Characterization of Prostaglandin G/H Synthase 1 and 2 in rat, dog, monkey, and human gastrointestinal tracts

Transcriptome Analysis Reveals Equine Endometrium's Gene Expression Profile Around Embryo Fixation

BACKGROUND/OBJECTIVES

The success or failure of embryo fixation is crucial for embryo attachment and later development. As an epithelial chorioallantoic placenta-type animal, the horse has a special process of embryo implantation, and the mechanism of embryo fixation in horses is still unclear.

METHODS

In this study, the structural and transcriptomic characteristics of endometrial tissue from the fixed and nonfixed sides of 20-day gestation embryos in Mongolian horses were investigated to search for important genes and potential molecular markers associated with the fixation phase of equine embryos.

RESULTS

A comparison of the structures of the endometrial tissues of the two sides revealed that the endometrium on the fixed side presented distinctive features, which were characterized mainly by the development of glands on the fixed side compared with those on the nonfixed side. A total of 3987 differentially expressed genes were identified in the transcriptome, among which 1931 genes were highly expressed on the fixed side of the embryo, including CDH1, DRA, DQB, CLND2, BOLA-DQB, CLDN10, PTGER2, and PTGFR. The differentially expressed genes were enriched in biological processes such as cell adhesion, morphogenesis, NOD signaling, and vitamin uptake, as well as prostatic hormones.

CONCLUSIONS

These results suggest that equine embryo fixation may depend at least on the regulation of prostaglandins and the establishment of cellular connections. This provides a foundation for exploring the molecular mechanisms of key genes and pathways related to equine embryo fixation and offers new insights into feeding management and the monitoring of mares in the early stages of pregnancy.

Cellular mechanisms of taste disturbance induced by the non-steroidal anti-inflammatory drug, diclofenac, in mice

Drug-induced taste disorders are a serious problem in an aging society. This study investigated the mechanisms underlying taste disturbances induced by diclofenac, a non-steroidal anti-inflammatory drug that reduces pain and inflammation by inhibiting the synthesis of prostaglandins by cyclooxygenase enzymes (COX-1 and COX-2). RT-PCR analyses demonstrated the expression of genes encoding arachidonic acid pathway components such as COX-1, COX-2 and prostaglandin synthases in a subset of mouse taste bud cells. Double-staining immunohistochemistry revealed that COX-1 and cytosolic prostaglandin E synthase (cPGES) were co-expressed with taste receptor type-1 member-3 (T1R3), a sweet/umami receptor component, or gustducin, a bitter/sweet/umami-related G protein, in a subset of taste bud cells. Long-term administration of diclofenac reduced the expression of genes encoding COX-1, gustducin and cPGES in mouse taste buds and suppressed both the behavioral and taste nerve responses to sweet and umami taste stimuli but not to other tastants. Furthermore, diclofenac also suppressed the responses of both mouse and human sweet taste receptors (T1R2/T1R3, expressed in HEK293 cells) to sweet taste stimuli. These results suggest that diclofenac may suppress the activation of sweet and umami taste cells acutely via a direct action on T1R2/T1R3 and chronically via inhibition of the COX/prostaglandin synthase pathway inducing down-regulated expression of sweet/umami responsive components. This dual inhibition mechanism may underlie diclofenac-induced taste alterations in humans.

NSAID-Associated Small Intestinal Injury: An Overview From Animal Model Development to Pathogenesis, Treatment, and Prevention

With the wide application of non-steroidal anti-inflammatory drugs (NSAIDs), their gastrointestinal side effects are an urgent health burden. There are currently sound preventive measures for upper gastrointestinal injury, however, there is a lack of effective defense against lower gastrointestinal damage. According to a large number of previous animal experiments, a variety of NSAIDs have been demonstrated to induce small intestinal mucosal injury in vivo. This article reviews the descriptive data on the administration dose, administration method, mucosal injury site, and morphological characteristics of inflammatory sites of various NSAIDs. The cells, cytokines, receptors and ligands, pathways, enzyme inhibition, bacteria, enterohepatic circulation, oxidative stress, and other potential pathogenic factors involved in NSAID-associated enteropathy are also reviewed. We point out the limitations of drug modeling at this stage and are also pleased to discover the application prospects of chemically modified NSAIDs, dietary therapy, and many natural products against intestinal mucosal injury.

Conserved and breed-specific differences in the cervical transcriptome of sheep with divergent fertility at the follicular phase of a natural oestrus cycle

BACKGROUND

The outcome of cervical artificial insemination (AI) with frozen-thawed semen in sheep is limited by the inability of sperm to traverse the cervix of some ewe breeds. Previous research has demonstrated that cervical sperm transport is dependent on ewe breed, as sperm can traverse the cervix in greater numbers in some higher fertility ewe breeds. However, the molecular mechanisms underlying ewe breed differences in sperm transport through the cervix remain unknown. In this study, we aimed to characterise the cervical transcriptome of four European ewe breeds with known differences in pregnancy rates following cervical AI using frozen-thawed semen at the follicular phase of a natural oestrous cycle. Cervical post mortem tissue samples were collected from two Irish ewe breeds (Belclare and Suffolk; medium and low fertility, respectively) and from two Norwegian ewe breeds (Norwegian White Sheep (NWS) and Fur; high fertility compared to both Irish breeds) at the follicular phase of a natural oestrous cycle (n = 8 to 10 ewes per breed).

RESULTS

High-quality RNA extracted from biopsies of the mid-region of the cervix was analysed by RNA-sequencing and Gene Ontology (GO). After stringent filtering (P <  0.05 and FC > 1.5), a total of 11, 1539 and 748 differentially expressed genes (DEGs) were identified in Belclare, Fur and NWS compared to the low fertility Suffolk breed, respectively. Gene ontology analysis identified significantly enriched biological processes involved in muscle contraction, extracellular matrix (ECM) development and the immune response. Gene co-expression analysis revealed similar patterns in muscle contraction and ECM development modules in both Norwegian ewe breeds, which differed to the Irish ewe breeds.

CONCLUSIONS

These breed-specific biological processes may account for impaired cervical sperm transport through the cervix in sheep during the follicular phase of the reproductive cycle. This novel and comprehensive dataset provides a rich foundation for future targeted initiatives to improve cervical AI in sheep.

Different Chemical Structures and Physiological/Pathological Roles of Cyclooxygenases

This review describes cyclooxygenase (COX), which synthesizes prostanoids that play an important role in living things. The authors conducted a national and international literature review on the subject. The COX enzyme uses arachidonic acid to form prostanoids, which play a role in several physiological and pathological conditions. This enzyme has different isoforms, mainly COX-1 and COX-2. The constitutive isoform is COX-1, while COX-2 is the inducible isoform. Both are expressed in different tissues and at different levels, but they may also coexist within the same tissue. Both isoforms show essentially the same mode of action, but their substrates and inhibitors may differ. The COX-1 isoform, which plays a role in the continuation of physiological events, has an increased expression level in various carcinomas, and the COX-2 isoform, which is increased in inflammatory conditions, is typically expressed at low physiological levels in some tissues such as the brain, kidney, and uterus. In addition to investigating the efficacies of the COX-1 and COX-2 isoforms, the discovery of potential new COX enzymes and their effect continues. This review also looks at the roles of the COX enzyme in certain physiological and pathological conditions.

Mechanism of Huang-lian-Jie-du decoction and its effective fraction in alleviating acute ulcerative colitis in mice: Regulating arachidonic acid metabolism and glycerophospholipid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-lian-Jie-du decoction (HLJDD) is a traditional Chinese medicine prescription for clearing away heat, purging fire and detoxifying, which can be used to treat sepsis, stroke, Alzheimer's disease and gastrointestinal diseases. Our previous studies have shown that HLJDD can effectively alleviate acute ulcerative colitis (UC) in mice, and its n-butanol fraction (HLJDD-NBA) is the effective fraction. The aim of this study is to further investigate the mechanism of HLJDD and HLJDD-NBA in relieving UC in mice from a holistic perspective.

METHODS

The acute UC model of BABL/c mice was induced by 3.5% (w/v) dextran sodium sulfate drinking water. At the same time of modeling, HLJDD and HLJDD-NBA were given orally for treatment respectively. During the experiment, the clinical symptoms of mice were recorded and the physiological and biochemical indexes of mice were detected after the experiment. In addition, the plasma metabolites of mice in each group were detected and analyzed by ultra-high performance liquid chromatography quadrupole time of flight mass spectrometry and multivariate statistical analysis method. Then, the potential target metabolic pathway of drug intervention was screened through the enrichment analysis of differential metabolites. Finally, we use molecular simulation docking technology to further explore the molecular regulatory mechanism of HLJDD and HLJDD-NBA on potential target metabolic pathways.

RESULTS

HLJDD and HLJDD-NBA intervention can significantly reduce the disease activity index of UC mice, inhibit colon length shortening and pathological damage, and relieve the abnormal changes of physiological and biochemical parameters of UC mice. Moreover, HLJDD and HLJDD-NBA can significantly inhibit the metabolic dysfunction of UC mice by reversing the abnormal changes of 24 metabolites in UC mice, and the arachidonic acid metabolic pathway and glycerophospholipid metabolic pathway are the target metabolic pathways regulated by them. Further literature review and molecular simulation docking analysis showed that HLJDD and HLJDD-NBA may inhibit the disorder of arachidonic acid metabolism pathway and glycerophospholipid metabolism pathway by inhibiting COX-2 protein expression and PLA2, 5-LOX activity.

CONCLUSIONS

Our experiments revealed that HLJDD and HLJDD-NBA can alleviate UC of mice by regulating arachidonic acid metabolism and glycerophospholipid metabolism, which points out the direction for further research and development of HLJDD as a new anti-ulcer drug.

An Activity-Based Sensing Approach for the Detection of Cyclooxygenase-2 in Live Cells

Cyclooxygenase-2 (COX-2) overexpression is prominent in inflammatory diseases, neurodegenerative disorders, and cancer. Directly monitoring COX-2 activity within its native environment poses an exciting approach to account for and illuminate the effect of the local environments on protein activity. Herein, we report the development of CoxFluor, the first activity-based sensing approach for monitoring COX-2 within live cells with confocal microscopy and flow cytometry. CoxFluor strategically links a natural substrate with a dye precursor to engage both the cyclooxygenase and peroxidase activities of COX-2. This catalyzes the release of resorufin and the natural product, as supported by molecular dynamics and ensemble docking. CoxFluor enabled the detection of oxygen-dependent changes in COX-2 activity that are independent of protein expression within live macrophage cells.

Study of Melatonin as Preventive Agent of Gastrointestinal Damage Induced by Sodium Diclofenac

Safety profile of nonsteroidal anti-inflammatory drugs (NSAIDs) has been widely studied and both therapeutic and side effects at the gastric and cardiovascular level have been generally associated with the inhibitory effect of isoform 1 (COX-1) and 2 (COX-2) cyclooxygenase enzymes. Now there are evidences of the involvement of multiple cellular pathways in the NSAIDs-mediated-gastrointestinal (GI) damage related to enterocyte redox state. In a previous review we summarized the key role of melatonin (MLT), as an antioxidant, in the inhibition of inflammation pathways mediated by oxidative stress in several diseases, which makes us wonder if MLT could minimize GI NSAIDs side effects. So, the aim of this work is to study the effect of MLT as preventive agent of GI injury caused by NSAIDs. With this objective sodium diclofenac (SD) was administered alone and together with MLT in two experimental models, ex vivo studies in pig intestine, using Franz cells, and in vivo studies in mice where stomach and intestine were studied. The histological evaluation of pig intestine samples showed that SD induced the villi alteration, which was prevented by MLT. In vivo experiments showed that SD altered the mice stomach mucosa and induced tissue damage that was prevented by MLT. The evaluation by quantitative reverse transcription PCR (RT-qPCR) of two biochemical markers, COX-2 and iNOS, showed an increase of both molecules in less injured tissues, suggesting that MLT promotes tissue healing by improving redox state and by increasing iNOS/NO that under non-oxidative condition is responsible for the maintenance of GI-epithelium integrity, increasing blood flow and promoting angiogenesis and that in presence of MLT, COX-2 may be responsible for wound healing in enterocyte. Therefore, we found that MLT may be a preventive agent of GI damages induced by NSAIDs.

NSAID-Gut Microbiota Interactions

Nonsteroidal anti-inflammatory drugs (NSAID)s relieve pain, inflammation, and fever by inhibiting the activity of cyclooxygenase isozymes (COX-1 and COX-2). Despite their clinical efficacy, NSAIDs can cause gastrointestinal (GI) and cardiovascular (CV) complications. Moreover, NSAID use is characterized by a remarkable individual variability in the extent of COX isozyme inhibition, therapeutic efficacy, and incidence of adverse effects. The interaction between the gut microbiota and host has emerged as a key player in modulating host physiology, gut microbiota-related disorders, and metabolism of xenobiotics. Indeed, host-gut microbiota dynamic interactions influence NSAID disposition, therapeutic efficacy, and toxicity. The gut microbiota can directly cause chemical modifications of the NSAID or can indirectly influence its absorption or metabolism by regulating host metabolic enzymes or processes, which may have consequences for drug pharmacokinetic and pharmacodynamic properties. NSAID itself can directly impact the composition and function of the gut microbiota or indirectly alter the physiological properties or functions of the host which may, in turn, precipitate in dysbiosis. Thus, the complex interconnectedness between host-gut microbiota and drug may contribute to the variability in NSAID response and ultimately influence the outcome of NSAID therapy. Herein, we review the interplay between host-gut microbiota and NSAID and its consequences for both drug efficacy and toxicity, mainly in the GI tract. In addition, we highlight progress towards microbiota-based intervention to reduce NSAID-induced enteropathy.

Expression of cyclooxygenase 2 in oral submucous fibrosis: An immunohistochemical pilot study

Introduction

Oral submucous fibrosis (OSF) is associated with inflammatory changes in at least some stages of the disease. Prostaglandin is one of the main inflammatory mediators and its production is controlled by various enzymes such as cyclooxygenase (COX). The genetic and pharmacological data strongly indicate that COX-2 should be investigated as a potential target for the prevention and treatment of OSF.

Methodology

The study group comprised histologically confirmed specimens (n = 10 each) of early OSF, moderate OSF, advanced OSF and normal oral mucosa for comparison. Immunohistochemistry was performed with avidin-biotin technique and evaluated with scoring methods.

Results

The difference in percentage of expression in normal tissue and OSF was statistically highly significant (P < 0.001). Positive COX-2 exhibited cytoplasmic staining. One-way analysis of variances test was performed to evaluate COX-2 expression in different grades of OSF. Cytoplasmic staining assessed in terms of intensity, percentage of expression and Q Score did not show any statistical difference (percentage of expression F = 0.029, P = 0.971; Q Score F = 0.154, P = 0.858).

Conclusions

Our study indicates that COX-2 may be an important marker of disease progression and might be a reliable prognostic indicator.

Induction of COX-1, suppression of COX-2 and pro-inflammatory cytokines gene expression by moringa leaves and its aqueous extract in aspirin-induced gastric ulcer rats

The Moringa plant (Moringa oleifera) is known for its potential medicinal properties and health benefits in addition to its high nutritional value. The current study aimed to investigate the antiulcer effect of moringa leaves and its aqueous extract on pro-inflammatory cytokines and inflammatory mediators in ulcerative rats. Rats were treated with either moringa leaves (10%) or moringa extract (300 mg/kg body weight) for 4 weeks then treated with a single dose of aspirin to induce gastric ulcer. Moringa leaves and its extract markedly reduced ulcer index, gastric volume and total acidity. Both treatments induced a significant increase in gastric mucosal mucin content and plasma NO level associated with significant decrease in plasma TNFα. Moringa leaves and its extract prompted down-regulation of TNFα, TGFβ1 and COX2 genes expression by 2.7, 3.5, and 8.4 fold-change for moringa leaves and 2.7, and 2.3, 4.1 fold-change for moringa extract, respectively. Moringa leaves and extract treatments altered the COX-1 gene expression levels to near normal values. This study confirms the gastro-protective influence of moringa leaves and its extract on aspirin-induced ulcer in rats as manifested by its significant reduction in inflammatory cytokines and normalization of gastric mucosal mucin and NO level. Overall, moringa leaves powder is more efficient as antiulcer agent than moringa extract.

Suppression of inflammatory mediators and matrix metalloproteinase (MMP)-13 by Morus alba stem extract and oxyresveratrol in RAW 264.7 cells and C28/I2 human chondrocytes

This study aimed to investigate the effects of Morus alba stem extract (MSE) and oxyresveratrol on the suppression of pro-inflammatory mediators in LPS-stimulated RAW 264.7 macrophages and IL-1β-stimulated C28/I2 human chondrocyte cell line. The chondroprotective effect was also investigated using the chondrocyte cell line. First, MSE was prepared and analyzed for the amount of oxyresveratrol. The anti-inflammatory effects of MSE at various concentrations were evaluated through the inhibition of nitric oxide (NO), prostaglandin (PG)-E₂ and cyclooxygenase (COX)-2 production. Oxyresveratrol at the equivalent amount found in the extract was investigated in the same manner. The chondroprotective effect was investigated through the suppression of MMP-13 production. The results showed that oxyresveratrol content in MSE was 15%. In RAW 264.7 cells, MSE (5-50 μg/mL) could inhibit the NO (24-30%) and PGE₂ (11-82%) production. Oxyresveratrol at 0.75 and 7.5 μg/mL could suppress NO and also inhibited PGE₂ but at only at high concentration. In the chondrocyte cell line, MSE at 5-100 μg/mL significantly decreased the PGE₂ and COX-2 production by 44-93% and 17-65%, respectively. Again, oxyresveratrol at both concentrations could significantly inhibit PGE₂ production by 50-92% but it inhibited COX-2 only at high concentration. In addition, MSE and oxyresveratrol was shown to significantly inhibit MMP-13 production by 14-57% and 16-56%, depending on their concentrations. The MSE demonstrates the potential to be used as an alternative treatment for reducing inflammation and preventing cartilage degradation. Its component, oxyresveratrol, may exert these effects to some extent.

Lack of Small Intestinal Dysbiosis Following Long-Term Selective Inhibition of Cyclooxygenase-2 by Rofecoxib in the Rat

Intestinal dysbiosis is linked to numerous gastrointestinal disorders, including inflammatory bowel diseases. It is a question of debate if coxibs, selective inhibitors of cyclooxygenase (COX)-2, cause dysbiosis. Therefore, in the present study, we aimed to determine the effect of long-term (four weeks) selective inhibition of COX-2 on the small intestinal microbiota in the rat. In order to avoid mucosal damage due to topical effects and inflammation-driven microbial alterations, rofecoxib, a nonacidic compound, was used. The direct inhibitory effect of rofecoxib on the growth of bacteria was ruled out in vitro. The mucosa-sparing effect of rofecoxib was confirmed by macroscopic and histological analysis, as well as by measuring the intestinal levels of cytokines and tight junction proteins. Deep sequencing of bacterial 16S rRNA revealed that chronic rofecoxib treatment had no significant influence on the composition and diversity of jejunal microbiota. In conclusion, this is the first demonstration that long-term selective inhibition of COX-2 by rofecoxib does not cause small intestinal dysbiosis in rats. Moreover, inhibition of COX-2 activity is not likely to be responsible per se for microbial alterations caused by some coxibs, but other drug-specific properties may contribute to it.

Cardiorenal Safety of OTC Analgesics

Over-the-counter analgesics are used globally for the relief of acute pain. Although effective, these agents can be associated with adverse effects that may limit their use in some people. In the early 2000s, observations from clinical trials of prescription-strength and supratherapeutic doses of nonselective and cyclooxygenase-2-selective nonsteroidal anti-inflammatory drugs (NSAIDs) raised safety concerns regarding the risk of cardiovascular adverse effects with the use of these medications. Subsequently, the US Food and Drug Administration mandated additional study of the cardiovascular safety of NSAIDs for a more comprehensive understanding of their risk. As these data were being collected, and based on a comprehensive review of prescription data and the recommendations of the US Food and Drug Administration Advisory Committee, the warning labels of over-the-counter NSAIDs were updated to emphasize the potential cardiovascular risks of these agents. The recently reported “Prospective Randomized Evaluation of Celecoxib Integrated Safety versus Ibuprofen or Naproxen” (PRECISION) trial, in which participants with osteoarthritis or rheumatoid arthritis and underlying cardiovascular risk factors were treated with prescription-strength celecoxib, ibuprofen, or naproxen, revealed similar rates of cardiovascular events (death from cardiovascular causes including hemorrhagic death, nonfatal myocardial infarction, or nonfatal stroke) among the 3 treatment groups. Although informative, the cardiovascular safety findings derived from PRECISION cannot be extrapolated to the safety of the over-the-counter pain relievers ibuprofen and naproxen, given that the doses used were higher (mean [standard deviation]: ibuprofen, 2045 [246] mg; naproxen, 852 [103] mg) and the durations of use longer (∼20 months) than recommended with over-the-counter use of NSAIDs, which for ibuprofen is up to 10 days. This review discusses the cardiorenal safety of the most commonly used over-the-counter analgesics, ibuprofen, naproxen, and acetaminophen. Available data suggest that there is little cardiovascular risk when over-the-counter formulations of these agents are used as directed in their labels.

Comparative Microbiome Signatures and Short-Chain Fatty Acids in Mouse, Rat, Non-human Primate, and Human Feces

Gut microbiome plays a fundamental role in several aspects of host health and diseases. There has been an exponential surge in the use of animal models that can mimic different phenotypes of the human intestinal ecosystem. However, data on host species-specific signatures of gut microbiome and its metabolites like short-chain fatty acids (SCFAs; i.e., acetate, propionate, and butyrate) and lactate in these models and their similarities/differences from humans remain limited, due to high variability in protocols and analyses. Here, we analyze the fecal microbiota composition and the fecal levels of SCFAs and lactate in three of the most-widely used animal models, i.e., mice, rats, and non-human primates (NHPs) and compare them with human subjects, using data generated on a single platform with same protocols. The data show several species-specific similarities and differences in the gut microbiota and fecal organic acids between these species groups. Based on β-diversity, the gut microbiota in humans seems to be closer to NHPs than to mice and rats; however, among rodents, mice microbiota appears to be closer to humans than rats. The phylum-level analyses demonstrate higher Firmicutes-Bacteroidetes ratio in humans and NHPs vs. mice and rats. Human microbiota is dominated by Bacteroides followed by Ruminococcaceae and Clostridiales. Mouse gut is predominated by members of the family S24-7 followed by those from the order Clostridiales, whereas rats and NHPs have higher abundance of Prevotella compared with mice and humans. Also, fecal levels of lactate are higher in mice and rats vs. NHPs and humans, while acetate is highest in human feces. These data of host species-specific gut microbiota signatures in some of the most widely used animal models in context to the human microbiota might reflect disparities in host factors, e.g., diets, genetic origin, gender and age, and hence call for prospective studies investigating the features of gut microbiome in such animal models by controlling for these host elements.

Selected Molecular Mechanisms Involved in the Parasite⁻Host System Hymenolepis diminuta⁻Rattus norvegicus

The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm’s scolex, which could cause mechanical damage to host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the host’s gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-host interaction, including the influence on ion transport and host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the host at the cellular level resulting from the direct impact of the parasite as well as host defense reactions that lead to changes in the host’s tissues and organs.

The prevalence of endoscopic gastric mucosal damage in patients with rheumatoid arthritis

OBJECTIVES

Rheumatoid arthritis (RA) patients often take non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids as supportive drugs. In this study, we investigated the prevalence of endoscopic gastric damage and their prescribed medications under an actual clinical condition.

METHODS

We collected the data of 1704 RA patients who underwent upper gastrointestinal fiberscopy. Gastric mucosal erosion and ulcer were classified using modified LANZA score. We analyzed these data with a multiple regression analysis.

RESULTS

The prevalence of endoscopic gastric mucosal damage in these RA patients was 16.7% (285 cases). A multiple regression analysis indicated that prednisolone (PSL), NSAIDs and proton pump inhibitors (PPIs) were independent risk factors associated with the modified LANZA score. PSL and NSAIDs were positively correlated with the score, while the administration of PPIs was inversely correlated with the score. The modified LANZA score in RA patients treated with both PSL and NSAIDs was significantly higher than that in those treated with PSL alone (no NSAIDs use).

CONCLUSIONS

Our findings suggest that PSL and NSAIDs were exacerbating factors for gastric mucosal damage, while PPIs usage was a protective factor. And, the combined usage of corticosteroids and NSAIDs may induce the development of gastric ulcers.

Molecular Signaling in Tumorigenesis of Gastric Cancer

Gastric cancer (GC) is regarded as the fifth most common cancer and the third cause of cancer-related deaths worldwide. Mechanism of GC pathogenesis is still unclear and relies on multiple factors, including environmental and genetic characteristics. One of the most important environmental factors of GC occurrence is infection with Helicobacter pylori that is classified as class one carcinogens. Dysregulation of several genes and pathways play an essential role during gastric carcinogenesis. Dysregulation of developmental pathways such as Wnt/β-catenin signaling, Hedgehog signaling, Hippo pathway, Notch signaling, nuclear factor-kB, and epidermal growth factor receptor have been found in GC. Epithelial-mesenchymal transition, as an important process during embryogenesis and tumorigenesis, is supposed to play a role in initiation, invasion, metastasis, and progression of GC. Although surgery is the main therapeutic modality of the disease, the understanding of biological processes of cell signaling pathways may help to develop new therapeutic targets for GC.

Effects of nonselective and selective cyclooxygenase inhibitors on the contractions of isolated bronchial smooth muscle in the horse

We evaluated the effects of nonselective cyclooxygenase (COX)-1/COX-2 inhibitors (acetylsalicylic acid, indomethacin, ibuprofen, flunixin meglumine, phenylbutazone), preferential COX-2 inhibitors (diclofenac, meloxicam, carprofen), selective COX-1 inhibitor (SC-560), and selective COX-2 inhibitors (celecoxib, firocoxib, parecoxib) on the contractions of isolated bronchi induced by electrical field stimulation (EFS). Bronchial rings, obtained from lungs of slaughtered horses, were put in isolated organ baths, and the mechanical activity was measured by means of isotonic transducers. Electrical Field Stimulation was applied to the preparations, and the effects of drugs on the amplitude of evoked contractions were measured. Nonselective COX inhibitors did not modify EFS-induced contractions to a relevant degree, except indomethacin which caused a concentration-dependent decrease of the contraction amplitude. Conversely, preferential COX-2 inhibitors enhanced the contractions in a concentration-related fashion, whilst the selective COX-1 inhibitor reduced them. Among selective COX-2 inhibitors, parecoxib increased EFS-evoked contractions whereas celecoxib and firocoxib were ineffective. These results suggest that the inhibition of prostanoid synthesis does not modify the electrical field-stimulated contractions of isolated horse bronchi. Since EFS-induced contractions of horse bronchi were previously shown to be of full cholinergic nature, the increase caused by diclofenac, meloxicam, carprofen, and parecoxib could be due to an inhibition of acetylcholinesterase; in accordance, these drugs potentiated exogenous acetylcholine-induced but not carbachol-induced bronchial contraction. Indomethacin and SC-560 might instead decrease bronchial contractions by inhibiting calcium currents. Clinical use of meloxicam and carprofen in horses with bronchial hyper-responsiveness requires caution for a potential risk of causing adverse effects due to bronchoconstriction.

A Carrier-Free Nanostructure Based on Platinum(IV) Prodrug Enhances Cellular Uptake and Cytotoxicity

Flurbiprofen, a hydrophobic COX inhibitor, was coordinated axially with oxoplatin to form a new conjugate, cis, cis, trans-[Pt(IV)(NH₃)₂Cl₂(flurbiprofen)₂]. The successful synthesis of this new conjugate was confirmed by ¹H, ¹³C, and ¹⁹⁵Pt NMR. The potential of this conjugate being reduced to cisplatin and subsequently exerting its DNA cross-linking ability was verified using cyclic voltammetry (CV), HPLC, and mass spectrometry (MS). This conjugate showed markedly higher cytotoxicity on many cancer cell lines than cisplatin, flurbiprofen, and their physical mixture (mole ratio, cisplatin:flurbiprofen = 1:2). This is consistent with the result of an apoptosis-inducing assay. This conjugate spontaneously assembles carrier-free nanoparticles in aqueous solution, which is confirmed by DLS, TEM, SEM, and AFM, and thus facilitates cellular uptake and markedly improves its cytotoxicity and apoptosis-inducing ability in vitro.

Gastroprotective potential of hydro-alcoholic extract of Pattanga (Caesalpinia sappan Linn.)

ETHNO-PHARMACOLOGICAL RELEVANCE

Pattanga is botanically equated as Caesalpinia sappan Linn. (Family: Caesalpiniaceae) and is used in Ayurveda system of medicine since ages. According to Ayurveda, useful part is Heartwood, which is bitter, astringent and acrid and is useful in vitiated conditions of vata and pitta, burning sensation, wounds, ulcers, leprosy, skin diseases, menorrhagia, leucorrhea, and diabetes. It is used as a major ingredient in Ayurvedic formulations and preparations like Patrangasava, Chandanadya Thalia, and Karpuradyarka.

AIM OF THE STUDY

The present study is planned to evaluate the gastroprotective activity of the selected Ayurvedic drug using three different in vivo gastric ulcer models, so as to provide scientific evidence for the Ayurvedic claims.

MATERIALS AND METHODS

For this study, Wistar albino rats fasted overnight were selected. The hydroalcoholic extract of Caesalpinia sappan heartwood at the dose level 250 and 500mg/kg body weight was selected and administered orally before necrotizing agents. Antioxidant and antiulcer parameters were evaluated and the stomach samples were subjected for histopathological studies. In addition, PGE2 estimation and protein expressions of COX-1, COX-2 and iNOS were analyzed by Western blot. The plant extract was subjected to LCMS/MS analysis. In addition, Cytoprotective effect in isolated gastric mucosal cells, TUNEL Assay, Acid neutralizing capacity assay, H⁺/K⁺ ATPase inhibitory assay were performed.

RESULTS

The ulcer protection was found to be 92%, 86% and 64% against ethanol, NSAID and pylorus ligation induced ulcer respectively. The hydro-alcoholic extract of C. sappan heartwood exhibited cytoprotective effect with 76.82% reduction against indomethacin-induced cytotoxicity at the concentration of 25µg/ml. C. sappan showed 63.91% inhibition in H⁺/K⁺ ATPase inhibitory assay at the concentration 500µg/ml.

CONCLUSIONS

Our results depict that Caesalpinia sappan heartwood possesses gastroprotective activity, possibly mediated through cytoprotection and antioxidant mechanisms. The data obtained in the present study provides scientific support for the traditional use of Caesalpinia sappan in the management of peptic ulcer.

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.

Targeting arachidonic acid pathway by natural products for cancer prevention and therapy

Arachidonic acid (AA) pathway, a metabolic process, plays a key role in carcinogenesis. Hence, AA pathway metabolic enzymes phospholipase A₂s (PLA₂s), cyclooxygenases (COXs) and lipoxygenases (LOXs) and their metabolic products, such as prostaglandins and leukotrienes, have been considered novel preventive and therapeutic targets in cancer. Bioactive natural products are a good source for development of novel cancer preventive and therapeutic drugs, which have been widely used in clinical practice due to their safety profiles. AA pathway inhibitory natural products have been developed as chemopreventive and therapeutic agents against several cancers. Curcumin, resveratrol, apigenin, anthocyans, berberine, ellagic acid, eugenol, fisetin, ursolic acid, [6]-gingerol, guggulsteone, lycopene and genistein are well known cancer chemopreventive agents which act by targeting multiple pathways, including COX-2. Nordihydroguaiaretic acid and baicalein can be chemopreventive molecules against various cancers by inhibiting LOXs. Several PLA₂s inhibitory natural products have been identified with chemopreventive and therapeutic potentials against various cancers. In this review, we critically discuss the possible utility of natural products as preventive and therapeutic agents against various oncologic diseases, including prostate, pancreatic, lung, skin, gastric, oral, blood, head and neck, colorectal, liver, cervical and breast cancers, by targeting AA pathway. Further, the current status of clinical studies evaluating AA pathway inhibitory natural products in cancer is reviewed. In addition, various emerging issues, including bioavailability, toxicity and explorability of combination therapy, for the development of AA pathway inhibitory natural products as chemopreventive and therapeutic agents against human malignancy are also discussed.

The inflammatory effect of infection with Hymenolepis diminuta via the increased expression and activity of COX-1 and COX-2 in the rat jejunum and colon

The aim of this study was to determine whether Hymenolepis diminuta may affect the expression and activity of cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2), resulting in the altered levels of their main products - prostaglandins (PGE2) and thromboxane B2 (TXB2). The study used the same experimental model as in our previous studies in which we had observed changes in the transepithelial ion transport, tight junctions and in the indicators of oxidative stress, in both small and large intestines of rats infected with H. diminuta. In this paper, we investigated not only the site of immediate presence of the tapeworm (jejunum), but also a distant site (colon). Inflammation related to H. diminuta infection is associated with the increased expression and activation of cyclooxygenase (COX), enzyme responsible for the synthesis of PGE2 and TXB2, local hormones contributing to the enhanced inflammatory reaction in the jejunum and colon in the infected rats. The increased COX expression and activity is probably caused by the increased levels of free radicals and the weakening of the host's antioxidant defense induced by the presence of the parasite. Our immunohistochemical analysis showed that H. diminuta infection affected not only the intensity of the immunodetection of COX but also the enzyme protein localization within intestinal epithelial cells - from the entire cytoplasm to apical/basal regions of cells, or even to the nucleus.

Elevated Expression of Cyclooxygenase-2 in Adenocarcinoma of the Parotid Gland: Insights into Malignant Transformation of Pleomorphic Adenoma

Pleomorphic adenoma, the most common type of tumor of the parotid gland, may transform into a malignant tumor. In the current study, we investigated whether the expression of cyclooxygenase-2 (COX-2) is elevated in adenocarcinoma as compared to pleomorphic adenoma. Ten pleomorphic adenomas and 10 adenocarcinomas were examined. The tumor specimens were immunohistochemically stained with antibodies against COX-2 and Ki-67. The labeling indices of COX-2 in pleomorphic adenoma and adenocarcinoma were 6.0% ± 4.1% and 16.1% ± 4.6%, respectively, and those of Ki-67 in pleomorphic adenoma and adenocarcinoma were 0.77% ± 0.62% and 6.9% ± 6.6%, respectively. The labeling indices of both COX-2 and Ki-67 were significantly greater (p < .001) in adenocarcinoma than in pleomorphic adenoma. Together with the biological effects of COX-2, these results suggest that overexpression of COX-2 plays a crucial role in the pathogenesis of malignant transformation of pleomorphic adenoma in the parotid gland.

Analgesic efficacy of celecoxib in patients after oral surgery: special reference to time to onset of analgesia and duration of analgesic effect

PURPOSE

Cyclooxygenase-2 inhibitor celecoxib is also used in the dental field for analgesia. However, there are few reports on the time to onset and duration of analgesia. We investigated the analgesic effect of celecoxib after oral surgery.

METHODS

A total of 138 patients undergoing unilateral mandibular third molar surgery under local anesthesia were enrolled. After surgery, the patients who felt pain and requested an analgesic were instructed to take celecoxib 400 mg and to record the time. Primary efficacy outcome measures were time to onset of analgesia. In addition, the conditions of pain at the time of taking celecoxib, at the onset time of analgesia, and 2 and 6 h after taking the drug were recorded. Pain assessments were evaluated using a 10-cm visual analog scale and four-point verbal rating score. These data were documented in the questionnaire forms handed to the patients and retrieved by post.

RESULTS

Effective responses without missing were returned from 103 patients. The median time to onset of the efficacy was 35 min. The pain scales at celecoxib administration was significantly higher compared with the time of onset of analgesia, 2 hours after administraton and 6 hours hours administration (P<0.05, respectively). The pain scales at the onset time of analgesia were significantly higher compared to that after 2 or 6 h of taking the drug (P<0.05, respectively). There were no statistically significant differences in the pain scales between 2 and 6 h after taking the drug (P>0.05).

CONCLUSION

The analgesic effect of celecoxib was exhibited quickly and sustained after oral surgery.

Deciphering the mechanism behind the varied binding activities of COXIBs through Molecular Dynamic Simulations, MM-PBSA binding energy calculations and per-residue energy decomposition studies

COX-2 is a well-known drug target in inflammatory disorders. COX-1/COX-2 selectivity of NSAIDs is crucial in assessing the gastrointestinal side effects associated with COX-1 inhibition. Celecoxib, rofecoxib, and valdecoxib are well-known specific COX-2 inhibiting drugs. Recently, polmacoxib, a COX-2/CA-II dual inhibitor has been approved by the Korean FDA. These COXIBs have similar structure with diverse activity range. Present study focuses on unraveling the mechanism behind the 10-fold difference in the activities of these sulfonamide-containing COXIBs. In order to obtain insights into their binding with COX-2 at molecular level, molecular dynamics simulations studies, and MM-PBSA approaches were employed. Further, per-residue decomposition of these energies led to the identification of crucial amino acids and interactions contributing to the differential binding of COXIBs. The results clearly indicated that Leu338, Ser339, Arg499, Ile503, Phe504, Val509, and Ser516 (Leu352, Ser353, Arg513, Ile517, Phe518, Val523, and Ser530 in PGHS-1 numbering) were imperative in determining the activity of these COXIBs. The binding energies and energy contribution of various residues were similar in all the three simulations. The results suggest that hydrogen bond interaction between the hydroxyl group of Ser516 and five-membered ring of diarylheterocycles augments the affinity in COXIBs. The SAR of the inhibitors studied and the per-residue energy decomposition values suggested the importance of Ser516. Additionally, the positive binding energy obtained with Arg106 explains the binding of COXIBs in hydrophobic channel deep in the COX-2 active site. The findings of the present work would aid in the development of potent COX-2 inhibitors.

Discovery of a potent cyclooxygenase-2 inhibitor, S4, through docking-based pharmacophore screening, in vivo and in vitro estimations

Cyclooxygenase (COX; EC: 1.14.99.1), the key enzyme in prostaglandin production in the human body, is a major pharmacological target for developing anti-inflammatory agents.

NSAID-induced small intestinal damage--roles of various pathogenic factors

BACKGROUND/AIMS

NSAID-induced enteropathy has been the focus of recent basic and clinical research subsequent to the development of the capsule endoscope and double-balloon endoscope. We review the possible pathogenic mechanisms underlying NSAID-induced enteropathy and discuss the role of the inhibition of COX-1/COX-2 and the influences of food as well as various prophylactic treatments on these lesions.

METHODS

Studies were performed in experimental animals.

RESULTS

Multiple factors, such as intestinal hypermotility, decreased mucus secretion, enterobacteria, and upregulation of iNOS/NO expression, are involved in the pathogenesis of NSAID-induced enteropathy, in addition to the decreased production of PGs due to the inhibition of COX. Enterobacterial invasion is the most important pathogenic event, and intestinal hypermotility, which was associated with this event, is essential for the development of these lesions. NSAIDs also upregulate the expression of COX-2, and the inhibition of both COX-1 and COX-2 is required for the intestinal ulcerogenic properties of NSAIDs to manifest. NSAID-induced enteropathy is prevented by PGE2, atropine, ampicillin, and aminoguanidine as well as soluble dietary fiber, and exacerbated by antisecretory drugs such as proton pump inhibitors.

CONCLUSION

These findings on the pathogenesis of NSAID-induced enteropathy will be useful for the future development of intestinal-sparing alternatives to standard NSAIDs.

Variable responses of human and non-human primate gut microbiomes to a Western diet

BACKGROUND

The human gut microbiota interacts closely with human diet and physiology. To better understand the mechanisms behind this relationship, gut microbiome research relies on complementing human studies with manipulations of animal models, including non-human primates. However, due to unique aspects of human diet and physiology, it is likely that host-gut microbe interactions operate differently in humans and non-human primates.

RESULTS

Here, we show that the human microbiome reacts differently to a high-protein, high-fat Western diet than that of a model primate, the African green monkey, or vervet (Chlorocebus aethiops sabaeus). Specifically, humans exhibit increased relative abundance of Firmicutes and reduced relative abundance of Prevotella on a Western diet while vervets show the opposite pattern. Predictive metagenomics demonstrate an increased relative abundance of genes associated with carbohydrate metabolism in the microbiome of only humans consuming a Western diet.

CONCLUSIONS

These results suggest that the human gut microbiota has unique properties that are a result of changes in human diet and physiology across evolution or that may have contributed to the evolution of human physiology. Therefore, the role of animal models for understanding the relationship between the human gut microbiota and host metabolism must be re-focused.

Model-based prediction of the acute and long-term safety profile of naproxen in rats

BACKGROUND AND PURPOSE

Despite the increasing importance of biomarkers as predictors of drug effects, toxicology protocols continue to rely on the experimental evidence of adverse events (AEs) as a basis for establishing the link between indicators of safety and drug exposure. Furthermore, biomarkers may facilitate the translation of findings from animals to humans. Combined with a model-based approach, biomarker data have the potential to predict long-term effects arising from prolonged drug exposure. Here, we used naproxen as a paradigm to explore the feasibility of a biomarker-guided approach for the prediction of long-term AEs in humans.

EXPERIMENTAL APPROACH

An experimental toxicology protocol was set up for evaluating the effects of naproxen in rats, in which four active doses were tested (7.5, 15, 40 and 80 mg·kg(-1) ). In addition to AE monitoring and histology, a few blood samples were also collected for the assessment of drug exposure, TXB2 and PGE2 levels. Non-linear mixed effects modelling was used to analyse the data and identify covariate factors on the incidence and severity of AEs.

KEY RESULTS

Modelling results showed that besides drug exposure, maximum PGE2 inhibition and treatment duration were also predictors of gastrointestinal ulceration. Although PGE2 levels were clearly linked to the incidence rates, it appeared that ulceration severity is better predicted by measures of drug exposure.

CONCLUSIONS AND IMPLICATIONS

These results show that the use of a model-based approach provides the opportunity to integrate pharmacokinetics, pharmacodynamics and toxicity data, enabling optimization of the design, analysis and interpretation of toxicology experiments.

Metformin does not reduce markers of cell proliferation in esophageal tissues of patients with Barrett's esophagus

BACKGROUND & AIMS

Obesity is associated with neoplasia, possibly via insulin-mediated cell pathways that affect cell proliferation. Metformin has been proposed to protect against obesity-associated cancers by decreasing serum insulin. We conducted a randomized, double-blind, placebo-controlled, phase 2 study of patients with Barrett's esophagus (BE) to assess the effect of metformin on phosphorylated S6 kinase (pS6K1), a biomarker of insulin pathway activation.

METHODS

Seventy-four subjects with BE (mean age, 58.7 years; 58 men [78%; 52 with BE >2 cm [70%]) were recruited through 8 participating organizations of the Cancer Prevention Network. Participants were randomly assigned to groups given metformin daily (increasing to 2000 mg/day by week 4, n = 38) or placebo (n = 36) for 12 weeks. Biopsy specimens were collected at baseline and at week 12 via esophagogastroduodenoscopy. We calculated and compared percent changes in median levels of pS6K1 between subjects given metformin vs placebo as the primary end point.

RESULTS

The percent change in median level of pS6K1 did not differ significantly between groups (1.4% among subjects given metformin vs -14.7% among subjects given placebo; 1-sided P = .80). Metformin was associated with an almost significant reduction in serum levels of insulin (median -4.7% among subjects given metformin vs 23.6% increase among those given placebo, P = .08) as well as in homeostatic model assessments of insulin resistance (median -7.2% among subjects given metformin vs 38% increase among those given placebo, P = .06). Metformin had no effects on cell proliferation (on the basis of assays for KI67) or apoptosis (on the basis of levels of caspase 3).

CONCLUSIONS

In a chemoprevention trial of patients with BE, daily administration of metformin for 12 weeks, compared with placebo, did not cause major reductions in esophageal levels of pS6K1. Although metformin reduced serum levels of insulin and insulin resistance, it did not discernibly alter epithelial proliferation or apoptosis in esophageal tissues. These findings do not support metformin as a chemopreventive agent for BE-associated carcinogenesis. ClinicalTrials.gov number, NCT01447927.

Importance of cyclooxygenase-1/prostacyclin in modulating gastric mucosal integrity under stress conditions

BACKGROUND AND AIM

We investigated the roles of cyclooxygenase (COX) isozymes and prostaglandins (PGs) and their receptors in mucosal defense against cold-restraint stress (CRS)-induced gastric lesions.

METHODS

Male C57BL/6 wild-type (WT) mice and those lacking COX-1 or COX-2 as well as those lacking EP1, EP3, or IP receptors were used after 18 h fasting. Animals were restrained in Bollman cages and kept in a cold room at 10°C for 90 min.

RESULTS

CRS induced multiple hemorrhagic lesions in WT mouse stomachs. The severity of these lesions was significantly worsened by pretreatment with the nonselective COX inhibitors (indomethacin, loxoprofen) or selective COX-1 inhibitor (SC-560), while neither of the selective COX-2 inhibitors (rofecoxib and celecoxib) had any effect. These lesions were also aggravated in animals lacking COX-1, but not COX-2. The expression of COX-2 mRNA was not detected in the stomach after CRS, while COX-1 expression was observed under normal and stressed conditions. The gastric ulcerogenic response to CRS was similar between EP1 or EP3 knockout mice and WT mice, but was markedly worsened in animals lacking IP receptors. Pretreating WT mice with iloprost (the PGI2 analog) significantly prevented CRS-induced gastric lesions in the presence of indomethacin. PGE2 also reduced the severity of these lesions, and the effect was mimicked by the EP4 agonist, AE1-329.

CONCLUSIONS

These results suggest that endogenous PGs derived from COX-1 play a crucial role in gastric mucosal defense during CRS, and this action is mainly mediated by PGI2 /IP receptors and partly by PGE2 /EP4 receptors.

Role of cyclooxygenase-2 in intestinal injury in neonatal rats

Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in premature neonates. The pathogenesis of NEC remains poorly understood. The present study aimed to investigate the dynamic change and role of cyclooxygenase-2 (COX-2) in neonatal rats with intestinal injury. Wistar rats, <24 h in age, received an intraperitoneal injection with 5 mg/kg lipopolysaccharide (LPS). Ileal tissues were collected at 1, 3, 6, 12 and 24 h following the LPS challenge for histological evaluation of NEC and for measurements of COX-2 mRNA. The correlation between the degree of intestinal injury and expression of COX-2 mRNA was determined. The LPS-injected pups showed a significant increase in injury scores compared to the control, and the most deteriorating change was at 12 h. COX-2 mRNA expression was upregulated following LPS injection. There was a significantly positive correlation between COX-2 mRNA and the grade of intestinal injury within 12 h, whereas COX-2 mRNA expression had a significantly negative correlation with the severity of intestinal injury at 24 h. COX-2 plays an important role in LPS-induced intestinal injury and the repair processes. Caution should be exerted concerning the potential therapeutic uses of COX-2 inhibitors or promoters in NEC.

At the bedside: Helicobacter pylori, dysregulated host responses, DNA damage, and gastric cancer

Clinical trials performed in populations at high GC risk have demonstrated that eradication of Helicobacter pylori from the stomach with a course of combination antimicrobials helps prevent gastric carcinogenesis when they are administered before precancerous lesions have yet developed. In this review, we consider the insights into H. pylori-associated gastric carcinogenesis that have been gained from these and many other clinical studies in the field to highlight priority areas for basic research and clinical investigation. Among these are defining the magnitude of the risk reduction that may be achieved in clinical practice and at a population level by H. pylori eradication and investigating when, during the slow multistep progression to GC, intervention will be of the most benefit. Additional strategies to prevent GC induced by H. pylori, including chemoprevention, dietary modification, and close endoscopic surveillance, may also have value in augmenting the risk reduction. Why only a small subpopulation of those infected by H. pylori go on to develop GC may be partially explained by genetic susceptibility related to SNPs in several genes regulating the intensity of the gastric inflammatory response to H. pylori. Investigation of the basic mechanisms underlying the promotion of GC by H. pylori and the associated inflammatory response will likely continue to improve clinical strategies for the prevention of one of the most common causes of cancer death globally. See related review, At the Bench: H. pylori, dysregulated host responses, DNA damage, and gastric cancer.

Role of cyclooxygenase-2 in gastric cancer development and progression

Although the incidence of gastric cancer has been declining in recent decades, it remains a major public health issue as the second leading cause of cancer death worldwide. In China, gastric cancer is still the main cause of death in patients with malignant tumors. Most patients are diagnosed at an advanced stage and mortality is high. Cyclooxygenase-2 (COX-2) is a rate-limiting enzyme in prostanoid synthesis and plays an important role in the development and progression of gastric cancer. The expression of COX-2 in gastric cancer is upregulated and its molecular mechanisms have been investigated. Helicobacter pylori infection, tumor suppressor gene mutation and the activation of nuclear factor-kappa B may be responsible for the elevated expression of COX-2 in gastric cancer. The mechanisms of COX-2 in the development and progression of gastric cancer are probably through promoting the proliferation of gastric cancer cells, while inhibiting apoptosis, assisting angiogenesis and lymphatic metastasis, and participating in cancer invasion and immunosuppression. This review is intended to discuss, comment and summarize recent research progress on the role of COX-2 in gastric cancer development and progression, and elucidate the molecular mechanisms which might be involved in the carcinogenesis.

Dillapiole, isolated from Peperomia pellucida, shows gastroprotector activity against ethanol-induced gastric lesions in Wistar rats

Peperomia pellucida is a plant used in traditional medicine to treat gastric ulcers. Although this gastroprotective activity was reported, the active compounds have not been identified. Therefore, the aim herein was to identify the most active compound in the gastroprotective activity of P. pellucida using an ethanol-induced gastric ulcer experimental rat model. A gastroprotective effect was observed when the hexane and dichloromethane extracts were tested, with the higher effect being obtained with the dichloromethane extract (82.3 ± 5.6%) at 100 mg/kg. Dillapiole was identified as the most active compound in this extract. Although there have been previous reports on dillapiole, this is the first on its gastroprotective activity. Rats treated with this compound at 3, 10, 30 and 100 mg/kg showed 23.1, 56.1, 73.2 and 85.5% gastroprotection, respectively. The effect elicited by dillapiole at 100 mg/kg was not attenuated by pretreatment with indomethacin (10 mg/kg, s.c.), a prostaglandin synthesis blocker, NG-nitro-l-arginine methyl ester (70 mg/kg, i.p.), a nitric oxide (NO) synthase inhibitor, or N-ethylmaleimide (10 mg/kg, s.c.), a blocker of sulfhydryl groups. This suggests that the gastroprotective mechanism of action of dillapiole does not involve prostaglandins, NO or sulfhydryl groups.

Impact of non-steroidal anti-inflammatory drugs on gastrointestinal cancers: current state-of-the science

Growing evidence from epidemiologic and preclinical studies suggests that nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of gastrointestinal (GI) cancers, including esophageal, gastric, pancreatic, colorectal cancer, and hepatocellular carcinoma. However, there is also evidence indicating the absence of this benefit. The exact mechanism of NSAIDs' action on GI tumors is not known. Although some studies have suggested inhibition of carcinogenesis by NSAIDs through suppression effect on inflammation-associated cyclooxygenase-2 (COX-2) expression, other studies have suggested COX-2-independent mechanisms. Herein, we summarize the current state of-the-science regarding NSAID benefit for patients with GI cancers.

ASP6537, a novel highly selective cyclooxygenase-1 inhibitor, exerts potent antithrombotic effect without "aspirin dilemma"

INTRODUCTION

Aspirin inhibits both the cyclooxygenase (COX)-1-dependent production of thromboxane A2 (TXA2) in platelets and COX-2-dependent production of anti-aggregatory prostaglandin I2 (PGI2) in vessel walls, resulting in "aspirin dilemma." Our objective is to investigate whether ASP6537 can overcome aspirin dilemma and exert a potent antithrombotic effect without a concurrent ulcerogenic effect.

METHODS

We evaluated the inhibitory effects of ASP6537 on recombinant human COX-1 (rhCOX-1) and rhCOX-2 activities using a COX-1/2 selectivity test. To determine whether ASP6537 induces aspirin dilemma, we examined the effects of ASP6537 on in vitro TXA2 and PGI2 metabolite production from platelets and isolated aorta of guinea pigs, and on plasma concentrations of TXA2 and PGI2 metabolites in aged rats. Finally, we evaluated the antithrombotic effects and ulcerogenic activity of ASP6537 using an electrically induced carotid arterial thrombosis model and a gastric ulcer model in guinea pigs.

RESULTS

The IC50 ratios of rhCOX-2 to rhCOX-1 for ASP6537 and aspirin were >142,000 and 1.63 fold, respectively. ASP6537 inhibited TXA2 production more selectively than aspirin in in vitro and in vivo TXA2/PGI2 production studies. ASP6537 exerted a significant antithrombotic effect at ≥3 mg/kg, while aspirin tended to inhibit thrombosis at 300 mg/kg but it was not statistically significant. Further, ASP6537 did not induce ulcer formation at 100 mg/kg, whereas aspirin exhibited an ulcerogenic effect at doses of ≥100 mg/kg.

CONCLUSIONS

ASP6537 functions as a highly selective COX-1 inhibitor with a superior ability to aspirin for normalizing TXA2/PGI2 balance, and exerts antithrombotic effect without ulcerogenic effect.

Hypolipidemic effect of ginger in 1,2-dimethyl hydrazine-induced experimental colon carcinogenesis

Colorectal cancer is increasingly common nowadays in Asian countries and still remains the second leading cause of cancer death in the United States. In our laboratory, we studied the chemopreventive and hypolipidemic effect of ginger, a dietary spice, in 1,2-dimethylhydrazine (DMH)-induced colon cancer. Rats were given a weekly subcutaneous injection of DMH (20 mg/kg body weight), a known colon carcinogen, in the groin for 15 weeks. Ginger (50 mg/kg body weight P.O.) was given at the initiation and also at the postinitiation stages of carcinogenesis. The animals were sacrificed at the end of the experimental period of 30 weeks. The fecal bile acids, neutral sterols, and tissue lipid profile were evaluated using various biochemical estimations. The levels of fecal bile acids, neutral sterols, cholesterol, HMG CoA reductase, free fatty acids, triglycerides, phospholipase A, and phospholipase C were significantly increased, whereas the levels of tissue phospholipids was decreased in DMH-treated rats as compared to control rats. On administering ginger at the initiation and also at the postinitiation stages of colon carcinogenesis, the levels of fecal bile acids, neutral sterols, tissue cholesterol, HMG CoA reductase, free fatty acids, triglycerides, phospholipase A, and phospholipase C were significantly decreased, whereas the levels of phospholipids were increased as compared to unsupplemented DMH treated rats. Thus, ginger supplementation was found to reduce the risk of colon cancer markedly by virtue of its hypolipidemic and antioxidative effects.

Managing the adverse effects of nonsteroidal anti-inflammatory drugs

Conventional medical treatment for rheumatoid arthritis and osteoarthritis includes the use of NSAIDs (traditional and selective inhibitors of cyclooxygenase [COX]-2), because they provide unmistakable and significant health benefits in the treatment of pain and inflammation. However, they are associated with an increased risk of serious gastrointestinal (GI) and cardiovascular (CV) adverse events. Both beneficial and adverse effects are due to the same mechanism of action, which is inhibition of COX-dependent prostanoids. Since CV and GI risk are related to drug exposure, a reduction in the administered dose is recommended. However, this strategy will not eliminate the hazard owing to a possible contribution of individual genetic background. Further studies will be necessary to develop genetic and/or biochemical markers predictive of the CV and GI risk of NSAIDs.