Differential Impact In Vivo of Pf4-ΔCre-Mediated and Gp1ba-ΔCre-Mediated Depletion of Cyclooxygenase-1 in Platelets in Mice

BACKGROUND

Low-dose aspirin is widely used for the secondary prevention of cardiovascular disease. The beneficial effects of low-dose aspirin are attributable to its inhibition of platelet Cox (cyclooxygenase)-1-derived thromboxane A2. Until recently, the use of the Pf4 (platelet factor 4) Cre has been the only genetic approach to generating megakaryocyte/platelet ablation of Cox-1 in mice. However, Pf4-ΔCre displays ectopic expression outside the megakaryocyte/platelet lineage, especially during inflammation. The use of the Gp1ba (glycoprotein 1bα) Cre promises a more specific, targeted approach.

METHODS

To evaluate the role of Cox-1 in platelets, we crossed Pf4-ΔCre or Gp1ba-ΔCre mice with Cox-1flox/flox mice to generate platelet Cox-1-/- mice on normolipidemic and hyperlipidemic (Ldlr-/-) backgrounds.

RESULTS

Ex vivo platelet aggregation induced by arachidonic acid or adenosine diphosphate in platelet-rich plasma was inhibited to a similar extent in Pf4-ΔCre Cox-1-/-/Ldlr-/- and Gp1ba-ΔCre Cox-1-/-/Ldlr-/- mice. In a mouse model of tail injury, Pf4-ΔCre-mediated and Gp1ba-ΔCre-mediated deletions of Cox-1 were similarly efficient in suppressing platelet prostanoid biosynthesis. Experimental thrombogenesis and attendant blood loss were similar in both models. However, the impact on atherogenesis was divergent, being accelerated in the Pf4-ΔCre mice while restrained in the Gp1ba-ΔCres. In the former, accelerated atherogenesis was associated with greater suppression of PGI2 biosynthesis, a reduction in the lipopolysaccharide-evoked capacity to produce PGE2 and PGD2, activation of the inflammasome, elevated plasma levels of IL-1β, reduced plasma levels of HDL-C, and a reduction in the capacity for reverse cholesterol transport. By contrast, in the latter, plasma HDL-C and α-tocopherol were elevated, and MIP-1α (macrophage inflammatory protein-1α) and MCP-1 (monocyte chemoattractant protein 1) were reduced.

CONCLUSIONS

Both approaches to Cox-1 deletion similarly restrain thrombogenesis, but a differential impact on Cox-1-dependent prostanoid formation by the vasculature may contribute to an inflammatory phenotype and accelerated atherogenesis in Pf4-ΔCre mice.

Preparation and Evaluation of 6-Gingerol Derivatives as Novel Antioxidants and Antiplatelet Agents

Ginger (Zingiber officinale) is widely used as a spice and a traditional medicine. Many bioactivities have been reported for its extracts and the isolated compounds, including cardiovascular protective effects. Different pathways were suggested to contribute to these effects, like the inhibition of platelet aggregation. In this study, we synthesised fourteen 6-gingerol derivatives, including eight new compounds, and studied their antiplatelet, COX-1 inhibitor, and antioxidant activities. In silico docking of selected compounds to h-COX-1 enzyme revealed favourable interactions. The investigated 6-gingerol derivatives were also characterised by in silico and experimental physicochemical and blood-brain barrier-related parameters for lead and preclinical candidate selection. 6-Shogaol (2) was identified as the best overall antiplatelet lead, along with compounds 3 and 11 and the new compound 17, which require formulation to optimize their water solubility. Compound 5 was identified as the most potent antioxidant that is also promising for use in the central nervous system (CNS).

Whole-Body PET Imaging in Humans Shows That 11C-PS13 Is Selective for Cyclooxygenase-1 and Can Measure the In Vivo Potency of Nonsteroidal Antiinflammatory Drugs

Both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) convert arachidonic acid to prostaglandin H₂, which has proinflammatory effects. The recently developed PET radioligand ¹¹C-PS13 has excellent in vivo selectivity for COX-1 over COX-2 in nonhuman primates. This study sought to evaluate the selectivity of ¹¹C-PS13 binding to COX-1 in humans and assess the utility of ¹¹C-PS13 to measure the in vivo potency of nonsteroidal antiinflammatory drugs. Methods: Baseline ¹¹C-PS13 whole-body PET scans were obtained for 26 healthy volunteers, followed by blocked scans with ketoprofen (n = 8), celecoxib (n = 8), or aspirin (n = 8). Ketoprofen is a highly potent and selective COX-1 inhibitor, celecoxib is a preferential COX-2 inhibitor, and aspirin is a selective COX-1 inhibitor with a distinct mechanism that irreversibly inhibits substrate binding. Because blood cells, including platelets and white blood cells, also contain COX-1, ¹¹C-PS13 uptake inhibition from blood cells was measured in vitro and ex vivo (i.e., using blood obtained during PET scanning). Results: High ¹¹C-PS13 uptake was observed in major organs with high COX-1 density, including the spleen, lungs, kidneys, and gastrointestinal tract. Ketoprofen (1-75 mg orally) blocked uptake in these organs far more effectively than did celecoxib (100-400 mg orally). On the basis of the plasma concentration to inhibit 50% of the maximum radioligand binding in the spleen (in vivo IC ₅₀), ketoprofen (<0.24 μM) was more than 10-fold more potent than celecoxib (>2.5 μM) as a COX-1 inhibitor, consistent with the in vitro potencies of these drugs for inhibiting COX-1. Blockade of ¹¹C-PS13 uptake from blood cells acquired during the PET scans mirrored that in organs of the body. Aspirin (972-1,950 mg orally) blocked such a small percentage of uptake that its in vivo IC ₅₀ could not be determined. Conclusion: ¹¹C-PS13 selectively binds to COX-1 in humans and can measure the in vivo potency of nonsteroidal antiinflammatory drugs that competitively inhibit arachidonic acid binding to COX-1. These in vivo studies, which reflect the net effect of drug absorption and metabolism in all organs of the body, demonstrated that ketoprofen had unexpectedly high potency, that celecoxib substantially inhibited COX-1, and that aspirin acetylation of COX-1 did not block binding of the representative nonsteroidal inhibitor ¹¹C-PS13.

Expression of Transcript Variants of PTGS1 and PTGS2 Genes among Patients with Chronic Rhinosinusitis with Nasal Polyps

To date, there has been no reliable test to identify unfavorable course of Chronic Rhinosinusitis with Nasal Polyps (CRSwNP), especially in aspirin intolerant patients. The research aimed to analyze the expression of transcript variants of PTGS1 and PTGS2 genes in the pathobiology of the disease. The study was performed on 409 adult patients: 206 CRSwNP patients including 44 (21.36%) aspirin intolerant patients and 203 healthy volunteers in the control group. Transcript variants of the PTGS1 and PTGS2 genes named as follows: COX1.1 for NM_000962, COX1.2 for NM_080591, COX1.3 for NM_001271165.1, COX1.4 for NM_001271368.1, COX1.5 for NM_001271166.1, COX2.1 for NM_000963.3, COX2.2 for AY_151286 and COX2.3 for BQ_722004 were confirmed using direct sequencing and quantified using targeted qPCR. The coexistence of all examined transcript variants in the study and the control group and significant differences between both were found. In aspirin sensitive patients, the levels of COX1.2, COX1.3, COX1.4 and COX1.5 isoforms were higher compared to aspirin-tolerant patients. The severity of symptoms was bigger in patients with higher expressions of variants: COX1.1 (R with dCt = −0.134; p = 0.0490), COX1.3 (R = −0.1429; p = 0.0400) and COX1.5 (Rs = −0.1499; p = 0.032). The expression of COX1.1 (Rs = −0.098; p = 0.049) and COX1.5 (Rs = −0.141; p = 0.043) isoforms increased with polyposis advancement in endoscopy. With the CT extent of sinuses opacification, COX1.1 isoform also significantly increased (Rs = −0.163; p = 0.020). The isoforms COX1.3, COX1.4, COX1.5 and COX2.1 may promote milder CRSwNP course. On the contrary, the variants COX1.1, COX1.2 and COX2.2 may be involved in a more aggressive disease.

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

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

Evaluation of Two Potent and Selective PET Radioligands to Image COX-1 and COX-2 in Rhesus Monkeys

This study assessed whether the newly developed PET radioligands ¹¹C-PS13 and ¹¹C-MC1 could image constitutive levels of cyclooxygenase (COX)-1 and COX-2, respectively, in rhesus monkeys. Methods: After intravenous injection of either radioligand, 24 whole-body PET scans were performed. To measure enzyme-specific uptake, scans of the 2 radioligands were also performed after administration of a nonradioactive drug preferential for either COX-1 or COX-2. Concurrent venous samples were obtained to measure parent radioligand concentrations. SUVs were calculated from 10 to 90 min. Results: ¹¹C-PS13 showed specific uptake in most organs, including spleen, gastrointestinal tract, kidneys, and brain, which was blocked by COX-1, but not COX-2, preferential inhibitors. Specific uptake of ¹¹C-MC1 was not observed in any organ except the ovaries and possibly kidneys. Conclusion: The findings suggest that ¹¹C-PS13 has adequate signal in monkeys to justify its extension to human subjects. In contrast, ¹¹C-MC1 is unlikely to show significant signal in healthy humans, though it may be able to do so in inflammatory conditions.

Prostaglandin E2 Is Required for BMP4-Induced Mesoderm Differentiation of Human Embryonic Stem Cells

The accurate control of early cell fate specification during differentiation of human embryonic stem cells (hESCs) is critical for acquiring pure therapeutic cell populations of interest. Bone morphogenetic protein 4 (BMP4) is a key mesoderm inducer from ESCs. However, the molecular mechanism of the mesodermal cell fate decision induced by BMP4 remains unclear. Here, we demonstrate the requirement of a bioactive lipid, prostaglandin E₂ (PGE₂), for the mesoderm specification from hESCs by BMP4 induction. We show that BMP4 directly regulates the expression of the key enzyme for PGE₂ synthesis, COX-1, and promotes PGE₂ production. More importantly, in the absence of BMP4, forced COX-1 expression or PGE₂ treatment is sufficient to initiate mesoderm specification of hESCs by activation of EP2-PKA signaling and modulation of nuclear translocation of β-catenin. Together, our findings provide insights into the critical role of BMP regulation of PGE₂ synthesis and its downstream signaling in initiating mesoderm commitment of hESCs.

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COX-1 and PGE₂ played pivotal roles in the mesoderm specification of hESCs

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Specific inhibition of COX-1 suppressed mesoderm differentiation of hESCs

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BMP4 directly upregulated the transcription of the COX-1

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PGE₂ stimulated differentiation mainly via the EP2-PKA-GSK3β/β-catenin signaling pathway

Aspirin and Cancer

The place of aspirin in primary prevention remains controversial, with North American and European organizations issuing contradictory treatment guidelines. More recently, the U.S. Preventive Services Task Force recommended "initiating low-dose aspirin use for the primary prevention of cardiovascular disease (CVD) and colorectal cancer in adults aged 50 to 59 years who have a 10% or greater 10-year CVD risk, are not at increased risk for bleeding, have a life expectancy of at least 10 years, and are willing to take low-dose aspirin daily for at least 10 years." This recommendation reflects increasing evidence for a chemopreventive effect of low-dose aspirin against colorectal (and other) cancer. The intent of this paper is to review the evidence supporting a chemopreventive effect of aspirin, discuss its potential mechanism(s) of action, and provide a conceptual framework for assessing current guidelines in the light of ongoing studies.

Highly Selective Cyclooxygenase-1 Inhibitors P6 and Mofezolac Counteract Inflammatory State both In Vitro and In Vivo Models of Neuroinflammation

Activated microglia secrete an array of pro-inflammatory factors, such as prostaglandins, whose accumulation contributes to neuronal damages. Prostaglandin endoperoxide synthases or cyclooxygenases (COX-1 and COX-2), which play a critical role in the inflammation, are the pharmacological targets of non-steroidal anti-inflammatory drugs, used to treat pain and inflammation. Since it was reported that COX-1 is the major player in mediating the brain inflammatory response, the aim of this study was to evaluate the effects of highly selective COX-1 inhibitors, such as P6 and mofezolac, in neuroinflammation models. Lipopolysaccharide (LPS)-activated mouse BV-2 microglial cells and LPS intracerebroventricular-injected mice as in vitro and in vivo neuroinflammation models, respectively, were used to probe the antiinflammatory efficacy of P6 and mofezolac. Both P6 and mofezolac reduce COX-1 expression in LPS-activated BV-2 cells. This reduction was accompanied with PGE₂ release reduction and NF-kB activation downregulation. Coextensively, in the in vivo model, both glial fibrillary acidic protein and ionized calcium-binding adapter molecule-1 expression, two markers of inflammation, were reduced by mofezolac to a rank depending on the encephalon area analyzed. The increase of COX-1 expression observed in all the brain sections of LPS-treated mice was selectively downregulated by the in vivo treatment with mofezolac as well as PGE₂ release and Ikβα phosphorylation amount assayed in the brain areas tested. These results indicate the capability of P6 and mofezolac to modulate the NF-kB signaling pathway, emphasizing the neuroprotective effect and therapeutic potential of COX-1 inhibitors in the control of neuroinflammatory diseases.

Blueberries inhibit cyclooxygenase-1 and cyclooxygenase-2 activity in human epithelial ovarian cancer

Ovarian cancer (OC) is the sixth and eighth leading cause of cancer mortality among women in developed and developing countries, respectively. Medical therapy is the main method for the treatment of OC. However, drug toxicity and the marked side effects of chemotherapy limit the usage and therapeutic results of the treatments. Therefore, the identification of multi-target agents with few side effects and high effectiveness is required. Traditional Chinese medicine has been used clinically to treat various types of cancer for thousands of years and is considered to possess multiple components and agents, which exert efficient therapeutic functions with few side effects. Although blueberries have previously been used to treat various types of cancer, the effect on OC and precise molecular mechanism of function of the fruit remains unknown. Cyclooxygenase (COX)-1 and COX-2 have been reported to be the biomarkers of OC. Blueberries may affect the progression of OC by affecting COX levels. To investigate the issue, COX-1 and COX-2 were overexpressed or silenced in ovarian cancer SKOV3 cells. The effect of blueberries on SKOV3 cell viability was determined by an MTT assay. Furthermore, a mouse model for OC was established. The results indicated that blueberries inhibited the proliferation of OC cells by downregulating the levels of COX-1 and COX-2. Blueberry (400 mg daily) consumption reduced tumor size significantly in mice with OC compared with the control without blueberry treatment (P<0.05). The results suggest that blueberries should be used to develop a potential non-pharmaceutical therapy for OC.

Patient-independent variables affecting the assessment of aspirin responsiveness by serum thromboxane measurement

The serum TXB₂ (sTXB₂) assay reflects the pharmacodynamics of platelet inhibition by low-dose aspirin. However, different studies reported variable sTXB₂ values. sTXB₂ assay requires whole blood incubation at 37 °C as a condition for optimal thrombin generation, arachidonic acid release and its metabolism by platelet cyclooxygenase-1 to form TXA₂. Access to 37 °C incubation may be variably delayed, and different methods to quantitate sTXB₂ may contribute to variable results between different Centers. We investigated whether delaying 37 °C incubation and/or analytical issues affect sTXB₂ concentrations, biasing the assessment of aspirin responsiveness. Sixty-eight samples from 54 volunteers, on- and off-aspirin, were incubated at 37 °C immediately after sampling (reference sample) or after 5, 10, 15, 20, 30 or 60 minutes at room temperature (RT); 8 samples remained at RT 60 minutes, without subsequent incubation; 314 sera were measured by enzyme immunoassay (EIA) and liquid chromatography-tandem mass-spectrometry (LC/MS-MS) methods. sTXB₂ concentrations decreased exponentially as a function of the delay before 37 °C incubation, ranging from 94 ± 11 % at 5 minutes to 23 ± 22 % of the reference sample after 60 minutes at RT. There was high agreement between EIA and LC/MS-MS. Moreover, we simulated the influence of a 15- or 30-minute delayed incubation on 300 sTXB2 measurements from previously-studied, aspirin-treated patients. Delayed incubation reduced the percentage of aspirin 'non-responders' by 22 % to 52 %, depending on the response threshold. In conclusion, a variable delay in the 37 °C incubation of blood samples may affect the assessment of platelet cyclooxygenase-1 inhibition by aspirin and confound the characterization of the determinants of aspirin responsiveness.

Aberrant over-expression of COX-1 intersects multiple pro-tumorigenic pathways in high-grade serous ovarian cancer

Cyclooxygenase-1 (COX-1) is implicated in ovarian cancer. However, patterns of COX expression and function have been unclear and controversial. In this report, patterns of COX-1 and COX-2 gene expression were obtained from RNA-seq data through The Cancer Genome Atlas. Our analysis revealed markedly higher COX-1 mRNA expression than COX-2 in high-grade serous ovarian cancers (HGSOC) and higher COX-1 expression in HGSOC tumors than 10 other tumor types. High expression of COX-1 in HGSOC tumors was confirmed in an independent tissue microarray. In contrast, lower or similar expression of COX-1 compared to COX-2 was observed in endometrioid, mucinous and clear cell tumors. Stable COX-1 knockdown in HGSOC-representative OVCAR-3 ovarian cancer cells reduced gene expression in multiple pro-tumorigenic pathways. Functional cell viability, clonogenicity, and migration/invasion assays were consistent with transcriptomic changes. These effects were reversed by stable over-expression of COX-1 in SKOV-3 cells. Our results demonstrate a distinct pattern of COX-1 over-expression in HGSOC tumors and strong association of COX-1 with multiple pro-tumorigenic pathways in ovarian cancer cells. These findings provide additional insight into the role of COX-1 in human ovarian cancer and support further development of methods to selectively target COX-1 in the management of HGSOC tumors.

The Effect of Cadmium on COX-1 and COX-2 Gene, Protein Expression, and Enzymatic Activity in THP-1 Macrophages

The aim of this study was to examine the effects of cadmium in concentrations relevant to those detected in human serum on cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) expression at mRNA, protein, and enzyme activity levels in THP-1 macrophages. Macrophages were incubated with various cadmium chloride (CdCl2) solutions for 48 h at final concentrations of 5 nM, 20 nM, 200 nM, and 2 μM CdCl2. The mRNA expression and protein levels of COXs were analyzed with RT-PCR and Western blotting, respectively. Prostaglandin E2 (PGE2) and stable metabolite of thromboxane B2 (TXB2) concentrations in culture media were determined using ELISA method. Our study demonstrates that cadmium at the highest tested concentrations modulates COX-1 and COX-2 at mRNA level in THP-1 macrophages; however, the lower tested cadmium concentrations appear to inhibit COX-1 protein expression. PGE2 and TXB2 production is not altered by all tested Cd concentrations; however, the significant stimulation of PGE2 and TXB2 production is observed when macrophages are exposed to both cadmium and COX-2 selective inhibitor, NS-398. The stimulatory effect of cadmium on COXs at mRNA level is not reflected at protein and enzymatic activity levels, suggesting the existence of some posttranscriptional, translational, and posttranslational events that result in silencing of those genes' expression.

Effect of common single nucleotide polymorphisms in COX-1 gene on related metabolic activity in diabetic patients treated with acetylsalicylic acid

INTRODUCTION

The objective of this study was to investigate the effect of common single nucleotide genomic polymorphisms in the cyclooxygenase-1 (COX-1) gene on the thromboxane A2 (TxA2) metabolite concentrations in serum and urine, as well as on prostaglandin F2α (PGF2α) urinary excretion in the diabetic population on acetylsalicylic acid (ASA) therapy.

MATERIAL AND METHODS

The study cohort consisted of 284 Caucasians with diabetes type 2 who had been taking ASA tablets at the dose of 75 mg/day for at least 3 months. Genotyping for the 4 selected SNPs within the COX-1 gene (two nonsynonymous-coding variants, rs3842787 [C50T, P17L] and rs5789 [C174A, L237M]; and two other synonymous SNPs, rs3842788 [G128A, Q41Q] and rs5788 [C644A]) was performed using the Sequenom iPLEX platform.

RESULTS

No statistically significant results were observed for the investigated SNPs and measured metabolites in the investigated cohort of patients. Statistically significant differences in S-TxB2 could however be observed for rs5788 in the subgroup of patients with very high S-TxB2 concentrations. In particular, more patients who were carriers of the minor allele for this polymorphism were observed in the group with S-TxB2 levels > 95(th) percentile, when compared with similar carriers in the group with S-TxB2 < 95(th) percentile (20% vs. 1.1%, respectively, p < 0.001, Mann-Whitney test).

CONCLUSIONS

The results of our study suggest that the four investigated common SNPs in the COX1 gene are not associated with obviously altered TxA2 metabolism and PGF2α synthesis in the investigated diabetic cohort treated with ASA.

Current concepts in colorectal cancer prevention with cyclooxygenase inhibitors

Colorectal cancer is one of the commonest malignancies worldwide. Recently, there has been much speculation regarding the role of cyclooxygenase-2 (COX-2) suppression in chemoprevention. Drugs with the ability to inhibit COX-2 expression include aspirin, nonsteroidal anti-inflammatory drugs (NSAID) and selective COX-2 inhibitors. Any strategy for chemoprevention must be able to quantify how effective the potential treatment is likely to be and which drugs will be most useful. We would also need to know for how long the agent could be taken safely and if any side-effects could preclude long-term use. Evidence from observational studies and recent updates of randomised controlled trials have been very encouraging - at least indicating benefit from the long term use of aspirin, even at low dose, with greatest impact on prevention of proximal colon cancers and adenomas. Most studies do, however, also warn that risks of gastrointestinal bleeding increase with long-term use of aspirin and related drugs. The risk-to-benefit ratio of a chemoprevention regimen using these medications needs to be carefully examined.

Intratracheal administration of cyclooxygenase-1-transduced adipose tissue-derived stem cells ameliorates monocrotaline-induced pulmonary hypertension in rats

The effect of intratracheal administration of cyclooxygenase-1 (COX-1)-modified adipose stem cells (ASCs) on monocrotaline-induced pulmonary hypertension (MCT-PH) was investigated in the rat. The COX-1 gene was cloned from rat intestinal cells, fused with a hemagglutanin (HA) tag, and cloned into a lentiviral vector. The COX-1 lentiviral vector was shown to enhance COX-1 protein expression and inhibit proliferation of vascular smooth muscle cells without increasing apoptosis. Human ASCs transfected with the COX-1 lentiviral vector (ASCCOX-1) display enhanced COX-1 activity while exhibiting similar differentiation potential compared with untransduced (native) ASCs. PH was induced in rats with MCT, and the rats were subsequently treated with intratracheal injection of ASCCOX-1 or untransduced ASCs. The intratracheal administration of ASCCOX-1 3 × 10(6) cells on day 14 after MCT treatment significantly attenuated MCT-induced PH when hemodynamic values were measured on day 35 after MCT treatment whereas administration of untransduced ASCs had no significant effect. These results indicate that intratracheally administered ASCCOX-1 persisted for at least 21 days in the lung and attenuate MCT-induced PH and right ventricular hypertrophy. In addition, vasodilator responses to the nitric oxide donor sodium nitroprusside were not altered by the presence of ASCCOX-1 in the lung. These data emphasize the effectiveness of ASCCOX-1 in the treatment of experimentally induced PH.

Reappraisal of the clinical pharmacology of low-dose aspirin by comparing novel direct and traditional indirect biomarkers of drug action

BACKGROUND

Even though the acetylation of platelet cyclooxygenase (COX)-1 at serine-529 is the direct mechanism of action of low-dose aspirin, its antiplatelet effect has been characterized using indirect indexes of COX-1 activity.

OBJECTIVES

We performed a clinical study with enteric-coated low-dose aspirin (EC-aspirin), in healthy subjects, to evaluate the effects on the extent and duration of platelet COX-1 acetylation, using a novel proteomic strategy for absolute protein quantification (termed AQUA), as compared with traditional pharmacokinetic and pharmacodynamic parameters.

SUBJECTS AND METHODS

In a phase I, single-arm, open-label study of EC aspirin (100 mg day(-1) ) administered to 24 healthy subjects, we compared, over a 24 h-period on day 1 and 7, % platelet acetylated COX-1 (AceCOX-1) with traditional pharmacokinetic and pharmacodynamics [i.e. serum thromboxane (TX) B2 , platelet function by monitoring CEPI(collagen/epinephrine) closure time (CT) using whole-blood PFA-100 and urinary excretion of 11-dehydro-TXB2 ] parameters.

RESULTS

Acetylation of platelet COX-1 was measurable before detection of aspirin levels in the systemic circulation and increased in a cumulative fashion upon repeated dosing. After the last dose of EC-aspirin, %AceCOX-1, serum TXB2 and CEPI-CT values were maximally and persistently modified throughout 24 h; they averaged 76 ± 2%, 99.0 ± 0.4% and 271 ± 5 s, respectively. EC-aspirin caused 75% reduction in urinary 11-dehydro-TXB2 excretion. After chronic dosing with aspirin, the pharmacokinetics of acetylsalicylic acid was completely dissociated from pharmacodynamics.

CONCLUSIONS

The demonstrated feasibility of quantifying the extent and duration of platelet COX-1 acetylation will allow characterizing the genetic, pharmacokinetic and pharmacodynamic determinants of the inter-individual variability in the antiplatelet response to low-dose aspirin as well as identifying extra-platelet sites of drug action.

Inhibition of COX-2 and PGE2 in LPS-stimulated RAW264.7 cells by lonimacranthoide VI, a chlorogenic acid ester saponin

Lonimacranthoide VI, first isolated from the flower buds of Lonicera macranthoides in our previous study, is a rare chlorogenic acid ester acylated at C-23 of hederagenin. In the present study, the anti-inflammatory effects of lonimacranthoide VI were studied. Lipopolysaccharides (LPS) induced an inflammatory response through the production of prostaglandin E₂ (PGE₂), and these levels were reduced when lonimacranthoide VI was pre-administered. Additionally, the mechanism of the anti-inflammatory effects of lonimacranthoide VI was investigated by measuring cyclooxygenase (COX) activity and mRNA expression. The results showed that lonimacranthoide VI inhibited mRNA expression and in vitro activity of COX-2 in a dose-dependent manner, whereas only the higher lonimacranthoide VI concentration possibly reduced COX-1 expression and in vitro activity. Taken together, these results indicate that lonimacranthoide VI is an important anti-inflammatory constituent of Lonicera macranthoides and that the anti-inflammatory effect is attributed to the inhibition of PGE₂ production through COX activity and mRNA expression.

Pharmacokinetics and pharmacodynamics of acetylsalicylic acid after intravenous and oral administration to healthy volunteers

Background

The pharmacology of single doses of acetylsalicylic acid (ASA) administered intravenously (250 or 500 mg) or orally (100, 300, or 500 mg) was evaluated in a randomized, placebo-controlled, crossover study.

Methods

Blood and urine samples were collected before and up to 24 hours after administration of ASA in 22 healthy volunteers. Pharmacokinetic parameters and measurements of platelet aggregation were determined using validated techniques.

Results

A comparison between administration routes showed that the geometric mean dose-corrected peak concentrations (C_max/D) and the geometric mean dose-corrected area under the curve (AUC_0–∞/D) were higher following intravenous administration of ASA 500 mg compared with oral administration (estimated ratios were 11.23 and 2.03, respectively). Complete inhibition of platelet aggregation was achieved within 5 minutes with both intravenous ASA doses, reflecting a rapid onset of inhibition that was not observed with oral dosing. At 5 minutes after administration, the mean reduction in arachidonic acid-induced thromboxane B₂ synthesis ex vivo was 99.3% with ASA 250 mg intravenously and 99.7% with ASA 500 mg intravenously. In exploratory analyses, thromboxane B₂ synthesis was significantly lower after intravenous versus oral ASA 500 mg (P<0.0001) at each observed time point up to the first hour after administration. Concentrations of 6-keto-prostaglandin_1α at 5 and 20 minutes after dosing were also significantly lower with ASA 500 mg intravenously than with ASA 500 mg orally.

Conclusion

This study demonstrates that intravenous ASA provides more rapid and consistent platelet inhibition than oral ASA within the first hour after dosing.

Effectiveness and tolerance of anti-inflammatory drugs' add-on therapy in major mental disorders: a systematic qualitative review

OBJECTIVE

To provide a systematic review of the literature regarding the efficacy of anti-inflammatory drugs in three major mental disorders [major depressive disorder (MDD), schizophrenia and bipolar disorders].

METHOD

Four databases were explored, without any year or language restrictions. The baseline search paradigm was limited to open-labelled clinical and randomized controlled trials (RCTs).

RESULTS

Four major classes of anti-inflammatory drugs were identified, namely polyunsaturated fatty acids (PUFAs), cyclooxygenase (COX) inhibitors, anti-TNFalpha and minocycline. Effectiveness and benefit/risk ratio of each class in MDD, bipolar disorders and schizophrenia was detailed when data were available. Several meta-analyses indicated effectiveness of PUFAs in MDD with a good tolerance profile. One meta-analysis indicated that COX-2 specific inhibitors showed effectiveness in schizophrenia. Anti-TNFalpha showed important effectiveness in resistant MDD with blood inflammatory abnormalities. Minocycline showed effectiveness in schizophrenia.

CONCLUSION

Polyunsaturated fatty acids seem to have the best benefit/risk ratio profile but proved their effectiveness only in MDD. A number of anti-inflammatory drugs are available as adjunct treatment for treatment-resistant patients with MDD, schizophrenia and bipolar disorder. If used with caution regarding their possible side-effects, they may be reasonable therapeutic alternatives for resistant symptomatology.

The Role of Cyclooxygenase-1 and -2 in Sevoflurane-Induced Postconditioning Against Myocardial Infarction

Cyclooxygenase (COX)-2 mediates ischemic pre- and postconditioning as well as anesthetic-induced preconditioning. However, the role of COX-1 and -2 in anesthetic-induced postconditioning has not been investigated. We evaluated the role of COX-1 and -2 in sevoflurane-induced postconditioning in vivo. Pentobarbital-anaesthetized male C57BL/6 mice were subjected to 45 minutes of coronary artery occlusion and 3 hours of reperfusion. Animals received either no intervention, the vehicle dimethyl sulfoxide (DMSO, 10 µL/g intraperitoneally), acetylsalicylic acid (ASA, 5 µg/g intraperitoneally), the selective COX-1 inhibitor SC-560 (10 µg/g intraperitoneally), or the selective COX-2 inhibitor NS-398 (5 µg/g intraperitoneally). 1.0 MAC (minimum alveolar concentration) sevoflurane was administered for 18 minutes during early reperfusion either alone or in combination with ASA, SC-560, and NS-398. Infarct size was determined with triphenyltetrazolium chloride. Statistical analysis was performed using 1-way and 2-way analyses of variance with post hoc Duncan testing. The infarct size in the control group was 44% ± 9%. DMSO (42% ± 7%), ASA (36% ± 6%), and NS-398 (44% ± 18%) had no effect on infarct size. Sevoflurane (17% ± 4%; P < .05) and SC-560 (26% ± 10%; P < .05) significantly reduced the infarct size compared with control condition. Sevoflurane-induced postconditioning was not abolished by ASA (16% ± 5%) and SC-560 (22% ± 4%). NS-398 abolished sevoflurane-induced postconditioning (33% ± 14%). It was concluded that sevoflurane induces postconditioning in mice. Inhibition of COX-1 elicits a myocardial infarct size reduction and does not abolish sevoflurane-induced postconditioning. Blockade of COX-2 abolishes sevoflurane-induced postconditioning. These results indicate that sevoflurane-induced postconditioning is mediated by COX-2.

The role of pro-inflammatory cytokines in the neuroinflammation and neurogenesis of schizophrenia

Schizophrenia is a serious mental illness with chronic symptoms and significant impairment in psychosocial functioning. Although novel antipsychotics have been developed, the negative and cognitive symptoms of schizophrenia are still unresponsive to pharmacotherapy. The high level of social impairment and a chronic deteriorating course suggest that schizophrenia likely has neurodegenerative characteristics. Inflammatory markers such as pro-inflammatory cytokines are well-known etiological factors for psychiatric disorders, including schizophrenia. Inflammation in the central nervous system is closely related to neurodegeneration. In addition to pro-inflammatory cytokines, microglia also play an important role in the inflammatory process in the CNS. Uncontrolled activity of pro-inflammatory cytokines and microglia can induce schizophrenia in tandem with genetic vulnerability and glutamatergic neurotransmitters. Several studies have investigated the possible effects of antipsychotics on inflammation and neurogenesis. Additionally, anti-inflammatory adjuvant therapy has been under investigation as a treatment option for schizophrenia. Further studies should consider the confounding effects of systemic factors such as metabolic syndrome and smoking. In addition, the unique mechanisms by which pro-inflammatory cytokines are involved in the etiopathology of schizophrenia should be investigated. In this article, we aimed to review (1) major findings regarding neuroinflammation and pro-inflammatory cytokine alterations in schizophrenia, (2) interactions between neuroinflammation and neurogenesis as possible neural substrates for schizophrenia, and (3) novel pharmacological approaches.

A prospective, randomized, double-blind, multicenter comparative study on the safety and efficacy of Celecoxib and GCSB-5, dried extracts of six herbs, for the treatment of osteoarthritis of knee joint

ETHNOPHARMACOLOGICAL RELEVANCE

This prospective, randomized, double-blind, multicenter study compared the efficacy and safety of Celecoxib and GCSB-5, a new product from extracts of six herbs, for the treatment of knee osteoarthritis.

MATERIALS AND METHODS

A total of 198 eligible patients were randomly assigned to the Celecoxib group (n=99 patients) or the GCSB-5 group (n=99 patients) for the 12-week study. The amount of change and percentage of the change in Western Ontario and McMaster Universities (WOMAC) Arthritis Index from the baseline, the change in pain on walking by visual analogue scale (VAS), physician's global assessment on response to therapy (PGART) by five point Likert scale, and the amount of rescue medicine taken were used as parameters for efficacy. Adverse drug reactions (ADRs) were carefully investigated.

RESULTS

The WOMAC score improved in both the Celecoxib group and GCSB-5 group by 20.5 and 21.3 (P=0.79). The percentage of the change in WOMAC score were -42.0% and -38.9% (P=0.54). The pain VAS score decreased by 29.9 and 27.9 (P=0.58). The responders by PGART were 95.3% and 93.8% (P= 0.66), and the median amount of rescue medicine taken were 2.0 and 6.5 tablets (P=0.06). The incidence of ADRs were 31.3% and 21.2% (P=0.11). The most common ADRs were gastrointestinal system related; 17.2% in GCSB-5 group and 22.2% in Celecoxib group. Any severe ADR was not observed in either group.

CONCLUSIONS

The result of this study supports that GCSB-5 is comparable to Celecoxib in terms of the efficacy and safety for the treatment of osteoarthritis of knee joint.

Characterization of a cellular denitrase activity that reverses nitration of cyclooxygenase

Protein 3-nitrotyrosine (3-NT) formation is frequently regarded as a simple biomarker of disease, an irreversible posttranslational modification that can disrupt protein structure and function. Nevertheless, evidence that protein 3-NT modifications may be site selective and reversible, thus allowing for physiological regulation of protein activity, has begun to emerge. We have previously reported that cyclooxygenase (COX)-1 undergoes heme-dependent nitration of Tyr(385), an internal and catalytically essential residue. In the present study, we demonstrate that nitrated COX-1 undergoes a rapid reversal of nitration by substrate-selective and biologically regulated denitrase activity. Using nitrated COX-1 as a substrate, denitrase activity was validated and quantified by analytic HPLC with electrochemical detection and determined to be constitutively active in murine and human endothelial cells, macrophages, and a variety of tissue samples. Smooth muscle cells, however, contained little denitrase activity. Further characterizing this denitrase activity, we found that it was inhibited by free 3-NT and may be enhanced by endogenous nitric oxide and exogenously administered carbon monoxide. Finally, we describe a purification protocol that results in significant enrichment of a discrete denitrase-containing fraction, which maintains activity throughout the purification process. These findings reveal that nitrated COX-1 is a substrate for a denitrase in cells and tissues, implying that the reciprocal processes of nitration and denitration may modulate bioactive lipid synthesis in the setting of inflammation. In addition, our data reveal that denitration is a controlled process that may have broad importance for regulating cell signaling events in nitric oxide-generating systems during oxidative/nitrosative stress.

Role of linoleic Acid hydroperoxide preformed by cyclooxygenase-1 or -2 on the regulation of prostaglandin formation from arachidonic Acid by the respective enzyme

Linoleic acid (LA) preincubated with cyclooxygenase (COX)-1 or -2 inhibited prostaglandin (PG) formation from arachidonic acid (AA) catalyzed by the respective enzyme, but LA without the preincubation did not. 13S-Hydroperoxy-9Z,11E-octadecadienoic acid (13-HPODE) a hydroperoxy adduct of LA inhibited PG formation catalyzed by COX-1 or -2. 13S-Hydroxy-9Z,11E-octadecadienoic acid had no effect on both COX-1 and -2 activities. These results suggest that 13-HPODE which is preformed from LA by COX reaction under normal physiological conditions can be a basal suppressor of PG formation from AA.

Chemopreventive effect of celecoxib and expression of cyclooxygenase-1 and cyclooxygenase-2 on chemically-induced rat mammary tumours

We investigated the chemopreventive effect of celecoxib on 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary tumours and also the expression and immunolocalization of cyclooxygenase-1 (COX-1) and COX-2 in the various stages of rat mammary carcinogenesis. Rats were divided into normal control group, DMBA-control group, 500 p.p.m. celecoxib-treated group, and 1500 p.p.m. celecoxib-treated group. Both incidence and multiplicity values of tumour for rats treated with celecoxib were less than those in rats of the DMBA-control group. The level of prostaglandin E2 was higher in tumours of the DMBA-control and both celecoxib-treated groups compared to normal mammary glands of each group. In Western blot analysis, all tumours of the DMBA-control group expressed COX-1, whereas normal mammary glands showed insignificant expression. COX-2 expression was observed in 67% of the DMBA-control group and 20% of both celecoxib-treated groups and was absent in normal mammary glands. COX-1 protein was localized in the nuclear membrane and cytoplasm of epithelial tumour cells abutting on glandular lumen, stromal cells, and endothelial cells. COX-2 protein was detected in the perinuclear cytoplasm of tumour cells bordering on glandular lumen and surrounding stroma, stromal cells, and vascular smooth muscle. In the DMBA-control group, invasive carcinoma cells showed higher positive immunoreactivity of COX-2 than carcinomas in situ and atypical tumours. Tumours displayed an increased number of mast-like cells with COX-2 expression in comparison to carcinomas in situ. Our results suggest that COX-1 and COX-2 expression in tumour cells and stromal cells play an important role in the various stages of DMBA-induced rat mammary carcinogenesis. In addition, we reconfirm that celecoxib reduces the growth of DMBA-induced rat mammary tumours.