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LE Magazine January 2001

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COX-2 Inhibitors

n-3 fatty acids specifically modulate catabolic factors involved in articular cartilage degradation.

This study describes specific molecular mechanisms by which supplementation with n-3 fatty acids (i.e. those present in fish oils) can modulate the expression and activity of degradative and inflammatory factors that cause cartilage destruction during arthritis. Our data show that incorporation of n-3 fatty acids (but not other polyunsaturated or saturated fatty acids) into articular cartilage chondrocyte membranes results in a dose-dependent reduction in: (i) the expression and activity of proteoglycan degrading enzymes (aggrecanases) and (ii) the expression of inflammation-inducible cytokines (interleukin (IL)-1alpha and tumor necrosis factor (TNF)-alpha) and cyclooxygenase (COX-2), but not the constitutively expressed cyclooxygenase COX-1. These findings provide evidence that n-3 fatty acid supplementation can specifically affect regulatory mechanisms involved in chondrocyte gene transcription and thus further advocate a beneficial role for dietary fish oil supplementation in alleviation of several of the physiological parameters that cause and propogate

J Biol Chem 2000 Jan 14;275(2):721-4

n-3 polyunsaturated fatty acids and cytokine production in health and disease.

Arachidonic-acid-derived eicosanoids modulate the production of pro-inflammatory and immunoregulatory cytokines. Overproduction of these cytokines is associated with both septic shock and chronic inflammatory diseases. The n-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA) and docosahexaenoic acid, which are found in fish oils, suppress the production of arachidonic-acid-derived eicosanoids and EPA is a substrate for the synthesis of an alternative family of eicosanoids. Thus, dietary fats which are rich in n-3 PUFAs have the potential to alter cytokine production. Animal studies have provided a great deal of evidence that feeding plant or fish oils rich in n-3 PUFAs does alter the ex vivo production of tumour necrosis factor (TNF), interleukin 1 (IL-1), IL-6 and IL-2, but many contradictory observations have been made; it is most likely that the discrepancies in the literature result from differences in the cell types and experimental protocols used. Human studies provide more consistent data: several studies have shown that supplementation of the diet of healthy volunteers results in reduced ex vivo production of IL-1, IL-6, TNF and IL-2 by peripheral blood mononuclear cells. Similar findings have been made in patients with rheumatoid arthritis and multiple sclerosis. Animal studies indicate that dietary fish oil reduces the response to endotoxin and to pro-inflammatory cytokines, resulting in increased survival; such diets have been beneficial in some models of bacterial challenge, chronic inflammation and auto-immunity. These beneficial effects of dietary n-3 PUFAs may be of use as a therapy for acute and chronic inflammation and for disorders which involve an inappropriately activated immune response.

Ann Nutr Metab 1997;41(4):203-34

Differential regulation of prostaglandin E2 and thromboxane A2 production in human monocytes: implications for the use of cyclooxygenase inhibitors.

There is an autocrine relationship between eicosanoid and cytokine synthesis, with the ratio of prostaglandin E2 (PGE2)/thromboxane A2 (TXA2) being one of the determinants of the level of cytokine synthesis. In monocytes, cyclooxygenase type 1 (COX-1) activity appears to favor TXA2 production and COX-2 activity appears to favor PGE2 production. This has led to speculation regarding possible linkage of COX isozymes with PGE and TXA synthase. We have studied the kinetics of PGE2 and TXA2 synthesis under conditions that rely on COX-1 or -2 activity. With small amounts of endogenously generated prostaglandin H2 (PGH2), TXA2 synthesis was greater than PGE2. With greater amounts of endogenously generated PGH2, PGE2 synthesis was greater than TXA2. Also, TXA synthase was saturated at lower substrate concentrations than PGE synthase. This pattern was observed irrespective of whether PGH2 was produced by COX-1 or COX-2 or whether it was added directly. Furthermore, the inhibition of eicosanoid production by the action of nonsteroidal anti-inflammatory drugs or by the prevention of COX-2 induction with the p38 mitogen-activated protein kinase inhibitor SKF86002 was greater for PGE2 than for TXA2. It is proposed that different kinetics of PGE synthase and TXA synthase account for the patterns of production of these eicosanoids in monocytes under a variety of experimental conditions. These properties provide an alternative explanation to notional linkage or compartmentalization of COX-1 or -2 with the respective terminal synthases and that therapeutically induced changes in eicosanoid ratios toward predominance of TXA2 may have unwanted effects in long-term anti-inflammatory and anti-arthritic therapy.

J Immunol 2000 Aug 1;165(3):1605-11

Proinflammatory cytokines detectable in synovial fluids from patients with temporomandibular disorders.

OBJECTIVE: To measure the levels of the proinflammatory cytokines, interleukin (IL)-1 beta, IL-6, tumor necrosis factor- (TNF) alpha, IL-8, and interferon- (IFN) gamma in synovial fluid samples taken from patients with temporomandibular disorders (TMD). STUDY DESIGN: We studied 6 asymptomatic volunteers and 51 patients with TMD. The IL-1 beta, IL-6, TNF-alpha, IL-8, and IFN-gamma levels in temporomandibular joint synovial fluid were measured using enzyme-linked immunosorbent assay. RESULTS: Measurable level of at least one cytokine in the synovial fluid was found in 40 (64.5%) of 62 joints in the patients: IL-1 beta and IFN-gamma were each detected in 18 (29.0%) of 62 joints; IL-6 in 13 (21.0%) of 62 joints; IL-8 in 11 (19.3%) of 57 joints; and TNF-alpha in only 5 (8.1%) of 62 joints. None of these cytokines was detectable in the synovial fluid in the control group. Furthermore, there was a strong correlation between the detection of IL-1 beta and pain in the joint area. CONCLUSIONS: These data clearly demonstrate increased levels of several proinflammatory cytokines in certain patients with TMD and suggest that these cytokines may play a role in the pathogenesis of synovitis and degenerative changes of the cartilaginous tissue and bone of the temporomandibular joint.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998 Feb;85(2):135-41

Plant extracts from stinging nettle (Urtica dioica), an antirheumatic remedy, inhibit the proinflammatory transcription factor NF-kappaB.

Activation of transcription factor NF-kappaB is elevated in several chronic inflammatory diseases and is responsible for the enhanced expression of many proinflammatory gene products. Extracts from leaves of stinging nettle (Urtica dioica) are used as antiinflammatory remedies in rheumatoid arthritis. Standardized preparations of these extracts (IDS23) suppress cytokine production, but their mode of action remains unclear. Here we demonstrate that treatment of different cells with IDS23 potently inhibits NF-kappaB activation. An inhibitory effect was observed in response to several stimuli, suggesting that IDS23 suppressed a common NF-kappaB pathway. Inhibition of NF-kappaB activation by IDS23 was not mediated by a direct modification of DNA binding, but rather by preventing degradation of its inhibitory subunit IkappaB-alpha. Our results suggests that part of the antiinflammatory effect of Urtica extract may be ascribed to its inhibitory effect on NF-kappaB activation.

FEBS Lett 1999 Jan 8;442(1):89-94

Inhibition of prostaglandin and leukotriene biosynthesis by gingerols and diarylheptanoids.

The rhizomes of Zingiber officinale (ginger) and Alpinia officinarum contain potent inhibitors against prostaglandin biosynthesizing enzyme (PG synthetase). Gingerols and diarylhepatanoids were identified as active compounds. Their possible mechanism of action which was deduced from the structures of active compounds indicated that the inhibitors would also be active against arachidonate 5-lipoxygenase, an enzyme of leukotriene (LT) biosynthesis. This was verified by testing their inhibitory effects on 5-lipoxygenase prepared from RBL-1 cells. A diarylheptanoid with catechol group was the most active compound against 5-lipoxygenase, while yakuchinone A was the most active against PG synthetase.

Chem Pharm Bull (Tokyo) 1992 Feb;40(2):387-91

Inhibition of human neutrophil 5-lipoxygenase activity by gingerdione, shogaol, capsaicin and related pungent compounds.

A series of structurally related pungent natural products including capsaicin, gingerol, and gingerdione among others were evaluated and found to be potent inhibitors of 5-HETE biosynthesis in intact human leukocytes, with IC50 values of 100 and 15 microM for capsaicin and gingerdione, respectively. Several compounds within this series were also found to inhibit PGE2 formation, with the most potent being gingerdione (IC50 = 18 microM). These and other data indicate that members of the capsaicin/gingerol family of pungent compounds can act as dual inhibitors of arachidonic acid metabolism, which could account in part for the antiinflammatory and analgesic properties of compounds within this group.

Prostaglandins Leukot Med 1986 Oct;24(2-3):195-8

Efficacy and safety of glucosamine sulfate versus ibuprofen in patients with knee osteoarthritis.

A double-blind therapeutic investigation was performed on 178 Chinese patients suffering from osteoarthritis of the knee randomized into two groups, one treated for 4 weeks with glucosamine sulfate (GS, CAS 29031-19-4, Viartril-S) at the daily dose of 1,500 mg and the other with ibuprofen (IBU, CAS 15687-27-1) at the daily dose of 1,200 mg. Knee pain at rest, at movement and at pressure, knee swelling, improvement and therapeutic utility as well as adverse events and drop-outs were recorded after 2 and 4 weeks of treatment. The variables were recorded also after 2 weeks of treatment discontinuation in order to appreciate the remnant therapeutic effect. Both GS and IBU significantly reduced the symptoms of osteoarthritis with the trend of GS to be more effective. After 2 weeks of drug discontinuation there was a remnant therapeutic effect in both groups, with the trend to be more pronounced in the GS group. GS was significantly better tolerated than IBU, as shown by the adverse drug reactions (6% in the patients of the GS group and 16% in the IBU group--p = 0.02) and by the drug-related drop-outs (0% of the patients in the GS group and 10% in the IBU group--p = 0.0017). The better tolerability of GS is explained by its mode of action, because GS specifically curbs the pathogenic mechanisms of osteoarthritis and does not inhibit the cyclo-oxygenases as the non-steroidal anti-inflammatory drugs (NSAIDs) do, with the consequent anti-inflammatory analgesic activities but also with the several adverse reactions due to this not targeted effect. The present study confirms that GS is a selective drug for osteoarthritis, as effective on the symptoms of the disease as NSAIDs but significantly better tolerated. For these properties GS seems particularly indicated in the long-term treatments needed in osteoarthritis.

Arzneimittelforschung 1998 May;48(5):469-74

Selective Inhibition of Cyclooxygenase-2 by C-Phycocyanin, a Biliprotein from Spirulina platensis.

We report data from two related assay systems (isolated enzyme assays and whole blood assays) that C-phycocyanin a biliprotein from Spirulina platensis is a selective inhibitor of cyclooxygenase-2 (COX-2) with a very low IC(50) COX-2/IC(50) COX-1 ratio (0.04). The extent of inhibition depends on the period of preincubation of phycocyanin with COX-2, but without any effect on the period of preincubation with COX-1. The IC(50) value obtained for the inhibition of COX-2 by phycocyanin is much lower (180 nM) as compared to those of celecoxib (255 nM) and rofecoxib (401 nM), the well-known selective COX-2 inhibitors. In the human whole blood assay, phycocyanin very efficiently inhibited COX-2 with an IC(50) value of 80 nM. Reduced phycocyanin and phycocyanobilin, the chromophore of phycocyanin are poor inhibitors of COX-2 without COX-2 selectivity. This suggests that apoprotein in phycocyanin plays a key role in the selective inhibition of COX-2. The present study points out that the hepatoprotective, anti-inflammatory, and anti-arthritic properties of phycocyanin reported in the literature may be due, in part, to its selective COX-2 inhibitory property, although its ability to efficiently scavenge free radicals and effectively inhibit lipid peroxidation may also be involved.

Biochem Biophys Res Commun 2000 Nov 2;277(3):599-603

Selective inhibition of cyclooxygenase-2 suppresses growth and induces apoptosis in human esophageal adenocarcinoma cells.

Adenocarcinoma in Barrett's esophagus has been increasing in incidence at a rapid rate for more than two decades. Cyclooxygenase (COX)-2 appears to play an important role in gastrointestinal carcinogenesis, and COX-2 overexpression has been demonstrated both in esophageal adenocarcinomas and in the metaplastic epithelium of Barrett's esophagus. The aim of our study was to determine whether selective inhibition of COX-2 by NS-398 would alter the rates of cell growth and apoptosis in human Barrett's-associated esophageal adenocarcinoma cell lines. COX-1 and COX-2 expression in adenocarcinoma cell lines was determined using reverse transcription-PCR and Western blotting for mRNA and protein, respectively. Esophageal adenocarcinoma cell lines were treated with various concentrations of NS-398 (selective for COX-2 inhibition) and flurbiprofen (selective for COX-1 inhibition). Cell growth was compared in flurbiprofen-treated and untreated tumor cell lines; cell growth and apoptosis were compared in NS-398-treated and untreated tumor cell lines. COX-2 mRNA and protein were detected in two of three cell lines (SEG-1 and FLO); the third cell line, BIC-1, did not express COX-2 mRNA or protein under basal conditions or after stimulation with phorbol 12-myristate 13-acetate. Treatment with COX-1-selective concentrations of flurbiprofen did not affect cell growth in any of the three tumor cell lines. In contrast, treatment with COX-2-selective concentrations of NS-398 significantly suppressed cell growth and increased apoptosis in the cell lines that expressed COX-2 (SEG-1 and FLO), but not in the cell line that did not express COX-2 (BIC-1). We conclude that the administration of a selective inhibitor of COX-2 significantly decreases cell growth and increases apoptosis in Barrett's-associated adenocarcinoma tumor cells that express COX-2. These observations suggest a potential role for selective COX-2 inhibitors in the prevention and treatment of esophageal adenocarcinoma for patients with Barrett's esophagus.

Cancer Res 2000 Oct 15;60(20):5767-72

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