylate and indomethacin did not share this action, and demonstrated either no effect or enhancement of IL-1 beta synthesis, respectively, in the presence of LPS. As expected, hydrocortisone demonstrated a marked decrease on IL-1 alpha and IL-1 beta, both in the presence and absence of LPS. These results bring forth new information on the action of these drugs and their effects on the OA pathophysiological process.

Are cytokines involved in osteoarthritic pathophysiology?

The putative role and mechanism of action of cytokines in the progression of arthritic diseases such as osteoarthritis (OA) has received particular attention because of the important interaction between articular cartilage and synovium in the pathophysiology of the diseased state. Maintaining matrix homeostasis in the normal adult cartilage phenotype requires normal turnover of matrix components, principally collagen and proteoglycan. Chondrocytes and synovial fibroblasts are targeted, via specific cell-surface receptors, by cytokines like interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) to produce matrix proteases and to suppress the synthesis of collagen and proteoglycan. Thus, cytokines not only favor tissue destruction, but also inhibit tissue repair. A structurally heterogeneous group of factors capable of directly antagonizing cytokine action is described, which acts either by blocking cytokine-receptor binding, inhibiting local cytokine synthesis, or complexing the cytokine into an inactive form. Furthermore, many growth factors, such as transforming growth factor-beta (TGF-beta), can counteract the net effect of cytokines by stimulating the synthesis of matrix components or natural inhibitors of cartilage degrading enzymes.

Induction of articular cartilage degradation by recombinant interleukin 1 alpha and 1 beta

The purpose of this study was to compare the effects of human recombinant interleukin 1, alpha and beta, on articular cartilage. The effects of rIL-1 alpha and rIL-1 beta on proteoglycan degradation and synthesis following treatment of bovine articular cartilage in serum-free organ culture were quantified. Purified human IL-1 and both rIL-1 alpha and rIL-1 beta induced a two-fold or greater increase in glycosaminoglycan (GAG) release from cultured articular cartilage. Levels or rIL-1 alpha as low as 15 pM induced increased proteoglycan degradation whereas identical levels of rIL-1 beta did not. Killing of the cartilage cells abolished induced GAG release by all forms of IL-1. Analysis of proteoglycan size following IL-1 treatment showed limited degradation of material released into the culture medium or remaining within cartilage. Both forms of recombinant IL-1 inhibited GAG synthesis when continually present in the culture medium. Actinomycin D and cycloheximide inhibited IL-1 dependent cartilage destruction whereas indomethacin did not.

Anti-rheumatic drugs and cartilage

In this chapter an attempt has been made to draw together the known biology of cartilage and some of the mechanisms thought to be responsible for its failure in arthritis. The picture is far from complete but we are now in a good position to use this information to help appraise the pros and cons of the wide range of drugs now available to treat articular disorders. For convenience, these drugs were classified as NSAIDs, corticosteroids and chondroprotective agents. The influence of each of these classes on the metabolism of cartilage was examined in the light of published laboratory and clinical studies. It has been clearly shown that not all NSAIDs are the same. While many of the older drugs provided no benefit to cartilage metabolism, and in some instances suppressed it, the more recently discovered molecules appear to be free of these undesirable effects. Tiaprofenic acid, diclofenac and piroxicam emerged as drugs with little or no harmful effects on cartilage metabolism when used at concentrations within the human therapeutic range. For all NSAIDs, their potential effects on cartilage must be weighed against their respective anti-inflammatory potency, half-life, and effects on the gastric mucosa and other tissues. Other chapters in this book have addressed these important problems. The long-acting corticosteroids, betamethasone and triamcinolone hexacetonide, also appear to offer some benefit in the management of OA; however, as in RA, their use should be restricted to short-term applications. In terms of cartilage metabolism the chondroprotective agents pentosan polysulphate, Arteparon and Rumalon have been the most extensively studied class of drugs. While the laboratory studies have provided convincing evidence of their chondroprotective efficacy, it has been difficult to prove this clinically. This dichotomy of opinion (laboratory versus clinical) stems largely from the inadequacy of the methodologies currently available for the objective clinical assessment of patient response to anti-rheumatic drug therapy. With the advent of nuclear magnetic resonance imaging techniques and monoclonal antibodies to detect specific proteoglycan breakdown fragments in synovial fluid and plasma, the prospects for a unified research approach for the evaluation of these agents may now be possible.

NSAIDs and cartilage metabolism

Data from experimental studies on the influence of non-steroidal anti-inflammatory drugs (NSAIDs) on cartilage is reviewed. There is evidence from this data that some NSAIDs exert a harmful effect, but also that other NSAIDs do not influence cartilage metabolism or could even have a moderate beneficial effect. So far the experimental data must be interpreted with great caution to the clinical situation and no firm conclusions could be drawn from the few clinical reports available. However, the high frequency of other side effects of NSAIDs in the elderly calls a restrictive prescription of these drugs to osteoarthritic patients.