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

A new potential cyclooxygenase-2 inhibitor, pyridinic analogue of nimesulide

In this paper, the binding mode of original pyridinic compounds structurally related to nimesulide, a preferential cyclooxygenase (COX)-2 inhibitor, is analyzed by docking simulations in order to understand structure-activity relationships of this family. Structural modifications are proposed to reverse the selectivity of the more active inhibitor of the series characterized by a preferential activity on COX-1. On the basis of these modifications, a new compound with a bromo substituent was designed and showed a COX-2 selective inhibition.

The role of cyclooxygenase in gastric mucosal protection

COX-1 and COX-2 are two cyclooxygenase enzymes responsible for prostanoid production. COX-2 is expressed in inflammatory cells and fibroblasts of the gastric mucosa, and through the production of various growth factors including hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF), plays a key role in the tissue repair process. Aspirin induces and acetylates COX-2 to produce 15-(R)-epi-lipoxinA4, an anti-inflammatory mediator thought to protect the gastric mucosa against aspirin-induced injury. Recently, three different PGE synthases have been identified, that convert COX-2 metabolites into PGE2. mPGE synthase (mPGES)-1 has been shown to be inducible, and to colocalize with COX-2 in fibroblasts and macrophages infiltrating the gastric ulcer bed. cPGES and mPGES-2 have been found expressed in normal gastric mucosa, with no change in expression levels seen in gastritis or gastric ulcer tissue. Finally, this review discusses the role of these enzymes in the pathophysiology of the gastric mucosa, as well as the biologcal significance of their inhibition.

Anti-inflammatory effects of specific cyclooxygenase 2,5-lipoxygenase, and inducible nitric oxide synthase inhibitors on experimental autoimmune anterior uveitis (EAAU)

PURPOSE

Inflammation, in general, causes the release of a variety of inflammatory mediators that in turn induce cyclooxygenase (COX) 2, nitric oxide synthase (iNOS) and 5-lipoxygense (LP) synthesis, producing large amounts of inflammatory prostaglandins (PG), nitric oxide (NO), and leukotriene (LT) B4. Therefore, inhibition of these enzymes may abrogate intraocular inflammation in experimental autoimmune anterior uveitis (EAAU).

METHODS

Lewis rats were immunized with melanin-associated antigen (MAA) isolated from bovine iris and ciliary body. These animals were divided into three groups. The first group of rats received subcutaneous injection of COX 2 inhibitor CS 236 at different time points. The second and third groups of animals received subcutaneous aminoguanidine (AG), an iNOS inhibitor, and nordihydroguaiaretic acid (NDGA), a 5-LP inhibitor, respectively. Control animals received vehicle. Rat eyes were examined daily by slit-lamp biomicroscopy from Day 7 to 30 post injection for uveitis. Animals were also sacrificed at various time points for histologic analysis.

RESULTS

Control animals developed severe EAAU in both eyes. The disease started in these animals on Day 12 post immunization and lasted for ten days. Interestingly, CS 236, a potent COX 2 inhibitor, completely abrogated EAAU when the animals were treated daily from the Day 0 to 14 or Day 0 to 20 after MAA injection. Furthermore, daily CS 236 treatment after the onset of EAAU (Day 14-20) significantly reduced the severity (both clinical and histologic) of EAAU and shortened the duration of disease. iNOS inhibitor (AG) and 5-LP inhibitor (NDGA) partially attenuated EAAU.

CONCLUSIONS

Our results show that EAAU was partially attenuated by AG and NDGA. Interestingly, CS 236, a potent COX 2 inhibitor, completely inhibited EAAU in male Lewis rats most likely by inhibiting the initial phase and onset of the disease.

Cyclooxygenase-2 expression is induced in rat brain after kainate-induced seizures and promotes neuronal death in CA3 hippocampus

Cyclooxygenase-2 (COX-2) is the predominant isoform of cyclooxygenase in brain. COX-2 activity produces oxidative stress and results in the production of prostaglandins that have many injurious effects. COX-2 transcription is induced by synaptic activity; therefore, COX-2 activity could contribute to epileptic neuronal injury. To address this hypothesis, COX-2 protein expression and PGE2 production were determined after kainate-induced limbic seizures in rats. The effects of a specific COX-2 inhibitor, SC58125, on neuronal survival and PGE2 concentration in the hippocampus were also determined. COX-2 protein expression was increased in CA3, dentate gyrus, and cortex at 18-24 h after seizures. Hippocampal PGE2 levels were increased at 24 h following seizures, and treatment with the selective COX-2 inhibitor SC58125, 3 mg/kg p.o., attenuated the increase in PGE2 concentration. The survival of CA3 neurons at 7 days after seizures was increased in rats treated with SC58125 compared to vehicle controls. There was no effect of drug treatment on body or brain temperature, nor on the duration or rate of Type IV EEG activity. These results suggest that COX-2 activity can contribute to epileptic neuronal injury and that selective COX-2 inhibitors are neuroprotective.

Anti-inflammatory effects of a traditional Korean herbal formulation, Silsosangami, consisting of seven medicinal herbs: effect on hemolysis, neutrophil function, and gene expressions of iNOS and COX-2

Silsosangami is a dried decoctum of a mixture of seven Korean herbal medicine, which is consisted of seven herbs (indicated as concentrations) of Typhae Pollen, Pteropi Faeces, Paeoniae Radicis rubra, Cnidii Rhizoma, Persicae Semen, Carthami Flos and Curcumae Tuber. In the present study, the effects of Silsosangami water extract (SSG) on hemolysis in human blood were studied. Using an in vitro system, only Curcumae Tuber, Persicae Semen and Paeoniae Radicis rubra had the strongest effects on hemolysis; Typhae Pollen and Pteropi Faeces had the slight effects; and Cnidii Rhizoma and Carthami Flos had no effect. On the other hand, the SSG inhibited neutrophil functions, including degranulation, superoxide generation, and leukotriene B4 production, without any effect on 5-lipoxygenase activity. This SSG reduced nitric oxide (NO) and prostaglanin E2 (PGE2) production in mouse peritoneal macrophages stimulated with lipopolysaccharide, without the influence on the activity of inducible NO synthase (iNOS), cyclooxygenase COX-2 and COX-1 being observed. SSG significantly reduced mouse paw oedema induced by carrageenan. Western blot analysis showed that SSG reduced the expression of iNOS and COX-2. These results suggested that SSG might be used as a novel antithrombotic therapeutic agents in post-myocardial infarction and also, indicated that SSG exerts anti-inflammatory effects related to the inhibition of neutrophil functions and of NO and PGE2 production, which could be due to a decreased expression of iNOS and COX-2.

In vitro antiproliferative activity against human colon cancer cell lines of representative 4-thiazolidinones. Part I

The characterization of two cyclooxygenase isoforms (COX), the rate-limiting enzyme for the synthesis of prostaglandins (PGs) from arachidonic acid, has allowed the development of COX-2 selective inhibitors as non-steroidal anti-inflammatory drugs (NSAIDs) with significant gastric tolerability. However, PGs are also important in cancer pathogenesis. Thus, there is an increasing interest in studying COX-2 inhibitors as potential drugs aimed at the prevention and treatment of cancer, especially colorectal cancer. The purpose of this study was to determine the inhibitory effects of some representative 4-thiazolidinones, already widely investigated as potential NSAIDs, on the growth of five human colon carcinoma cell lines with a different COX-2 expression, and to correlate them with COX-2 inhibitory properties. Our results preliminarily revealed that 2-phenylimino derivative 3 and 2,4-thiazolidindione 4 were the most active compounds. In particular, 3 mainly inhibited the HT29 cell line characterized by a high COX-2 expression, whereas 4 showed antiproliferative properties on all tested cell lines, suggesting molecular targets other than COX-2 inhibition.

Synergistic anti-inflammatory interaction between meloxicam and aminoguanidine hydrochloride in carrageenan-induced acute inflammation in rats

Interaction studies with inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) inhibitor have been conducted to assess the nature of interaction and the possible therapeutic advantage. The interaction between meloxicam--a selective COX-2 inhibitor--and aminoguanidine hydrochloride--a selective iNOS inhibitor-- was examined in carrageenan-induced paw edema in rats. Appropriate statistical method was applied to detect the nature of anti-inflammatory interaction. Different doses of meloxicam (1, 3, 10 and 30 mg/kg) or aminoguanidine hydrochloride (10, 30, 100 and 300 mg/kg) were administered orally to adult male albino rats. Higher doses of meloxicam (3, 10 and 30 mg/kg) showed statistically significant anti-inflammatory effect. However, aminoguanidine hydrochloride did not show any anti-inflammatory activity. Combination of sub-threshold dose of meloxicam (1 mg/kg) with increasing doses of aminoguanidine hydrochloride (30, 100 and 300 mg/kg) resulted in synergistic anti-inflammatory effect. Combined therapy with sub-threshold dose of aminoguanidine hydrochloride (30 mg/kg) with increasing doses of meloxicam (1, 3, 10 and 30 mg/kg) also resulted in synergistic anti-inflammatory effect. The possible mechanism of interaction could be the stimulation of COX-2 activity by nitric oxide (NO) by combining with heme component. These results suggest that co-administration of meloxicam and aminoguanidine hydrochloride may be an alternative in clinical control of inflammation.

Neuroprotective effects of cyclooxygenase-2 inhibitor celecoxib against toxicity of LPS-stimulated macrophages toward motor neurons

AIM

To establish an in vitro injured motor neuronal model and investigate the neuroprotective effects and possible mechanism of celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, on this model.

METHODS

After macrophages were stimulated with lipopolysaccharide (LPS)+interferon-gamma (IFN-gamma) in the presence or absence of celecoxib for 24 h, the cell-free supernatant of LPS-stimulated macrophages was transferred to the culture of NSC34 cells. Viability of NSC34 cells was assessed by MTT assay after a further 24 h and 72 h incubation. After macrophages were stimulated by LPS+IFN-gamma for 12 h or 24 h, the release of prostaglandin E2 (PGE2), nitric oxide (NO), reactive oxygen species (ROS), tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) from macrophages was measured by radioimmunoassay, Griess assay, fluorescence assay and enzyme-linked immunosorbent assay, respectively. The mRNA levels of COX-2, inducible nitric oxide synthase (iNOS), TNF-alpha and IL-1beta in macrophages were determined by reverse transcription-polymerase chain reaction after macrophages were stimulated for 6 h and 12 h.

RESULTS

The supernatant of LPS-stimulated mouse macrophages induced the death of NSC34 cells and celecoxib protected the NSC34 cells against this toxicity. The LPS-induced increases in the release of PGE2, NO, TNF-alpha and IL-1beta from macrophages were attenuated by pre-treatment with celecoxib. However, celecoxib showed no effect on the ROS levels upregulated by LPS+IFN-gamma in the macrophage supernatant. The mRNA levels of COX-2, iNOS, TNF-alpha and IL-1beta were increased in LPS-activated macrophages and, except COX-2, reduced by pre-treatment with celecoxib.

CONCLUSION

An in vitro injured motor neuronal model was established by using the toxicity of LPS-stimulated mouse macrophages toward motor neuronal NSC34 cells. In this model, celecoxib exerted neuroprotective effects on motor neurons via an inhibition of the neurotoxic secretions from activated macrophages.

Effect of mechanical compression on the lumbar nerve root: localization and changes of intraradicular inflammatory cytokines, nitric oxide, and cyclooxygenase

STUDY DESIGN

Investigation of intraradicular inflammation induced by mechanical compression.

OBJECTIVE

To investigate the mechanism of nerve root pain, this study used a lumbar nerve root compression model.

SUMMARY OF BACKGROUND DATA

The manifestation of pain at sites of inflammation has a close relationship with the release of mediators from macrophages. However, the mediators involved in inflammation of nerve roots as a result of mechanical compression remain almost unknown.

METHODS

In this study, the seventh lumbar nerve root of dogs was compressed with a clip for 3 weeks to observe the changes caused by compression. Immunohistochemistry was performed using the avidin-biotin-peroxidase complex method to observe the changes of T cells (CD45) and macrophages (Mac-1) after compression. Antibodies against as interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), inducible nitric oxide synthase (i-NOS), and cyclooxygenase (COX)-1 and 2 were used to examine the localization and changes of these mediators caused by nerve root compression.

RESULTS

In control animals, resident T cells were detected, but there were no macrophages. IL-1beta and COX-2 were positive in the Schwann cells and vascular endothelial cells, while COX-1 was detected in the vascular endothelial cells. However, no cells showed TNF-alpha or i-NOS positively. After nerve root compression, numerous T cells and macrophages appeared among the demyelinized nerve fibers. The macrophages were positive for IL-1beta, TNF-alpha, i-NOS, and COX-2.

CONCLUSION

Inflammatory cytokines, NO, and COX-2 may be deeply involved in radiculitis caused by mechanical compression, and these mediators seem to be important in the manifestation of root pain.

Preoperative analgesia management with rofecoxib in thoracotomy patients

OBJECTIVE

Pain management after thoracotomy is significant because pain reduces the postoperative respiratory performance. In this study, the analgesic efficacy and safety of rofecoxib in thoracotomy patients were evaluated.

DESIGN

A prospective, randomized, double-blind, and placebo-controlled study.

SETTING

This study was performed in the Meram Medical School of Selcuk University Departments of Cardiovascular Surgery and Anesthesiology.

PARTICIPANTS

Sixty patients undergoing elective thoracic surgery via thoracotomy were randomized to receive either oral placebo or rofecoxib, 50 mg, 1 hour before surgery.

INTERVENTIONS

All patients received a standard anesthetic. Pain scores, sedation scores, heart rate, mean arterial pressure, respiratory rate, analgesic requirements, and side effects were noted 2, 4, 8, 12, 18, 24, 32, 40, and 48 hours after operation.

MEASUREMENTS AND MAIN RESULTS

There were no significant differences between the 2 study groups with respect to demographics, sedation score, intraoperative blood loss, and postoperative drainage. Compared with placebo, morphine consumption and pain scores at rest and during coughing were significantly lower with rofecoxib.

CONCLUSIONS

The preoperative administration of rofecoxib, 50 mg, provides significant analgesia for postoperative pain relief and decreases additional opioid requirements after thoracotomy.

Anti-inflammatory potential of Antrodia Camphorata through inhibition of iNOS, COX-2 and cytokines via the NF-kappaB pathway

Antrodia camphorata (A. camphorata), well known in Taiwan as a traditional Chinese medicine, has been shown to exhibit antioxidant and anticancer effects. In the present study, therefore, we have examined the effects of the fermented culture broth of A. camphorata (25-100 microg/ml) in terms of lipopolysaccharide (LPS)-induced nitric oxide (NO) and prostaglandin E2 (PGE2) production, and inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein expression in RAW 264.7 macrophages. Our results indicate concentration-dependent A. camphorata inhibition of LPS-induced NO and PGE2 production, without appreciable cytotoxicity on the RAW 264.7 cells. A. camphorata also attenuates the production of LPS-induced tumor necrosis factor (TNF-alpha) and interleukin (IL)-1beta. Furthermore, A. camphorata blocks the IkappaB-alpha degradation induced by LPS. These results indicate that A. camphorata inhibits LPS induction of cytokine, iNOS and COX-2 expression by blocking NF-kappaB activation. Therefore, we report the first confirmation of the anti-inflammatory potential of this traditionally employed herbal medicine in vitro.

Cyclooxygenase-2 inhibitors: A new therapeutic option in the treatment of macular edema after cataract surgery

Two patients had uneventful phacoemulsification. After initial improvement, vision deteriorated because of cystoid macular edema (CME). In 1 patient, treatment with systemic nonsteroidal antiinflammatory drugs showed significant improvement in visual acuity but had to be discontinued because of side effects and a relapse of the disease. In the other patient, this therapy was not sufficient. Both patients were given valdecoxib, a cyclooxygenase-2 inhibitor. The new therapy was tolerated well and led to significant and stable improvement in visual acuity in both patients. To our knowledge, this is the first report of using a cyclooxygenase-2 inhibitor in the treatment of clinically significant CME.

Up-regulation of cyclooxygenase-2 expression by TSG-6 protein in macrophage cell line

TNF-stimulated gene 6 (TSG-6) encodes a 35 kDa inducible secreted glycoprotein important in inflammation and female fertility. Previous studies have shown that TSG-6 has anti-inflammatory activity in models of acute and chronic inflammation. In the present study, we show that treatment of the RAW 264.7 murine macrophage cell line with TSG-6 protein up-regulates the expression of inducible cyclooxygenase-2 (COX-2), a key enzyme in inflammation and immune responses. This action of TSG-6 protein was abolished by heat denaturation, trypsin digestion, or anti-TSG-6 antibodies. TSG-6 treatment also resulted in a rapid increase in COX-2 mRNA levels, suggesting that TSG-6 up-regulates COX-2 gene expression. Up-regulation of COX-2 was accompanied by an increase in the production of prostaglandins, especially PGD2. As the PGD2 metabolite, 15-deoxy-Delta12,14-PGJ2, can act as a negative regulator of inflammation, these TSG-6 actions may explain, at least in part, the anti-inflammatory effect of TSG-6 observed in the intact organism.

Modulation of prostaglandin biosynthesis by nitric oxide and nitric oxide donors

The biosynthesis and release of nitric oxide (NO) and prostaglandins (PGs) share a number of similarities. Two major forms of nitric-oxide synthase (NOS) and cyclooxygenase (COX) enzymes have been identified to date. Under normal circumstances, the constitutive isoforms of these enzymes (constitutive NOS and COX-1) are found in virtually all organs. Their presence accounts for the regulation of several important physiological effects (e.g. antiplatelet activity, vasodilation, and cytoprotection). On the other hand, in inflammatory setting, the inducible isoforms of these enzymes (inducible NOS and COX-2) are detected in a variety of cells, resulting in the production of large amounts of proinflammatory and cytotoxic NO and PGs. The release of NO and PGs by the inducible isoforms of NOS and COX has been associated with the pathological roles of these mediators in disease states as evidenced by the use of selective inhibitors. An important link between the NOS and COX pathways was made in 1993 by Salvemini and coworkers when they demonstrated that the enhanced release of PGs, which follows inflammatory mechanisms, was nearly entirely driven by NO. Such studies raised the possibility that COX enzymes represent important endogenous "receptor" targets for modulating the multifaceted roles of NO. Since then, numerous papers have been published extending the observation across various cellular systems and animal models of disease. Furthermore, other studies have highlighted the importance of such interaction in physiology as well as in the mechanism of action of drugs such as organic nitrates. More importantly, mechanistic studies of how NO switches on/off the PG/COX pathway have been undertaken and additional pathways through which NO modulates prostaglandin production unraveled. On the other hand, NO donors conjugated with COX inhibitors have recently found new interest in the understanding of NO/COX reciprocal interaction and potential clinical use. The purpose of this article is to cover the advances which have occurred over the years, and in particular, to summarize experimental data that outline how the discovery that NO modulates prostaglandin production has impacted and extended our understanding of these two systems in physiopathological events.

Cyclooxygenase-2-specific inhibitor improves functional outcomes, provides neuroprotection, and reduces inflammation in a rat model of traumatic brain injury

OBJECTIVE

Increases in brain cyclooxygenase-2 (COX2) are associated with the central inflammatory response and with delayed neuronal death, events that cause secondary insults after traumatic brain injury. A growing literature supports the benefit of COX2-specific inhibitors in treating brain injuries.

METHODS

DFU [5,5-dimethyl-3(3-fluorophenyl)-4(4-methylsulfonyl)phenyl-2(5)H)-furanone] is a third-generation, highly specific COX2 enzyme inhibitor. DFU treatments (1 or 10 mg/kg intraperitoneally, twice daily for 3 d) were initiated either before or after traumatic brain injury in a lateral cortical contusion rat model.

RESULTS

DFU treatments initiated 10 minutes before injury or up to 6 hours after injury enhanced functional recovery at 3 days compared with vehicle-treated controls. Significant improvements in neurological reflexes and memory were observed. DFU initiated 10 minutes before injury improved histopathology and altered eicosanoid profiles in the brain. DFU 1 mg/kg reduced the rise in prostaglandin E2 in the brain at 24 hours after injury. DFU 10 mg/kg attenuated injury-induced COX2 immunoreactivity in the cortex (24 and 72 h) and hippocampus (6 and 72 h). This treatment also decreased the total number of activated caspase-3-immunoreactive cells in the injured cortex and hippocampus, significantly reducing the number of activated caspase-3-immunoreactive neurons at 72 hours after injury. DFU 1 mg/kg amplified potentially anti-inflammatory epoxyeicosatrienoic acid levels by more than fourfold in the injured brain. DFU 10 mg/kg protected the levels of 2-arachidonoyl glycerol, a neuroprotective endocannabinoid, in the injured brain.

CONCLUSION

These improvements, particularly when treatment began up to 6 hours after injury, suggest exciting neuroprotective potential for COX2 inhibitors in the treatment of traumatic brain injury and support the consideration of Phase I/II clinical trials.

Mitochondrial localization of cyclooxygenase-2 and calcium-independent phospholipase A2 in human cancer cells: Implication in apoptosis resistance

Cyclooxygenase-2 (COX-2) is inducible by myriad stimuli. The inducible COX-2 in primary cultured human cells has been reported to localize to nuclear envelope, endoplasmic reticulum, nucleus and caveolae. As COX-2 plays an important role in tumor growth, we were interested in its subcellular location in cancer cells. We examined COX-2 localization in several cancer cell lines by confocal microscopy. A majority of COX-2 was colocalized with heat shock protein 60, a mitochondrial protein, in colon cancer (HT-29, HCT-15 and DLD-1), breast cancer (MCF7), hepatocellular cancer (HepG2) and lung cancer cells (A549) with a similar distribution pattern. By contrast, COX-2 was not localized to mitochondria in human foreskin fibroblasts or endothelial cells. Immunoblot analysis of COX-2 in mitochondrial and cytosolic fractions confirmed localization of COX-2 to mitochondria in HT-29 and DLD-1 cells but not in fibroblasts. Calcium-independent phospholipase A2 was colocalized with heat shock protein 60 to mitochondria not only in cancer cells (HT-29 and DLD-1) but also in fibroblasts. HT-29 which expressed more abundant mitochondrial COX-2 than DLD-1 was highly resistant to arachidonic acid and H2O2-induced apoptosis whereas DLD-1 was less resistant and human fibroblasts were highly susceptible. Treatment of HT-29 cells with sulindac or SC-236, a selective COX-2 inhibitor, resulted in loss of resistance to apoptosis. These results suggest that mitochondrial COX-2 in cancer cells confer resistance to apoptosis by reducing the proapoptotic arachidonic acid.

Modified Ant Colony Optimization Algorithm for Variable Selection in QSAR Modeling: QSAR Studies of Cyclooxygenase Inhibitors

A new version of an ant colony optimization (ACO) algorithm has been proposed. A modified ACO algorithm is proposed to select variables in QSAR modeling and to predict inhibiting action of some diarylimidazole derivatives on cyclooxygenase (COX) enzyme. As a comparison to this method, the evolution algorithm (EA) was also tested. Experimental results have demonstrated that the modified ACO is a useful tool for variable selection that needs few parameters to be adjusted and converges quickly toward the optimal position.

Activated human B lymphocytes express cyclooxygenase-2 and cyclooxygenase inhibitors attenuate antibody production

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for the treatment of inflammatory diseases and target cyclooxygenases 1 and 2 (Cox-1, Cox-2) that are responsible for PG production. Newer Cox-2-selective drugs have been heavily prescribed to quench inflammation. Little is known about whether or not these drugs influence human B lymphocytes and their ability to produce Ab. We report herein that activated human B cells not only highly express Cox-2 and produce PGs, but that the NSAID indomethacin and Cox-2-selective drugs profoundly inhibit the ability of human B cells to produce IgG and IgM in vitro. Human blood B cells highly express Cox-2 mRNA and protein and produce PGs after activation with CD40L, pansorbin, or CD40L plus BCR engagement. Cox-2 is also highly expressed by human tonsil B cells, as shown by immunohistochemistry. Cox-inhibiting drugs modestly affect purified B cell proliferation but profoundly reduce Ab production. The ability of whole blood to produce IgM and IgG following stimulation is also strongly inhibited. In support that Cox-2 plays a seminal role in B lymphocyte Ab production, Cox-2 knockout mice have 64% less IgM and 35% less IgG than normal littermate controls. These findings support that NSAIDs and the new Cox-2-selective drugs have an unsuspected target, the B cell, and attenuate Ab production in humans. Use of NSAIDs may therefore influence autoantibody production in autoimmune diseases and may dampen humoral immunity in response to antigenic challenge/vaccination.

Regulation of the cyclooxygenase-2 system by interleukin-1beta through mitogen-activated protein kinase signaling pathways: a comparative study of human neuroglioma and neuroblastoma cells

Glial activation and inflammation following brain injury may initiate and maintain the process of neurodegeneration. Both glia and neurons synthesize proinflammatory mediators such as interleukin 1 beta (IL-1beta), cytosolic phospholipase A2 (cPLA2), cyclooxygenase-2 (COX-2), and prostaglandins. The molecular mechanisms by which IL-1beta regulates inflammatory genes such as cPLA2 and COX-2 in glial and neuronal cells are poorly understood. We have studied IL-1beta-mediated gene regulation in an established glial and neuronal human cell lines. We report that IL-1beta induced cPLA2 and COX-2 mRNA and protein expression and subsequent prostaglandin E2 (PGE2) release in a time-dependent manner in H4 neuroglioma cells. Both SB203580 and PD98059 [p38 and p42/44 mitogen-activated protein kinase (MAPKs) inhibitors, respectively] reduced IL-1beta-induced PGE2 production, while only SB203580 reduced both cPLA2 and COX-2 expression. Similarly, in SKNSH neuroblastoma cells, both SB203580 and PD98059 reduced IL-1beta-induced PGE2 release, with no detectable COX-2 and cPLA2 protein expression in these cells. Our results indicate that the signaling mechanisms of p38 and p42/44 MAPKs play a role in IL-1beta-mediated PGE2 release in both of these cell lines, with differences upstream at the level of cPLA(2)/COX-2 expression. IL-1beta-induced cPLA2 and COX-2 gene expression is modulated through the p38 MAPK pathway in both neuroglioma and neuroblastoma cells. Understanding the signaling mechanisms involved in IL-1beta-mediated inflammatory processes in both glia and neuronal cells may provide potential targets for therapeutic intervention for neurological disorders.

Peripheral and spinal mechanisms of antinociceptive action of lumiracoxib

The possible participation of the nitric oxide (NO)-cyclic GMP-K(+) channel pathway, serotonergic or opioidergic system on lumiracoxib-induced local or intrathecal antinociception was assessed in the formalin test. Local or intrathecal administration of lumiracoxib dose-dependently produced antinociception in the second phase of the test. Moreover, local or intrathecal pretreatment with N(G)-L-nitro-arginine methyl ester (L-NAME, NO synthesis inhibitor), 1H-(1,2,4)-oxadiazolo(4,2-a)quinoxalin-1-one (ODQ, guanylyl cyclase inhibitor), glibenclamide (ATP-sensitive K(+) channel blocker), charybdotoxin and apamin (large- and small-conductance Ca(2+)-activated-K(+) channel blockers, respectively) or margatoxin (voltage-dependent K(+) channel blocker), but not N(G)-D-nitro-arginine methyl ester (D-NAME) or vehicle, significantly prevented lumiracoxib-induced antinociception. The intrathecal injection of methiothepin (serotonin receptor antagonist) reduced lumiracoxib-induced intrathecal antinociception. Local peripheral or intrathecal naloxone did not modify either local or intrathecal lumiracoxib-induced antinociception. Results suggest that lumiracoxib activates the NO-cyclic GMP-K(+) channels to produce local and intrathecal antinociception. Data also suggest that lumiracoxib activates the intrathecal serotonergic system, but not opioid receptors either at peripheral or spinal sites.

Effect of celecoxib, a cyclooxygenase-2 inhibitor, on the pathophysiology of adjuvant arthritis in rat

We investigated the efficacy of celecoxib, a specific cyclooxygenase (COX)-2 inhibitor, on arthritic pathophysiology and confirmed its gastric safety in adjuvant-induced arthritis rats. Results were compared with those for loxoprofen, a non-selective COX inhibitor. Arthritis was induced by injection of 1 mg of Mycobacterium butyricum in 50 microl of liquid paraffin into the left footpad of Lewis rats. The drugs were given by twice daily oral administration for 10 days beginning 15 days after adjuvant injection, with celecoxib at 0.01-3 mg/kg/day and loxoprofen at 0.01-3 mg/kg/day. Celecoxib significantly inhibited paw swelling, hyperalgesic response, and joint destruction (radiographic and histopathological findings) in these arthritic rats. These effects of celecoxib were superior to those of loxoprofen. Further, the administration of loxoprofen (3 mg/kg/day) caused significant gastric lesions, whereas celecoxib at the same dose did not. These results suggest that COX-2-mediated prostaglandins may play an important role in the progression of pathophysiology in this model and that celecoxib may be a useful therapeutic agent for the treatment of rheumatoid arthritis, with greater safety than non-selective COX inhibitors.

Protective effects of thiazolo[3,2-b]-1,2,4-triazoles on ethanol-induced oxidative stress in mouse brain and liver

A series of 3-[1-(4-(2-methylpropyl) phenyl) ethyl]-1 ,2,4-triazole-5-thione (I) and its bicyclic condensed derivatives 6-benzylidenethiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones (IIa-IIf) were investigated for the prevention of ethanol-induced oxidative stress in liver and brain of mice. Administration of ethanol (0.1 mL/mice, p.o.) resulted in a drop of total thiol groups (T-SH) and non-protein thiol groups (NP-SH), and an increase in thiobarbituric acid reactive substances (TBARS) in both liver and brain tissue of mice (p < 0.001). Among the compounds investigated (at a dose of 200 mg/kg, p.o.), I and IId ameliorated the peroxidative injury in these tissues effectively. Compounds IIa, IIc and IIe improved the peroxidative tissue injury only in brain. These findings suggest that certain condensed thiazolo-triazole compounds may contribute to the control of ethanol-induced oxidative stress in an organ selective manner.

Involvement of prostaglandins in inflammation induced by latex of Calotropis procera

INTRODUCTION:The aerial parts of the plant Calotropis procera produce milky white latex that causes inflammation of the skin and mucous membranes. Prostaglandins are one of the mediators released in an inflammatory response following induction of cyclooxygenase (COX). In the present study, we have evaluated the role of prostaglandins in inflammatory response elicited by the latex of C. procera. METHODS: Aqueous extract of dried latex of C. procera was injected into the 6-day air-pouch in the rat. The inflammatory response was evaluated by studying the air-pouch fluid for its volume, protein and prostaglandin (PG) E2 concentrations, and leucocyte counts. The granulation tissue from the pouch was quantified and studied for COX-2 expression by reverse transcriptase-polymerase chain reaction. The inhibitory effect of celecoxib and dexamethasone was evaluated on the aforementioned parameters. RESULTS: Dried latex produced an inflammatory response that was maximum at 6 h. It was associated with the accumulation of protein-rich fluid, leucocytes and PGE2 production. It also resulted in granulation of the pouch cavity that was a maximum on day 3. COX-2 expression could be detected in the granulation tissue on day 1 and it increased progressively up to day 5. The anti-inflammatory drugs celecoxib and dexamethasone significantly attenuated the inflammatory response and inhibited COX-2 expression in granulation tissue. CONCLUSIONS: Latex of C. procera induces an inflammatory response characterized by an early exudative phase accompanied by PGE2 production and a late proliferative phase associated with COX-2 induction. Both the phases were effectively inhibited by COX-2 inhibitors.

Effects of celecoxib and naproxen on renal function in nonazotemic patients with cirrhosis and ascites

Nonselective inhibition of cyclooxygenase (COX) by nonsteroidal anti-inflammatory drugs frequently induces renal failure in decompensated cirrhosis. Studies in experimental cirrhosis suggest that selective inhibitors of the inducible isoform COX-2 do not adversely affect renal function. However, very limited information is available on the effects of these compounds on renal function in human cirrhosis. This investigation consists of a double-blind, randomized, placebo-controlled trial aimed at comparing the effects of the selective COX-2 inhibitor celecoxib (200 mg every 12 hours for a total of 5 doses) on platelet and renal function and the renal response to furosemide (40 mg intravenously) with those of naproxen (500 mg every 12 hours for a total of 5 doses) and placebo in 28 patients with cirrhosis and ascites. A significant reduction (P < .05) in glomerular filtration rate (113 +/- 27 to 84 +/- 22 mL/min), renal plasma flow (592 +/- 158 to 429 +/- 106 mL/min) and urinary prostaglandin E(2) excretion (3430 +/- 430 to 2068 +/- 549 pg/min) and suppression of the diuretic (urine volume: 561 +/- 128 to 414 +/- 107 mL/h) and natriuretic (urine sodium: 53 +/- 13 to 34 +/- 10 mEq/h) responses to furosemide were observed in the group of patients treated with naproxen but not in the other two groups. Naproxen, but not celecoxib or placebo, significantly inhibited platelet aggregation (72% +/- 8% to 47% +/- 8%, P < .05) and thromboxane B(2) production (41 +/- 12 to 14 +/- 5 pg/mL, P < .05). In conclusion, our results indicate that short-term administration of celecoxib does not impair platelet and renal function and the response to diuretics in decompensated cirrhosis. Further studies are needed to evaluate the long-term safety of this drug in cirrhosis.

The effect of cyclooxygenase-2 inhibition on analgesia and spinal fusion

BACKGROUND

Cyclooxygenase (COX)-2-specific inhibitors demonstrate analgesic efficacy comparable with that of conventional nonsteroidal anti-inflammatory drugs but are associated with reduced gastrointestinal side effects and an absence of antiplatelet activity. Thus, they can be administered to patients undergoing spinal fusion surgery without an added risk of bleeding. However, concerns regarding a possible deleterious effect on bone-healing have limited their routine use. Celecoxib, a COX-2 inhibitor, recently was approved for the treatment of acute pain. The goals of the present study were to examine the analgesic efficacy of celecoxib and to determine the incidence of nonunion at one year following spinal fusion surgery.

METHODS

Eighty patients who were scheduled to undergo spinal fusion received either celecoxib or placebo one hour before the induction of anesthesia and every twelve hours after surgery for the first five postoperative days. Pain scores and morphine use were recorded one hour after arrival in the post-anesthesia care unit and at four, eight, twelve, sixteen, twenty, and twenty-four hours later. Intraoperative blood loss was recorded. The status of the fusion was determined radiographically at the time of the one-year follow-up.

RESULTS

There were no differences in demographic data or blood loss between the two groups. Pain scores were lower in the celecoxib group at one, four, eight, sixteen, and twenty hours postoperatively. There were no differences between the two groups with regard to the pain scores at twelve and twenty-four hours postoperatively. Morphine use was lower in the celecoxib group at all postoperative time-intervals. There was no difference between the celecoxib group and the placebo group with regard to the incidence of nonunion at the time of the one-year follow-up (7.5% [three of forty] compared with 10% [four of forty]).

CONCLUSIONS

The perioperative administration of celecoxib resulted in a significant reduction in postoperative pain and opioid use following spinal fusion surgery. In addition, the short-term administration of this COX-2-specific non-steroidal anti-inflammatory drug had no apparent effect on the rate of nonunion at the time of the one-year follow-up.

Valdecoxib: assessment of cyclooxygenase-2 potency and selectivity

The discovery of a second isoform of cyclooxygenase (COX) led to the search for compounds that could selectively inhibit COX-2 in humans while sparing prostaglandin formation from COX-1. Celecoxib and rofecoxib were among the molecules developed from these efforts. We report here the pharmacological properties of a third selective COX-2 inhibitor, valdecoxib, which is the most potent and in vitro selective of the marketed COX-2 inhibitors that we have studied. Recombinant human COX-1 and COX-2 were used to screen for new highly potent and in vitro selective COX-2 inhibitors and compare kinetic mechanisms of binding and enzyme inhibition with other COX inhibitors. Valdecoxib potently inhibits recombinant COX-2, with an IC(50) of 0.005 microM; this compares with IC values of 0.05 microM for celecoxib, 0.5 microM for rofecoxib, and 5 microM for etoricoxib. Unique binding interactions of valdecoxib with COX-2 translate into a fast rate of inactivation of COX-2 (110,000 M/s compared with 7000 M/s for rofecoxib and 80 M/s for etoricoxib). The overall saturation binding affinity for COX-2 of valdecoxib is 2.6 nM (compared with 1.6 nM for celecoxib, 51 nM for rofecoxib, and 260 nM for etoricoxib), with a slow off-rate (t(1/2) approximately 98 min). Valdecoxib inhibits COX-1 in a competitive fashion only at very high concentrations (IC(50) = 150 microM). Collectively, these data provide a mechanistic basis for the potency and in vitro selectivity of valdecoxib for COX-2. Valdecoxib showed similar activity in the human whole-blood COX assay (COX-2 IC(50) = 0.24 microM; COX-1 IC(50) = 21.9 microM). We also determined whether this in vitro potency and selectivity translated to significant potency in vivo. In rats, valdecoxib demonstrated marked potency in acute and chronic models of inflammation (air pouch ED(50) = 0.06 mg/kg; paw edema ED(50) = 5.9 mg/kg; adjuvant arthritis ED(50) = 0.03 mg/kg). In these same animals, COX-1 was spared at doses greater than 200 mg/kg. These data provide a basis for the observed potent anti-inflammatory activity of valdecoxib in humans.

The potential application of cyclo-oxygenase type 2 inhibitors to Alzheimer’s disease

In recent years, dramatic progress has been made in the understanding of the neurogenetics and neurobiology of Alzheimer's disease (AD). A great deal of experimental evidence has accumulated to support the hypothesis that inflammatory mechanisms are involved in the pathophysiology of AD. In addition, epidemiological studies have revealed that anti-inflammatory medications reduce the risk of developing AD. However, long-term use of conventional anti-inflammatory drugs is associated with significant toxicity which limits their potential application to the treatment or prevention of AD. It is believed that the inhibition of cyclo-oxygenase type-1 (COX-1) causes much of this toxicity, while inhibition of COX type-2 (COX-2), which is induced by inflammatory stimuli, may confer the anti-inflammatory effect. COX-2 is also constitutively expressed in brain regions preferentially affected in Alzheimer's disease and may be directly involved in neuronal cell death. Therefore, selective COX-2 inhibitors represent a promising class of drugs for the treatment of AD.

Stylopine from Chelidonium majus inhibits LPS-induced inflammatory mediators in RAW 264.7 cells

Stylopine is a major component of the leaf of Chelidonium majus L. (Papaveraceae), which has been used for the removal of warts, papillomas and condylomas, as well as the treatment of liver disease, in oriental countries. Stylopine per se had no cytotoxic effect in unstimulated RAW 264.7 cells, but concentration-dependently reduced nitric oxide (NO), prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta), and the IL-6 production and cyclooxygenase-2 (COX-2) activity caused by the LPS stimulation. The levels of inducible nitric oxide synthase (iNOS) and COX-2 protein expressions were markedly suppressed by stylopine in a concentration dependent manner. These results suggest that stylopine suppress the NO and PGE2 production in macrophages by inhibiting the iNOS and COX-2 expressions. These biological activities of stylopine may contribute to the anti-inflammatory activity of Chelidonium majus.

QSAR studies on some thiophene analogs as anti-inflammatory agents: enhancement of activity by electronic parameters and its utilization for chemical lead optimization

Small molecule heterocycle is an integral part of new drug discovery in anti-inflammatory research. In our previous papers we reported the synthesis of thiophene analogs substituted at the fifth position with alpha-oximino propionic ester moiety and the fact that such new chemical entities exhibit anti-inflammatory activity in male/female Sprague-Dawley rats. In this paper we report the quantitative structure activity relationship (QSAR) studies of a series of 43 thiophene analogs. The analogs when subjected to cluster analysis technique led to the formation of four homogeneous groups. The cluster analysis technique grouped the 2-anilino-5-substituted-4-methyl-thiophene-3-carboxylic acid methyl esters as one homogeneous group. The clusters were individually taken up for a Hansch type of QSAR study with 10 molecular descriptors. The QSAR equations generated were cross validated by the leave out one method. The studies gave an insight into the dominant role played by electronic properties like energy of the lowest unoccupied molecular orbital (ELUMO) and dipole moment (dipole) in modulating the anti-inflammatory activity. From the QSAR studies a three point pharmacophore has been established for designing novel anti-inflammatory molecules.

Control of cyclooxygenase-2 transcriptional activation by pro-inflammatory mediators

Cyclooxygenase-2 (COX-2) plays a key role in diverse inflammatory conditions. Its cellular levels depend on transcriptional activation by pro-inflammatory mediators. The mechanism by which phorbol esters and cytokines activate COX-2 gene expression has been extensively characterized. Several endogenous molecules and natural products have been reported to inhibit COX-2 expression by targeting at the transcriptional activation induced by pro-inflammatory mediators. This review highlights the importance of C/EBP beta and NF-kappa B in COX-2 transcriptional activation by proinflammatory mediators and as targets of inhibition by endogenous molecules such as melatonin and natural products including salicylate and polyphenols.

Decreased susceptibility to renovascular hypertension in mice lacking the prostaglandin I2 receptor IP

Persistent reduction of renal perfusion pressure induces renovascular hypertension by activating the renin-angiotensin-aldosterone system; however, the sensing mechanism remains elusive. Here we investigated the role of PGI2 in renovascular hypertension in vivo, employing mice lacking the PGI2 receptor (IP-/- mice). In WT mice with a two-kidney, one-clip model of renovascular hypertension, the BP was significantly elevated. The increase in BP in IP-/- mice, however, was significantly lower than that in WT mice. Similarly, the increases in plasma renin activity, renal renin mRNA, and plasma aldosterone in response to renal artery stenosis were all significantly lower in IP-/- mice than in WT mice. All these parameters were measured in mice lacking the four PGE2 receptor subtypes individually, and we found that these mice had similar responses to WT mice. PGI2 is produced by COX-2 and a selective inhibitor of this enzyme, SC-58125, also significantly reduced the increases in plasma renin activity and renin mRNA expression in WT mice with renal artery stenosis, but these effects were absent in IP-/- mice. When the renin-angiotensin-aldosterone system was activated by salt depletion, SC-58125 blunted the response in WT mice but not in IP-/- mice. These results indicate that PGI2 derived from COX-2 plays a critical role in regulating the release of renin and consequently renovascular hypertension in vivo.

ABT-963 [2-(3,4-difluoro-phenyl)-4-(3-hydroxy-3-methyl-butoxy)-5-(4-methanesulfonyl-phenyl)-2H-pyridazin-3-one], a highly potent and selective disubstituted pyridazinone cyclooxgenase-2 inhibitor

Nonsteriodal anti-inflammatory drugs (NSAIDs) are efficacious for the treatment of pain associated with inflammatory disease. Clinical experience with marketed selective cyclooxygenase-2 (COX-2) inhibitors (celecoxib, rofecoxib, and valdecoxib) has confirmed the utility of these agents in the treatment of inflammatory pain with an improved gastrointestinal safety profile relative to NSAID comparators. These COX-2 inhibitors belong to the same structural class. Each contains a core heterocyclic ring with two appropriately substituted phenyl rings appended to adjacent atoms. Here, we report the identification of vicinally disubstituted pyridazinones as potent and selective COX-2 inhibitors. The lead compound in the series, ABT-963 [2-(3,4-difluoro-phenyl)-4-(3-hydroxy-3-methyl-butoxy)-5-(4-methanesulfonyl-phenyl)-2H-pyridazin-3-one], has excellent selectivity (ratio of 276, COX-2/COX-1) in human whole blood, improved aqueous solubility compared with celecoxib and rofecoxib, high oral anti-inflammatory potency in vivo, and gastric safety in the animal studies. After oral administration, ABT-963 reduced prostaglandin E2 production in the rat carrageenan air pouch model (ED50 of 0.4 mg/kg) and reduced the edema in the carrageenan induced paw edema model with an ED30 of 1.9 mg/kg. ABT-963 dose dependently reduced nociception in the carrageenan hyperalgesia model (ED50 of 3.1 mg/kg). After 14 days of dosing in the adjuvant arthritis model, ABT-963 had an ED(50) of 1.0 mg/kg in reducing the swelling of the hind paws. Magnetic resonance imaging examination of the diseased paws in the adjuvant model showed that ABT-963 significantly reduced bone loss and soft tissue destruction. ABT-963 is a highly selective COX-2 inhibitor that may have utility in the treatment of the pain and inflammation associated with arthritis.

Cyclooxygenase-2 activity contributes to neuronal expression of cyclin D1 after anoxia/ischemia in vitro and in vivo

Cyclooxygenase-2 (COX-2) activity has been implicated in the pathogenesis of neuronal cell death in ischemia and other diseases, but the mechanism by which COX-2 exacerbates cell death is unknown. COX-2 activity is known to induce expression of cyclin D1 in neoplastic cells, and cyclin D1 expression can induce cell death in postmitotic neurons. In the present study, the role of COX-2 and cyclin D1 in neuronal cell death induced by anoxia and ischemia was examined. Treatment with the COX-2 specific inhibitor (NS 398 25 microM) and cyclin D1 inhibitor (flavopiridol 1 microM) increased neuronal survival and inhibited DNA fragmentation after anoxia. NS-398 suppressed anoxia-induced expression of cyclin D1. Flavopiridol inhibited the anoxia-induced increased expression of cyclin D1, but had no effect on COX-2 expression. Treatment with the selective COX-2 inhibitor, SC58125, had no affect on COX-2 expression but partially suppressed cyclin D1 expression in the cortex following middle cerebral artery occlusion in vivo. These results show that COX-2 activity is required for cyclin D1 expression after ischemia in vivo and anoxia in vitro. These data provide support for the hypothesis that cyclin D1 expression is an important mechanism by which COX-2 activity exacerbates ischemic neuronal death.

Monocyte cyclooxygenase-2 overactivity: a new marker of subclinical atherosclerosis in asymptomatic subjects with cardiovascular risk factors?

AIMS

Cyclooxygenase-2 (COX-2)-mediated prostaglandin production by activated macrophages is associated with inflammation and atherosclerosis. We investigated the relationship between COX-2-mediated prostaglandin-E2 (PGE2) release, cardiovascular risk factors, and carotid atherosclerosis in apparently healthy subjects.

METHODS AND RESULTS

PGE2 release by lipopolysaccharide-stimulated blood monocytes was measured by ELISA in 291 subjects (76.5% men, mean age 58) who underwent global vascular risk assessment and carotid ultrasonography. COX-2 expression (real-time RT-PCR) was analysed in a subgroup of 100 subjects (76% men, mean age 59). Inducible PGE2 production was associated with smoking and diabetes (P<0.05), but not with arterial hypertension, dyslipidaemia, or obesity. Subjects in the highest tertile of PGE2 (>8.1 ng/mL) had significantly higher mean carotid intima-media thickness (IMT) than those in the lowest tertile (P<0.01). No significant differences among tertiles were observed in the levels of inflammatory markers (C-reactive protein, fibrinogen, and von Willebrand factor). The association between PGE2 and carotid IMT remained statistically significant (P=0.012) after adjustment for a number of cardiovascular and inflammatory risk factors. A correlation between COX-2 expression and PGE2 production was observed (P<0.005).

CONCLUSIONS

COX-2-mediated PGE2 overproduction by stimulated monocytes might provide a new marker of subclinical atherosclerosis in asymptomatic subjects exposed to cardiovascular risk factors.

A new pyrazolo pyrimidine derivative inhibitor of cyclooxygenase-2 with anti-angiogenic activity

In a previous study, we reported a new pyrazolo pyrimidine derivative, N(4)-benzyl-N(6),N(6)-dimethyl-1-1(tert-butyl)-1H-pyrazolo[3,4-d]pyrimidine-6,4-diamine (DPP), which inhibited potently cyclooxygenase-2 activity in intact cell assays with minor activity against cyclooxygenase-1 (IC(50)=0.9 nM for cyclooxygenase-2 versus IC(50)=59.6 nM for cyclooxygenase-1). In the present work, this behaviour was confirmed in vivo by using the 24-h zymosan-injected mouse air pouch model (ID(50)=1.36 nM/pouch for prostaglandin E(2) level). We also studied the possible beneficial effect of DPP in the angiogenesis-dependent murine air pouch granuloma and rat paw carrageenan-induced hyperalgesia models. DPP exerted analgesic and anti-angiogenic (52% reduction in angiogenesis at 10 mg/kg, i.p.) effects that may be associated with inhibition of cyclooxygenase-2 activity.

Toxic effects of nonsteroidal antiinflammatory drugs on the small bowel, colon, and rectum

The gastrointestinal toxicity of conventional nonsteroidal antiinflammatory drugs (NSAIDs) is not confined to the stomach and proximal duodenum but extends also to the rest of the small bowel, colon, and rectum. Long-term NSAID therapy usually induces clinically silent enteropathy characterized by increased intestinal permeability and inflammation. Chronic occult bleeding and protein loss may result in iron-deficiency anemia and hypoalbuminemia. NSAIDs can also induce small bowel ulcers that infrequently lead to acute bleeding, perforation, or chronic scarring responsible for diaphragm-like strictures. At the colon and rectum, NSAID use can result in de novo lesions such as nonspecific colitis and rectitis, ulcers, and diaphragm-like strictures. NSAIDs have been implicated in the development of segmental ischemic colitis. In patients with diverticular disease, NSAID use increases the risk of severe diverticular infection and perforation. NSAIDs can trigger exacerbations of ulcerative colitis or Crohn's disease. With selective COX-2 inhibitors, the risk of gastrointestinal toxicity is reduced as compared to conventional NSAIDs but is not completely eliminated. Experimental studies suggest that long-term COX-2 inhibitor therapy may cause damage to the previously healthy small bowel. Similar to conventional NSAIDs, COX-2 inhibitors may be capable of triggering exacerbations of inflammatory bowel disease.

Effect of a Korean Traditional Formulation, Hwaotang, on Superoxide Generation in Human Neutrophils, Platelet Aggregation in Human Blood, and Nitric Oxide, Prostaglandin E2 Production and Paw Oedema Induced by Carrageenan in Mice

Hwaotang, a traditional Korean medicinal formulation, is a dried decoctum of a mixture of 7 herbal medicines, consisting of Angelica gigantis Radix, Rehmanniae radix, Paeoniae radix, Ciniamomi cortex, Cnidii rhizoma, Persicae semen and Carthami flos. We have investigated that Hwaotang water extract (HOT) has various effects on stimulus-induced superoxide generation in human neutrophils. The effects of HOT on superoxide generation in human neutrophils were investigated. HOT significantly inhibited N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced superoxide generation in a concentration-dependent manner, but not that induced by arachidonic acid (AA). On the other hand, HOT enhanced superoxide generation induced by phorbol 12-myristate 13-acetate (PMA) in a concentration-dependent manner. The superoxide generation induced by PMA with HOT was suppressed by staurosporine, an inhibitor of protein kinase C, but was not suppressed by genistein, an inhibitor of protein tyrosine kinase. Tyrosyl phosphorylation of a 58 kDa protein, which was increased by fMLP, was inhibited by HOT. HOT also inhibited the generation of a 47 kDa protein and platelet aggregation in human blood. The results suggest that protein tyrosine kinase participates in fMLP-mediated superoxide generation by HOT-treated human neutrophils. HOT inhibited neutrophil functions, including degranulation, superoxide generation, and leukotriene B4 production, without any effect on 5-lipoxygenase activity. HOT reduced nitric oxide (NO) and prostaglandin E2 production in mouse peritoneal macrophages stimulated with lipopolysaccharide, whereas no influence on the activity of iNOS, COX-2 or COX-1 was observed. HOT significantly reduced mouse paw oedema induced by carrageenan. Western blot analysis showed that HOT reduced the expression of iNOS and COX-2. The results indicate that HOT exerts anti-inflammatory effects related to the inhibition of neutrophil functions and of NO and prostaglandin E2 production, which could be due to a decreased expression of iNOS and COX-2.

Identification of 2,3-diaryl-pyrazolo[1,5-b]pyridazines as potent and selective cyclooxygenase-2 inhibitors

GW406381 (8), currently undergoing clinical evaluation for the treatment of inflammatory pain is a member of a novel series of 2,3-diaryl-pyrazolo[1,5-b]pyridazine based cyclooxygenase-2 (COX-2) inhibitors, which have been shown to be highly potent and selective. Several examples of the series, in addition to possessing favourable pharmacokinetic profiles and analgesic activity in vivo, have also demonstrated relatively high brain penetration in the rat compared with the clinically available compounds, which may ultimately prove beneficial in the treatment of pain.

Quantitative analysis of binding of transcription factor complex to biotinylated DNA probe by a streptavidin-agarose pulldown assay

Gene expression is regulated by a large complex of proteins that bind to the promoter/enhancer region of a gene. We determined whether a streptavidin-bead binding assay might be useful in detecting individual proteins in the complex comprising transactivators, coactivators, mediators, and general transcription factors. We used biotinylated cyclooxygenase-2 promoter probes as a model. Nuclear extracts obtained from human fibroblasts treated with or without an agonist were incubated with a 5(')-biotinylated probe and streptavidin-agarose beads at room temperature for 1h. After centrifugation, the pellet was washed and proteins in the complex were assessed by immunoblots. An array of transcription factors was detectable concurrently in the same batch of pellets at basal state. p300 and its associated factor PCAF levels but not Srb7, Med7, or TFII(B) were increased by phorbol ester or tumor necrosis factor alpha stimulation. Only trace of CREB-binding protein was detected. These results suggest that p300 and PCAF are the predominant coactivators for COX-2 promoter activation. Our findings indicate that the streptavidin-bead pulldown assay is valuable for determining the binding of a large number of transcription factors to promoter/enhancer and evaluating the relationship of protein binding with regulation of gene expression.

Nociception and the differential expression of cyclooxygenase-1 (COX-1), the COX-1 variant retaining intron-1 (COX-1v), and COX-2 in mouse dorsal root ganglia (DRG)

Prostaglandins (PGs) formed via the cyclooxygenase (COX) pathway mediate hyperalgesia in sensory nerve endings. To investigate the role of the COX isoforms in pain transmission we recently studied nociception in COX-isozyme-deficient mice using models of "sharp" rapidly transmitted pain (hot-plate) and slowly developing, diffuse pain (writhing) [Ballou L, Botting RM, Goorha S, Zhang J, Vane JR. Nociception in cyclooxygenase isozyme-deficient mice. Proc Natl Acad Sci USA 2000;97:10272]. Our results demonstrated that COX-1 (and not COX-2) was the primary isoform involved in nociception in both model systems. Given the importance of dorsal root ganglia (DRG) in pain transmission we examined the expression patterns of COX-1, -2 and the recently described variant of COX-1 retaining intron-1, originally referred to as "COX-3" but hereafter referred to as COX-1 variant (COX-1v), in mouse L4 or L5 DRG taken from normal and COX-isozyme-deficient mice. Messenger RNA and protein for COX isoforms from DRG, spinal cord as well as, heart, brain, kidney, spleen and skin of adult mice were isolated and analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Patterns of COX-isoform expression were determined using immunohistochemical techniques. We found that COX-1 and COX-1v were both expressed in neurons while COX-2 expression was completely undetectable in the DRG. Immunohistochemical analysis of COX expression in DRG of mice exhibiting the chronic pain and inflammation associated with collagen-induced arthritis (CIA) expressed COX-1 and COX-1v while no COX-2 could be detected. For purposes of comparison, COX-1v mRNA was also expressed in heart, brain, spinal cord, kidney, spleen and skin. Together, these data support a role for COX-1 and perhaps COX-1v, not COX-2, as the primary producers of PGs in mouse DRG in normal and in mice subject to chronic pain and inflammation. These data also suggest potential alternative analgesic mechanisms of action for the newly developed, COX-2 selective inhibitors and the nonsteroidal anti-inflammatory drugs (NSAIDs) in pain transmission in the peripheral nervous system.

Anti-inflammatory and anti-nociceptive effects of the extract from Kalopanax pictus, Pueraria thunbergiana and Rhus verniciflua

The combined extracts obtained from three Chinese herb medicine, Kalopanax pictus, Pueraria thunbergiana and Rhus verniciflua, have been used as therapeutics for diabetes mellitus in Korea. In the present study, we have investigated their possible anti-inflammatory effects by comparing the potency of individual extracts with that of the combined extracts. An individual water extract prepared from Kalopanax pictus, Pueraria thunbergiana, and Rhus verniciflua was named K-1, P-1, and R-1, respectively. Simultaneously, we also prepared the combined extracts from above three plant materials by identical methods and named KPR-1. These four extracts were further fractionated into the EtOAc extracts, and these were designated as K-2, P-2, R-2, and KPR-2, respectively. These eight samples were subjected to the nitrite assays in LPS-induced macrophage 264.7 cells. KPR-2 exhibited the most pronounced effect on the inhibition of NO production among all the extracts. KPR-2 also significantly decreased PGE2, and TNF-alpha release. In addition, KPR-2 showed in vivo anti-inflammatory activity against acute paw edema induced by carrageenan in rats. When analgesic activity was measured by the acetic acid-induced abdominal constriction and hot plate test, KPR-2 showed a dose-dependent inhibition in animal models. These results suggested that the mixture extract and successive fractionation could lead to the better use of anti-inflammatory medicinal crude drugs.

Cyclooxygenase isozymes: the biology of prostaglandin synthesis and inhibition

Nonsteroidal anti-inflammatory drugs (NSAIDs) represent one of the most highly utilized classes of pharmaceutical agents in medicine. All NSAIDs act through inhibiting prostaglandin synthesis, a catalytic activity possessed by two distinct cyclooxygenase (COX) isozymes encoded by separate genes. The discovery of COX-2 launched a new era in NSAID pharmacology, resulting in the synthesis, marketing, and widespread use of COX-2 selective drugs. These pharmaceutical agents have quickly become established as important therapeutic medications with potentially fewer side effects than traditional NSAIDs. Additionally, characterization of the two COX isozymes is allowing the discrimination of the roles each play in physiological processes such as homeostatic maintenance of the gastrointestinal tract, renal function, blood clotting, embryonic implantation, parturition, pain, and fever. Of particular importance has been the investigation of COX-1 and -2 isozymic functions in cancer, dysregulation of inflammation, and Alzheimer's disease. More recently, additional heterogeneity in COX-related proteins has been described, with the finding of variants of COX-1 and COX-2 enzymes. These variants may function in tissue-specific physiological and pathophysiological processes and may represent important new targets for drug therapy.

Reduced incidence of upper gastrointestinal ulcer complications with the COX-2 selective inhibitor, valdecoxib

AIM

In a predefined analysis, data were pooled from eight blinded, randomized, controlled trials, and separately from three long-term, open-label trials to determine the rate of upper gastrointestinal ulcer complications with the cyclo-oxygenase-2 selective inhibitor, valdecoxib, vs. non-selective non-steroidal anti-inflammatory drugs.

METHODS

In randomized, controlled trials, 7434 osteoarthritis and rheumatoid arthritis patients received placebo (n = 973), valdecoxib 5-80 mg daily (n = 4362), or a non-selective non-steroidal anti-inflammatory drug (naproxen, ibuprofen or diclofenac; n = 2099) for 12-26 weeks. In long-term, open-label trials, 2871 patients received valdecoxib 10-80 mg daily for up to 1 year. All potential events were reviewed by a blinded, independent review committee based on a priori definitions of ulcer complications (perforations, obstructions, bleeds).

RESULTS

In randomized, controlled trials, 19 of 955 potential events were adjudicated to be ulcer complications. Valdecoxib was associated with a significantly lower ulcer complication rate than non-selective non-steroidal anti-inflammatory drugs (0.68% vs. 1.96%, all patients; 0.29% vs. 2.08%, non-aspirin users; P < 0.05). In long-term, open-label trials, seven of 310 potential events were adjudicated to be ulcer complications; the annualized incidence for valdecoxib was 0.39% (seven of 1791 patient-years) for all patients and 0.2% (three of 1472 patient-years) for non-aspirin users.

CONCLUSIONS

Valdecoxib, including above recommended doses, is associated with a significantly lower rate of upper gastrointestinal ulcer complications than therapeutic doses of non-selective non-steroidal anti-inflammatory drugs.

Treatment of painful temporomandibular joints with a cyclooxygenase-2 inhibitor: a randomized placebo-controlled comparison of celecoxib to naproxen

To compare the efficacy and adverse effects of celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, with naproxen, a non-steroidal anti-inflammatory drug, and placebo in the treatment of painful temporomandibular joints (TMJs). In this randomized, double-blind, placebo-controlled trial, 68 subjects with painful TMJs secondary to disc-displacement with reduction, received celecoxib 100 mg twice a day; naproxen, 500 mg twice a day; or placebo for 6 weeks. Subjects were evaluated with standard measures of efficacy: pain intensity measured by visual analogue scale, maximal comfortable mandibular opening, and quality of life (SF-36), at baseline (1 week after discontinuing previous analgesic therapy) and again after 6 weeks of drug treatment. Naproxen significantly reduced the symptoms of painful temporomandibular joint disc-displacement (TMJ DD) with reduction as determined by most efficacy measures. Significant improvement in pain intensity occurred within 3 weeks of treatment, and was sustained throughout the 6-week study. Clinically significant improvement in mandibular range of motion was observed for naproxen compared to celecoxib and placebo. Celecoxib showed slightly better pain reduction than placebo, but was not significantly effective for temporomandibular disorder pain. Celecoxib and naproxen were well tolerated, with similar number of reported adverse effects. Dual COX-1 and COX-2 inhibition with naproxen was demonstrated to be effective for the treatment of painful TMJs, as seen by significant improvement in clinical signs and symptoms of TMJ DD with reduction compared to celecoxib and placebo. Inhibition of both COX isozymes is needed to achieve effective analgesia for this type of musculoskeletal pain.