Pharmacological and biochemical demonstration of the role of cyclooxygenase 2 in inflammation and pain

Incidence of gastroduodenal ulcers in patients with rheumatoid arthritis after 12 weeks of rofecoxib, naproxen, or placebo: a multicentre, randomised, double blind study

BACKGROUND

Previous studies in patients with osteoarthritis have suggested that the selective cyclooxygenase (COX)-2 inhibitor rofecoxib results in less gastrointestinal damage than non-selective non-steroidal antiinflammatory drugs (NSAIDs). This study compared the incidence of endoscopically detected gastroduodenal ulcers in rheumatoid arthritis patients treated with rofecoxib or a non-selective NSAID.

METHODS

In this multicentre, randomised, double blind, 12 week study, patients with rheumatoid arthritis were allocated to rofecoxib 50 mg once daily (n=219), naproxen 500 mg twice daily (n=220), or placebo (n=221). Endoscopy was performed at baseline and at six and 12 weeks. Lifetable analysis and log rank tests were used to analyse the incidence of gastroduodenal ulcers > or =3 mm. Gastric or duodenal ulcers > or =5 mm and erosions were also evaluated as secondary end points. Tolerability was assessed by adverse events.

RESULTS

The cumulative incidence of ulcers > or =3 mm at 12 weeks was significantly higher in patients on naproxen (25.5%) than in patients receiving rofecoxib (6.8%; difference 18.7% (95% confidence interval (CI) 11.7%, 25.7%); p<0.001) or placebo (2.9%; difference 22.6% (95% CI 16.1%, 29.1%); p<0.001). The difference between rofecoxib (6.8%) and placebo (2.9%) did not reach statistical significance (p=0.066). Results were similar for ulcers > or =5 mm and for mean changes from baseline in the number of gastroduodenal erosions. The overall incidence of clinical adverse events was similar among treatment groups (61% of patients on placebo, 62% in patients on rofecoxib, and 66% in patients on naproxen).

CONCLUSIONS

Rofecoxib 50 mg daily (twice the dose recommended for this patient population) resulted in a lower incidence of endoscopically detected gastroduodenal ulcers and erosions than treatment with naproxen 500 mg twice daily.

Preoperative oral celecoxib versus preoperative oral rofecoxib for pain relief after thyroid surgery

BACKGROUND AND OBJECTIVE

The study compared the analgesic efficacy and safety of two preoperatively administered cyclo-oxygenase-2 inhibitors, celecoxib and rofecoxib.

METHODS

Ninety adult patients undergoing thyroid surgery were divided into three groups (each n = 30). They were given a single oral dose of placebo, celecoxib 200 mg or rofecoxib 50 mg 1 h before induction of anaesthesia. All patients received a standard anaesthetic. Intraoperative blood loss was measured. Pain scores, sedation scores, heart rate, mean arterial pressure and respiratory rate were noted at 0, 1, 2, 4, 6, 12 and 24 h postoperatively. Analgesic (meperidine) requirements and adverse effects were recorded during the first postoperative 24 h.

RESULTS

Compared with placebo, pain scores were significantly lower with rofecoxib at all time points (P < 0.05) and were significantly lower with celecoxib (P < 0.05) during the first 4 h. Pain scores were significantly lower with rofecoxib compared with celecoxib at 6, 12 and 24 h (P < 0.05). The average cumulative 24 h meperidine dose was significantly lower with both celecoxib (54.9 +/- 34.4mg) and rofecoxib (42.8 +/- 40.9 mg) compared with placebo (76.8 +/- 6.2 mg) (P < 0.01 and P < 0.001, respectively). There were no differences in the intraoperative blood loss, heart rate, mean arterial pressure, respiratory rate, sedation scores and incidence of adverse effects among groups.

CONCLUSIONS

The preoperative administration of rofecoxib 50 mg and less so of celecoxib 200 mg provide a significant analgesic benefit with regard to postoperative pain relief and decrease in additional opioid requirements after thyroid surgery.

Cyclooxygenase-2 in human pathological disease

To understand the potential role of cyclooxygenase (COX) in normal and inflammatory human diseases, we characterized the expression of COX-1 and COX-2 in biopsies of osteoarthritis, atherosclerosis, and cancer. Tissues were prepared for immunohistochemistry by standard methods, and representative cases assayed via Western blot and quantitative RT-PCR. COX-2 was not detected in normal human tissues with few exceptions. Moderate to marked COX-2 was observed in the macula densa (MD) and thick ascending limb (TAL) in human fetal kidneys, but was not detected in neonatal and adult MD and TALs. Low level, constitutive COX-2 was detected in colonic epithelium, peribronchial glands, and pancreatic ductal epithelium. Low to moderate COX-2 was detected basally in the cortex, hippocampus, hypothalamus, and spinal cord, and in reproductive tissues during ovulation, implantation and labor. No COX-2 was detected in the existing vasculature in normal tissues, and was also not expressed throughout the ductus arteriosus. COX-2 was markedly induced in human tissues of osteoarthritis, atherosclerosis and cancer. COX-2 was prominently expressed in the synovium, fibrocartilage of osteophytes, and in the blood vessels in the osteoarthritic (OA) knee joint. COX-2 was also prominently detected in the macrophages/foam cells in atherosclerotic plaques, and in the endothelium overlying and immediately adjacent to the fibrofatty lesion. Moderate- to intense COX-2 expression was consistently observed in the inflammatory cells, neoplastic lesions, and blood vessels in all epithelial-derived human cancers studied. In contrast, COX-1 was relatively ubiquitously observed in both normal and pathophysiological conditions. These data collectively imply COX-2 plays an important role in mediating a variety of inflammatory diseases, and imply COX-2 inhibitors may be effective in the prevention and/or treatment of OA, heart disease, and epithelial cancers.

[Studies on the new antiarthritic drug candidate S-2474]

Various 1,2-isothiazolidine-1,1-dioxide (gamma-sultam) derivatives containing an antioxidant moiety, 2,6-di-tert-butyl-phenol substituent, were prepared. Some compounds that have a lower alkyl group at the 2-position of the gamma-sultam skeleton showed potent inhibitory effects on both cyclooxygenase (COX)-2 and 5-lipoxygenase (5-LO), as well as production of interleukin-1 (IL-1) in in vitro assays. They also proved to be effective in several animal arthritic models without any ulcerogenic activities. Among these compounds, (E)-(5)-(3,5-di-tert-butyl-4-hydroxybenzylidence)-2-ethyl-1,2- isothiazolidine-1,1-dioxide (S-2474) was selected as an antiarthritic drug candidate. The structure-activity relationships examined and some pharmacological evaluations are described. Furthermore, we have developed an efficient and E-selective synthesis of S-2474, in which alpha-methoxy-p-quinone methide is used as a key intermediate. alpha-Methoxy-p-quinone methide was revealed to be equivalent to a p-hydroxy-protected benzaldehyde. It reacts smoothly with alpha-sulfonyl carbanion to give 1,6-addition intermediates, which can be further processed to provide S-2474 directly in the presence of a base. This procedure gives S-2474 as an almost single isomer on the benzylidene double bond in excellent yield and thus is a very practical method adaptable to large-scale synthesis. The detailed mechanistic aspects are studied and discussed.

A novel dehydroepiandrosterone analog improves functional recovery in a rat traumatic brain injury model

The purpose of this study was to investigate the efficacy of a novel steroid, fluasterone (DHEF, a dehydroepiandrosterone (DHEA) analog), at improving functional recovery in a rat model of traumatic brain injury (TBI). The lateral cortical impact model was utilized in two studies of efficacy and therapeutic window. DHEF was given (25 mg/kg, intraperitoneally) at the initial time point and once a day for 2 more days. Study A included four groups: sham injury, vehicle treated (n = 22); injured, vehicle treated (n = 30); injured, pretreated (5-10 min prior to injury, n = 24); and injured, posttreated (initial dose 30 min postinjury, n = 15). Study B (therapeutic window) included five groups: sham injury, vehicle treated (n = 17); injured, vehicle treated (n = 26); and three posttreatment groups: initial dose at 30 min (n = 18), 2 h (n = 23), or 12 h (n = 16) postinjury. Three criteria were used to grade functional recovery. In study A, DHEF improved beam walk performance both with pretreatment (79%) and 30-min posttreatment group (54%; p < 0.01, Dunnett vs. injured vehicle). In study B, the 12-h posttreatment group showed a 97% improvement in beam walk performance (p < 0.01, Dunnett). The 30-min and 12-h posttreatment groups showed a decreased incidence of falls from the beam, which reached statistical significance (p < 0.05, Dunnett). Tests of memory (Morris water maze) and neurological reflexes both revealed significant improvements in all DHEF treatment groups. In cultured rat mesangial cells, DHEF (and DHEA) potently inhibited interleukin-1beta-induced cyclooxygenase-2 (COX2) mRNA and prostaglandin (PGE2) production. In contrast, DHEF treatment did not alter injury-induced COX2 mRNA levels in the cortex or hippocampus. However, DHEF (and DHEA) relaxed ex vivo bovine middle cerebral artery preparations by about 30%, with an IC(50) approximately 40 microM. This was a direct effect on the vascular smooth muscle, independent of the endothelial cell layer. Fluasterone (DHEF) treatments improved functional recovery in a rat TBI model. Possible mechanisms of action for this novel DHEA analog are discussed. These findings suggest an exciting potential use for this agent in the clinical treatment of traumatic brain injury.

Cycloamphilectenes, a new type of potent marine diterpenes: inhibition of nitric oxide production in murine macrophages

The inhibitory effect of a series of 6 cycloamphilectenes, novel marine diterpenes based on amphilectene skeletons and isolated from the Vanuatu sponge Axinella sp., on NO, PGE(2) and TNFalpha production in murine peritoneal macrophages was studied. These compounds reduced potently nitric oxide production in a concentration-dependent manner with IC(50) values in the submicromolar range (0.1-4.3 microM). Studies on intact cells and Western blot analysis showed that the more potent cycloamphilectenes reduced the expression of inducible nitric oxide synthase without affecting cyclo-oxygenase-2 expression. Among them cycloamphilectene 2, the unique compound bearing an exocyclic methylene group, was able to reduce NO production without affecting TNFalpha release. Cycloamphilectene 2, which is an inhibitor of the nuclear factor-kB pathway, exhibited topical anti-inflammatory activity.

Theoretical studies on the inhibition mechanism of cyclooxygenase-2. Is there a unique recognition site?

The mechanism of binding of different nonsteroidal anti-inflammatory drugs to the cyclooxygenase active site of cyclooxygenase-2 (COX-2) has been studied by means of a wide range of theoretical techniques including molecular dynamics and free energy calculations. It is found that theoretical methods predict accurately the binding of different drugs based on different scaffolds. Calculations allow us to describe in detail the key recognition sites and to analyze how these recognition sites change depending on the scaffold of the drug. It is concluded that the recognition site of COX-2 is very flexible and can adapt its structure to very subtle structural changes in the drug.

Inhibition of methanol extract from the aerial parts of Saururus chinensis on lipopolysaccharide-induced nitric oxide and prostagladin E2 production from murine macrophage RAW 264.7 cells

As an attempt to search for bioactive natural products exerting antiinflammatory activity, we have evaluated the effects of the methanol extract from the aerial parts of Saururus chinensis (LOUR.) BAILL (Saururaceae) on lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E(2) (PGE(2)) release by the macrophage cell line RAW 264.7. Our data indicate that this extract is a potent inhibitor of NO production and it also significantly decreased PGE(2) release. Consistent with these observations, the protein and mRNA expression level of inducible NO synthase (iNOS) and cyclooxygenase (COX)-2 was inhibited by MeOH extracts of the aerial part of S. chinensis (SCM) in a dose-dependent manner. Furthermore, SCM inhibited the LPS-induced DNA binding activity of nuclear factor-kappaB (NF-kappaB), which was associated with decreased p65 protein levels in the nucleus. These results suggest that SCM inhibits LPS-induced iNOS and COX-2 expression by blocking NF-kappaB activation.

Characterization of celecoxib and valdecoxib binding to cyclooxygenase

Two compounds (celecoxib and valdecoxib) from the diarylheterocycle class of cyclooxygenase inhibitors were radiolabeled and used to characterize their binding to cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), several single-point variants of COX-2 (Val523Ile, Tyr355Ala, Arg120Ala, Arg120Gln, Arg120Asn) and one triple-point variant of COX-2 [Val523Ile, Arg513His, Val434Ile (IHI)]. We demonstrate highly specific and saturable binding of these inhibitors to COX-2. Under the same assay conditions, little or no specific binding to COX-1 could be detected. The affinity of [(3)H]celecoxib for COX-2 (K(D) = 2.3 nM) was similar to the affinity of [(3)H]valdecoxib (K(D) = 3.2 nM). The binding to COX-2 seems to be both rapid and slowly reversible with association rates of 5.8 x 10(6)/M/min and 4.5 x 10(6)/M/min and dissociation rates of 14 x 10(-3)/min (t(1/2) = 50 min) and 7.0 x 10(-3)/min (t(1/2) = 98 min) for [(3)H]celecoxib and [(3)H]valdecoxib, respectively. These association rates increased (4- to 11-fold) when the charged arginine residue located at the entrance to the main hydrophobic channel was mutated to smaller uncharged amino acids (Arg120Ala, Arg120Gln, and Arg120Asn). Mutation of residues located within the active site of COX-2 that define a 'side pocket' (Tyr355Ala, Val523Ile, IHI) of the main channel had a greater effect on the dissociation rate than the association rate. These mutations, which modified the shape of and access to the 'side pocket', affected the binding affinity of [(3)H]valdecoxib more than that of [(3)H]celecoxib. These binding studies provide direct insight into the properties and binding constants of celecoxib and valdecoxib to COX-2.

Oral bioavailability and pharmacokinetics of DRF-4367, a new COX-2 inhibitor in rats

The pharmacokinetic characterization of DRF-4367 (a new diaryl pyrazole derivative), a potent selective COX-2 inhibitor was performed in Wistar rats. In the first study, a single dose of 2, 5, 10, 30 or 100 mg/kg DRF-4367 was given orally to rats for investigating the dose proportionality and/or linearity in the pharmacokinetics. In the second study, a single intravenous bolus dose of DRF-4367 was given at a dose of 10 mg/kg to calculate the absolute oral bioavailability, clearance and volume of distribution parameters. Blood samples were drawn at predetermined intervals up to 24 h post-dose. The concentrations of DRF-4367 in various plasma samples were determined by a validated HPLC method. Plasma concentration versus time data was generated following oral and i.v dosing and subjected to a noncompartmental pharmacokinetic analysis. Following oral administration, maximum concentrations of DRF-4367 were achieved at about 3 h and were unchanged with incremental doses. Both Cmax and AUC0-infinity appeared to increases less than proportional to the administered oral doses. While the doses increased in the ratio of 1.0 : 2.5 : 5.0 : 15.0 : 50.0, the mean AUC0-infinity and Cmax increased in the ratios of 1.0 : 2.8 : 4.5 : 8.6 : 14.5 and 1 : 2.4 : 4.1 : 6.2 : 8.3, respectively. Following i.v. administration, the concentration of DRF4367 declined in a monoexponential fashion with terminal elimination half-life of 5.7 h. The systemic clearance and volume of distribution of DRF-4367 in rats were 0.36 L/h/Kg and 2.2 L/Kg respectively after i.v administration. Elimination half-life was unchanged with route of administration and with increase in oral doses. Absolute oral bioavailability of DRF-4367 in the efficacy dose range was 70-80%.

ttCH, a selective inhibitor of inducible nitric oxide synthase expression with antiarthritic properties

In a previous work, we investigated the effects of a series of dimethoxy- and trimethoxychalcone derivatives, with various patterns of fluorination, on nitric oxide production in lipopolysaccharide-stimulated murine RAW 264.7 cells. The present study was designed to determine if 2,4,6-trimethoxy-2'-trifluoromethylchalcone (ttCH) could modulate the production of nitric oxide (NO) and/or prostaglandins in vitro and in vivo. On the mouse macrophage cell line RAW 264.7, ttCH inhibited dose-dependently NO and prostaglandin E(2) production, with IC(50) in the micromolar range. This compound had no direct inhibitory effect on inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 activities. NO reduction was the consequence of inhibition of the expression of iNOS. This compound also exhibited in vivo an inhibitory behaviour on nitrite and prostaglandin E(2) levels. We have assessed the effect of ttCH in the treatment of acute and chronic inflammatory processes such as the mouse carrageenan paw oedema and the rat adjuvant-induced arthritis. The present study demonstrated that ttCH exerts acute and chronic anti-inflammatory effects that may be related with the inhibition of iNOS expression.

Regulation of cyclooxygenase-2 expression by iloprost in human vascular smooth muscle cells. Role of transcription factors CREB and ICER

Prostaglandin-endoperoxide synthase-2 (PGH-synthase) or cyclooxygenase-2 (COX-2) is inducible by a variety of stimuli, e.g. inflammatory mediators, growth factors and hormones and is believed to be responsible for the majority of inflammatory prostanoid production. Moreover, it has been demonstrated that COX-2 contributes substantially to prostacyclin-synthesis in patients with atherosclerosis. In this study, we demonstrate an up-regulation of COX-2 mRNA, protein and product formation by the prostacyclin-mimetic iloprost in human vascular smooth muscle cells (hSMC). COX-2 mRNA expression was induced transiently between 1 and 6 hr and returned to basal levels after 16 hr of iloprost stimulation. COX-2 protein was induced concomitantly between 3 and 6 hr of iloprost stimulation. This was accompanied by an increase in PGI(2) formation. Forskolin, a direct activator of adenylyl cyclase, and dibutyryl cAMP, a cell-permeable cAMP analogue-induced COX-2 mRNA, suggesting a cAMP-dependent COX-2 expression in hSMC. Iloprost-induced COX-2 protein expression and PGI(2) formation was synergistically elevated by co-stimulation with the phorbolester PMA (phorbol-12-myristate-13-acetate). It is concluded, that the observed up-regulation of COX-2 with subsequent release of newly synthesized PGI(2) and the synergistic effect of iloprost and phorbolester on PGI(2) formation provide a positive feedback of prostaglandins on their own synthesizing enzyme. This might be important for control of hSMC proliferation, migration and differentiation as well as inhibition of platelet aggregation.

Selective inhibitors of cyclooxygenase-2 delay the activation of nuclear factor kappa B and attenuate the expression of inflammatory genes in murine macrophages treated with lipopolysaccharide

The effect of rofecoxib, a selective cyclooxygenase-2 inhibitor, on inflammatory signaling has been investigated in elicited murine peritoneal macrophages. Macrophages treated with 10 microM rofecoxib exhibited an important inhibition in the early activation of nuclear factor kappa B (NF-kappa B) and the mitogen-activated protein kinase p38, the extracellular-regulated kinase p44, and the c-Jun N-terminal kinase. Moreover, this drug decreased the protein levels of nitric-oxide synthase-2 and cyclooxygenase-2 in lipopolysaccharide (LPS)-treated macrophages. Rofecoxib delayed and attenuated NF-kappa B activation, which impaired significantly the expression of kappa B-dependent genes. This drug and related coxibs did not affect cell viability and protected against LPS-induced apoptosis through the impairment of the inflammatory response. These data show an additional anti-inflammatory mechanism of selective cyclooxygenase-2 inhibitors through the attenuation of macrophage activation.

The development of COX2 inhibitors

Aspirin, arguably the world's favourite drug, has been around since the late nineteenth century, but it wasn't until the late 1970s that its ability to inhibit prostaglandin production by the cyclooxygenase enzyme was identified as the basis of its therapeutic action. Early hints of a second form of the cyclooxygenase that was differentially sensitive to other aspirin-like drugs ultimately ushered in an exciting era of drug discovery, culminating in the introduction of an entirely new generation of anti-inflammatories. This article reviews the story of this discovery and looks at the future of cyclooxygenase pharmacology.

Up-regulation of p300 binding and p50 acetylation in tumor necrosis factor-alpha-induced cyclooxygenase-2 promoter activation

It is well established that p300 plays an important role in mediating gene expressions. However, it is less clear how its binding is influenced by physiological stimuli and how its altered binding affects transactivator acetylation and binding. In this study, we determined p300 binding to a core cyclooxygenase-2 (COX-2) promoter region by chromatin immunoprecipitation and streptavidin-agarose pull-down assays in basal and tumor necrosis factor-alpha (TNFalpha)-treated human foreskin fibroblasts. We found basal binding of p300, p50/p65 NF-kappaB, cyclic AMP regulatory element-binding protein-2, CCAAT/enhancer-binding protein beta, and c-Jun. p50/p65 and p300 binding was selectively increased by TNFalpha. Immunoprecipitation confirmed direct interaction of p300 with NF-kappaB and the other involved transactivators. p50 acetylation was detected in resting cells and was increased by TNFalpha or lipopolysaccharide. Overexpression of p300 augmented p50 acetylation, which was attenuated by deletion of its histone acetyltransferase domain. Enhanced p50 acetylation correlated with increased p50 binding to COX-2 promoter and transcriptional activation. Co-transfection of E1A with p300 abrogated p50 acetylation and p50 binding. These findings suggest that up-regulation of p300 binding and its acetylation of NF-kappaB occupies a central position in COX-2 promoter activation.

Anti-inflammatory and antinociceptive activities of Loasa speciosa in rats and mice

In the range of doses of 250-500 mg/kg (given i.p.) the aqueous extract of Loasa speciosa leaves showed an inhibitory effect on leukocyte migration, and a reduction on the pleural exudate, as well as dose-dependent anti-inflammatory and peripheral antinociceptive activities.

[NSAIDs caused gastric mucosal injury: with a special reference to COX-2]

Nonsteroidal antiinflammatory drugs (NSAIDs) have been shown to cause mucosal injury in the gastrointestinal tract as a side effect, occasionally turning out to be severe complications such as bleeding and perforation. So far NSAIDs-caused mucosal injury was attributed to their inhibitory effects on the activity of cyclooxygenase-1 (COX-1) which is expressed and shown to play a crucial role for the mucosal protection via producing prostaglandin E2 in the stomach. However, a recent progress of the understanding about COX physiology has revealed that NSAIDs cause gastric mucosal injury by inhibiting not only COX-1 but also COX-2 in the stomach. COX-1 inhibition alone has been demonstrated not to cause gastric mucosal injury. In addition, a selective COX-2 inhibitor which is demonstrated to have much less harmful effect in the stomach is now widely used as a safer NSAID in USA. Moreover, a selective COX-2 inhibitor is recently considered to have an inhibitory effect on growth of a certain type of cancers, thereby being in the spotlight as a chemopreventive agent.

PGE2 reduces arachidonic acid release in murine podocytes: evidence for an autocrine feedback loop

Increased glomerular prostaglandin E(2) (PGE(2)) production is associated with the progression of diseases such as membranous nephropathy, nephrotic syndrome, and anti-Thy1 nephritis. We investigated the signaling pathways that regulate the synthesis and actions of PGE(2) in glomerular podocytes. To study its actions, we assessed the ability of PGE(2) to regulate the production of its own precursor, arachidonic acid (AA), in a mouse podocyte cell line. PGE(2) dose-dependently reduced phorbol ester (PMA)-mediated AA release. Inhibition of PMA-stimulated AA release by PGE(2) was found to be cAMP/PKA-dependent, because PGE(2) significantly increased levels of this second messenger, whereas the inhibitory actions of PGE(2) were reversed by PKA inhibition and reproduced by the cAMP-elevating agents forskolin and IBMX. PGE(2) synthesis in this podocyte cell line increased fourfold at 60 min in response to PMA, coinciding with upregulation of cyclooxygenase (COX)-2 but not COX-1 levels. However, PGE(2) synthesis was significantly reduced by COX-1-selective inhibition, yet to a lesser extent by COX-2-selective inhibition. Our findings suggest that PMA-stimulated PGE(2) synthesis in mouse podocytes requires both basal COX-1 activity and induced COX-2 expression, and that PGE(2) reduces PMA-stimulated AA release in a cAMP/PKA-dependent manner. Such an autocrine regulatory loop might have important consequences for podocyte and glomerular function in the context of renal diseases involving PGE(2) synthesis.

Selective cyclooxygenase-2 inhibition does not affect the healing of cutaneous full-thickness incisional wounds in SKH-1 mice

BACKGROUND

The inducible cyclooxygenase-2 (COX-2) enzyme is upregulated in inflammatory diseases, as well as in epithelial cancers, and has an established role in angiogenesis and tissue repair.

OBJECTIVE

Because of these physiological effects and the widespread use of the selective COX-2 inhibitor, celecoxib, we wanted to determine if inhibition of COX-2 would affect incisional skin wound healing.

METHODS

Using a cutaneous full-thickness, sutured, incisional wound model in hairless SKH-1 mice, we evaluated the role of COX-2 in the wound healing process by comparing the effects of a nonselective COX inhibitor, diclofenac, with a selective COX-2 inhibitor, SC-791. Healing was monitored for up to 28 days postincision histologically and for recovery of wound strength.

RESULTS

COX-2 expression was observed over the first week of healing, peaking at day 3 and was not affected by treatment with the selective COX-2 or nonselective COX inhibitors. Infiltrating macrophages, as well as keratinocytes and dermal fibroblasts at the wound site, expressed COX-2. Neither selective COX-2, nor nonselective COX inhibition had a significant effect on the macroscopic or microscopic morphology of the wounds, whereas dexamethasone treatment resulted in epidermal and granulation tissue atrophy. In addition, neither selective COX-2, nor nonselective COX inhibition altered keratinocyte proliferation and differentiation, dermal angiogenesis or the recovery of wound tensile strength, whereas dexamethasone reduced the tensile strength of the wounds by 30-38% throughout the healing period.

CONCLUSIONS

These data indicate that selective COX-2 inhibition does not affect the healing of surgical skin wounds.

Mechanisms and applications of non-steroidal anti-inflammatory drugs in the chemoprevention of cancer

Biological and chemical irritants can be the cause of irritation in a variety of organ sites. It is becoming well understood that chronic irritation in any form can initiate and accelerate the cancer process in these same organs. This understanding comes in part from the many epidemiologic studies which point out that chronic inflammation correlates with increased risk of developing cancer in that organ which is affected. One of the hallmarks of chronic irritation is the increased activity in the arachidonic acid pathway which provides many of the necessary inflammatory biochemical mediators to this process. Arachidonic acid metabolism diverges down two main pathways, the cyclooxygenase (COX) and the lipoxygenase (LOX) pathways. The COX pathway leads to prostaglandin and thromboxane production and the LOX pathway leads to the leukotrienes (LTs) and hydroxyeicosatetraenoic acids (HETEs). These classes of inflammatory molecules exert profound biological effects which enhance the development and progression of human cancers. A large number of synthetic drugs and natural products have been discovered that block many of these key pathways. Much experimental evidence in animals has shown that inhibition of the key enzymes which drive these pathways can, in fact, prevent, slow or reverse the cancer process. The data are convincing in a number of organ sites including colon, breast, lung, bladder and skin. More recently, double-blinded randomize clinical trials in humans have shown the prevention of colonic polyps by anti-inflammatory agents. These studies have primarily used non-steroidal anti-inflammatory drugs (NSAIDS) which block the COX pathways. Recent preclinical studies indicate that the LOX pathway also may be an important target for cancer prevention strategy. The expression of high levels of these enzymes in cancerous tissues make them an obvious first target for cancer prevention strategies. As newer more specific drugs are developed with few adverse effects this important prevention strategy may become a reality.

Hippocampal kindling epileptogenesis upregulates neuronal cyclooxygenase-2 expression in neocortex

Recurrent and spontaneous seizures in epilepsy result from poorly defined cell signaling aberrations thought to include synaptic and extracellular matrix remodeling. Here we have used a rat hippocampal kindling model to study cyclooxygenase-2 (COX-2) gene expression in epileptogenesis. COX-2, encoded in an early-response gene, increases in a synaptic activity-dependent fashion and also during kainic acid-induced hippocampal damage. We found that during kindling, COX-2 induction occurred initially only in hippocampal neurons, and then spread to neocortical neurons. When rats were rekindled 34 days later, this spreading of COX-2 expression persisted. Induction of hippocampal and neocortical cytosolic phospholipase A(2) (cPLA(2)), an enzyme that catalyzes the synthesis of COX-2 substrate arachidonic acid (AA), occurred after 4 days of stimulation during kindling and rekindling. Moreover the COX-2 selective inhibitor nimesulide attenuated kindling development. We conclude that neuronal COX-2 gene induction and cPLA(2) activation are key signaling events in epileptogenesis.

Cyclooxygenase-2 (COX-2) in acute myocardial infarction: cellular expression and use of selective COX-2 inhibitor

Our previous work has shown strong expression of COX-2 in the myocardium of patients with end-stage ischemic heart failure. The purpose of this study was to determine the cellular expression of this enzyme in the setting of acute myocardial infarction (AMI) and determine the role of COX-2 in experimental animals using a selective COX-2 inhibitor. Experimental AMI was induced in rats by ligating the left coronary artery. Animals were either treated with a selective COX-2 inhibitor (5 mg x kg(-1) x day(-1)) or vehicle. Three days after ligation, cardiac function was assessed and infarct size was determined. Myocardial specimens were immunostained with antiserum to COX-2. Plasma concentration of prostanoids was measured by enzyme immunoassay. There was strong expression of COX-2 in the myocytes, endocardium, vascular endothelial cells, and macrophages in the infarcted zone of the myocardium. In contrast, little expression was seen in the myocardium of control rats. Animals treated with the COX-2 inhibitor showed a significant improvement in left ventricular (LV) end-diastolic pressure (P < 0.05) and LV systolic pressure (P < 0.01), and a reduction in infarct size (P < 0.05). Inhibition of COX-2 significantly decreased plasma concentration of thromboxane B2 (P < 0.05); however, it did not affect 6-keto-prostaglandin F1alpha. Induction of COX-2 during AMI appears to contribute to myocardial injury, and treatment with the specific inhibitor of the enzyme ameliorated the course of the disease.

Novel drug designing approach for dual inhibitors as anti-inflammatory agents: implication of pyridine template

Compounds incorporating thiophene moiety, a pi excess five membered heterocycle, have attracted a great deal of research interest, owing to the therapeutic utility of the template as useful drug molecular scaffolding. We report the synthesis and pharmacological evaluation of thiophenes substituted with 4-methanesulfonyl benzoyl moiety at the fifth position of the ring, as possible anti-inflammatory lead candidates. The aryl sulfonyl methyl thiophene analogs AP29, AP82, and AP37, when screened for anti-inflammatory activity in carrageenin induced rat paw edema, an acute in vivo model, exhibited moderate to good activity at a dose level of 100 mg/kg body weight P.o compared to Ibuprofen. In a five day formalin induced rat paw edema, a chronic in vivo anti-inflammatory model, candidates AP29, AP82, and AP37 inhibited the disease progression by 53%, 34%, and 65%, respectively on the fifth day, at a dose level of 100 mg/kg body weight P.o compared to Rofecoxib, Ibuprofen, and Dexamethasone at therapeutic doses which gave a protection of 53.8%, 81.5%, and 81.5%, respectively. The replacement of the 4-methanesulfonyl benzoyl moiety in AP82 with the pyridine template, 3,5-dimethyl-4-methoxy-2-pyridyl function, gave rise to AP84, which was less active in the acute model, but gave 54% and 75% protection both during the first day and fifth day, respectively, in the chronic model. A dual mechanism of action is proposed for AP84, a non-steroidal drug which has exhibited remarkable activity when compared to the steroid dexamethasone. These results open up new avenues in designing novel anti-inflammatory drugs as dual inhibitors with the incorporation of a pyridine template as part of the pharmacophore.

Requirement of cyclooxygenase-2 expression and prostaglandins for human prostate cancer cell invasion

The PC-3 Low Invasive cells and the PC-3 High Invasive cells were used to investigate the correlation of the COX-2 expression and its arachidonic acid metabolites, prostaglandins, with their invasiveness through Matrigel using a Boyden chamber assay. The COX-2 expression in PC-3 High Invasive cells was approximately 3-fold higher than in PC-3 Low Invasive cells while the COX-1 expression was similar in both cell sublines. When incubated with arachidonic acid, PGE2 was the major prostaglandin produced by these cells. PC-3 High Invasive cells produced PGE2 approximately 2.5-fold higher than PC-3 Low Invasive cells. PGD2 was the second most abundant prostaglandin produced by these cells. Both indomethacin (a nonspecific COX inhibitor) and NS-398 (a specific COX-2 inhibitor) inhibited the production of prostaglandins and the cell invasion. PGE2 alone did not induce the cell invasion of PC-3 Low Invasive cells. However, PGE2 reversed the inhibition of cell invasion by NS-398 and enhanced the cell invasion of the PC-3 High Invasive cells. In contrast, PGD2 slightly inhibited the cell invasion. These results suggest that in the PC-3 Low Invasive cells, COX-2-derived PGE2 may not be sufficient to induce cell invasion while in the PC-3 High Invasive cells, PGE2 may be sufficient to act as an enhancer for the cell invasion. Further, PGD2 may represent a weak inhibitor and counteracts the effect of PGE2 in the cell invasion.

Advances in the pathophysiology of constitutive and inducible cyclooxygenases: two enzymes in the spotlight

The aim of this commentary is to discuss recent data on the role of prostaglandins generated by both constitutive and inducible cyclooxygenases (COXs). According to a popular hypothesis, COX-1 generates 'good' prostaglandins for physiological 'housekeeping' functions like gastrointestinal (GI) mucosal integrity and regulation of renal blood flow, while COX-2 forms the 'bad' prostaglandins responsible for inflammatory symptoms. However, recent data show that the biological functions of prostanoids formed by the two enzymes are much more complex and interrelated than previously appreciated. Experimental evidence indicates that a full inflammatory response is likely sustained by prostanoids generated by both enzymes, and an effective anti-inflammatory effect requires the inhibition of the two enzymes. Similarly, the selective inhibition of either COX-1 or COX-2 does not elicit GI damage, but inhibition of both enzymes is necessary for GI mucosal damage to develop. Prostaglandins generated by both enzymes contribute to normal renal function by regulating the vascular tone and the normal blood flow. The synthesis of endothelial prostacyclin is mainly driven by COX-2, so that the selective COX-2 inhibition may bias vascular prostaglandin synthesis in favour of COX-1-derived thromboxane A(2) in platelets, leading to a prothrombotic outcome. Moreover, prostaglandins formed by COX-2 appear to have a major role in myocardial protection. We propose that the complexity of the situation in the field of COX-derived mediators should be borne in mind when anti-inflammatory therapy is required.

Reduction of scar formation in full-thickness wounds with topical celecoxib treatment

Adult wound repair occurs with an initial inflammatory response, reepithelialization, and the formation of a permanent scar. Although the inflammatory phase is often considered a necessity for successful adult wound healing, fetal healing studies have shown the ability to regenerate skin and to heal wounds in a scarless manner in the absence of inflammation. The cyclooxygenase-2 (COX-2) enzyme, a known mediator of inflammation, has been shown to contribute to a variety of inflammatory conditions and to the development of cancer in many organs. To examine the role of COX-2 in the wound healing process, incisional wounds were treated topically with the anti-inflammatory COX-2 inhibitor celecoxib. Acutely, celecoxib inhibited several parameters of inflammation in the wound site. This decrease in the early inflammatory phase of wound healing had a significant effect on later events in the wound healing process, namely a reduction in scar tissue formation, without disrupting reepithelialization or decreasing tensile strength. Our data suggest that in the absence of infection, adult wound healing is able to commence with decreased inflammation and that anti-inflammatory drugs may be used to improve the outcome of the repair process in the skin by limiting scar formation.

A Randomised, Double-Blind, Clinical Trial Comparing the Efficacy of Nimesulide, Celecoxib and Rofecoxib in Osteoarthritis of the Knee

Joint pain is the main complaint in patients affected by osteoarthritis (OA), and NSAIDs are commonly used to treat pain associated with OA. Over the past few years, cyclo-oxygenase (COX)-2-selective inhibitors have been proved to have certain advantages over non-selective NSAIDs and have been increasingly used for pain management in patients with OA.

OBJECTIVE

The main objective of this randomised, double-blind, within-patient study was to compare the analgesic efficacy of three COX-2 inhibitors in 30 patients affected by symptomatic OA of the knee. We evaluated the effects of oral nimesulide (100mg), celecoxib (200mg) and rofecoxib (25mg). Each drug was administered for 7 days.

METHODS

Analgesic efficacy was determined using the patient's assessment of pain on a visual analogue scale (VAS) and by total pain relief over 3 hours (TOPAR3) on the first and last days of treatment. In addition, the overall analgesic efficacy and tolerability were determined by a global assessment by the patient at the end of each week of treatment, using 5-point categorical scales. At the end of the study, each patient was asked about which of the three forms of treatment they would choose as a continuation of the pain therapy.

RESULTS

Taking all the results into consideration, nimesulide proved to be significantly more effective in providing symptomatic relief than did celecoxib and rofecoxib. Furthermore, nimesulide provided more rapid relief of pain associated with walking than did the other two drugs tested. Patients expressed similar preference for nimesulide and rofecoxib, but a lesser preference for celecoxib treatment. No patient withdrew from the study because of adverse events and the three different forms of treatment were generally safe and well tolerated.

CONCLUSION

The present data confirm our previous observations in patients with rheumatoid arthritis, further suggesting that nimesulide represents an effective agent for the treatment of joint pain, with particular reference to the rapid onset of its analgesic effect.

Horseradish peroxidase: a valuable tool in biotechnology

Peroxidases have conquered a prominent position in biotechnology and associated research areas (enzymology, biochemistry, medicine, genetics, physiology, histo- and cytochemistry). They are one of the most extensively studied groups of enzymes and the literature is rich in research papers dating back from the 19th century. Nevertheless, peroxidases continue to be widely studied, with more than 2000 articles already published in 2002 (according to the Institute for Scientific Information). The importance of peroxidases is emphasised by their wide distribution among living organisms and by their multiple physiological roles. They have been divided into three superfamilies according to their source and mode of action: plant peroxidases, animal peroxidases and catalases. Among all peroxidases, horseradish peroxidase (HRP) has received a special attention and will be the focus of this review. A brief description of the three super-families is included in the first section of this review. In the second section, a comprehensive description of the present state of knowledge of the structure and catalytic action of HRP is presented. The physiological role of peroxidases in higher plants is described in the third section. And finally, the fourth section addresses the applications of peroxidases, especially HRP, in the environmental and health care sectors, and in the pharmaceutical, chemical and biotechnological industries.

Cyclooxygenase inhibitory and antioxidant compounds from the fruiting body of an edible mushroom, Agrocybe aegerita

In the search for bioactive natural products from edible mushrooms, we have investigated the fruiting body of Agrocybe aegerita. The methanol extract of this mushroom yielded a fatty acid fraction (FAF), along with palmitic acid (1), ergosterol (2), 5,8-epidioxy-ergosta-6,22-dien-3beta-ol (3), mannitol (4) and trehalose (5). The composition of FAF was confirmed by GC-MS and by comparison to the retention values of authentic samples of palmitic, stearic, oleic and linoleic acids. The structures of 1-5 were established using spectroscopic methods. FAF and compounds 1-3 showed cyclooxygenase (COX) enzyme inhibitory and antioxidant activities. The inhibition values of liposome peroxidation by FAF, compounds 1 and 2 at 100 microg/ml were 75, 45, and 43%, respectively. The inhibition values of COX-I enzyme by FAF and 1-3 at 100 microg/ml were 80, 39, 19, and 57%, respectively. Similarly, COX-II enzyme activity was reduced by FAF and 1-3 at 100 microg/ml with values of 88, 45, 28, and 22%, respectively. Compounds 1, 3 and fatty acids were isolated here for the first time from the fruiting body of A. aegerita.

Effect of H. pylori infection on the expression of cyclooxygenase-2 in human gastric mucosa

Cyclooxygenase-1 is the primary isoform responsible for the production of cytoprotective prostaglandins (PGE(2) and PGI(2)) in the stomach. In contrast COX-2 is induced at the sites of inflammation. Using Helicobacter pylori infection as a model of inflammation, this study was designed to evaluate the effects of H. pylori infection on prostanoid synthesis and expression of COX-2 in human gastric mucosa. Prostaglandin (PGE(2)) and prostacyclin (PGI(2)) synthesis in gastric biopsies obtained from 21 patients undergoing diagnostic endoscopy, were determined. H. pylori was detected by CLO test, histology and culture. Biopsy samples were incubated either with NS-398, selective COX-2 inhibitor or aspirin. Samples were also treated with endotoxin (LPS) in order to induce COX-2 expression. Tissue was also analysed for COX-2 expression in vivo by immunohistochemistry. In 15 out of 21 patients, H. pylori was detected by at least two of the three methods. Higher levels of PGE(2) and PGI(2) were seen in patients infected with H. pylori (191+/-30 and 245+/-88ng/mg protein, respectively) compared with non-infected patients (77+/-17 and 120+/-36ng/mg protein, respectively). There was significant inhibition of PGE(2) and PGI(2) with aspirin in both H. pylori infected (28+/-6.6 and 53+/-43ng/mg, respectively) and in non-infected patients (16+/-7 and 12.5+/-3.5ng/mg protein, respectively). However, NS-398 and LPS did not alter prostaglandin function significantly. Immunohistochemistry in all patients irrespective of Hp status demonstrated expression of COX-2.Lower concentration of constitutive expression of COX-2 was detected in human gastric mucosa by immunohistochemistry, however, H. pylori infection failed to induce COX-2 protein. In addition, increased prostaglandin synthesis in Hp-infected patients appears to be COX-1 mediated rather than COX-2. Furthermore, failure of endotoxaemia-treated sample to produce more PGE(2) in the face of enhanced COX-2 expression in gastric mucosa further suggests that increased prostanoids in human gastric stomach are COX-1 mediated.

Role of endogenous glucocorticoids in hyperalgesia and edema in old arthritic rats

We compared the intensity and frequency of arthritis in old (8-12 months, N = 12) and juvenile (2 months, N = 10) rats and determined the role played by adrenal glands in this disorder. Arthritis was induced by subcutaneous injection of Mycobacterium butyricum at the base of the tail of female Holtzman rats at day zero. Paw edema and hyperalgesia were monitored from day zero to day 21 after induction as signs of arthritis development. Some (N = 11) old animals were adrenalectomized bilaterally and treated with dexamethasone or celecoxib immediately following surgery. All bilaterally adrenalectomized old animals became susceptible to arthritis and the onset of disease was shortened from the 10th to the 5th day. Hyperalgesia and paw edema responses were less frequent in older animals (50 and 25% compared to control juvenile rats, respectively), although old responder animals showed responses of similar intensity to those of their juvenile counterparts: by the 14th day the data for hyperalgesia were juvenile = 0.8 +/- 0.07/old = 0.8 +/- 0.09, and for paw edema juvenile = 56.6 +/- 6.04/old = 32.24 +/- 12.7, reported as delta% increase in paw edema. Chronic treatment of adrenalectomized old animals with dexamethasone (0.01 or 0.1 mg/kg) but not celecoxib (3 mg/kg), once daily for 21 days by gavage, abolished the effects of adrenalectomy, in particular those related to the hyperalgesia response (old = 0.95 +/- 0.03/dexamethasone = 0 +/- 0; 14th day), thus suggesting a specific participation of circulating corticosteroids in the modulation of pain in old arthritic rats.

Origins of prostaglandin E2: involvements of cyclooxygenase (COX)-1 and COX-2 in human and rat systems

Prostaglandin (PG) E2 is a major cyclooxygenase (COX) product at inflammatory sites where it contributes to local increases in blood flow, edema formation, and pain sensitization. Using rats in vivo and rat and human blood in vitro, we have examined the roles of COX-1 and COX-2 in the production of PGE2. In anesthetized rats treated with bacterial lipopolysaccharide (LPS) to induce the expression of COX-2, the marked increase in PGE2 production that followed bolus intravenous injection of arachidonic acid (3 mg x kg(-1)) was strongly inhibited by diclofenac but largely unaffected by the COX-2-selective inhibitor DFP (5,5- dimethyl-3-(2-propoxy)-4-methanesulfonylphenyl)-2(5H)-furanone). In rat blood in vitro, aspirin strongly inhibited the production of PGE2 that followed either acute exposure to calcium ionophore, A23187 (calcimycin) (50 microM, 15 min), or incubation with LPS for 18 h. In contrast, human whole blood only produced significant levels of PGE2 when incubated with LPS. Rat leukocytes expressed COX-2 and produced PGE2 when exposed to LPS but not when acutely stimulated with A23187. Rat platelets, but not human platelets, also produced significant amounts of PGE2 when acutely stimulated with A23187. These data show that when exposed to an inflammatory stimulus, rat whole blood produces increased levels of PGE2 through induction of COX-2 in blood leukocytes. Rat blood, unlike human blood, may also produce copious amounts of PGE2 via the actions of COX-1 enzyme constitutively present in platelets. These data may well explain why in rats COX-2-selective inhibitors have been reported not to produce the full anti-inflammatory effects associated with standard nonsteroid anti-inflammatory drugs.

Lansoprazole induces mucosal protection through gastrin receptor-dependent up-regulation of cyclooxygenase-2 in rats

Proton pump inhibitors (PPIs) are antiulcer agents that have both gastric antisecretory and mucosal protective actions. The mechanisms of PPI-induced gastric mucosal protection are not known. The present study was designed to examine the mechanism for lansoprazole-induced gastric mucosal protection in rats. Rats were given 0.5, 5, and 50 mg/kg/day lansoprazole alone or both lansoprazole (50 mg/kg/day) and a specific gastrin receptor antagonist 3R-1-(2,2-diethoxyethyl)-((4-methylphenyl)amino-carbonyl methyl)-3-((4-methylphenyl)ureidoindoline-2- one) (AG-041R) (3, 10, and 30 mg/kg/day) for 14 days. Serum gastrin concentrations were measured. The expression of cyclooxygenases (COX-1 and COX-2) in the gastric mucosa was analyzed using Western blotting and immunohistochemical staining. Another series of rats was used to examine the 1) levels of prostaglandin (PG) E2 in gastric mucosa, 2) influences of the drugs on gastric damage caused by absolute ethanol, and 3) effects of a COX-2-specific inhibitor on PGE2 in the gastric mucosa and the mucosal protection afforded by lansoprazole. Lansoprazole dose dependently increased the serum gastrin concentration and enhanced the mucosal expression of COX-2 but not that of COX-1. Lansoprazole increased gastric mucosal PGE2 and reduced gastric damage caused by ethanol. Concomitant administration of AG-041R abolished the lansoprazole-induced COX-2 expression, and increased mucosal PGE2 and mucosal protection. A specific COX-2 inhibitor blocked the lansoprazole-induced increase in mucosal PGE2 and mucosal protection. Activation of gastrin receptors by endogenous gastrin has a pivotal role in the effects of lansoprazole on COX-2 up-regulation and mucosal protection in the rat stomach.

Expression of Ku70 and Ku80 mediated by NF-kappa B and cyclooxygenase-2 is related to proliferation of human gastric cancer cells

Cyclooxygenase-2 (COX-2) expression is mediated by constitutive NF-kappaB and regulates human gastric cancer cell growth and proliferation. Inactivating Ku70 or Ku80 suppresses cell growth and induces apoptosis. It has been hypothesized that Ku70 and Ku80 expression may be associated with NF-kappaB activation and COX-2 expression and is involved in cell proliferation. In this study, we found that inhibition of constitutive NF-kappaB (by transfecting a mutated IkappaBalpha gene) and of COX-2 (by treatment with indomethacin and NS-398) suppressed Ku70 and Ku80 expression in cells. Treatment with prostaglandin E(2) adenocarcinoma gastric (AGS) increased expression of these Ku proteins in cells with low constitutive NF-kappaB levels. Inhibition of the Ku DNA end-binding activity by transfection with the C-terminal Ku80 expression gene suppressed cell proliferation. Ku70 or Ku80 overexpression by transfection with the Ku70 or Ku80 expression gene, respectively, enhanced proliferation of cells with low NF-kappaB levels. These results demonstrate that Ku70 and Ku80 expression is mediated by constitutively activated NF-kappaB and constitutively expressed COX-2 in gastric cancer cells and that the high Ku DNA end-binding activity contributes to cell proliferation. Ku70 and Ku80 expression may be related to gastric cell proliferation and carcinogenesis.

Effect of selective cyclooxygenase-2 inhibition on the development of ligature-induced periodontitis in rats

BACKGROUND

The purpose of this study was to evaluate the effect of a selective cyclooxygenase-2 inhibitor on the progression of alveolar bone loss in an experimental periodontitis model in rats.

METHODS

One hundred eighty (180) Wistar rats were separated into 3 experimental groups. Cotton ligatures were placed at the gingival margin level of lower right first molars. The rats were randomly assigned to one of the following groups that received: a daily oral dose of 10 mg/kg body weight of celecoxib (Ce1); 20 mg/kg body weight of celecoxib (Ce2); or 10 ml/kg of saline solution (C). Serum levels of celecoxib and white blood cell count were determined. Standardized digital radiographs were taken after sacrifice at 3, 5, 10, 18, and 30 days to measure the amount of bone loss around the mesial root surface of the first molar tooth in each rat.

RESULTS

Two-way analysis of variance (ANOVA) indicated that groups treated with celecoxib had significantly less bone loss compared to controls (P < 0.0001) and that there was a significant interaction between treatment with celecoxib and time (P < 0.03). Post-hoc comparisons showed that in both groups treated with celecoxib, the bone loss became significant only after 10 days of ligature placement, while in the control group it was already significant after 5 days. However, differences in mean bone loss between control and Ce1 were significant only at 18 days and, between control and Ce2, at 5 and 18 days. There was no significant difference in bone loss among experimental groups at the end of the experimental period.

CONCLUSION

These data provide evidence that systemic therapy with celecoxib can modify the progression of experimentally induced periodontitis in rats.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

The effects of cyclooxygenase isozyme inhibition on incisional wound healing in mouse skin

In addition to their proinflammatory activities, prostaglandins recently have been shown to be beneficial in the resolution of tissue injury and inflammation. Thus, inhibition of cyclooxygenase-2, the predominant prostaglandin endoperoxide synthase under these conditions, may not only result in attenuating the inflammatory response but also in delaying tissue regeneration and repair. To this end, we investigated cyclooxygenase isozyme expression and the effects of cyclooxygenase inhibitors on wound healing upon full-thickness incisions in mouse skin. Immunohistochemical analysis revealed prominent expression of cyclooxygenase isozymes in keratinocytes of the hyperplastic epithelium, with cyclooxygenase-1 immunosignals predominating in the suprabasal compartment and cyclooxygenase-2 immunosignals spread throughout the whole epidermis. Moreover, dendritic cells, resembling Langerhans cells, as well as endothelial cells and macrophages in the vicinity of or within the granulation tissue were found to express both isozymes. Inhibition of prostaglandin E2 synthesis by oral administration of the cyclooxygenase-1-selective inhibitor SC-560 or the cyclooxygenase-2-selective inhibitor valdecoxib did not retard wound healing in mouse skin macroscopically. Except for a slight transient retardation of epithelialization early after wounding wound-induced neoangiogenesis, collagen deposition, and the restoration of tensile strength were not delayed by these agents. Likewise, the nonselective inhibitor indomethacin had no effect on the tensile strength of incisional skin wounds.

Inhibition of prostaglandin E(2) production by taiwanin C isolated from the root of Acanthopanax chiisanensis and the mechanism of action

Five lignans, l-sesamin, savinin, helioxanthin, taiwanin C, and cis-dibenzylbutyrolactone, were isolated from the root of Acanthopanax chiisanensis (Araliaceae), a Korean medicinal plant, and their inhibitory effects on the production of prostaglandin (PG) E(2) stimulated by 12-O-tetradecanoylphorbol 13-acetate (TPA) in rat peritoneal macrophages were examined. Among the five lignans, taiwanin C was the most potent (IC(50)=0.12 microM), followed by helioxanthin, cis-dibenzylbutyrolactone, and savinin. l-Sesamin had no effect. Taiwanin C showed no inhibitory effect on the TPA-induced release of radioactivity from [3H]arachidonic acid-labeled macrophages, nor did it inhibit the expression of cyclooxygenase (COX)-2 protein induced by TPA. However, the activities of isolated COX-1 and COX-2 were inhibited by taiwanin C (IC(50)=1.06 and 9.31 microM, respectively), reflecting the inhibition of both COX-1- and COX-2-dependent PGE(2) production in the cell culture system. These findings suggest that the mechanism of action of taiwanin C in the inhibition of PGE(2) production is the direct inhibition of COX enzymatic activity.

Ulcerogenic influence of selective cyclooxygenase-2 inhibitors in the rat stomach with adjuvant-induced arthritis

Cyclooxygenase (COX)-2 inhibitors have been developed as new gastric sparing anti-inflammatory drugs. We previously reported that the ulcerogenic response to conventional nonselective COX inhibitors, such as indomethacin and aspirin, was markedly increased in arthritic rats. The ulcerogenic effect of selective COX-2 inhibitors in arthritic animals, however, remains unknown. The present study was designed to examine the influence of selective COX-2 inhibitors, such as rofecoxib and celecoxib, on gastric mucosal integrity in rats with adjuvant-induced arthritis. Arthritis was induced in male dark Agouti rats by injection of Freund's complete adjuvant into the right hind paw. Two weeks after the injection, the animals were fasted for 18 h, various COX inhibitors were administered orally, and the mucosa was examined for lesions 4 h later. Oral administration of indomethacin caused hemorrhagic gastric lesions in both normal and arthritic rats, although the severity of lesions was significantly greater in the latter group. In contrast, neither rofecoxib nor celecoxib caused any gastric damage in normal rats, but both drugs provoked hemorrhagic gastric lesions in arthritic rats. The expression of COX-2 mRNA and immuno-positive cells was observed in the gastric mucosa of arthritic but not normal rats. The gastric mucosal prostaglandin (PG) E(2) content was significantly elevated in arthritic rats in a rofecoxib-sensitive manner. In conclusion, COX-2 inhibitors produce gastric lesions in arthritic rats, similar to the nonselective COX-inhibitors. COX-2 is up-regulated in the stomach of arthritic rats, and PGs produced by COX-2 play a role in maintaining the integrity of the gastric mucosa.

Cellular localization of cyclooxygenase-1 and cyclooxygenase-2 in the normal mouse, rat, and human retina

Prostaglandins, synthesized by cyclooxygenase (COX), regulate diverse neurophysiological actions such as regulation of autonomic responses, transmission of pain, generation of fever, control of sleep-wake cycle, synaptic signaling, and cross-talk between neurons and glia in the central nervous system. Although prostaglandins have been widely studied in the anterior segment tissues of the eye, relatively little is known about prostaglandins in the neural retina. By using immunohistochemistry, we have compared the cellular expression and localization of COX-1 and COX-2 in the normal mouse, rat, and human retina. In the normal mouse retina, COX-1 immunoreactivity is present in the outer segments of photoreceptor cells, horizontal cells, microglia, retinal ganglion cells, and displaced amacrine cells. In the normal rat retina, COX-1 immunoreactivity is present in microglia, retinal ganglion cells, and displaced amacrine cells. In the normal human retina, COX-1 immunoreactivity is present in microglia, astrocytes, retinal ganglion cells, and displaced amacrine cells. In the normal mouse and rat retina, COX-2 immunoreactivity is present in processes of the outer plexiform layer and in certain amacrine cells and retinal ganglion cells. In the normal human retina, COX-2 immunoreactivity is only present in processes of the outer plexiform layer. These results suggest that prostaglandins, synthesized by COX-1 or COX-2, may contribute to normal physiological and homeostatic functions in the retina.

NS-398: cyclooxygenase-2 independent inhibition of leukocyte priming for lipid body formation and enhanced leukotriene generation

Because the induction of new lipid body formation in leukocytes correlates with and likely contributes to their enhanced 'primed' prostaglandin and leukotriene formation, we evaluated two selective cyclooxygenase (COX)-2 inhibitors. Three types of stimuli, cis -unsaturated fatty acids, platelet activating factor and protein kinase C activators, stimulate lipid body formation. NS-398 (0.1-10 microM), but not another COX-2 inhibitor, SC58125 (0.1- 10 microM), blocked leukocyte lipid body formation elicited by all three types of stimuli and also blocked priming for enhanced LTB(4) production and PGE(2) production. The effect of NS-398 on lipid body formation was independent of its inhibitory effects on COX-2 since arachidonate-induced lipid body formation in COX-2-deficient mouse leukocytes was also inhibited by NS-398. By means of its ability to inhibit leukocyte lipid body formation, NS-398 may exert actions independent of its COX-2 inhibition and more broadly contribute to the suppression of formation of COX-1 and lipoxygenase-derived eicosanoids.

The Renal Effects of Traditional Nonsteroidal Anti-Inflammatory Agents Versus Cyclooxygenase-2 Inhibitors

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used for the management of acute and chronic pain as well as for rheumatoid arthritis and osteoarthritis. Although gastrointestinal complications are the most common adverse events associated with the use of these drugs, the renal adverse effects such as acute renal failure, electrolyte abnormalities, nephrotic syndrome, interstitial nephritis, and papillary necrosis can be serious. The cyclooxygenase-2 (COX-2)- selective NSAIDs (celecoxib, rofecoxib) have been associated with a reduced frequency of gastrointestinal adverse events, but questions still remain as to their renal safety. Recent information has suggested an increased role for COX-2 as a constitutive renal enzyme, thus implying its importance for normal kidney homeostasis. Clinical studies and published case reports of renal adverse events associated with COX-2 inhibitors suggest that patients with decreased effective circulating blood volume, salt depletion, and renal insufficiency have an increased likelihood of renal-related adverse events. Because many older patients have conditions that place them in one of the “at-risk” categories, this population should be monitored closely for the development of renal adverse events from any NSAIDs, including COX-2-selective agents.

Therapeutic effect of the endogenous fatty acid amide, palmitoylethanolamide, in rat acute inflammation: inhibition of nitric oxide and cyclo-oxygenase systems

1. The anti-inflammatory activity of the endogenous fatty acid amide palmitoylethanolamide and its relationship to cyclo-oxygenase (COX) activity, nitric oxide (NO) and oxygen free radical production were investigated in the rat model of carrageenan-induced acute paw inflammation and compared with the nonsteroidal anti-inflammatory drug (NSAID) indomethacin. 2. Palmitoylethanolamide (1, 3, 5, 10 mg kg(-1); p.o.) and indomethacin (5 mg kg(-1); p.o.) were administered daily after the onset of inflammation for three days and the paw oedema was measured daily; 24 h after the last dose (fourth day) the rats were killed and the COX activity and the content of nitrite/nitrate (NO(2)(-)/NO(3)(-)), malondialdehyde (MDA), endothelial and inducible nitric oxide synthase (eNOS and iNOS) were evaluated in the paw tissues. 3. Palmitoylethanolamide had a curative effect on inflammation, inhibiting the carrageenan-induced oedema in a dose- and time-dependent manner. This effect was not reversed by the selective CB(2) receptor antagonist (N-[(1S)-endo-1,3,3-trimethylbicyclo[2.2.1]heptan-2yl]-5-(4-chloro-3-methylphenyl)-1-(4-methylbenzyl)pyrazole-3 carboxamide) (SR144528), 3 mg kg(-1) p.o. On the fourth day after carrageenan injection, COX activity and the level of NO(2)(-)/NO(3)(-), eNOS and MDA were increased in the inflamed paw, but iNOS was not present. Palmitoylethanolamide (10 mg kg(-1)) and indomethacin markedly reduced these increases. 4. Our findings show, for the first time, that palmitoylethanolamide has a curative effect in a model of acute inflammation. The inhibition of COX activity and of NO and free radical production at the site of inflammation might account for this activity.