Inhibition of 5-lipoxygenase product formation and polymorphonuclear cell degranulation by tenidap sodium in patients with rheumatoid arthritis

Safer anti-inflammatory therapy through dual COX-2/5-LOX inhibitors: A structure-based approach

Inflammatory mediators of the arachidonic acid cascade from cyclooxygenase (COX) and lipoxygenase (LOX) pathways are primarily responsible for many diseases in human beings. Chronic inflammation is associated with the pathogenesis and progression of cancer, arthritis, autoimmune, cardiovascular and neurological diseases. Traditional non-steroidal anti-inflammatory agents (tNSAIDs) inhibit cyclooxygenase pathway non-selectively and produce gastric mucosal damage due to COX-1 inhibition and allergic reactions and bronchospasm resulting from increased leukotriene levels. 'Coxibs' which are selective COX-2 inhibitors cause adverse cardiovascular events. Inhibition of any of these biosynthetic pathways could switch the metabolism to the other, which can lead to fatal side effects. Hence, there is undoubtedly an urgent need for new anti-inflammatory agents having dual mechanism that prevent release of both prostaglandins and leukotrienes. Though several molecules have been synthesized with this objective, their unfavourable toxicity profile prevented them from being used in clinics. Here, this integrative review attempts to identify the promising pharmacophore that serves as dual inhibitors of COX-2/5-LOX enzymes with improved safety profile. A better acquaintance of structural features that balance safety and efficacy of dual inhibitors would be a different approach to the process of understanding and interpreting the designing of novel anti-inflammatory agents.

Tenidap sodium inhibits secretory non-pancreatic phospholipase A(2) synthesis by foetal rat calvarial osteoblasts

Tenidap (TD) was initially defined as a dual inhibitor of cyclooxygenase and lipoxygenase. This study was designed to assess its inhibitory activity against proinflammatory phospholipase A(2). This study shows that TD inhibits the synthesis of pro-inflammatory secretory non-pancreatic phospholipase A(2) (sPLA(2)). Concentrations as low as 0.25 mug/ml (0.725 muM) reduced the release of sPLA(2) by 40% from foetal rat calvarial osteoblasts stimulated with IL-1beta and TNFalpha, whereas a concentration of 2.5 mug/ml (7.25 muM) reduced the release by over 80%. TD also markedly reduced the release of sPLA(2) from unstimulated cells. There was no direct inhibition of sPLA(2) enzymatic activity by TD in vitro. Northern blot analysis showed that TD did not affect the sPLA(2) mRNA levels; however, immunoblotting showed a dose-dependent reduction in sPLA(2) enzyme. These results, together with a marked reduction in sPLA(2) enzymatic activity, suggest that TD inhibits sPLA(2) synthesis at the post-transcriptional level. Therefore TD seems to inhibit the arachidonic acid cascade proximally to cyclooxygenase and lipoxygenase and its anti-inflammatory activity may be related at least in part to the inhibition of sPLA(2) synthesis.

Beneficial and Harmful Interactions of Antibiotics with Microbial Pathogens and the Host Innate Immune System

In general antibiotics interact cooperatively with host defences, weakening and decreasing the virulence of microbial pathogens, thereby increasing vulnerability to phagocytosis and eradication by the intrinsic antimicrobial systems of the host. Antibiotics, however, also interact with host defences by several other mechanisms, some harmful, others beneficial. Harmful activities include exacerbation of potentially damaging inflammatory responses, a property of cell-wall targeted agents, which promotes the release of pro-inflammatory microbial cytotoxins and cell-wall components. On the other hand, inhibitors of bacterial protein synthesis, especially macrolides, possess beneficial anti-inflammatory/cytoprotective activities, which result from interference with the production of microbial virulence factors/cytotoxins. In addition to these pathogen-directed, anti-inflammatory activities, some classes of antimicrobial agent possess secondary anti-inflammatory properties, unrelated to their conventional antimicrobial activities, which target cells of the innate immune system, particularly neutrophils. This is a relatively uncommon, potentially beneficial property of antibiotics, which has been described for macrolides, imidazole anti-mycotics, fluoroquinolones, and tetracyclines. Although of largely unproven significance in the clinical setting, increasing awareness of the pro-inflammatory and anti-inflammatory properties of antibiotics may contribute to a more discerning and effective use of these agents.

Tenidap, an anti-inflammatory agent, inhibits DNA and collagen syntheses, depresses cell proliferation, and lowers intracellular pH in cultured human gingival fibroblasts

The effect of tenidap [(+/-)-5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H-indole-1-carboxamide], a new anti-inflammatory agent, was investigated on DNA synthesis by means of [(3)H]thymidine incorporation, collagen synthesis by means of [(3)H]proline incorporation, cell proliferation, and intracellular pH in nicardipine-reactive human gingival fibroblasts. Tenidap significantly inhibited [(3)H]thymidine incorporation at concentrations greater than 20 microM on the 4th and 8th day of treatment. Tenidap also significantly inhibited [(3)H]proline incorporation at a concentration greater than 50 microM on the 4th day and at more than 20 microM on the 8th day of treatment. The presence of 1 microM nifedipine or 1 microM nicardipine did not alter the depressing effect of tenidap. Tenidap (20 microM) also lowered intracellular pH. These results suggest that tenidap might be effective for the prevention of gingival overgrowth caused by calcium channel blockers.

Adhesion-Dependent Release of Elastase From Human Neutrophils in a Novel, Flow-Based Model: Specificity of Different Chemotactic Agents

Neutrophils must adhere to the vessel wall, migrate, and degranulate in an ordered manner to perform their protective function. Disruption of these processes may be pathogenic. Current knowledge of the degranulation process is derived almost exclusively from studies on neutrophils in suspension, in which priming with the nonphysiological agent cytochalasin B is necessary to obtain elastase release in response to activating agents. To avoid this, we have adopted a different approach. Using a novel flow-based adhesion system, we have been able to quantify the release of elastase from the primary granules of activated neutrophils adherent to immobilized platelets or purified receptors without priming. Comparing stimuli, formyl tripeptide (fMLP), interleukin-8 (IL-8), activated complement fragment C5a, and platelet-activating factor (PAF) all induced rapid conversion to CD11b/CD18 (MAC-1) -mediated stationary adhesion when perfused over neutrophils already rolling on platelet monolayers or purified P-selectin. However, fMLP, C5a, and IL-8, but not PAF, induced release of elastase from the adherent cells in minutes. Neutrophils stimulated in suspension showed little degranulation. Treatment of neutrophils with an inhibitor of 5-lipoxygenase–activating protein (MK886) and thus synthesis of leukotrienes (LTs) or with an antagonist of the LTB4 receptor (LY223982) blocked the release of elastase. This indicated that endogenous synthesis of 5-lipoxygenase products such as LTs and autocrine activation of neutrophils was required for fMLP-driven elastase release. We hypothesize that the differential ability of PAF and fMLP to induce elastase release from surface-adherent neutrophils could arise from differential ability to generate leukotrienes, such as LTB4, and would be an appropriate mechanism for the control of elastase release during inflammation in vivo, where it is important that cytotoxic agents are not released until activated neutrophils have migrated into the extravascular tissues.

Adhesion-Dependent Release of Elastase From Human Neutrophils in a Novel, Flow-Based Model: Specificity of Different Chemotactic Agents

Neutrophils must adhere to the vessel wall, migrate, and degranulate in an ordered manner to perform their protective function. Disruption of these processes may be pathogenic. Current knowledge of the degranulation process is derived almost exclusively from studies on neutrophils in suspension, in which priming with the nonphysiological agent cytochalasin B is necessary to obtain elastase release in response to activating agents. To avoid this, we have adopted a different approach. Using a novel flow-based adhesion system, we have been able to quantify the release of elastase from the primary granules of activated neutrophils adherent to immobilized platelets or purified receptors without priming. Comparing stimuli, formyl tripeptide (fMLP), interleukin-8 (IL-8), activated complement fragment C5a, and platelet-activating factor (PAF) all induced rapid conversion to CD11b/CD18 (MAC-1) -mediated stationary adhesion when perfused over neutrophils already rolling on platelet monolayers or purified P-selectin. However, fMLP, C5a, and IL-8, but not PAF, induced release of elastase from the adherent cells in minutes. Neutrophils stimulated in suspension showed little degranulation. Treatment of neutrophils with an inhibitor of 5-lipoxygenase–activating protein (MK886) and thus synthesis of leukotrienes (LTs) or with an antagonist of the LTB4 receptor (LY223982) blocked the release of elastase. This indicated that endogenous synthesis of 5-lipoxygenase products such as LTs and autocrine activation of neutrophils was required for fMLP-driven elastase release. We hypothesize that the differential ability of PAF and fMLP to induce elastase release from surface-adherent neutrophils could arise from differential ability to generate leukotrienes, such as LTB4, and would be an appropriate mechanism for the control of elastase release during inflammation in vivo, where it is important that cytotoxic agents are not released until activated neutrophils have migrated into the extravascular tissues.

Tenidap enhances P2Z/P2X7 receptor signalling in macrophages

Tenidap is an anti-inflammatory drug whose mechanism of action is not fully understood. It has been shown to block plasma membrane anion transport and to decrease release of interleukin-1beta, probably via the inhibition of interleukin-1beta converting enzyme. In the present study we showed that: (a) tenidap increases the sensitivity of mouse macrophages to cytotoxic effects mediated by extracellular ATP; (b) tenidap increases lucifer yellow uptake through the macrophage ATP receptor; (c) pretreatment with oxidised ATP, a blocker of the P2Z/P2X7 receptor, inhibits cytotoxicity and lucifer yellow uptake due to the combined effects of ATP and tenidap; (d) macrophages lacking the P2Z/P2X7 receptor are resistant to the synergistic effect of tenidap and ATP. The results suggest that tenidap synergises with extracellular ATP for activation of the P2Z/P2X7 receptor.

Tenidap decreases IL-8 and monocyte chemotactic peptide-1 (MCP-1) mRNA expression in the synovial tissue of rabbits with antigen arthritis and in cultured synovial cells

Since IL-8 and MCP-1 are chemoattractant proteins that participate in the recruitment of inflammatory cells into the arthritic joint, we examined the effects of tenidap, a new anti-inflammatory drug of the oxindole family, on IL-8 and MCP-1 expression in the joints of rabbits with acute antigen arthritis. The model was induced by injecting 5 mg/ml ovalbumin into the knees of 20 preimmunized rabbits. Animals were randomized into two groups: treated with tenidap (15 mg/kg per 12 h), or untreated. The effect of tenidap treatment was evaluated on chemokine production in synovial membranes of rabbits with arthritis and in cultured monocytic and synovial cells (SC). By immunoperoxidase staining, chemokines were localized in the synovial tissue. Chemokine messenger RNA levels in the synovial membranes and in cultured cells were analysed by reverse transcription-polymerase chain reaction (RT-PCR). At the end of the study, tenidap significantly reduced neutrophil infiltration into the joint cavity (27+/-4 x 10(6) cells/ml versus 45+/-6 x 10(6) cells/ml in untreated; P<0.05), and synovial effusion (134+/-15 microl versus 236+/-19 microl in untreated; P<0.005). Untreated rabbits showed synovial membrane up-regulation in mRNA expression of IL-8 and MCP-1 (11- and seven-fold versus healthy rabbits, respectively) that was markedly decreased by tenidap (two- and three-fold versus healthy rabbits, respectively). IL-8 and MCP-1 were localized in the synovial tissue in a perivascular pattern and areas of the interstitium and lining, mostly coinciding with cell infiltration. Tenidap also reduced the accumulation of IL-8 and MCP-1 proteins. In cultured synovial and monocytic cells, tumour necrosis factor-alpha (TNF-alpha) elicited an increase in gene expression of IL-8 (four- and nine-fold, respectively) and MCP-1 (nine- and four-fold, respectively) that was significantly reversed in both cell types by 10 microM tenidap. These results suggest that the beneficial effect of tenidap in acute antigen arthritis could be related to the down-regulation in gene expression and synthesis of IL-8 and MCP-1, two key chemokines involved in the recruitment of inflammatory cells.

Effects of tenidap on intracellular signal transduction and the induction of proinflammatory cytokines: a review

Tenidap is a novel, once-daily antirheumatic drug which has shown promising results against rheumatoid arthritis in extensive clinical trials. It combines NSAID-like cyclooxygenase inhibition with suppression of the acute phase response. In macrophages, tenidap inhibits the lipopolysaccharide-induced synthesis of interleukins-1 and -6, but it tends to potentiate the lipopolysaccharide-induced synthesis of tumor necrosis factor alpha, due to its cyclooxygenase inhibition. In macrophages, tenidap is a potent inhibitor of zymosan-induced responses, not only the induction of proinflammatory cytokines, but also arachidonate mobilization, protein phosphorylation, and inositol phosphate formation, possibly through interference with the receptor-mediated upregulation of phospholipase C. Tenidap also acts as an intracellular acidifier in many cell types, which may explain at least some of its other effects. Recent studies have indicated that, in addition to modulation of prostanoid and cytokine formation, tenidap has many other effects beneficial in rheumatic disease. It has been shown to inhibit bone resorption, neutrophil adhesion and degranulation, the interleukin-1-induced suppression of glycosaminoglycan synthesis, as well as the production of active metalloproteinases from chondrocytes.

Differential effects of tenidap on the zymosan- and lipopolysaccharide-induced expression of mRNA for proinflammatory cytokines in macrophages

Tenidap is a novel antirheumatic drug that combines cyclooxygenase inhibition with cytokine modulating qualities. We demonstrate here that tenidap inhibits the zymosan-induced expression of both interleukin 1 and tumor necrosis factor alpha in macrophages, at the mRNA and protein levels. The concentration-dependence of the tenidap-induced inhibition of the expression of mRNA for these proinflammatory cytokines agrees with that of its inhibitory effects on zymosan-induced arachidonate mobilization and changes in phosphoprotein pattern. The effects of tenidap on the lipopolysaccharide-induced expression of these cytokines are more complex. Tenidap inhibits the induction of interleukin 1 by lipopolysaccharide or bacteria, but less potently than the interleukin 1-response induced by zymosan. In contrast, the drug markedly potentiates the lipopolysaccharide-induced expression of tumor necrosis factor alpha at both the mRNA and protein levels. The latter effect is demonstrated to be due to cyclooxygenase inhibition and is reversed by prostaglandin E2.

A factor derived from polymorphonuclear leukocytes enhances interleukin-1-induced synovial cell collagenase and prostaglandin E2 production in rats

We found that short-term culture medium and homogenate of casein-induced rat peritoneal polymorphonuclear leukocytes (PMN) markedly induced collagenase and prostaglandin E2 (PGE2) production by normal rat synovial cells and these effects were abrogated by anti-(rat interleukin-1 alpha) (IL-1 alpha) polyclonal antibodies. However, collagenase activity and PGE2 induced by recombinant rat IL-1 alpha were less than those induced by rat PMN culture medium. It was also proved by radioimmunoassay that rat PMN culture medium contains a relatively small amount of IL-1 alpha. The introduction of IL-1 alpha-deleted PMN culture medium and recombinant rat IL-1 alpha together into the synovial cell culture system revealed that IL-1 alpha deleted PMN culture medium has a significant enhancing activity on IL-1 alpha-induced synovial cell collagenase and PGE2 production. This new factor, which was shown to be a negatively charged protein of about 80 kDa, may have important roles in connective tissue destruction and chronic inflammation in diseases such as rheumatoid arthritis.

Tenidap, a structurally novel drug for the treatment of arthritis: antiinflammatory and analgesic properties

Tenidap is a new anti-rheumatic agent which has clinical properties characteristic of a disease modifying drug combined with acute antiinflammatory and analgesic activity. This paper details tenidap's cyclooxygenase (COX) inhibitory activity and the resulting pharmacological properties in experimental animals. Tenidap inhibited calcium ionophore-stimulated prostaglandin D2 synthesis by rat basophilic leukemia cells (COX-1) with an IC50 of 20 nM. In two different in vitro human test systems, tenidap inhibited COX-1 activity more potently than COX-2, although the relative potency ratio (COX-1/COX-2) differed markedly between the two systems. Tenidap inhibited the COX pathway when added to human blood in vitro (IC50, 7.8 mu M) and when administered orally to monkeys, rats and dogs (at 5, 2.5 and 10 mg/kg p.o., respectively) and COX activity measured ex vivo in blood collected 2 to 4 hours post dose. After oral administration to rats, tenidap inhibited carrageenan-induced paw edema with an ED50 of 14 mg/kg and inhibited the glucocorticoid-resistant UV erythema in guinea pigs with an ED50 of 1.4 mg/kg. It retained antiinflammatory activity in adrenalectomized rats indicating that this property is independent of adrenal stimulation. Oral administration of tenidap inhibited the development of adjuvant-induced polyarthritis in the rat and exhibited antinociceptive activity in the murine phenylbenzoquinone and rat acetic acid abdominal constriction tests. These data indicate that tenidap is an effective antiinflammatory and analgesic agent in animal models. These cyclooxygenase-dependent pharmacologic activities do not explain tenidap's disease modifying anti-arthritic properties but add a useful symptom modifying component to its clinical profile.

Meloxicam: influence on arachidonic acid metabolism. Part II. In vivo findings

Meloxicam is a new nonsteroidal anti-inflammatory drug (NSAID) derived from enolic acid. Preclinical studies have indicated that meloxicam has potent anti-inflammatory activity, together with a good gastrointestinal and renal tolerability profile. This report summarizes studies undertaken to compare meloxicam to other NSAIDs in the inhibition of the inducible cyclooxygenase (COX-2) in inflamed areas (pleurisy of the rat, peritonitis of mice) and their influence on the activity of the constitutive cyclooxygenase (COX-1) in stomach, kidney, brain, and blood. In pleurisy of the rat, meloxicam was twice as potent as tenoxicam, 3 times as potent as flurbiprofen, 8 times as potent as diclofenac, and 20 times as potent as tenidap at inhibiting prostaglandin E2 (PGE2) biosynthesis. In the peritonitis model in mice, meloxicam was approximately twice as active as piroxicam, and more than 10 times as active as diclofenac in the suppression of PGE biosynthesis. Doses of meloxicam sufficient to inhibit PGE2 biosynthesis in the pleural exudate and peritoneal exudate had no influence on leukotriene-B4 (LTB4) or leukotriene-C4 (LTC4) content. The effect of meloxicam on the PGE2 content of rat gastric juice and rat urine was weaker than that of piroxicam or diclofenac. Meloxicam was a weaker inhibitor of the increased PGE2 concentration in brain of rats and mice (induced by convulsant doses of pentetrazole) than piroxicam, diclofenac, or indomethacin. Meloxicam had a weaker effect on serum thromboxane-B2 (TXB2) concentration in rats than piroxicam or tenoxicam. The in vivo findings confirm the results of in vitro tests, conducted separately, showing that meloxicam preferentially inhibits COX-2 over COX-1. COX-2 is the inducible isoenzyme implicated in the inflammatory response, whereas COX-1 has cytoprotective effects in the gastric mucosa. Therefore, a preferential selectivity for one isoenzyme over another, as displayed by meloxicam, may have implications in the clinical setting in terms of a more favorable risk: benefit profile.

Tenidap, but not nonsteroidal anti-inflammatory drugs, inhibits T-cell proliferation and cytokine induction

T-lymphocytes are involved in the inflammatory response that occurs in affected joints of patients with rheumatoid arthritis (RA). Some second-line disease modifying anti-rheumatic drugs used in the treatment of patients with RA are known to block T-cell activation. The present study assessed whether tenidap, an investigational anti-rheumatic drug, affects in vitro T-cell responses such as proliferation and cytokine production. It was found that tenidap, in contrast to several nonsteroidal anti-inflammatory drugs, inhibits anti-CD3 or IL-2 driven proliferative responses of cloned human T-cells. Furthermore, tenidap was found to inhibit IFN-gamma production as well as the induction of mRNA encoding IFN-gamma or TNF-alpha. The results indicate that tenidap may exert at least part of its anti-inflammatory activity via inhibition of T-cell function and cytokine production.

Tenidap in rheumatoid arthritis. A 24-week double-blind comparison with hydroxychloroquine-plus-piroxicam, and piroxicam alone

OBJECTIVE

To compare the clinical efficacy, effect on serum C-reactive protein (CRP), serum amyloid A (SAA), and plasma interleukin-6 (IL-6) levels, and safety of tenidap with a combination of hydroxychloroquine-plus-piroxicam, and piroxicam alone, in the treatment of rheumatoid arthritis (RA) patients.

METHODS

A double-blind, randomized, multicenter study in which patients with active RA were treated with tenidap 120 mg/day, hydroxychloroquine 400 mg/day and piroxicam 20 mg/day, or piroxicam alone 20 mg/day, for 24 weeks.

RESULTS

At weeks 12 and 24, tenidap produced greater improvements than piroxicam based on 5 primary efficacy parameters; this improvement showed statistical significance in 4 of the 5 measures at week 12, and in 3 of the 5 measures at week 24. Clinical improvements in the hydroxychloroquine-plus-piroxicam-treated with tenidap. Compared with piroxicam, tenidap was associated with significantly greater reductions in serum CRP concentrations at 4, 12, and 24 weeks, and significantly greater reductions in SAA concentrations at weeks 12 and 24. The decrease in SAA concentrations was also significantly greater at weeks 4 and 24 in the tenidap-treated group than in the hydroxychloroquine-plus-piroxicam-treated group. Significant reductions in plasma IL-6 levels were observed at weeks 4, 12, and 24 within the tenidap group, and at week 24 within the hydroxychloroquine-plus-piroxicam-treated group. The overall occurrence of side effects, including gastrointestinal side effects, was similar in all 3 treatment groups. A small proportion of tenidap-treated patients (6.4%) manifested mild, nonprogressive, reversible proteinuria of presumed renal proximal tubular origin, and 3-4% of patients had elevated transaminase levels.

CONCLUSION

In the treatment of patients with RA, tenidap is as effective as the combination of hydroxychloroquine-plus-piroxicam, and is more effective than piroxicam alone; moreover, tenidap's safety profile is comparable to that observed with piroxicam alone, and with hydroxychloroquine-plus-piroxicam. The clinical response observed in this study, as well as the prompt decreases in acute-phase protein levels of CRP and SAA, and in plasma IL-6 levels, suggest that tenidap represents a new type of antiarthritic medication, with properties similar to, but not identical to, a therapeutic combination of a nonsteroidal antiinflammatory drug with disease-modifying antirheumatic drugs.

Effects of tenidap on superoxide-generating enzymes. Non-competitive inhibition of xanthine oxidase

The anti-rheumatic drug tenidap has been shown previously to attenuate superoxide production by activated neutrophils. Given the importance of leukocyte as well as endothelial cell derived superoxide in mediating inflammatory responses, the effects of tenidap on mammalian enzymes capable of generating superoxide were determined. Tenidap had no effect on the generation of superoxide by NADPH oxidase reconstituted from fractionated neutrophil lysates. However, significant inhibition of superoxide production by mixtures of hypoxanthine and xanthine oxidase was observed in the presence of 3-30 micrograms/mL tenidap. The kientics of xanthine oxidase inhibition by tenidap were non-competitive; the Ki of tenidap for xanthine oxidase was 11 micrograms/mL (34 microM). No inhibition of xanthine oxidase was observed in the presence of other known inhibitors of cyclooxygenase. Inhibition of xanthine oxidase may be a heretofore unrecognized mechanism of the antirheumatic effects of tenidap.

Effects of tenidap on Ca(2+)- and protein kinase C-mediated protein phosphorylation, activation of the arachidonate-mobilizing phospholipase A2 and subsequent eicosanoid formation in macrophages

Tenidap is a novel antirheumatic drug which combines non-steroidal antiinflammatory drug-like cyclooxygenase inhibition with cytokine modulating qualities in rheumatoid arthritis. We show herein that tenidap (5-20 microM) inhibited protein kinase C-mediated signalling leading to release of arachidonate in mouse macrophages by interfering with the up-regulation of the 85 kDa arachidonate-mobilizing phospholipase A2, although it did not inhibit this enzyme directly. The Ca(2+)-mediated activation of arachidonate mobilization was inhibited only at higher concentrations (20-40 microM). Studies of protein phosphorylation indicated that tenidap in itself was capable of inducing the phosphorylation of several protein bands through interaction with intracellular protein kinases and/or phosphatases. Importantly, tenidap inhibited both arachidonate release and the increase in intracellular protein phosphorylation when the cells were stimulated with zymosan. We propose that the main inhibitory influence of tenidap on the macrophage signalling investigated here is exerted at some level between protein kinase C and the 85 kDa phospholipase A2 and quite possibly also at the receptor-linked activation of phospholipase C.

The effects of Tenidap on cytokine induced proliferation of human synovial fibroblasts in vitro

OBJECTIVES

Tenidap, a new anti-rheumatic agent, is a lipoxygenase and cyclooxygenase inhibitor, and is reported to inhibit the production and action of interleukin 1 (IL-1). Since eicosanoids, IL-1, and other cytokines may influence the growth of fibroblasts in the joint synovium the study was carried out to determine the effects of Tenidap on cytokine induced proliferation of these cells in vitro.

METHODS

Cell cultures derived from patients with a variety of rheumatic diseases were cultured in different concentrations of Tenidap sodium, with or without IL-1, tumour necrosis factor alpha (TNF), IL-6, basic fibroblast growth factor (bFGF), or transforming growth factor beta (TGF beta). Cell proliferation was measured using a crystal violet colourimetric assay. Prostaglandin E2 levels in culture supernatants were measured by radioimmunoassay.

RESULTS

Tenidap at concentrations above 10 micrograms/ml inhibited cell growth, while at 1.25-5 micrograms/ml there was a small but significant increase in proliferation compared with controls. A further increase in growth was obtained when cells were incubated with Tenidap+IL-1, TNF or bFGF, and this was significantly higher than in the presence of any cytokine alone. Stimulation of IL-1 induced growth by Tenidap was reduced by addition of high levels of exogenous PGE2 (100 ng/ml) although growth was still higher than in IL-1 alone.

CONCLUSIONS

Depending on concentration, Tenidap may inhibit or stimulate synovial fibroblast growth. Our results suggest that augmentation of growth by low concentrations cannot be explained by inhibition of PGE2 production alone. Tenidap may directly stimulate cell growth or may block other fibroblast factors which are involved in control of cytokine induced proliferation.

Tenidap: a novel cytokine-modulating antirheumatic drug for the treatment of rheumatoid arthritis

Tenidap is a novel, once-daily, cytokine modulating antirheumatic drug indicated for the treatment of rheumatoid arthritis (RA). In vitro, tenidap significantly inhibits the production of the pro-inflammatory cytokines, interleukin-1, interleukin-6 and tumour necrosis factor in human cell lines, and inhibits cytokine-mediated processes such as cartilage degradation, bone resorption, metalloprotease synthesis, endothelial cell adhesion and monocyte differentiation. Tenidap also inhibits cyclo-oxygenase. In RA patients, tenidap 120 mg/day is clinically equivalent to the combination of disease-modifying antirheumatic agents plus non-steroidal anti-inflammatory drugs (NSAIDs) and significantly more effective than NSAIDs. Tenidap also produces rapid, profound and sustained reductions in the serum levels of the acute phase proteins, C-reactive protein and serum amyloid A, an effect suggestive of disease modifying properties. In addition, tenidap reduces circulating levels of IL-6 in RA patients. Tenidap is well tolerated.

Regulation of human normal and osteoarthritic chondrocyte interleukin-1 receptor by antirheumatic drugs

OBJECTIVE

To determine the effect of antirheumatic drugs and corticosteroids on interleukin-1 receptor (IL-1R) levels in, and IL-1-stimulated metalloprotease synthesis and expression by, normal and osteoarthritic (OA) human articular chondrocytes.

METHODS

IL-1R affinity and density of human chondrocytes were determined using radioligand binding experiments. Collagenase and stromelysin synthesis activities were analyzed by 14C-labeled type I collagen and Azocoll assays, respectively. Their messenger RNA (mRNA) levels were determined by Northern blot analysis. IL-1 alpha, IL-1 beta, IL-1 receptor antagonist, and beta 2-microglobulin were measured using enzyme-linked immunosorbent assays. Protein synthesis was determined by 3H-leucine incorporation.

RESULTS

Antirheumatic drugs reduced the IL-1R level in normal and OA chondrocytes in a dose-dependent manner. In normal chondrocytes, tenidap reduced the IL-1R level by 44% at 5 micrograms/ml to 88% at 100 micrograms/ml (50% inhibition constant [IC50] 10.1 micrograms/ml), indomethacin reduced IL-1R by 6% at 1.5 micrograms/ml to 43% at 60 micrograms/ml, and naproxen reduced IL-1R by 10% at 10 micrograms/ml to 41% at 300 micrograms/ml; the effects observed with indomethacin and naproxen occurred only when the drugs were used at levels above their therapeutic concentrations. In OA chondrocytes, the effect of indomethacin and naproxen on the IL-1R level was greatly reduced, whereas tenidap still had a marked effect (IC50 22.5 micrograms/ml). Dexamethasone and hydrocortisone had no consistent effect on the IL-1R level. At a therapeutic concentration (20 micrograms/ml), tenidap was found to reduce the IL-1R level in a time-dependent manner, with maximum inhibition (98%) by 48 hours. Tenidap was also found to markedly reduce collagenase and stromelysin synthesis and mRNA levels in IL-1-stimulated chondrocytes.

CONCLUSION

The suppressive effects of tenidap on IL-1-stimulated metalloprotease synthesis and expression in OA and normal chondrocytes are likely related to a decrease in IL-1R levels. At therapeutic concentrations, tenidap has a greater effect on the IL-1R level than is seen with indomethacin or naproxen, and glucocorticoids have no effect on IL-1R.

Effect of tenidap on cartilage integrity in vitro

OBJECTIVES

The maintenance of articular cartilage integrity during long term treatment with non-steroidal anti-inflammatory drugs (NSAIDs) is of clinical importance. These experiments were set up to test the action of tenidap, naproxen, and diclofenac on bovine and porcine cartilage, matrix synthesis, and catabolism.

METHODS

Short term organ culture techniques were used to determine the effect of interleukin 1 (IL-1) on synthesis and degradation, and the action of tenidap and the other drugs on these parameters. The retention of glycosaminoglycans (GAGs) and the synthesis of GAGs by incorporation of sulphur-35 labelled sulphate was used to determine the chondrocyte metabolic activity.

RESULTS

The action of human recombinant interleukin 1 alpha (hrIL-1 alpha) in increasing catabolic activity and inhibiting synthetic activity of the animal cartilages was confirmed. Tenidap was shown to give substantial and significant protection against the catabolic effects of hrIL-1 alpha and, to a lesser degree, against the inhibition of matrix synthesis by the cytokine. Neither diclofenac nor naproxen in doses expected to occur in the synovial fluid showed this action. Tenidap also inhibited the GAG loss from cocultures and, to a moderate degree, reversed the inhibition of synthesis by synovial tissue. Tenidap also stimulated cartilage repair activity during recovery from IL-1 treatment. The optimum concentration of the action against IL-1 was between 5 and 10 micrograms/ml. Above this concentration tenidap itself showed some inhibitory action on GAG synthesis.

CONCLUSIONS

Bearing in mind the problems in extrapolating from in vitro work on animal cartilages to humans, it seems possible that tenidap may be useful in decreasing the deleterious action of cytokines such as IL-1 on cartilage integrity during arthritic disease and in stimulating chondrocyte repair processes.

Tenidap: a novel inhibitor of calcium influx in a mast cell line

The anti-inflammatory agent tenidap has previously been shown to inhibit antigen-induced secretion in tumor mast cells. We have investigated the possibility that this effect is due to modulation of the Ca2+ response in mast cells and in particular that tenidap might be an inhibitor of the Ca2+ influx pathway or channel in these and other non-excitable cells. Tenidap inhibited the antigen-induced increase in intracellular Ca2+ measured both in cell suspensions and at the single cell level using digital imaging of Fura-2 fluorescence. Tenidap also inhibited both antigen- and thapsigargin-induced 45Ca influx across the plasma membrane at concentrations similar to those required for the inhibition of secretion. Somewhat unexpectedly, the compound itself caused some release of calcium from intracellular stores; however, this effect did not appear to be related to the inhibition of calcium influx or secretion. In mouse pituitary tumour (AtT-20) cells, tenidap inhibited depolarization-induced increases in intracellular Ca2+ suggesting that this compound also inhibits Ca2+ influx through voltage-sensitive calcium channels. We conclude that tenidap has a number of interesting effects on calcium handling which makes it a potentially valuable tool for the study of calcium movements particularly in non-excitable cells.

Immunoaffinity purification of prostaglandin E2 and leukotriene C4 prior to radioimmunoassay: application to human synovial fluid

When human synovial fluid as such was subjected to radioimmunoassays of prostaglandin E2 (PGE2) and leukotriene C4 (LTC4), there was no linear increase in PGE2 and LTC4 as the amount of synovial fluid was raised. For removal of substances thus disturbing the assay we developed a method of immunoaffinity purification of PGE2 and LTC4. A monoclonal antibody against PGE2 or LTC4 was coupled to BrCN-activated Sepharose 4B. When synovial fluid mixed with radiolabelled PGE2 or LTC4 was applied to the column of immobilized antibody, the ligand was adsorbed to the column and eluted with a mixture of methanol/water in a recovery of about 80%. The purified material showed a linearity between the amount of the sample and the value of radioimmunoassay. The one-step method was applied to synovial fluid from patients with rheumatoid arthritis, osteoarthritis and other joint diseases.

Alpha, mu and pi class glutathione S-transferases in human synovium and cultured synovial fibroblasts: effects of interleukin-1 alpha, hydrogen peroxide and inhibition of eicosanoid synthesis

We describe expression of alpha, mu and pi class glutathione S-transferase (GST) and, CuZn- and Mn superoxide dismutase (SOD) in human synovium and cultured synovial fibroblasts. Immunohistochemical and immunoblotting studies showed synovium and cultured cells expressed pi GST and both isoforms of SOD. Cellular localisation was largely perinuclear. No expression of alpha or mu GST was detected even though polymerase chain reaction analysis showed 4/6 subjects had positive genotypes at the polymorphic, mu class GSTM1 locus. Incubation of cultured synovial fibroblasts with H2O2, IL-1 alpha and the cyclooxygenase and lipoxygenase inhibitor, Tenidap, did not induce expression of alpha, mu or pi GST though treatment with IL-1 alpha caused a marked increase in the expression of Mn SOD.

Antiarthritic profile of BF-389--a novel anti-inflammatory agent with low ulcerogenic liability

BF-389, dihydro-4-(3,5-di-tert-butyl-4-hydroxybenzylidene)-2-methyl-2H-1,2- oxazin-3(4H)-one, is a potent, orally active, antiarthritic and analgesic agent with low ulcerogenic potential. A comparison of the activity profiles of BF-389 and naproxen showed similarities in: (1) suppression of developing and chronic adjuvant arthritis (AA); (2) maximal inhibitory response, as shown by the E(max) values in the developing and established AA models; (3) inhibition of bone degenerative changes associated with chronic adjuvant arthritis; and (4) analgesic activity in the acetic acid and phenylquinone writhing assays. Though BF-389 has been shown to be a potent inhibitor of cyclooxygenase, IC50 = 0.84 +/- 0.25 microM against the production of PGE2 in vitro, there is a great difference from most cyclooxygenase inhibitors; it also inhibits the 5-lipoxygenase enzyme. For BF-389, the IC50 for in vitro LTB4 formation was found to be 3.65 +/- 1.19 microM. The ulcerogenic potential of BF-389 was compared to that of naproxen using a five-day in vivo ulcerogenic rat assay. The UD50 for naproxen was found to be approximately 30 mg/kg/day, p.o. Based upon efficacy in the DEV AA and EST AA models, UD50/ED50 values for naproxen were estimated to be 0.7 and 1.9, respectively. For BF-389 the UD50 was shown to be 520 (389-695) mg/kg/day, p.o., and the corresponding UD50/ED50 values were calculated to be 84 and 28, respectively, thus demonstrating the wide margin of safety between efficacy and ulcerogenicity in rats.

Strategies for the development of new antiarthritic agents

Therapeutic advances in rheumatoid arthritis (RA) have largely focused on the development of non-steroidal antiinflammatory drugs (NSAIDs) with improved characteristics compared with aspirin [Brooks & Day, New Engl. J. Med., 324, 1716-1725 (1991)]. For example, greater potency, safety, improved tolerance in the elderly and reduced frequency of dosing have been achieved. However, these agents are generally considered to be palliative treating of the symptoms of the disease. The development of disease modifying drugs (DMD), also known as second line drugs, for RA has not been very successful. Most of the agents that are currently used in this category were originally used to treat other diseases such as malignancy (cyclophosphamide, methotrexate), Wilson's disease (d-penicillamine) and tuberculosis (gold salts) [Pullar, Br. J. clin. Pharmac., 30, 501-510 (1990)]. Unfortunately, none of the agents is ideal and each has potentially serious side-effects. There have been several attempts to develop agents with new mechanisms of action that hopefully will greatly improve these current therapies.

Effect of the anti-inflammatory agent tenidap on the pharmacokinetics and pharmacodynamics of prednisolone

The effect of tenidap, a new nonsteroidal anti-inflammatory agent, on the pharmacokinetics and pharmacodynamics of prednisolone was studied in healthy male subjects. In a randomized crossover study, 12 subjects received either tenidap sodium 120 mg daily or placebo orally for 28 days. On day 21, each subject received a single dose of either 0.8 mg/kg oral prednisone or 0.66 mg/kg intravenous prednisolone followed by the other steroid on day 28. Blood and urine samples were collected, and the pharmacokinetic parameters of prednisone and prednisolone were determined in each treatment period. Pretreatment with tenidap did not cause any significant changes in the overall disposition of prednisone or prednisolone. For example, for free prednisolone, the intravenous area under concentration was 1,144 +/- 195 ng.h/mL and 1,244 +/- 140 ng.h/mL, and the systemic availability after oral prednisone was 53 +/- 10% and 51 +/- 12% with placebo and tenidap, respectively. The renal clearance of prednisolone was significantly reduced after tenidap pretreatment, however (from 143 to 77 mL/min/1.73 m2). The suppression of plasma cortisol and whole blood histamine levels were analyzed to evaluate the potential pharmacodynamic interactions between tenidap and prednisolone. There were no significant changes in the pharmacodynamic parameters between placebo and tenidap groups. The excretion of less than 20% of the dose of prednisolone in urine makes the overall effects of tenidap on prednisolone kinetics and dynamics of inconsequential clinical importance.

5-lipoxygenase inhibitors and their anti-inflammatory activities

A wide variety of agents have been reported as 5-LO inhibitors. The majority of the series appear to be lipophilic reducing agents, including phenols, partially saturated aromatics, and compounds containing heteroatom-heteroatom bonds. Many of these are not selective 5-LO inhibitors, but often affect CO and other LOs as well. In vivo systemic activity for many of these has been, in general, disappointing, probably because of poor bioavailability caused by lipophilicity and metabolic instability (oxidation, and conjugation of phenolic compounds). However, topically a number of agents have shown promise for skin inflammation, with Syntex's lonapalene the most advanced of these. Most results published to date appear more disappointing in the allergy/asthma field. More excitingly, a few structural types are selective 5-LO inhibitors which have shown systemic activity in vivo and in the clinic. Abbott's zileuton (136) appears to be one of the leading compounds in this category, along with other hydroxamates such as BW-A4C (129) from Burroughs-Wellcome. Recent selective non-reducing agents such as Wyeth-Ayerst's Wy-50,295 (143) and the similar ICI compounds such as ICI 216800 (145) also hold promise. The enantiospecific effects of (106) and (145) are especially interesting for the design of new inhibitors. If compounds like these validate the hypothesis that inhibition of 5-LO will have a significant anti-inflammatory effect, a redoubling of effort throughout the industry to find second- and third-generation selective agents may be expected. Part of the difficulty in interpreting and comparing the 5-LO literature is the plethora of test methods and activity criteria. As pointed out in the introduction, inhibition of product release from cells, often stimulated with A23187, has commonly been used to demonstrate 5-LO inhibition. However, this type of assay cannot be assumed to be diagnostic for 5-LO inhibition. Only if specificity for 5-LO product generation and (ideally) activity in cell-free enzymes is also shown should mechanistic interpretations be made. Recently, a new class of compounds was found at Merck which inhibited LT biosynthesis without inhibiting 5-LO, but apparently by a novel, specific mechanism. L-655,240 (169) and L-663,536 (MK-886) (170) were both active in human ISN, with IC50 values in the low micromolar range. Both also orally inhibited GPB (< 1 mg/kg). MK-886 was effective in Ascaris-induced asthma in squirrel monkeys, in rat carrageenan pleurisy, in rat Arthus pleurisy, and (topically) in guinea-pig ear oedema induced by A23187.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhibition of leukotriene biosynthesis in the rat peritoneal cavity

In the search for a model of leukotriene (LT) production to provide a method to determine in vivo 5-lipoxygenase (5-LO) inhibitory activity by various compounds, a passive anaphylactic reaction in the rat peritoneal cavity was examined, refined and characterized. The reaction, produced by passive sensitization with an i.p. injection of rabbit anti-bovine serum albumin (anti-BSA) followed by an i.p. injection of BSA, resulted in the biosynthesis of large amounts of sulfidopeptide LTs measurable by immunoassay or by reversed phase high performance liquid chromatography. The oral activity of several 5-LO inhibitors has been examined using this model. An example of these is zileuton (Abbott-64077), a potent 5-lipoxygenase inhibitor now under clinical evaluation. Zileuton inhibited sulfidopeptide LT biosynthesis in the rat peritoneal cavity in a dose-dependent manner (ED50 = 3 mg/kg). WY-49,232, MK-866, BW A4C and phenidone also produced good activity with ED50 values of 6, 8, 11 and 17 mg/kg, respectively. This modified rat peritoneal anaphylaxis model appears to be a valuable tool for establishing in vivo activity of 5-LO inhibitors.