Effects of inhibition of prostaglandin endoperoxide synthase-2 in chronic gastro-intestinal ulcer models in rats

Comprehensive and critical view on the anti-inflammatory and immunomodulatory role of natural phenolic antioxidants

The immune response encompasses innate and adaptive immunity, each with distinct and specific activities. The innate immune system is constituted by phagocytic cells, macrophages, monocytes and neutrophils, the cascade system, and different classes of receptors such as toll-like receptors that are exploited by the innate immune cells. The adaptive immune system is antigen-specific, encompassing memory lymphocytes and the corresponding specific receptors. Inflammation is understood as an activation of different signaling pathways such as toll-like receptors or nuclear factor kappa-light-chain-enhancer of activated B cells, with an increase in nitric oxide, inflammatory cytokines and chemokines. Increased oxidative stress has been identified as main source of chronic inflammation. Phenolic antioxidants modulate the activities of lymphocytes and macrophages by impacting cytokines and nitric oxide release, exerting anti-inflammatory effect. The nuclear-factor kappa-light-chain-enhancer of activated B cells signaling pathway and the mitogen-activated protein kinase pathway are targeted, alongside an increase in nuclear factor erythroid 2-related factor mediated antioxidant response, triggering the activity of antioxidant enzymes. The inhibitive potential on phospholipase A2, cyclooxygenase and lipoxygenase in the arachidonic acid pathway, and the subsequent reduction in prostaglandin and leukotriene generation, reveals the potential of phenolics as inflammation antagonists. The immunomodulative potential encompasses the capacity to interfere with proinflammatory cytokine synthesis and with the expression of the corresponding genes. A diet rich in antioxidants can result in prevention of inflammation-related pathologies. More investigations are necessary to establish the role of these antioxidants in therapy. The appropriate delivery system and the prooxidant effects exhibited at large doses, or in the presence of heavy metal cations should be regarded.

Phytochemical mediated modulation of COX-3 and NFκB for the management and treatment of arthritis

In this study, we investigated whether zerumbone (ZBN), ellagic acid (ELA) and quercetin (QCT), the plant-derived components, can modulate the role of COX-3 or cytokines liable in arthritic disorder. Initially, the effect of ZBN, ELA, and QCT on inflammatory process was investigated using in-vitro models. In-silico docking and molecular dynamics study of these molecules with respective targets also corroborate with in-vitro studies. Further, the in-vivo anti-arthritic potential of these molecules in Complete Freund's adjuvant (CFA)-induced arthritic rats was confirmed. CFA increases in TNF-α and IL-1β levels in the arthritic control animals were significantly (***p < 0.001) attenuated in the ZBN- and ELA-treated animals. CFA-induced attenuation in IL-10 levels recovered under treatment. Moreover, ELA attenuated CFA-induced upregulation of COX-3 and ZBN downregulated CFA-triggered NFκB expression in arthritic animals. The bonding patterns of zerumbone in the catalytic sites of targets provide a useful hint in designing and developing suitable derivatives that can be used as a potential drug. To our best knowledge, the first time we are reporting the role of COX-3 in the treatment of arthritic disorders which could provide a novel therapeutic approach for the treatment of inflammatory disorders.

Changes in Protease-Activated Receptor and Trypsin-1 Expression Are Involved in the Therapeutic Effect of Mg2+ Supplementation in Type 2 Diabetes-Induced Gastric Injury in Male Adult Rats

Purpose

Gastric inflammation is common and usually severe in patients with type 2 diabetes mellitus (T2DM). Evidence suggests protease-activated receptors (PARs) are a link between inflammation and gastrointestinal dysfunction. Given that magnesium (Mg²⁺) deficiency is a highly prevalent condition in T2DM patients, we assessed the therapeutic role of Mg²⁺ on the factors involved in gastric inflammation in T2DM.

Methods

A rat model of T2DM gastropathy was established using a long-term high-fat diet + a low dose of streptozocin. Twenty-four rats were divided into control, T2DM , T2DM + insulin (positive control), and T2DM + Mg²⁺ groups. At the end of 2-month therapies, changes in the expression of gastric trypsin-1, PAR1, PAR2, PAR3, PI3K/Akt, and COX-2 proteins were measured by western blot. Hematoxylin and eosin and Masson's trichrome staining were used to detect gastric mucosal injury and fibrosis.

Results

The expression of trypsin-1, PAR1, PAR2, PAR3, and COX-2 increased in diabetes, and Mg²⁺/insulin treatment strongly decreased their expression. The PI3K/p-Akt significantly decreased in T2DM, and treatment with Mg²⁺/insulin improved PI3K in T2DM rats. Staining of the gastric antrum tissue of the insulin/Mg²⁺-treated T2DM rats showed a significantly minimal mucosal and fibrotic injury compared with those of rats from the T2DM group.

Conclusion

Mg²⁺ supplement, comparable to insulin, via decreasing PARs expression, mitigating COX-2 activity, and decreasing collagen deposition could exert a potent gastroprotective effect against inflammation, ulcer, and fibrotic development in T2DM patients.

The Role of Resveratrol in Eye Diseases—A Review of the Literature

Resveratrol (3,5,4′-trans-trihydroxystilbene) is a polyphenolic phytoalexin belonging to the stilbene family. It is commonly found in grape skins and seeds, as well as other plant-based foods. Oxidative stress and inflammation play a key role in the initiation and progression of age-related eye disorders (glaucoma, cataracts, diabetic retinopathy, and macular degeneration) that lead to a progressive loss of vision and blindness. Even though the way resveratrol affects the human body and the course of many diseases is still the subject of ongoing scientific research, it has been shown that the broad spectrum of anti-inflammatory and neuroprotective properties of resveratrol has a beneficial effect on eye tissues. In our research, we decided to analyze the current scientific literature on resveratrol, its possible mechanisms of action, and its therapeutic application in order to assess its effectiveness in eye diseases.

Irigenin, a novel lead from Iris confusa for management of Helicobacter pylori infection with selective COX-2 and HpIMPDH inhibitory potential

The development of new natural drugs for Helicobacter pylori (H. pylori) management has recently received significant attention. Iris confusa (I. confusa) was long used for the treatment of bacterial infections and gastritis. This study aimed at evaluating its effect on management of H. pylori infection and exploring its bioactive metabolites. The inhibitory potential of the polar (PF), non-polar (NPF) fractions and the isolated compounds against H. pylori using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay in addition to their cyclooxygenases (COX-1 and COX-2), and nitric oxide (NO) inhibitory activities were assessed. The most biologically active compound was tested for its selective H. pylori inosine-5′-monophosphate dehydrogenase (HpIMPDH) inhibitory potential. Chromatographic purification of PF and NPF allowed isolation of tectoridin, orientin, irigenin, tectorigenin, isoarborinol and stigmasterol. The PF exhibited significant anti-H. pylori (MIC 62.50 µg/mL), COX-1, COX-2 (IC₅₀ of 112.08 ± 0.60 and 47.90 ± 1.50 µg/mL respectively, selectivity index SI of 2.34), and NO (IC₅₀ 47.80 ± 0.89 µg/mL) inhibitory activities, while irigenin was the most potent isolated compound. Irigenin was found to have a promising activity against HpIMPDH enzyme (IC₅₀ of 2.07 ± 1.90 μM) with low activity against human hIMPDH2 (IC₅₀ > 10 μM) than clarithromycin, assuring its selectivity. Overall, I. confusa and its isolated compounds may serve as a potential source of plant-based drugs for H. pylori control. This study scientifically validated the claimed anti-bacterial activity of I. confusa and revealed irigenin potential as a novel lead exhibiting anti H. pylori activity in a first record.

Phyllanthus reticulatus Prevents Ethanol-Induced Gastric Ulcer via Downregulation of IL-8 and TNF-α Levels

The current study aimed to determine the protective effect of P. reticulatus on ethanol-induced gastric ulcer. For this purpose, thirty-six Sprague-Dawley rats were divided into six groups. The first group served as normal control, while, in other five groups, absolute ethanol was used to induce gastric ulcer. Group II served as a diseased group, while groups III, IV, and V were treated with methanol extract, ethyl acetate fraction, and n-hexane fraction, respectively, in a dose of 400 mg/kg bodyweight. Group VI was given omeprazole in a dose 20 mg/kg bodyweight. The stomachs were removed, ulcer score was evaluated, and histopathological examination of gastric lumen was conducted. Total acidity and pH values were determined in gastric juice. TNF-α and IL-8 mRNA expressions levels were determined using the reverse transcription real-time PCR method. The data indicated that P. reticulatus protected against gastric ulcer, which was evident by attenuation of ulcer score. The pretreatment with P. reticulatus raised the gastric pH and improved all evaluated histopathological parameters such as ulcer score, erosion score, hemorrhage score, fibrinoid necrosis score, inflammatory infiltrate score, and edema score. P. reticulatus significantly reduced mRNA expression levels of TNF-α and IL-8. In conclusion, P. reticulatus possess antiulcer property which might be attributed to downregulation of TNF-α and IL-8 expression levels.

Anti-Inflammatory Action and Mechanisms of Resveratrol

Resveratrol (3,4',5-trihy- droxystilbene), a natural phytoalexin polyphenol, exhibits anti-oxidant, anti-inflammatory, and anti-carcinogenic properties. This phytoalexin is well-absorbed and rapidly and extensively metabolized in the body. Inflammation is an adaptive response, which could be triggered by various danger signals, such as invasion by microorganisms or tissue injury. In this review, the anti-inflammatory activity and the mechanism of resveratrol modulates the inflammatory response are examined. Multiple experimental studies that illustrate regulatory mechanisms and the immunomodulatory function of resveratrol both in vivo and in vitro. The data acquired from those studies are discussed.

Olive-Derived Hydroxytyrosol Shows Anti-inflammatory Effect without Gastric Damage in Rats

Hydroxytyrosol (HT) is a simple phenol compound present in olive oil. In a previous in vitro study, we showed that HT downregulated lipopolysaccharide-mediated expression of inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), tumor necrosis factor alpha, and interleukin-1β, resulting in reduced nitric oxide and prostaglandin E₂ production. In the present study, we aimed to determine whether HT suppresses COX-2-induced inflammation in a carrageenan-induced rat paw edema model. Additionally, we compared its activity with those of the selective COX-2 inhibitor, celecoxib for a comparative control, and a representative nonsteroidal anti-inflammatory drug (NSAID), indomethacin for a positive control. HT, celecoxib, and indomethacin significantly suppressed swelling in carrageenan-injected rat paws. Although HT was less effective than celecoxib and indomethacin, it had a delayed onset of action. Moreover, we evaluated whether HT aggravates gastric damage, which is a typical adverse effect associated with NSAIDs and COX-2 inhibitors under low dose aspirin (LDA) treatment, in an aspirin-induced gastric damage rat model. Unlike celecoxib and indomethacin, HT did not cause gastric damage when co-administered with aspirin. Our results indicate that HT exerts a delayed but sustained anti-inflammatory effect against COX-2-mediated inflammation. Finally, the combination of short-acting conventional anti-inflammatory drugs and long-acting HT can be considered a new, safe, and effective anti-inflammatory treatment modality even when continuously administered for a long period under LDA treatment.

NSAID-induced injury of gastric epithelial cells is reversible: roles of mitochondria, AMP kinase, NGF, and PGE2

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (DFN) and indomethacin (INDO) are extensively used worldwide. Their main side effects are injury of the gastrointestinal tract, including erosions, ulcers, and bleeding. Since gastric epithelial cells (GEPCs) are crucial for mucosal defense and are the major target of injury, we examined the extent to which DFN- and INDO-induced GEPC injury can be reversed by nerve growth factor (NGF), 16,16 dimethyl prostaglandin E2 (dmPGE2), and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), the pharmacological activator of the metabolic sensor AMP kinase (AMPK). Cultured normal rat gastric mucosal epithelial (RGM1) cells were treated with PBS (control), NGF, dmPGE2, AICAR, and/or NSAID (DFN or INDO) for 1-4 h. We examined cell injury by confocal microscopy, cell death/survival using calcein AM, mitochondrial membrane potential using MitoTracker, and phosphorylation of AMPK by Western blotting. DFN and INDO treatment of RGM1 cells for 2 h decreased mitochondrial membrane potential and cell viability. NGF posttreatment (initiated 1 or 2 h after DFN or INDO) reversed the dissipation of mitochondrial membrane potential and cell injury caused by DFN and INDO and increased cell viability versus cells treated for 4 h with NSAID alone. Pretreatment with dmPGE2 and AICAR significantly protected these cells from DFN- and INDO-induced injury, whereas dmPGE2 and AICAR posttreatment (initiated 1 h after NSAID treatment) reversed cell injury and significantly increased cell viability and rescued the cells from NSAID-induced mitochondrial membrane potential reduction. DFN and INDO induce extensive mitochondrial injury and GEPC death, which can be significantly reversed by NGF, dmPGE2, and AICAR.NEW & NOTEWORTHY This study demonstrated that mitochondria are key targets of diclofenac- and indomethacin-induced injury of gastric epithelial cells and that diclofenac and indomethacin injury can be prevented and, importantly, also reversed by treatment with nerve growth factor, 16,16 dimethyl prostaglandin E2, and 5-aminoimidazole-4-carboxamide ribonucleotide.

Secretome from hypoxia-conditioned adipose-derived mesenchymal stem cells promotes the healing of gastric mucosal injury in a rodent model

Studies have indicated that the definitive engraftment and transdifferentiation potential of stem cells do not seem crucial for its property of tissue repair. Our previous study showed that transplantation of adipose-derived mesenchymal stem cells (ADMSCs) enhanced the healing of sutured gastric perforation. This study aimed to investigate the paracrine role of ADMSCs in the experimental gastric mucosal injury. Normoxia-conditioned medium (Nor CM) and hypoxia (HPO) CM were obtained after culturing ADMSCs in 20% O₂ and 5% O₂ for 48h. Cell migration, proliferation, viability, and angiogenesis in vitro were significantly enhanced upon incubation with CM, especially the HPO CM. Experiments in vivo using a rodent model of gastric ulcer demonstrated that HPO CM treatment significantly accelerated wound healing by suppressing inflammation and promoting neovascularization and re-epithelization. Meanwhile, the infusion of HPO CM activated the COX₂-PGE₂ axis both in vitro and in vivo. And the upregulation of COX₂ was further dependent on the activation of ErK1/2-MAPK pathway. In addition, vascular endothelial growth factor, tissue inhibitors of metalloproteinases-1, and chemokine (C-C motif) ligand 20 (CCL-20) were analyzed as being highly abundant factors secreted by ADMSCs under hypoxic condition. Notably, the blockade of CCL-20 abrogated the HPO CM-induced COX₂ signaling in the primary gastric mucosal epithelial cells, while incubation with recombinant CCL-20 increased the expression of COX₂. In conclusion, the secretome from hypoxia-conditioned ADMSCs facilitates the repair of gastric mucosal injury through the enhancement of angiogenesis and re-epithelization, as well as the activation of COX₂-PGE₂ axis with a paracrine activity involving CCL-20 factor.

Comparison between tocotrienol and omeprazole on gastric growth factors in stress-exposed rats

AIM

To investigate and compare the effects of tocotrienol and omeprazole on gastric growth factors in rats exposed to water-immersion restraint stress (WIRS).

METHODS

Twenty-eight male Wistar rats were randomly assigned to four groups of seven rats. The two control groups were administered vitamin-free palm oil (vehicle) and the two treatment groups were given omeprazole (20 mg/kg) or tocotrienol (60 mg/kg) by oral gavage. After 28 d of treatment, rats from one control group and both treated groups were subjected to WIRS one time for 3.5 h. Gastric lesions were measured and gastric tissues were obtained to measure vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), and transforming growth factor-alpha (TGF-α) mRNA expression.

RESULTS

Rats exposed to WIRS for 3.5 h demonstrated the presence of considerable ulcers in the form of gastric erosion. The lesion index in the stressed control (S) group was increased (P < 0.001) compared to the tocotrienol treated and omeprazole treated groups. Stress led to a decrease in gastric VEGF (P < 0.001), bFGF (P < 0.001) and TGF-α (P < 0.001) mRNA levels and caused an increase in EGF mRNA (P < 0.001) that was statistically significant compared to the non-stressed control group. Although both treatment agents exerted similar ulcer reducing ability, only treatment with tocotrienol led to increased expression of VEGF (P = 0.008), bFGF (P = 0.001) and TGF-α (P = 0.002) mRNA.

CONCLUSION

Tocotrienol provides gastroprotective effects in WIRS-induced ulcers. Compared to omeprazole, tocotrienol exerts a similar protective effect, albeit through multiple mechanisms of protection, particularly through up-regulation of growth factors that assist in repair of gastric tissue injuries.

Gastrointestinal Inflammation: A Central Component of Mucosal Defense and Repair

The mucosal layer of the gastrointestinal (GI) tract is able to resist digestion by the endogenous substances that we secrete to digest foodstuffs. So-called “mucosal defense” is multifactorial and can be modulated by a wide range of substances, many of which are classically regarded as inflammatory mediators. Damage to the GI mucosa, and its subsequent repair, are also modulated by various inflammatory mediators. In this article, we provide a review of some of the key Inflammatory mediators that modulate GI mucosal defense, Injury, and repair. Among the mediators discussed are nitric oxide, polyamines, the elcosanolds (prostaglandins and II-poxlns), protease-activated receptors, and cytokines. Many of these endogenous factors, or the enzymes involved in their synthesis, are considered potential therapeutic targets for the treatment of diseases of the digestive tract that are characterized by Inflammation and ulceration.

The low molecular weight fraction of human serum albumin upregulates COX2, prostaglandin E2, and prostaglandin D2 under inflammatory conditions in osteoarthritic knee synovial fibroblasts

Background

The ability to decrease inflammation and promote healing is important in the intervention and management of a variety of disease states, including osteoarthritis of the knee (OAK). Even though cyclooxygenase 2 (COX2) has an established pro-inflammatory role, evidence suggests it is also critical to the resolution that occurs after the initial activation phase of the immune response. In this study, we investigated the effects of the low molecular weight fraction of 5% human serum albumin (LMWF-5A), an agent that has proven to decrease pain and improve function in OAK patients after intra-articular injection, on the expression of COX2 and its downstream products, prostaglandins (PGs).

Methods

Fibroblast-like synoviocytes from the synovial membrane of OAK patients were treated with LMWF-5A or saline as a control with or without the addition of interleukin-1β (IL-1β) or tumor necrosis factor α (TNFα) to elicit an inflammatory response. Cells were harvested for RNA and protein at 2, 4, 8, 12, and 24 h, and media was collected at 24 h for analysis of secreted products. COX2 mRNA expression was determined by qPCR, and COX2 protein expression was determined by western blot analysis. Levels of prostaglandin E2 (PGE2) and prostaglandin D2 (PGD2) in the media were quantified by competitive ELISA.

Results

In the presence of either IL-1β or TNFα, LMWF-5A increased the expression of both COX2 mRNA and protein, and this increase was significant compared to that observed with IL-1β- or TNFα-stimulated, saline-treated cells. Downstream of COX2, the levels of PGE2 were increased only in TNFα-stimulated, LMWF-5A-treated cells; however, in both IL-1β- and TNFα-stimulated cells, LMWF-5A increased the release of the anti-inflammatory prostaglandin PGD2.

Conclusion

LMWF-5A appears to trigger increased anti-inflammatory PG signaling, and this may be a primary component of its therapeutic mode of action in the treatment of OAK.

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Proposed mechanism of action for biologic drug to treat osteoarthritis of the knee.

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LMWF-5A affects the COX2 pathway in primary synoviocytes from osteoarthritic knees.

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LMWF-5A may promote resolution of inflammation, healing, and cartilage regeneration.

The mixture of Salvia miltiorrhiza-Carthamus tinctorius (Danhong injection) alleviates low-dose aspirin induced gastric mucosal damage in rats

BACKGROUND

Danhong injection (DHI) is quite often used in combination with low-dose aspirin (ASA, 75-325mg daily) in clinic, particularly for the treatment of cardiovascular diseases. Exploring their interaction profile is of great clinical importance.

PURPOSE

The current study aims to explore the interaction between DHI and low-dose ASA in rats.

METHODS

Sixty four rats were randomly divided into eight groups. Stomach and other four vital organs were collected for histological evaluation. Organs which exhibited histological changes were selected for a further study to evaluate the damage score and mode of action. We tested the protective effect of DHI on gastric mucosal damage in different regimes of administration. COX activity, gastric mucus secretion, pepsin activity, antioxidant activity and ROS level were assayed to reflect the protective effect of DHI on gastric mucosal damage induced by ASA.

RESULTS

Stomach was the target organ of interaction when DHI and ASA were used in combination. DHI alleviated gastric mucosal damage by 55.8% when DHI was injected before ASA (Group E) and by 53.5% when DHI was injected 2h after ASA administration (Group F). Additionally, if DHI treatment was appended to the long-term administration of ASA, DHI still decreased the gastric mucosal damage score in 52.0% from 2.50 to 1.20. DHI improved gastric mucus secretion, as well as decreased pepsin activity to maintain the integrity of gastric mucosal barrier (P<0.05). Furthermore, DHI recovered antioxidant activity which was impaired by ASA. In details, DHI decreased gastric mucosal ROS level, increased CAT, GSH-Px and SOD activity, and reduced MDA concentration (P<0.05). When ASA (71.9µM) was used in combination with DHI (23-fold dilution, presented in terms of concentrations of DSS, PA, SaD RA, SaB and SaA were 6.45-6.92, 1.10-1.14, 1.09-1.10, 0.86-0.90, 16.76-19.38 and 1.83-1.94µg/ml, respectively) in vitro, the inhibition rate of ASA increased from 38.6% (ASA alone) to 62.8% (ASA-DHI) on COX-1 and from 28.9% (ASA alone) to 38.8% (ASA-DHI) on COX-2 (P<0.05). DHI strengthened the inhibition activity of ASA on both COX-1 and COX-2, which showed that DHI alleviated ASA induced gastric mucosal damage but not antagonized anti-COX effect of ASA.

CONCLUSIONS

Gastric protective benefits were clearly produced when DHI and ASA were used in combination, which provided rational guidance for clinical combined application of DHI and ASA.

Pharmacokinetics and pharmacodynamics of three formulations of firocoxib in healthy horses

The objectives of this study were to compare the pharmacokinetics and COX selectivity of three commercially available formulations of firocoxib in the horse. Six healthy adult horses were administered a single dose of 57 mg intravenous, oral paste or oral tablet firocoxib in a three-way, randomized, crossover design. Blood was collected at predetermined times for PGE2 and TXB2 concentrations, as well as plasma drug concentrations. Similar to other reports, firocoxib exhibited a long elimination half-life (31.07 ± 10.64 h), a large volume of distribution (1.81 ± 0.59L/kg), and a slow clearance (42.61 ± 11.28 mL/h/kg). Comparison of the oral formulations revealed a higher Cmax , shorter Tmax , and greater AUC for the paste compared to the tablet. Bioavailability was 112% and 88% for the paste and tablet, respectively. Maximum inhibition of PGE2 was 83.76% for the I.V. formulation, 52.95% for the oral paste formulation, and 46.22% for the oral tablet formulation. Pharmacodynamic modeling suggests an IC50 of approximately 27 ng/mL and an IC80 of 108 ng/ mL for COX2 inhibition. Inhibition of TXB2 production was not detected. This study indicates a lack of bioequivalence between the oral formulations of firocoxib when administered as a single dose to healthy horses.

Cyclooxygenase-1 and -2: molecular targets for cervical neoplasia

Cyclooxygenase (COX) is a key enzyme responsible for inflammation, converting arachidonic acid to prostaglandin and thromboxane. COX has at least two isoforms, COX-1 and COX-2. While COX-1 is constitutively expressed in most tissues for maintaining physiologic homeostasis, COX-2 is induced by inflammatory stimuli including cytokines and growth factors. Many studies have shown that COX-2 contributes to cancer development and progression in various types of malignancy including cervical cancer. Human papillomavirus, a necessary cause of cervical cancer, induces COX-2 expression via E5, E6 and E7 oncoproteins, which leads to prostaglandin E2 increase and the loss of E-cadherin, promotes cell proliferation and production of vascular endothelial growth factor. It is strongly suggested that COX-2 is associated with cancer development and progression such as lymph node metastasis. Many studies have suggested that non-selective COX-2 inhibitors such as non-steroidal anti-inflammatory drugs (NSAIDs), and selective COX-2 inhibitors might show anti-cancer activity in COX-2 -dependent and -independent manners. Two phase II trials for patients with locally advanced cervical cancer showed that celecoxib increased toxicities associated with radiotherapy. Contrary to these discouraging results, two phase II clinical trials, using rofecoxib and celecoxib, demonstrated the promising chemopreventive effect for patients with cervical intraepithelial neoplasia 2 or 3. However, these agents cause a rare, but serious, cardiovascular complication in spite of gastrointestinal protection in comparison with NSAIDs. Recent pharmacogenomic studies have showed that the new strategy for overcoming the limitation in clinical application of COX-2 inhibitors shed light on the use of them as a chemopreventive method.

Mechanisms, prevention and clinical implications of nonsteroidal anti-inflammatory drug-enteropathy

This article reviews the latest developments in understanding the pathogenesis, detection and treatment of small intestinal damage and bleeding caused by nonsteroidal anti-inflammatory drugs (NSAIDs). With improvements in the detection of NSAID-induced damage in the small intestine, it is now clear that this injury and the associated bleeding occurs more frequently than that occurring in the stomach and duodenum, and can also be regarded as more dangerous. However, there are no proven-effective therapies for NSAID-enteropathy, and detection remains a challenge, particularly because of the poor correlation between tissue injury and symptoms. Moreover, recent studies suggest that commonly used drugs for protecting the upper gastrointestinal tract (i.e., proton pump inhibitors) can significantly worsen NSAID-induced damage in the small intestine. The pathogenesis of NSAID-enteropathy is complex, but studies in animal models are shedding light on the key factors that contribute to ulceration and bleeding, and are providing clues to the development of effective therapies and prevention strategies. Novel NSAIDs that do not cause small intestinal damage in animal models offer hope for a solution to this serious adverse effect of one of the most widely used classes of drugs.

Nitric oxide-releasing aspirin but not conventional aspirin improves healing of experimental colitis

AIM: To determine the effect of non-selective cyclooxygenase (COX) inhibitors, selective COX-2 inhibitors and nitric oxide (NO)-releasing aspirin in the healing of ulcerative colitis.

METHODS: Rats with 2,4,6 trinitrobenzenesulfon-ic acid (TNBS)-induced colitis received intragastric (ig) treatment with vehicle, aspirin (ASA) (a non-selective COX inhibitor), celecoxib (a selective COX-2 inhibitor) or NO-releasing ASA for a period of ten days. The area of colonic lesions, colonic blood flow (CBF), myeloperoxidase (MPO) activity and expression of proinflammatory markers COX-2, inducible form of nitric oxide synthase (iNOS), IL-1β and tumor necrosis factor (TNF)-α were assessed. The effects of glyceryl trinitrate (GTN), a NO donor, and 2-(4-carboxyphenyl)-4,5-dihydro-4,4,5,5-​tetramethyl-1H-imidazolyl-1-oxy-3-oxide, onopotassium salt (carboxy-PTIO), a NO scavenger, administered without and with ASA or NO-ASA, and the involvement of capsaicin-sensitive afferent nerves in the mechanism of healing the experimental colitis was also determined.

RESULTS: Rats with colitis developed macroscopic and microscopic colonic lesions accompanied by a significant decrease in the CBF, a significant rise in colonic weight, MPO activity and plasma IL-1β and TNF-α levels. These effects were aggravated by ASA and 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC-560), but not celecoxib and counteracted by concurrent treatment with a synthetic prostaglandin E₂ (PGE₂) analog. Treatment with NO-ASA dose-dependently accelerated colonic healing followed by a rise in plasma NO_x content and CBF, suppression of MPO and downregulation of COX-2, iNOS, IL-1β and TNF-α mRNAs. Treatment with GTN, the NO donor, significantly inhibited the ASA-induced colonic lesions and increased CBF, while carboxy-PTIO or capsaicin-denervation counteracted the NO-ASA-induced improvement of colonic healing and the accompanying increase in the CBF. These effects were restored by co-treatment with calcitonin gene related peptide (CGRP) and NO-ASA in capsaicin-denervated animals.

CONCLUSION: NO-releasing ASA, in contrast to ASA, COX-1 inhibitors, and SC-560, accelerated the healing of colitis via a mechanism involving NO mediated improvement of microcirculation and activation of sensory nerves releasing CGRP.

The influence of chronic eicosanoid biosynthesis inhibition on life history of the greater waxmoth, Galleria mellonella and its ectoparasitoid, Bracon hebetor

Eicosanoids are oxygenated metabolites of three C20 polyunsaturated fatty acids, mainly arachidonic acid (AA; 20:4n-6), but also 20:3n-6 and 20:5n-3. Aside from their importance in biomedicine, eicosanoids act in invertebrate biology. Prostaglandins (PGs) influence salt and water transport physiology in insect rectal epithelia and in Malpighian tubules. PGs also influence a few insect behaviors, including releasing oviposition behavior and behavioral fever. Eicosanoids act in ovarian development and in insect immunity. Because eicosanoids act in several areas of insect biology, we posed the hypothesis that chronic inhibition of eicosanoid biosynthesis, in the absence of microbial challenge, can influence insect life table parameters, including developmental time, survival, adult longevity and parasitoid fecundity. Here we report that inhibiting eicosanoid biosynthesis throughout the larval life exerted minor influences on some life table parameters of the greater wax moth, Galleria mellonella and its ectoparasitoid, Bracon hebetor, however, the inhibitors strongly reduced the production and hatchability of the parasitoids' eggs. The significance of the work relates to the potentials of understanding and targeting eicosanoid systems as a platform for developing new technologies of insect pest management. As seen here, the impact of targeting eicosanoid systems is seen in crucial moments of insect life histories, such as reproduction or immune challenge rather than in overall larval development.

Influence of cyclodextrin complexation with NSAIDs on NSAID/cold stress-induced gastric ulceration in rats

The aim of this work was to study the ability of beta-cyclodextrin (beta-CD) or hydroxypropyl beta-cyclodextrin (HP-beta-CD) to ameliorate the induction of gastric ulcers by a nonsteroidal anti-inflammatory drug, indomethacin or piroxicam, in rats exposed to restraint and hypothermic stress at 4 degrees C. Using oral gavage, rats fasted for 72 h were administered the equivalent of a 100 mg/kg dose of the assigned drug, alone or with the designated cyclodextrin (CD). The rats were placed in suitable rodent restrainers and then placed inside a ventilated refrigerator maintained at a temperature of 4 degrees C. Six hours later, each animal was removed, anaesthetized with ether, and the abdomen opened. Each stomach was removed, opened along the greater curvature and gently rinsed with isotonic saline solution. The induced gastric ulcers were examined and assessed with the help of a 10x binocular magnifier. Pronounced and marked gastric ulceration with complete loss of the mucosa, extensive deposition of fibrin and dense neutrophilic infiltrate were observed in rats treated with each of the drugs alone. Treatment with indomethacin or piroxicam alone induced ulcer indices of 26 +/- 2.3 or 14 +/- 1.8, respectively. However, beta-CD and HP-beta-CD each significantly suppressed ulceration due to restraint and cold stress. Rats treated with indomethacin or piroxicam in the presence of either beta-CD or HP-beta-CD exhibited normal tissues. Therefore, beta-CD and HP-beta-CD act as protective agents against gastrointestinal disorders produced by restraint and cold stress, even with the added stress from administration of either indomethacin or piroxicam.

Expression of cyclooxygenase isoforms in ulcerated tissues of the nonglandular portion of the stomach in horses

OBJECTIVE

To characterize the expression of the cyclooxygenase (COX)-1 and COX-2 isoforms in naturally occurring ulcers of the nonglandular portion of the stomach in horses. SPECIMEN POPULATION: 38 specimens from ulcerated stomachs and 10 specimens from healthy stomachs.

PROCEDURES

Specimens were collected at an abbatoir; for each specimen of squamous gastric mucosa, 1 portion was fixed in neutral-buffered 10% formalin for immunohistochemical analysis and another was frozen at -70 degrees C for immunoblotting analysis. Immunoreactivity to 2 antibodies, MF241 (selective for COX-1) and MF243 (selective for COX-2), was evaluated by a veterinary pathologist using a scoring system. Expression of COX-1 and COX-2 was confirmed by use of immunoblotting analyses.

RESULTS

All specimens from healthy stomachs strongly expressed COX-1, whereas only 2 of 10 expressed COX-2. The expression of both isoforms varied greatly in the ulcerated mucosal specimens. Expression of COX-1 was significantly lower and expression of COX-2 was significantly higher in ulcerated versus healthy specimens.

CONCLUSIONS AND CLINICAL RELEVANCE

Increased expression of COX-2 in gastric ulcers of the squamous portion of the stomach in horses suggested a role for this enzyme in gastric ulcer healing.

In vivo models to study cyclooxygenase products in health and disease: Introduction to Part III

Inflammation is a primordial response that protects against injury and infection with the ultimate aim of restoring damaged tissue to its normal physiological functioning state. In fact, our well-being and survival depends upon its efficiency and carefully balanced control and to which we are alerted in the form of pain, swelling, and redness. Prostaglandins (PG), lipids derived from arachidonic acid metabolism by the enzyme cyclooxygenase, are historically one of the most well-studied mediators of the acute inflammatory response; so much so that their inhibition by so-called non-steroidal anti-inflammatory drugs (NSAIDs) has been the mainstay for the treatment of diseases where inflammation becomes a pathological driving force. However, while NSAIDs relieve the symptoms of dyregulated inflammatory responses, they do not cure the underlying disease and have associated gastrointestinal and renal toxicity. These side effects arose from inhibiting constitutively expressed, protective cyclooxygenase (COX-1). Finding another inducible COX (COX-2) expressed only at sites of injury provided a new era in inflammation research and a new era in treating inflammation-driven diseases. The hope was that high levels of COX-2 expression at sites of pain and tissue injury drove that disease process and that its inhibition would possess all the benefits of traditional NSAIDS without the side effects that arise from the inhibition of protective COX-1. However, by discussing data derived from experimental disease models of acute inflammation, in this chapter we suggest that delineating between the roles of COX-1 and COX-2 might not be as simple as once thought. We provide examples of data where a pathological role for COX-1 is evident and where COX-2 is clearly protective.

COX-2 inhibitors are contraindicated for treatment of combined injury

Casualties of radiation dispersal devices, nuclear detonation or major ionizing radiation accidents, in addition to radiation exposure, may sustain physical and/or thermal trauma. Radiation exposure plus additional tissue trauma is known as combined injury. There are no definitive therapeutic agents. Cyclooxygenase-2 (COX-2), an inducible enzyme expressed in pathological disorders and radiation injury, plays an important role in inflammation and the production of cytokines and prostaglandin E(2) (PGE(2)) and could therefore affect the outcome for victims of combined injury. The COX-2 inhibitors celecoxib and meloxicam were evaluated for their therapeutic value against combined injury in mice. In survival studies, the COX-2 inhibitors had no beneficial effect on 30-day survival, wound healing or body weight gain after radiation injury alone or after combined injury. Meloxicam accelerated death in both wounded and combined injury mice. These drugs also induced severe hepatic toxicity, exaggerated inflammatory processes, and did not enhance hematopoietic cell regeneration. This study points to potential contraindications for use of COX-2 inhibitors in patients undergoing therapy for radiation injury and combined injury.

Characterization of mechanisms underlying the effects of esomeprazole on the impairment of gastric ulcer healing with addition of NSAID treatment

BACKGROUND

The efficacy of proton pump inhibitors in patients at high risk of gastrointestinal injury receiving non-steroidal anti-inflammatory drugs is currently debated.

AIMS

To evaluate the effects of esomeprazole on the impairment of gastric ulcer healing associated with non-steroidal anti-inflammatory drug treatment.

METHODS

Gastric ulcers were induced in rats by acetic acid. Four days later, animals were treated daily with equivalent acid-inhibiting doses of esomeprazole or famotidine, alone or in combination with indomethacin. At day 3 or 7 of treatment, ulcerated tissues were processed to assess: ulcer area; malondialdehyde; prostaglandin E(2); nuclear factor-kB; proliferating cell nuclear antigen and caspase-3 (Western blot).

RESULTS

In indomethacin-treated animals, esomeprazole was more effective than famotidine or the antioxidant melatonin in promoting ulcer healing. Malondialdehyde levels were increased by indomethacin, and this effect was counteracted by esomeprazole, but not famotidine. Esomeprazole and famotidine, given alone or in combination with indomethacin, increased proliferating cell nuclear antigen expression. Increased levels of prostaglandin E(2) were detected in ulcerated tissues. Ulcer prostaglandin E(2) production was reduced by indomethacin, alone or in combination with esomeprazole or famotidine, while it was enhanced when esomeprazole or famotidine were tested alone. The activation of caspase-3 was induced by indomethacin, and this effect was prevented by esomeprazole, but not famotidine. In the presence of indomethacin, esomeprazole, but not famotidine, enhanced nuclear factor-kB activation in gastric ulcers.

CONCLUSIONS

Esomeprazole counteracts the detrimental action of indomethacin on ulcer repair through both acid-dependent and acid-independent effects. The acid-independent actions are related to decrease in tissue oxidation and apoptosis and to enhancement of nuclear factor-kB activation.

In vitro and in vivo pharmacological role of TLQP-21, a VGF-derived peptide, in the regulation of rat gastric motor functions

BACKGROUND AND PURPOSE

Vgf gene expression has been detected in various endocrine and neuronal cells in the gastrointestinal tract. In this study we investigated the pharmacological activity of different VGF-derived peptides. Among these, TLQP-21, corresponding to the 556-576 fragment of the protein was the unique active peptide, and its pharmacological profile was further studied.

EXPERIMENTAL APPROACH

The effects of TLQP-21 were examined in vitro by smooth muscle contraction in isolated preparations from the rat gastrointestinal tract and, in vivo, by assessing gastric emptying in rats. Rat stomach tissues were also processed for immunohistochemical and biochemical characterization.

KEY RESULTS

In rat longitudinal forestomach strips, TLQP-21 (100 nmol x L(-1)-10 micromol x L(-1)) concentration-dependently induced muscle contraction (in female rats, EC(50) = 0.47 micromol.L(-1), E(max): 85.7 +/- 7.9 and in male rats, 0.87 micromol x L(-1), E(max): 33.4 +/- 5.3; n = 8), by release of prostaglandin (PG)E(2) and PGF(2a) from the mucosal layer. This effect was significantly antagonized by indomethacin and selective inhibitors of either cyclooxygenase-1 (S560) or cyclooxygenase-2 (NS398). Immunostaining and biochemical studies confirmed the presence of VGF in the gastric neuronal cells. TLQP-21, injected i.c.v. (2-32 nmol per rat), significantly decreased gastric emptying by about 40%. This effect was significantly (P < 0.05) blocked by i.c.v. injection of indomethacin, suggesting that, also in vivo, this peptide acts in the brain stimulating PG release.

CONCLUSIONS AND IMPLICATIONS

The present results demonstrate that this VGF-derived peptide plays a central and local role in the regulation of rat gastric motor functions.

The effect of parecoxib and indometacin on tendon-to-bone healing in a bone tunnel

Conventional non-steroidal anti-inflammatory drugs (NSAIDs) and newer specific cyclo-oxygenase-2 (cox-2) inhibitors are commonly used in musculoskeletal trauma and orthopaedic surgery to reduce the inflammatory response and pain. These drugs have been reported to impair bone metabolism. In reconstruction of the anterior cruciate ligament the hamstring tendons are mainly used as the graft of choice, and a prerequisite for good results is healing of the tendons in the bone tunnel. Many of these patients are routinely given NSAIDs or cox-2 inhibitors, although no studies have elucidated the effects of these drugs on tendon healing in the bone tunnel.

In our study 60 female Wistar rats were randomly allocated into three groups of 20. One received parecoxib, one indometacin and one acted as a control. In all the rats the tendo-Achillis was released proximally from the calf muscles. It was then pulled through a drill hole in the distal tibia and sutured anteriorly. The rats were given parecoxib, indometacin or saline intraperitoneally twice daily for seven days. After 14 days the tendon/bone-tunnel interface was subjected to mechanical testing.

Significantly lower maximum pull-out strength (p < 0.001), energy absorption (p < 0.001) and stiffness (p = 0.035) were found in rats given parecoxib and indometacin compared with the control group, most pronounced with parecoxib.

Mechanism of action of celecoxib on normal and acid-challenged gastric mucosa

Selective COX-2 inhibitor, celecoxib, delays the healing of gastric ulcers by inhibiting prostaglandins synthesis. Therefore, the effect of celecoxib on normal and acid-challenged gastric mucosa was studied. Wistar rats were distributed into four groups: group-1 (vehicle treated), group-2 (celecoxib treated), group-3 (given 0.6N HCl) and group-4 (HCl+celecoxib treated). The gastric mucosa was assessed histopathologically and by evaluating gastric adherent mucus. To assess the role of oxidative stress, the levels of free radicals and antioxidants were measured. The histopathological examination showed mild inflammation in group-2, moderate inflammation in group-3 and severe inflammation in group-4. The results showed an increase in malondialdehyde and a decrease in gastric adherent mucus, nitrite, reactive thiols and glutathione in groups-2-4 as compared to control group. Activity of superoxide dismutase, catalase and glutathione-s-transferase was increased in all the groups except the group-1. The present study suggested that celecoxib aggravated the gastric damage caused by acid which may be mediated by altering the balance between free radicals and antioxidants.

Prostaglandins, NSAIDs, and gastric mucosal protection: why doesn't the stomach digest itself?

Except in rare cases, the stomach can withstand exposure to highly concentrated hydrochloric acid, refluxed bile salts, alcohol, and foodstuffs with a wide range of temperatures and osmolarity. This is attributed to a number of physiological responses by the mucosal lining to potentially harmful luminal agents, and to an ability to rapidly repair damage when it does occur. Since the discovery in 1971 that prostaglandin synthesis could be blocked by aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), there has been great interest in the contribution of prostaglandins to gastric mucosal defense. Prostaglandins modulate virtually every aspect of mucosal defense, and the importance of this contribution is evident by the increased susceptibility of the stomach to injury following ingestion of an NSAID. With chronic ingestion of these drugs, the development of ulcers in the stomach is a significant clinical concern. Research over the past two decades has helped to identify some of the key events triggered by NSAIDs that contribute to ulcer formation and/or impair ulcer healing. Recent research has also highlighted the fact that the protective functions of prostaglandins in the stomach can be carried out by other mediators, in particular the gaseous mediators nitric oxide and hydrogen sulfide. Better understanding of the mechanisms through which the stomach is able to resist injury in the presence of luminal irritants is helping to drive the development of safer anti-inflammatory drugs, and therapies to accelerate and improve the quality of ulcer healing.

Effects of pantoprazole on ulcer healing delay associated with NSAID treatment

Nonsteroidal anti-inflammatory drugs delay gastric ulcer healing, and the ability of proton pump inhibitors to counteract this detrimental effect is debated. This study evaluates the effects of pantoprazole on experimental gastric ulcer healing in the presence of indomethacin. Rats with acetic-acid-induced gastric ulcers were orally treated for 3 or 7 days with pantoprazole (15 micromol/kg/day) or famotidine (20 micromol/kg/day), alone or in combination with indomethacin (3 micromol/kg/day). Ulcerated tissues were processed to assess ulcer area, malondialdehyde, proliferating cell nuclear antigen (PCNA) and cleaved caspase-3. Experiments on pylorus-ligated rats indicated that pantoprazole and famotidine were employed at equivalent inhibitory doses on gastric acid secretion (-67.9% and -64.5%, respectively). Indomethacin delayed ulcer healing both at days 3 and 7 (+22 and +35 mm(2) vs control ulcer, respectively). At day 3, pantoprazole was more effective than famotidine in promoting ulcer healing in indomethacin-treated animals (-53.6 and -31.6 mm(2) vs indomethacin, respectively). Malondialdehyde levels and caspase-3 activation in ulcers were increased by indomethacin (+79% and +3.7 folds vs control ulcer, respectively), and these effects were counteracted by pantoprazole (-77.9% and -3.5 folds vs indomethacin, respectively), but not famotidine. Increments of ulcer PCNA expression (+2.5 folds vs normal) were enhanced further by pantoprazole or famotidine, alone or in combination with indomethacin (+8.6 and +10.3 folds vs normal, respectively). Similar results were obtained after 7-day treatments of ulcerated animals with test drugs. It is concluded that, along with acid suppression, pantoprazole exerts acid-independent effects on ulcer healing, which can be ascribed to a decrease in tissue oxidation and apoptosis.

A vascular endothelial growth factor mimetic accelerates gastric ulcer healing in an iNOS-dependent manner

Angiogenesis is crucial to all types of wound healing, including gastric ulcer healing. The most potent promoter of angiogenesis is vascular endothelial growth factor (VEGF). We hypothesized that a 15-amino acid peptide designed to mimic the angiogenic action of VEGF would accelerate gastric ulcer healing. Gastric ulcers were induced in mice by serosal application of acetic acid. Treatment with the VEGF mimetic accelerated gastric ulcer healing when administered orally or intraperitoneally, at a dose of 50 ng/kg or greater. Such healing was not observed when the reverse sequence pentadecapeptide or the full-length VEGF protein was administered. Contrary to our hypothesis, the VEGF mimetic did not significantly increase angiogenesis in the ulcerated stomach. The enhancement of ulcer healing by the VEGF mimetic occurred independently of cyclooxygenase-2 (COX-2) activity but was blocked by inhibitors of inducible nitric oxide synthase (iNOS). These results demonstrate that a VEGF mimetic is a potent stimulus for gastric ulcer healing, even when given orally. The effects of the mimetic were independent of stimulatory effects on angiogenesis and COX-2 activity but were dependent on iNOS-derived NO production.

Gastric mucosal defense and cytoprotection: bench to bedside

The gastric mucosa maintains structural integrity and function despite continuous exposure to noxious factors, including 0.1 mol/L HCl and pepsin, that are capable of digesting tissue. Under normal conditions, mucosal integrity is maintained by defense mechanisms, which include preepithelial factors (mucus-bicarbonate-phospholipid "barrier"), an epithelial "barrier" (surface epithelial cells connected by tight junctions and generating bicarbonate, mucus, phospholipids, trefoil peptides, prostaglandins (PGs), and heat shock proteins), continuous cell renewal accomplished by proliferation of progenitor cells (regulated by growth factors, PGE(2) and survivin), continuous blood flow through mucosal microvessels, an endothelial "barrier," sensory innervation, and generation of PGs and nitric oxide. Mucosal injury may occur when noxious factors "overwhelm" an intact mucosal defense or when the mucosal defense is impaired. We review basic components of gastric mucosal defense and discuss conditions in which mucosal injury is directly related to impairment in mucosal defense, focusing on disorders with important clinical sequelae: nonsteroidal anti-inflammatory drug (NSAID)-associated injury, which is primarily related to inhibition of cyclooxygenase (COX)-mediated PG synthesis, and stress-related mucosal disease (SRMD), which occurs with local ischemia. The annual incidence of NSAID-associated upper gastrointestinal (GI) complications such as bleeding is approximately 1%-1.5%; and reductions in these complications have been demonstrated with misoprostol, proton pump inhibitors (PPIs) (only documented in high-risk patients), and COX-2 selective inhibitors. Clinically significant bleeding from SRMD is relatively uncommon with modern intensive care. Pharmacologic therapy with antisecretory drugs may be used in high-risk patients (eg, mechanical ventilation >or=48 hours), although the absolute risk reduction is small, and a decrease in mortality is not documented.

The effect of age on prostaglandin-synthesizing enzymes in the development of gingivitis

BACKGROUND AND OBJECTIVE

The aim of this study was to identify the expression of cyclooxygenase-1, cyclooxygenase-2, cyclooxygenase-3, and microsomal prostaglandin E synthase-1 in young and elderly subjects.

MATERIAL AND METHODS

Periodontally healthy subjects were divided into young (18-30 years, n = 7) and elderly (46-77 years, n = 7). A gingival biopsy was taken at baseline. After experimental gingivitis, clinical examination was repeated and a second biopsy was taken. The expression of cyclooxygenase-1, cyclooxygenase-2, cyclooxygenase-3, and microsomal prostaglandin E synthase-1 was analyzed by means of immunohistochemistry.

RESULTS

In both healthy age groups, cyclooxygenase-1 and microsomal prostaglandin E synthase-1 were expressed in epithelial cells, endothelial cells and fibroblast-like connective tissue cells. Cyclooxygenase-1 was found in Langerhans' cells of the epithelium. Cyclooxygenase-2 expression was observed in cells exhibiting the morphology of epithelial mitosis cells, and the expression of cyclooxygenase-2 in periodontally healthy elderly subjects was significantly lower (p < or = 0.05). Following experimental gingivitis, cyclooxygenase-1 and microsomal prostaglandin E synthase-1 expression did not change. However, the expression of cyclooxygenase-2 was significantly increased in both age groups (p < or = 0.05). Cyclooxygenase-3 was not detected in any group investigated.

CONCLUSION

Cyclooxygenase-1 and microsomal prostaglandin E synthase-1 were expressed constitutively in gingival tissue, and expression was unaffected by age or inflammation states. In contrast, the expression of cyclooxygenase-2 was weaker in elderly subjects. In the course of experimental gingivitis, cyclooxygenase-2 was induced in both age groups.

Inhibition of angiogenic tubule formation and induction of apoptosis in human endothelial cells by the selective cyclooxygenase-2 inhibitor 5-bromo-2-(4-fluorophenyl)-3-(methylsulfonyl) thiophene (DuP-697)

There are indications that inhibitors of the cyclooxygenase-2 (COX-2) enzyme may cause inhibition of angiogenesis, proliferation of endothelial cells and induce apoptosis in cell systems. The concentrations of inhibitors required for such effects are however much higher than those needed to inhibit COX-2, suggesting that the latter may not be involved in these actions of the drugs. We have however generated data that strongly indicates a critical role for COX-2 suppression in the inhibition of angiogenesis and induction of apoptosis in human cultured umbilical vein endothelial cells (HUVECs) by the selective cyclooxygenase-2 (COX-2) inhibitor 5-bromo-2-(4-fluorophenyl)-3-(methylsulfonyl) thiophene (DuP-697). DuP-697 concentration-dependently inhibited prostaglandin E(2) (PGE(2)) production by HUVECs and at its known IC(50) for COX-2 inhibition of 10 nM inhibited basal and vascular endothelial cell growth factor (VEGF)-induced PGE(2) production by 80% and 85% respectively. DuP-697 also induced apoptosis as shown by FACs analysis, an increase in chromatin condensation and DNA laddering in HUVECS treated with the drug. Moreover, these effects were reversed by PGE(2) and by VEGF. In parallel studies, DuP-697 induced caspases 3, 8 and 9, with the caspase-3 specific inhibitor N-Acetyl-Asp-Glu-Val-Asp-al (DEVD-CHO) blocking the induction of apoptosis. Capillary-like tubule formation by HUVECs cultured on Matrigel was inhibited by DuP-697 and this inhibition was prevented by PGE(2) but not by DEVD-CHO. These results indicate that the induction of apoptosis and inhibition of tubule formation by DuP-697 involves the inhibition of COX-2 and that whereas the induction of apoptosis is caspase-dependent, the inhibition of tubule formation occurs through a caspase-independent mechanism.

A critical appraisal of COX-2 selective inhibition and analgesia: how good so far?

The development of COX-2 selective inhibitors has opened a new era of clinical investigation in NSAIDs. Discussion of the established concepts of inflammation and therapeutical uses of these drugs has changed the rationale for its clinical use and therapeutic labeling of these drugs. A comprehensive discussion across basic science and clinical areas involved in each of these concepts is presented. This led to a remarkable re-evaluation of our insights on their traditionally proposed mechanisms of analgesia, their side-effects, and the clinical indication of NSAIDs as "over the counter" pain killers. This may shift physicians toward a more rational use of this drug class.

Antipyretic analgesics: nonsteroidal antiinflammatory drugs, selective COX-2 inhibitors, paracetamol and pyrazolinones

Antipyretic analgesics are a group of heterogeneous substances including acidic (nonsteroidal antiinflammatory drugs, NSAIDs) and nonacidic (paracetamol, pyrazolinones) drugs. Moreover, various selective cyclooxygenase-2 (COX-2) inhibitors with improved gastrointestinal tolerability as compared with conventional NSAIDs have been established for symptomatic pain treatment in recent years. The present review summarizes the pharmacology of all of these drugs with particular emphasis on their rational use based on the diverse pharmacokinetic characteristics and adverse drug reaction profiles. Referring to the current debate, potential mechanisms underlying cardiovascular side effects associated with long-term use of COX inhibitors are discussed.