Differential effect of FR122047, a selective cyclo-oxygenase-1 inhibitor, in rat chronic models of arthritis

EVI1 upregulates PTGS1 (COX1) and decreases the action of tyrosine kinase inhibitors (TKIs) in chronic myeloid leukemia cells

Tyrosine kinase inhibitors (TKIs) are highly effective in treating chronic myelogenous leukemia (CML). However, primary and acquired drug resistance to TKIs have been reported. In this study, we used RNA sequencing followed by RQ-PCR to show that the proto-oncogene EVI1 targets the drug-metabolizing gene PTGS1 in CML. The PTGS1 promoter element had an EVI1 binding site, and CHIP assay confirmed its presence. Data from a publicly available CML microarray dataset and an independent set of CML samples showed a significant positive correlation between EVI1 and PTGS1 expression in CML. Downregulation of EVI1 in K562 cells and subsequent treatment with TKIs resulted in a lower IC₅₀ in the control cells. Furthermore, combined inhibition of BCR-ABL with imatinib and PTGS1 with FR122047 (PTGS1 inhibitor) synergistically reduced the viability of imatinib-resistant K562 cells. We conclude that elevated EVI1 expression contributes to TKIs resistance and that combined inhibition of PTGS1 and BCR-ABL may represent a novel therapeutic approach.

Catalytically active phospholipase A2 myotoxin from Crotalus durissus terrificus induces proliferation and differentiation of myoblasts dependent on prostaglandins produced by both COX-1 and COX-2 pathways

Although crotoxin B (CB) is a well-established catalytically active secretory phospholipase A₂ group IIA (sPLA₂-IIA) myotoxin, we investigated its potential stimulatory effect on myogenesis with the involvement of prostaglandins (PGs) produced by cyclooxygenase (COX)-1 and -2 pathways. Myoblast C2C12 were cultured in proliferation or commitment protocols and incubated with CB followed by lumiracoxib (selective COX-2 inhibitor) or valeryl salicylate (selective COX-1 inhibitor) and subjected to analysis of PG release, cell proliferation and activation of myogenic regulatory factors (MRFs). Our data showed that CB in non-cytotoxic concentrations induces an increase of COX-2 protein expression and stimulates the activity of both COX isoforms to produce PGE₂, PGD₂ and 15d-PGJ₂. CB induced an increase in the proliferation of C2C12 myoblast cells dependent on PGs from both COX-1 and COX-2 pathways. In addition, CB stimulated the activity of Pax7, MyoD, Myf5 and myogenin in proliferated cells. Otherwise, CB increased myogenin activity but not MyoD in committed cells. Our findings evidence the role of COX-1- and COX-2-derived PGs in modulating CB-induced activation of MRFs. This study contributes to the knowledge that CB promote early myogenic events via regulatory mechanisms on PG-dependent COX pathways, showing new concepts about the effect of sPLA₂-IIA in skeletal muscle repair.

The identification and isolation of anti-inflammatory ingredients of ethno medicine Breynia fruticosa

ETHNOPHARMACOLOGICAL RELEVANCE

Breynia fruticosa is a folk medicine in China, traditionally used to treat gastroenteritis, sore throat, eczema and arthritis. However, the bioactive ingredients are unknown.

AIM OF THE STUDY

To identify and isolate the anti-inflammatory ingredients of B. fruticosa.

MATERIALS AND METHODS

B. fruticosa extracts were fractioned by Amberchrom CG161M and Toyopearl HW40C resins. Acetic acid-induced capillary permeability mice model was used to evaluate the anti-inflammation activities of fractions. The anti-inflammatory ingredients were identified by high performance liquid chromatography/mass spectroscopy (HPLC-MS). On-line two dimensional liquid chromatography system was constructed to remove the tannins and enrich the breynins. The breynins were purified by preparative HPLC and evaluated for their anti-arthritis activities using complete Freund's adjuvant (CFA) induced arthritis rats model.

RESULTS

The anti-inflammatory ingredients of B. fruticosa are sulfur containing sesquiterpenoids (breynins). The on-line two dimensional preparative liquid chromatography system can effectively remove the tannins and enrich the bioactive ingredients in large scale within 1 h. Four major breynins were purified, and their structures were elucidated by analysis of MS and NMR data. Breynins can significantly prevent the rats' arthritis deterioration, with inhibition ratio 50% at dose 0.2 mg kg^-1, comparable with that of indomethacin at dose 2 mg kg^-1.

CONCLUSION

The breynins have strong anti-arthritis activities, which is responsible to the anti-inflammatory effects of B. fruticosa. However, breynins are also toxic components of B. fruticosa.

Cyclooxygenase-1 (COX-1) and COX-1 Inhibitors in Cancer: A Review of Oncology and Medicinal Chemistry Literature

Prostaglandins and thromboxane are lipid signaling molecules deriving from arachidonic acid by the action of the cyclooxygenase isoenzymes COX-1 and COX-2. The role of cyclooxygenases (particularly COX-2) and prostaglandins (particularly PGE₂) in cancer-related inflammation has been extensively investigated. In contrast, COX-1 has received less attention, although its expression increases in several human cancers and a pathogenetic role emerges from experimental models. COX-1 and COX-2 isoforms seem to operate in a coordinate manner in cancer pathophysiology, especially in the tumorigenesis process. However, in some cases, exemplified by the serous ovarian carcinoma, COX-1 plays a pivotal role, suggesting that other histopathological and molecular subtypes of cancer disease could share this feature. Importantly, the analysis of functional implications of COX-1-signaling, as well as of pharmacological action of COX-1-selective inhibitors, should not be restricted to the COX pathway and to the effects of prostaglandins already known for their ability of affecting the tumor phenotype. A knowledge-based choice of the most appropriate tumor cell models, and a major effort in investigating the COX-1 issue in the more general context of arachidonic acid metabolic network by using the systems biology approaches, should be strongly encouraged.

Selective COX-1 inhibition as a target of theranostic novel diarylisoxazoles

Cyclooxygenase(COX)-1 role in some diseases is increasingly studied. 3-(5-Chlorofuran-2-yl)-5-methyl-4-phenylisoxazole (P6), a highly selective cyclooxygenase-1 inhibitor, was used as a "lead" to design new isoxazoles (2a-m), differently selective towards COX-1. Those isoxazoles might be useful as novel theranostic agents and also to better clarify COX-1 role in the human physiology and diseases. 2a-m were prepared in fair to good yields developing suitable synthetic strategies. They were evaluated in vitro for their COX-inhibitory activity and selectivity. Structure-activity relationship studies of the novel set of diarylisoxazoles allowed to identify new key determinants for COX-1 selectivity, and to uncover compounds appropriate for a deep pharmacokinetic and pharmacodynamic investigation. 3-(5-Chlorofuran-2yl)-4-phenylisoxazol-5-amine (2f) was the most active compound of the series, its inhibitory activity was assessed in purified enzyme (COX-1 IC₅₀ = 1.1 μM; COX-2 IC₅₀ > 50 μM) and in the ovarian cancer cell line (OVCAR-3) expressing only COX-1 (IC₅₀ = 0.58 μM). Furthermore, the high inhibitory potency of 2f was rationalized through docking simulations in terms of interactions with a crystallographic model of the COX-1 binding site. We found critical interactions between the inhibitor and constriction residues R120 and Y355 at the base of the active site, as well as with S530 at the top of the side pocket.

Attenuation of arthritis in rodents by a novel orally-available inhibitor of sphingosine kinase

Pro-inflammatory cytokines like TNF-α activate sphingosine kinase (SK). Therefore, inhibition of SK is a potential molecular target for the treatment of rheumatoid arthritis.

AIMS

The primary goal of this study was to assess the efficacy of ABC249640 (a selective SK-2 inhibitor) in two models of rodent arthritis. A secondary goal was to evaluate the pharmacological profile of ABC294640, when given in combination with methotrexate.

METHODS

The efficacy of ABC294640 was determined by paw diameter/volume measurements, histological evaluations, and micro-CT analyses.

RESULTS

ABC294640 attenuated both collagen-induced arthritis in mice, as well as adjuvant-induced arthritis in rats. With the adjuvant arthritis model, the prophylactic efficacy profile of ABC294640 was similar to indomethacin. Of note, ABC294640 reduced the bone and cartilage degradation, associated with adjuvant-induced arthritis. Rats treated with a suboptimal dose of MTX (50 μg/kg/day) in combination with ABC249640 (100 mg/kg/day) had better anti-arthritis effects in the adjuvant model, than treatment with either agent alone.

CONCLUSION

Our results suggest that ABC249640 is an orally available drug candidate with a good pre-clinical efficacy profile for the prevention and/or treatment of RA.

Involvement of caspase-9 in autophagy-mediated cell survival pathway

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been considered for use in the prevention and treatment of cancer malignancy. FR122047 (FR) is known to have an anti-inflammatory effect, but the anticancer activity of the chemical has not yet been identified. In the present study, we could find that treatment of breast cancer MCF-7 cells with FR led to apoptosis accompanying with apparent activation of caspases. Treatment of caspase-specific inhibitors revealed that FR-induced apoptosis was caspase-8-dependent and inhibition of caspase-9 activity resulted in unexpected, marked enhancement of cell death. Knockdown of caspase-9 expression by specific siRNA caused increased susceptibility to FR-induced cell death, consistent with the results obtained with treatment of caspase-9 inhibitor. Inhibition of caspase-9 blocked the autophagic process by modulating lysosomal pH and acid-dependent cathepsin activities and augmented cell death due to blockage of cytoprotective autophagy. MCF-7 cells treated with sulforaphane, an autophagy-inducing drug, also showed marked accumulation of LC3-II, and co-treatment with caspase-9 inhibitor brought about increased susceptibility to sulforaphane-induced cell death. Different from the cases with FR or sulforaphane, etoposide- or doxorubicin-induced cell death was suppressed with co-treatment of caspase-9 inhibitor, and the drugs failed to induce significant autophagy in MCF-7 cells. Taken together, our data originally suggest that inhibition of caspase-9 may block the autophagic flux and enhance cell death due to blockage of cytoprotective autophagy.

Effect of the oral absorption of benzenesulfonanilide-type cyclooxygenase-1 inhibitors on analgesic action and gastric ulcer formation

A benzensulfonanilide-type cyclooxygenase-1 (COX-1)-selective inhibitor, ZXX2-77: 4-amino-4'-chloro-N-methylbenzenesulfonanilide (4a), has been reported as a novel analgesic that does not cause gastric damage. This compound has a weak analgesic effect but has potent in vitro COX-1 inhibitory activity. Since the reason for the weak analgesic effect in vivo was thought to be the low rate of oral absorption, the blood concentration of ZXX2-77 (4a) was measured in rats. It was found that the C(max) value (1.2 microM) of ZXX2-77 (4a) at a dose of 30 mg/kg did not reach the COX-1 IC(50) value (3.2 microM). On the other hand, ZXX2-79 (4b) (SO(2)NH derivative of ZXX2-77 (4a); 4-amino-4'-chlorobenzenesulfonanilide), which shows less potent COX inhibitory activities (COX-1 IC(50) = 12 microM, COX-2 IC(50) = 150 microM) than those of ZXX2-77 (4a) in vitro, was found to be more absorbable (C(max) = 16 microM at a dose of 30 mg/kg in rats) than ZXX2-77 (4a). Furthermore, ZXX2-79 (4b) not only showed a potent analgesic effect in a formalin test but also caused little gastric damage. These findings indicate that demethylated sulfonamide compounds are more easily absorbed than are N-methylated sulfonamide compounds and suggest that COX-1-selective inhibitors will be useful as analgesics that do not cause gastric damage.

Inhibition of pro-inflammatory enzymes by inuviscolide, a sesquiterpene lactone from Inula viscosa

This work concerns the pharmacological activity of inuviscolide, a sesquiterpenoid from Inula viscosa. It exerts inhibitory effects on elastase, cyclooxygenase 1 and secretory phospholipase A(2). Furthermore, it reduces the skin leukocyte infiltration in a murine model of dermatitis induced by repeated application of 12-O-tetradecanoylphorbol 13-acetate.

Dual, but not selective, COX-1 and COX-2 inhibitors, attenuate acetic acid-evoked bladder irritation in the anaesthetised female cat

Non-selective cyclooxygenase (COX) inhibitors exert effects on lower urinary tract function in several species. The exact contributions of COX-1 and COX-2 isozymes have not been studied much. The present studies investigated the effects of non- and selective COX inhibitors on bladder irritation in the cat.Chloralose-anaesthetised female cats were catheterised through the bladder dome for cystometric evaluation of bladder responses to intravesical infusion of saline or acetic acid. Bladder capacity, voiding efficiency, threshold pressure, and reflex-evoked bladder contraction amplitude and duration were measured. The cat COX selectivity of the doses of inhibitors examined was determined using an in vitro whole-blood assay and analysis of plasma levels. Pretreatment with indomethacin or ketoprofen (non-selective COX inhibitors; 0.3 mg kg(-1) i.v.) inhibited acetic acid-evoked irritation (characterised by a decrease in bladder capacity in vehicle pretreated animals). FR-122047 (selective COX-1 inhibitor), NS-398 and nimesulide (selective COX-2 inhibitors; 1 and 3 mg kg(-1) i.v.) had no effects on bladder irritation. Analysis of plasma levels of the doses examined and determination of COX-1 and COX-2 inhibition in cat whole blood confirmed the reported selectivity of these compounds in this species. The present studies suggest that dual COX inhibition is required to attenuate acetic acid-evoked bladder irritation in the cat.

tNOX, an alternative target to COX-2 to explain the anticancer activities of non-steroidal anti-inflammatory drugs (NSAIDS)

Our work has identified a cancer-specific, cell surface and growth-related quinol oxidase with both NADH oxidase and protein disulfide-thiol interchange activities, a member of the ECTO-NOX protein family designated tNOX. We provide evidence for tNOX as an alternative drug target to COX-2 to explain the anticancer activity of COX inhibitors. Non-steroidal anti-inflammatory drugs (NSAIDS), piroxicam, aspirin, ibuprofen, naproxen and celecoxib all specifically inhibited tNOX activity of HeLa (human cervical carcinoma) and BT-20 (human mammary carcinoma) cells (IC(50) in the nanomolar range) without effect on ECTO-NOX activities of non-cancer MCF-10A mammary epithelial cells. With cancer cells, rofecoxib was less effective and two NSAIDS selective for COX-1 were without effect in inhibiting NOX activity. The IC(50) for inhibition of tNOX activity of HeLa cells and the IC(50) for inhibition of growth of HeLa cells in culture were closely correlated. The findings provide evidence for a new drug target to account for anticancer effects of NSAIDS that occur independent of COX-2.

Signaling pathways leading to prostaglandin E(2) production by rat cerebral frontal cortex

In this paper, we have determined the effect of both muscarinic acetylcholine receptor (mAChR) and exogenous prostaglandin E(2) (PGE(2)) on PGE(2) production and cyclooxygenases (COX) mRNA gene expression on rat cerebral frontal cortex. Carbachol and PGE(2) increase endogenous PGE(2) production and the COX-1 mRNA levels by activation of PLA(2)s. The COX-1 and COX-2 activity participated in the production of PGE(2) triggered by exogenous PGE(2). While in carbachol-PGE(2) only COX-1 activity is affected. The specific inhibition of PGE(2) receptor was able to impair the increase of endogenous PGE(2) production triggered by both carbachol and exogenous PGE(2). These results suggest that carbachol-activation mAChR increased PGE(2) production that in turn interacting with its own receptor triggers an additional production of PGE(2). Both mechanisms appear to occur by using PLA(2) signaling system. This data should be able to contribute to understand the involvement of PGE(2) in normal brain function and its participation in neuroinflammatory processes.

Differential Effects of Selective Cyclooxygenase (COX)-1 and COX-2 Inhibitors on Anorexic Response and Prostaglandin Generation in Various Tissues Induced by Zymosan

We have shown that anorexic response is induced by intraperitoneal injection of zymosan in mice, although the role of prostaglandins in this response is relatively unknown as compared with lipopolysaccharide (LPS)-induced anorexic response. Indomethacin (0.5 and 2.0 mg/kg), a non-selective cyclooxygenase (COX) inhibitor, as well as meloxicam (0.5 mg/kg), a selective COX-2 inhibitor, but not FR122047 (2.0 mg/kg), a selective COX-1 inhibitor, attenuated zymosan-induced anorexia. Zymosan injection elevated COX-2 expression in brain and liver but not in small intestine and colon. Meloxicam (0.5 mg/kg) and FR122047 treatment (2.0 mg/kg) similarly suppressed the generation of brain prostaglandin E(2) (PGE(2)) and peritoneal prostacyclin (PGI(2)) upon zymosan injection. PGE(2) generation in liver upon zymosan injection was suppressed by meloxicam (0.5 mg/kg) but not by FR122047 treatment (2.0 mg/kg). Our observations suggest that COX-2 plays an important role in zymosan-induced anorexia, which is a similar feature in LPS-induced anorexic response. However, non-selective inhibition by selective COX-1 and COX-2 inhibitors of brain PGE(2) generation upon zymosan injection does not support the role of COX-2 expressed in brain in zymosan-induced anorexic response. PGE(2) generation in liver may account for peripheral role of COX-2 in zymosan-induced anorexic response.

Arginase I in myeloid suppressor cells is induced by COX-2 in lung carcinoma

Myeloid suppressor cells (MSCs) producing high levels of arginase I block T cell function by depleting l-arginine in cancer, chronic infections, and trauma patients. In cancer, MSCs infiltrating tumors and in circulation are an important mechanism for tumor evasion and impair the therapeutic potential of cancer immunotherapies. However, the mechanisms that induce arginase I in MSCs in cancer are unknown. Using the 3LL mouse lung carcinoma, we aimed to characterize these mechanisms. Arginase I expression was independent of T cell–produced cytokines. Instead, tumor-derived soluble factors resistant to proteases induced and maintained arginase I expression in MSCs. 3LL tumor cells constitutively express cyclooxygenase (COX)-1 and COX-2 and produce high levels of PGE₂. Genetic and pharmacological inhibition of COX-2, but not COX-1, blocked arginase I induction in vitro and in vivo. Signaling through the PGE₂ receptor E-prostanoid 4 expressed in MSCs induced arginase I. Furthermore, blocking arginase I expression using COX-2 inhibitors elicited a lymphocyte-mediated antitumor response. These results demonstrate a new pathway of prostaglandin-induced immune dysfunction and provide a novel mechanism that can help explain the cancer prevention effects of COX-2 inhibitors. Furthermore, an addition of arginase I represents a clinical approach to enhance the therapeutic potential of cancer immunotherapies.

[In vitro effects of diclofenac and selective cyclooxygenase-2 inhibitors on prostaglandin release from inflamed bursa subacromialis tissue in patients with subacromial syndrome]

BACKGROUND

To compare the in vitro effects of selective COX-2 inhibitors (L-745,337, NS-398 and DFU) and of COX-unspecific diclofenac on release of PGE(2 )and 6-keto-PGF(1alpha) from inflamed bursa subacromialis tissue (IBST) obtained from a total of 35 patients with shoulder impingement syndrome (SIS).

PATIENTS AND METHODS

Bursal specimens were incubated in the presence of drugs (0.01-1000 microM) for 20 min and 16 h.

RESULTS

After 20 min 10 microM diclofenac significantly inhibited formation of PGE(2) and 6-keto-PGF(1alpha), whereas L-745,337 and NS-398 (10-1000 microM) induced significant inhibition only at concentrations > or =100 microM. In contrast to equimolar diclofenac, DFU (0.01-10 microM) induced no inhibition of bursal PGE(2) release but a dose-dependent, although statistically not significant inhibition after 16 h. The inhibitory potency of diclofenac (0.01-10 microM) was even more increased during long-term incubation showing greater inhibition than DFU at all concentrations studied.

CONCLUSION

The data suggest that in IBST in SIS in vitro the majority of PG is generated via the COX-1 pathway.

Effects of intravenous administration of FR122047 (a selective cyclooxygenase 1 inhibitor) and FR188582 (a selective cyclooxygenase 2 inhibitor) on prostaglandin-E2-induced aqueous flare elevation in pigmented rabbits

PURPOSE

Two isoforms of cyclooxygenase (COX-1 and COX-2) exist. To determine in vivo effects of the intravenous administration of FR122047 (a selective COX-1 inhibitor), FR188582 (a selective COX-2 inhibitor), diclofenac sodium or dexamethasone phosphate disodium on prostaglandin-E2 (PGE2)-induced aqueous flare elevation and mRNA levels for COX-1 and COX-2 in pigmented rabbits.

METHODS

To produce aqueous flare elevation in rabbits, PGE2, 25 microg/ml, was applied to the cornea with the use of a glass cylinder. FR122047, FR188582, diclofenac sodium or dexamethasone phosphate disodium was intravenously injected before PGE2 application. Aqueous flare was measured with a laser flare-cell meter. The mRNA levels for COX-1 and COX-2 in the iris-ciliary body were determined by real-time polymerase chain reaction.

RESULTS

FR122047, FR188582 and diclofenac sodium (15 micromol/kg each) injected intravenously 30 min before PGE2 application inhibited 29 +/- 5, 40 +/- 12 and 50 +/- 9% of aqueous flare elevation, respectively. Simultaneous injection of FR122047 (15 micromol/kg) and FR188582 (15 micromol/kg) 30 min before PGE2 application inhibited 61 +/- 8% of flare elevation. Dexamethasone phosphate disodium (15 micromol/kg) injected intravenously 300 min before PGE2 application inhibited 68 +/- 8% of aqueous flare elevation. Less than 3-fold changes in mRNA levels for COX-1 and COX-2 in the iris-ciliary body were noted after PGE2, FR122047, FR188582, diclofenac sodium or dexamethasone phosphate disodium treatment.

CONCLUSION

It is possible that enzyme activities of both COX-1 and COX-2 may be involved in the mechanism of PGE2-induced aqueous flare elevation in pigmented rabbits.

Significance of cyclooxygenase-2 induced via p38 mitogen-activated protein kinase in mechanical stimulus-induced peritoneal adhesion in mice

Postoperative peritoneal adhesion represents a major complication of surgery, but the molecular mechanism underlying pathogenesis of adhesion is not fully understood. The present study investigated the roles of cyclooxygenase (COX)-1 and COX-2 in peritoneal adhesion induced by scraping the surface of the cecum and abdominal wall in mice. Slight, but macroscopically observable, peritoneal adhesion was induced even on day 1, and the extent of adhesion reached a maximum on day 7 and beyond. COX-1 mRNA was constitutively expressed in the intact cecum, and its expression level was not altered after the mechanical stimulus. In contrast, expression of the COX-2 gene was markedly increased after the stimulus, and maximum expression was observed on days 3 to 7. Mofezolac, a specific COX-1 inhibitor, had no effect on peritoneal adhesion at 30 mg/kg and had only marginal effects on prostaglandin (PG)E2 levels in the cecum or peritoneal fluid. On the other hand, two highly selective inhibitors for COX-2, NS-398 (N-[2-(cyclohexyloxy)-4-nitrophenyl]-methanesulfonamide) and CAY10404 [3-(4-methylsulphonylphenyl)-4-phenyl-5-trifluoromethylisoxazole], dose-dependently inhibited both adhesion formation and the increase in PGE2 levels (3-30 mg/kg). The effects of NS-398 were eliminated when PGE2 or (R)-butaprost was administered exogenously. A COX-2 antisense oligonucleotide also attenuated adhesion formation. Activation of p38 mitogen-activated protein (MAP) kinase was observed in the traumatized cecum, and an MAP kinase inhibitor, SB202190 [4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)-1H-imidazole], inhibited adhesion formation (54% inhibition at 15 microM) and also reduced the COX-2 mRNA level and PGE2 levels. In conclusion, COX-2, but not COX-1, plays a significant role in mechanical stimulus-induced peritoneal formation in the mouse cecum.

Participation of cyclooxygenase-1 in prostaglandin E2 release from synovitis tissue in primary osteoarthritis in vitro

OBJECTIVES

To investigate the relative contribution of the cyclooxygenase (COX) isoenzymes COX-1 and COX-2 to prostaglandin E2 (PGE2) release from inflamed synovial tissue in N=10 patients with primary osteoarthritis (OA) in vitro and to determine possible effects of COX inhibitors on the gene expression of synovial COX-1 and COX-2.

DESIGN

The effects of a COX-unspecific nonsteroidal anti-inflammatory drug (NSAID; diclofenac), a selective COX-1 inhibitor (SC-560) and a selective COX-2 inhibitor (SC-58125) on PGE2 release from inflamed synovial tissue (0.1-10 microM, 3 and 6 h incubation time) were compared. Release of PGE2 into the incubation media was measured by means of the enzyme-linked immunosorbent assay. Expression of synovial COX-1/-2 was quantified by means of real-time reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

All agents inhibited synovial PGE2 release dose-dependently. Compared to short-term incubations, the inhibitory potency of diclofenac, SC-58125 and SC-560 was increased (0.1-10 microM) and decreased (0.1-1 microM), respectively, during 6 h: At 10 microM, SC-560 and SC-58125 had obviously lost their specificity for COX-1 and COX-2, respectively, indicated by a comparable inhibitory potency of the selective COX-1 inhibitor (86.6%) and the selective COX-2 inhibitor (96.6%) within identical tissue specimens. In contrast, at 1 microM, 83% and 62.8% inhibition was seen for diclofenac and SC-58125, respectively. SC-560 showed 30.6% inhibition (P<0.05). In contrast to synovial COX-1, RT-PCR revealed a significant induction of COX-2 through PGE2.

CONCLUSIONS

With respect to the concentrations studied, the data suggest that in inflamed synovial tissue in OA, up to 30% of PGE2 might be generated via the COX-1 pathway. In therapy of OA, the relative contribution of COX-1 in synovial inflammation should be considered, weighing the potency of COX-unspecific NSAID against the assumed superior gastrointestinal safety profile of selective COX-2 inhibitors.

Effect of systemic FR140423, a new analgesic compound, in a rat model of postoperative pain: contribution of delta-opioid receptors

We investigated the anti-hyperalgesic effect of FR140423, 3-(difluoromethyl)-1-(4-methoxyphenyl-5-[4-(methylsulfinyl)phenyl]pyrazole, in a rat model of postoperative pain. Oral administration of FR140423 at doses between 1 and 100 mg/kg after surgery dose dependently attenuated the punctate mechanical hyperalgesia caused by an incision of the plantar surface of the hind paw with an ED50 value of 59 mg/kg. The anti-hyperalgesic effect of systematically administered FR140423 was blocked by naloxone, a non-selective opioid receptor antagonist. Furthermore, the delta-opioid receptor antagonist naltrindole (0.2 mg/kg) reversed anti-hyperalgesia induced by FR140423. Naloxonazine and nor-binaltorphimine failed to antagonize the anti-hyperalgesic effect of FR140423. The action of FR140423 differs from the naloxonazine-reversible anti-hyperalgesia induced by morphine. The present findings suggest that delta-opioid systems play a role in the rat anti-hyperalgesia produced by FR140423 for postoperative pain characterized by mechanical hyperalgesia.

Role of cyclooxygenase-2, but not cyclooxygenase-1, on type II collagen-induced arthritis in DBA/1J mice

The purpose of this paper is to explore the contribution of isoforms of cyclooxygenase (COX) to chronic inflammation in DBA/1J mice with type II collagen-induced arthritis (CIA). To address this question pharmacologically, we tested the effects of selective inhibitors of COX-1 and COX-2 on paw edema and the formation of arachidonic acid metabolites in the inflamed paws immunized with type II collagen (CII). Oral administration of FR140423 (3-(difluoromethyl)-1-(4-methoxyphenyl)-5-[4-(methylsulfinyl)phenyl]pyrazole), a selective inhibitor of COX-2, showed a dose-dependent anti-inflammatory effect in mouse CIA with ED(50) value of 0.20mg/kg. Indomethacin, a non-selective inhibitor of COX, also inhibited paw edema in this arthritic model. In contrast, the selective COX-1 inhibitors, FR122047 (1-[(4,5-bis(4-methoxyphenyl)-2-thiazoyl)carbonyl]-4-methylpiperazine hydrochloride) and SC-560 (5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethylpyrazole), had no effect in mouse CIA model. The increase of prostaglandin (PG) E(2) and thromboxane (TX) B(2) in the mouse inflamed paws was associated with the development of paw edema induced by CII. FR140423 dose dependently inhibited the levels of PGE(2) and TXB(2) in the CIA mouse paws with ED(50) values of 0.20 and 0.12 mg/kg, respectively, similar to indomethacin. In contrast, FR122047 and SC-560 had no effect. These results suggest that COX-2, but not COX-1, contributes to the edema and the formation of PGE(2) and TXB(2) in mouse CIA model.

NSAIDs: the emperor's new dogma?

The spectacular marketing success of the selective cyclooxygenase 2 (COX-2) inhibitors is largely based on efficacy comparable with conventional non-steroidal anti-inflammatory drugs (NSAIDs) with vastly improved gastrointestinal safety. The additional key to the marketing success is the purity and simplicity of the message-that is, COX-1 inhibition causes the gastrointestinal side effects of NSAIDs (COX-1 dogma) while COX-2 blocking confers the therapeutic benefits (COX-2 dogma). Adherence to the COX dogmas with development of COX-2 selective agents has undoubtedly benefited many patients, but ironically their scientific basis is now seriously challenged by experimentation.

Microsomal prostaglandin E synthase-1 is a major terminal synthase that is selectively up-regulated during cyclooxygenase-2-dependent prostaglandin E2 production in the rat adjuvant-induced arthritis model

To better define the role of the various prostanoid synthases in the adjuvant-induced arthritis (AIA) model, we have determined the temporal expression of the inducible PGE synthase (mPGES-1), mPGES-2, the cytosolic PGES (cPGES/p23), and prostacyclin synthase, and compared with that of cyclooxygenase-1 (COX-1) and COX-2. The profile of induction of mPGES-1 (50- to 80-fold) in the primary paw was similar to that of COX-2 by both RNA and protein analysis. Quantitative PCR analysis indicated that induction of mPGES-1 at day 15 was within 2-fold that of COX-2. Increased PGES activity was measurable in membrane preparations of inflamed paws, and the activity was inhibitable by MK-886 to >or=90% with a potency similar to that of recombinant rat mPGES-1 (IC(50) = 2.4 microM). The RNA of the newly described mPGES-2 decreased by 2- to 3-fold in primary paws between days 1 and 15 postadjuvant. The cPGES/p23 and COX-1 were induced during AIA, but at much lower levels (2- to 6-fold) than mPGES-1, with the peak of cPGES/p23 expression occurring later than that of COX-2 and PGE(2) production. Prostacyclin (measured as 6-keto-PGF(1alpha)) was transiently elevated on day 1, and prostacyclin synthase was down-regulated at the RNA level after day 3, suggesting a diminished role of prostacyclin during the maintenance of chronic inflammation in the rat AIA. These results show that mPGES-1 is up-regulated throughout the development of AIA and suggest that it plays a major role in the elevated production of PGE(2) in this model.

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.