Expression and activity of prostaglandin endoperoxide synthase-2 in agonist-activated human neutrophils

Effect of Cannabidiol on Cyclooxygenase Type 1 and 2 Expression and Function in Human Neutrophils

Introduction: In this study, the effects of the cannabinoid CBD were assessed on cyclooxygenase (COX)-1 and COX-2 expression and activity in resting and activated human neutrophils (polymorphonuclear [PMN] leukocytes). Methods: COX expression was measured at the mRNA levels, whereas COX activity was assessed by enzyme-linked immunosorbent assay measurement of prostaglandin (PG)E2. In vitro experiments in a standard commercial acellular assay of COX-1/COX-2 activity completed the study. Results: Results show that CBD profoundly inhibits expression of COX-1 and COX-2 mRNA in activated PMN, however, without any significant consequences for PGE2 production. CBD, however, was able to induce a slight but significant direct inhibition of COX-2 in the acellular model. Conclusion: The effects of CBD occur in the μM concentration range, which is attained in humans with therapeutic doses of the drug, suggesting the clinical relevance of these findings.

Local shifts in inflammatory and resolving lipid mediators in response to tendon overuse

Tendon inflammation has been implicated in both adaptive connective tissue remodeling and overuse-induced tendinopathy. Lipid mediators control both the initiation and resolution of inflammation, but their roles within tendon are largely unknown. Here, we profiled local shifts in intratendinous lipid mediators via liquid chromatography-tandem mass spectrometry in response to synergist ablation-induced plantaris tendon overuse. Sixty-four individual lipid mediators were detected in homogenates of plantaris tendons from ambulatory control rats. This included many bioactive metabolites of the cyclooxygenase (COX), lipoxygenase (LOX), and epoxygenase (CYP) pathways. Synergist ablation induced a robust inflammatory response at day 3 post-surgery characterized by epitenon infiltration of polymorphonuclear leukocytes and monocytes/macrophages (MΦ), heightened expression of inflammation-related genes, and increased intratendinous concentrations of the pro-inflammatory eicosanoids thromboxane B₂ and prostaglandin E₂ . By day 7, MΦ became the predominant myeloid cell type in tendon and there were further delayed increases in other COX metabolites including prostaglandins D₂ , F_2α , and I₂ . Specialized pro-resolving mediators including protectin D1, resolvin D2 and D6, as well as related pathway markers of D-resolvins (17-hydroxy-docosahexaenoic acid), E-resolvins (18-hydroxy-eicosapentaenoic acid), and lipoxins (15-hydroxy-eicosatetraenoic acid) were also increased locally in response to tendon overuse, as were anti-inflammatory fatty acid epoxides of the CYP pathway (eg, epoxy-eicosatrienoic acids). Nevertheless, intratendinous prostaglandins remained markedly increased even following 28 days of tendon overuse together with a lingering MΦ presence. These data reveal a delayed and prolonged local inflammatory response to tendon overuse characterized by an overwhelming predominance of pro-inflammatory eicosanoids and a relative lack of specialized pro-resolving lipid mediators.

Analysis of HETEs in human whole blood by chiral UHPLC-ECAPCI/HRMS

The biosynthesis of eicosanoids occurs enzymatically via lipoxygenases, cyclooxygenases, and cytochrome P450, or through nonenzymatic free radical reactions. The enzymatic routes are highly enantiospecific. Chiral separation and high-sensitivity detection methods are required to differentiate and quantify enantioselective HETEs in complex biological fluids. We report here a targeted chiral lipidomics analysis of human blood using ultra-HPLC-electron capture (EC) atmospheric pressure chemical ionization/high-resolution MS. Monitoring the high-resolution ions formed by the fragmentation of pentafluorobenzyl derivatives of oxidized lipids during the dissociative EC, followed by in-trap fragmentation, increased sensitivity by an order of magnitude when compared with the unit resolution MS. The 12(S)-HETE, 12(S)-hydroxy-(5Z,8E,10E)-heptadecatrienoic acid [12(S)-HHT], and 15(S)-HETE were the major hydroxylated nonesterified chiral lipids in serum. Stimulation of whole blood with zymosan and lipopolysaccharide (LPS) resulted in stimulus- and time-dependent effects. An acute exposure to zymosan induced ∼80% of the chiral plasma lipids, including 12(S)-HHT, 5(S)-HETE, 15(R)-HETE, and 15(S)-HETE, while a maximum response to LPS was achieved after a long-term stimulation. The reported method allows for a rapid quantification with high sensitivity and specificity of enantiospecific responses to in vitro stimulation or coagulation of human blood.

Primed neutrophil infiltrations into multiple organs in child physical abuse cases: A preliminary study

Physical abuse of the elderly induces a massive primed neutrophil infiltration into the lung and liver through chemotaxis by interleukin (IL)-8, similar to cases of traumatic or hemorrhagic shock. Here, we used immunohistochemical analyses to investigate this infiltration in cases of physically abused children. In addition, we examined the expression of neutrophil elastase (NE) as the inflammatory mediator and α1-antitrypsin (AAT) as the elastase inhibitor. The number of neutrophils in the abuse cases was increased significantly in the heart, lung, liver, and kidney, compared with that of control cases. IL-8-positive cells and NE-positive cells in all organs of abuse cases were significantly greater than those in control cases. Large quantities of oxidized AAT, which fails to inactivate NE and results in tissue damage, was detected in the liver of abuse cases. Neutrophil infiltration showed positive correlation with the degree of systemic accumulation of non-fatal injuries caused by repetitive abusive behavior. Although further investigation using more autopsy samples is necessary, results of our preliminary study indicate that massive neutrophil infiltration induced by IL-8 in multiple organs is a new complementary diagnostic indicator of physical abuse in children. Moreover, the demonstration of NE-positive cells and oxidized AAT provides firm evidence of tissue damage.

Adenosine effectively restores endotoxin-induced inhibition of human neutrophil chemotaxis via A1 receptor-p38 pathway

Neutrophil chemotaxis plays an essential role in recruiting neutrophils to sites of inflammation. Neutrophil chemotaxis is suppressed both after exposure to lipopolysaccharide (LPS) in vitro and during clinical and experimental endotoxemia, leading to serious consequences. Adenosine (ADO) is a potent anti-inflammatory agent that acts on a variety of neutrophil functions. However, its effects on human neutrophil chemotaxis during infection have been less well characterized. In the present study, we investigated the effect of ADO and its receptor-specific antagonist and agonist on neutrophil chemotaxis in an in vitro LPS-stimulated model. The results showed that increasing the concentration of ADO effectively restored the LPS-inhibited neutrophil chemotaxis to IL-8. A similar phenomenon occurred after intervention with a selective A1 receptor agonist but not with a selective antagonist. Pre-treatment with cAMP antagonist failed to restore LPS-inhibited chemotaxis. Furthermore, protein array and western blot analysis showed that the activation of A1 receptor significantly decreased LPS-induced p38 MAPK phosphorylation. However, the surface expression of the A1 receptor in LPS-stimulated neutrophils was not significantly changed. Taken together, these data indicated that ADO restored the LPS-inhibited chemotaxis via the A1 receptor, which downregulated the phosphorylation level of p38 MAPK, making this a promising new therapeutic strategy for infectious diseases.

A broad-spectrum lipidomics screen of antiinflammatory drug combinations in human blood

Current methods of drug screening in human blood focus on the immediate products of the affected pathway and mostly rely on approaches that lack sensitivity and the capacity for multiplex analysis. We have developed a sensitive and selective method based on ultra-performance liquid chromatography-tandem mass spectrometry to scan the effect of drugs on the bioactive eicosanoid lipidome in vitro and ex vivo. Using small sample sizes, we can reproducibly measure a broad spectrum of eicosanoids in human blood and capture drug-induced substrate rediversion and unexpected shifts in product formation. Microsomal prostaglandin E synthase-1 (mPGES-1) is an antiinflammatory drug target alternative to COX-1/-2. Contrasting effects of targeting mPGES-1 versus COX-1/-2, due to differential substrate shifts across the lipidome, were observed and can be used to rationalize and evaluate drug combinations. Finally, the in vitro results were extrapolated to ex vivo studies by administration of the COX-2 inhibitor, celecoxib, to volunteers, illustrating how this approach can be used to integrate preclinical and clinical studies during drug development.

Prostaglandin E2 promotes M2 polarization of macrophages via a cAMP/CREB signaling pathway and deactivates granulocytes in teleost fish

The profile of prostaglandin (PG) production is determined by the differential expression of the enzymes involved in their production and degradation. Although the production of PGE2 by fish leukocytes has been relatively well studied in several fish species, knowledge of how its production is regulated, its biological activities and the signaling pathways activated by this PG is scant or even contradictory. In this work we show that in the teleost fish gilthead seabream (Sparus aurata L.) macrophages regulate PGE2 release mainly by inducing the expression of the genes encoding the enzymes responsible for its synthesis, while acidophilic granulocytes (AGs) not only induce these genes quickly after activation but also inhibit the expression of the genes encoding the enzymes responsible for PGE2 degradation at later time points. In addition, treatment of macrophages with PGE2 promoted their M2 polarization, which is characterized by high expression levels of interleukin-10, mannose-receptor c-type 1 and arginase 2 genes. In sharp contrast, PGE2 promoted the deactivation of AGs, since it decreased the production of reactive oxygen species and the expression of genes encoding pro-inflammatory cytokines. These differences are the result of the alternative signaling pathways used by PGE2 in macrophages and AGs, a cAMP/CREB signaling pathway operating in macrophages, but not in AGs, downstream of PGE2. Our data identify for the first time a role for professional phagocyte-derived-PGE2 in the resolution of inflammation in fish and highlight key differences in the PGE2 signaling pathway in macrophages and granulocytes.

Professional phagocytic granulocyte-derived PGD2 regulates the resolution of inflammation in fish

Prostaglandins (PGs) play a key role in the development on the immune response through the regulation of both pro- and anti-inflammatory processes. PGD(2) can be either pro- or anti-inflammatory depending on the inflammatory milieu. Prostaglandin D synthase (PGDS) is the enzyme responsible for the conversion of PGH(2) to PGD(2). In mammals, two types of PGDS synthase have been described, the hematopoietic (H-PGDS) and the lipocalin (L-PGDS). In the present study we describe the existence of two orthologs of the mammalian L-PGDS (PGDS1 and PGDS2) in the gilthead seabream and characterize their gene expression profiles and biological activity. The results showed a dramatic induction of the gene coding for PGDS1 in acidophilic granulocytes (AGs), which are functionally equivalent to mammalian neutrophils, after a prolonged in vitro activation with different pathogen associated molecular patterns (PAMPs). In contrast PGDS2 was not expressed in these cells. The functional relevance of the induction of PGDS1 in AGs was confirmed by the ability of these cells to release PGD(2) upon PAMP stimulation. To gain further insight into the role of PGD(2) in the resolution of inflammation in fish, we examined the ability of PGD(2) or its cyclopentenone derivates (cyPGs) to modulate the main functional activities of AGs. It was found that both PGD(2) and cyPGs inhibited the production of reactive oxygen species and downregulated the transcript levels of the gene encoding interleukin-1β. Taken together, these results demonstrate that the use of PGD(2) and its metabolites in the resolution of inflammation was established before the divergence of fish from tetrapods more than 450 million years ago and support a critical role for granulocytes in the resolution of inflammation in vertebrates.

Neutrophil migration towards C5a and CXCL8 is prevented by non-steroidal anti-inflammatory drugs via inhibition of different pathways

BACKGROUND AND PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to induce PG-independent anti-inflammatory actions. Here, we investigated the role of three different NSAIDs (naproxen, ibuprofen and oxaprozin) on neutrophil responses to CXCL8 and C5a.

EXPERIMENTAL APPROACH

Human neutrophils were isolated from healthy volunteers by dextran and Ficoll-Hypaque density gradients. Neutrophils were pre-incubated with different concentrations (1-100 µM) of NSAIDs or kinase inhibitors. Neutrophil degranulation into supernatants was tested by elisa and zymography. Neutrophil chemotaxis was determined using Boyden chambers. F-actin polymerization was determined by Alexa-Fluor 488-conjugated phalloidin fluorescent assay. Integrin expression was assessed by flow cytometry. The phosphorylation of intracellular kinases was studied by Western blot.

KEY RESULTS

Pretreatment with NSAIDs did not affect neutrophil degranulation, but inhibited neutrophil migration and polymerization of F-actin, in response to CXCL8 and C5a. Pretreatment with different NSAIDs prevented C5a-induced integrin (CD11b) up-regulation, while only ibuprofen reduced CXCL8-induced CD11b up-regulation. Pre-incubation with naproxen or oxaprozin, but not ibuprofen, inhibited the PI3K/Akt-dependent chemotactic pathways. Both endogenous (released in cell supernatants) or exogenous (added to cell cultures) PGE2 did not affect C5a- or CXCL8-induced activities. Short-term incubation with NSAIDs did not affect neutrophil PGE2 release.

CONCLUSION AND IMPLICATIONS

Treatment with NSAIDs reduced C5a- and CXCL8-induced neutrophil migration and F-actin polymerization via different mechanisms. Inhibition by ibuprofen was associated with integrin down-regulation, while naproxen and oxaprozin blocked the PI3K/Akt pathway. Both NSAID actions were independent of COX inhibition and PGE2 release.

Protective effect of boswellic acids versus pioglitazone in a rat model of diet-induced non-alcoholic fatty liver disease: influence on insulin resistance and energy expenditure

Non-alcoholic fatty liver disease (NAFLD) is closely linked to insulin resistance, oxidative stress, and cytokine imbalance. Boswellic acids, a series of pentacyclic triterpene molecules that are produced by plants in the genus Boswellia, has been traditionally used for the treatment of a variety of diseases. This study aimed at evaluating the protective effect of boswellic acids in a model of diet-induced NAFLD in rats in comparison to the standard insulin sensitizer, pioglitazone. Rats were fed with a high-fat diet (HFD) for 12 weeks to induce NAFLD. Starting from week 5, rats received boswellic acids (125 or 250 mg/kg) or pioglitazone parallel to the HFD. Feeding with HFD induced hepatic steatosis and inflammation in rats. In addition, liver index, insulin resistance index, activities of liver enzymes, and serum lipids deviated from normal. Further, serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and cyclooxygenase 2 were elevated; this was associated with an increase in hepatic expression of inducible nitric oxide synthase (iNOS) and formation of 4-hydroxy-2-nonenal (HNE). Rats treated with boswellic acids (125 or 250 mg/kg) or pioglitazone showed improved insulin sensitivity and a reduction in liver index, activities of liver enzymes, serum TNF-α and IL-6 as well as hepatic iNOS expression and HNE formation compared to HFD group. Furthermore, at the cellular level, boswellic acids (250 mg/kg) ameliorated the expression of thermogenesis-related mitochondrial uncoupling protein-1 and carnitine palmitoyl transferase-1 in white adipose tissues. Data from this study indicated that boswellic acids might be a promising therapy in the clinical management of NAFLD if appropriate safety and efficacy data are available.

Triterpenoid resinous metabolites from the genus Boswellia: pharmacological activities and potential species-identifying properties

The resinous metabolites commonly known as frankincense or olibanum are produced by trees of the genus Boswellia and have attracted increasing popularity in Western countries in the last decade for their various pharmacological activities. This review described the pharmacological specific details mainly on anti-inflammatory, anti-carcinogenic, anti-bacterial and apoptosis-regulating activities of individual triterpenoid together with the relevant mechanism. In addition, species-characterizing triterpenic markers with the methods for their detection, bioavailability, safety and other significant properties were reviewed for further research.

Expression and regulation of glycogen synthase kinase 3 in human neutrophils

Glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase involved in the regulation of cellular processes ranging from glycogen metabolism to cell cycle regulation. Its two known isoforms, α and β, are differentially expressed in tissues throughout the body and exert distinct but often overlapping functions. GSK-3 is typically active in resting cells, inhibition by phosphorylation of Ser21 (GSK-3α) or Ser9 (GSK-3β) being the most common regulatory mechanism. GSK-3 activity has been linked recently with immune system function, yet little is known about the role of this enzyme in neutrophils, the most abundant leukocyte type. In the present study, we examined GSK-3 expression and regulation in human neutrophils. GSK-3α was found to be the predominant isoform, it was constitutively expressed and cell stimulation with different agonists did not alter its expression. Stimulation by fMLP, LPS, GM-CSF, Fcγ receptor engagement, or adenosine A2A receptor engagement all resulted in phosphorylation of Ser21. The use of metabolic inhibitors revealed that combinations of Src kinase, PKC, PI3K/AKT, ERK/RSK and PKA signaling pathways could mediate phosphorylation, depending on the agonist. Neither PLC nor p38 were involved. We conclude that GSK-3α is the main isoform expressed in neutrophils and that many different pathways can converge to inhibit GSK-3α activity via Ser21-phosphorylation. GSK-3α thus might be a hub of cellular regulation.

Eicosanoid modulation by the short-chain fatty acid n-butyrate in human monocytes

n-Butyrate deriving from bacterial fermentation in the mammalian intestine is a key determinant in gastrointestinal homeostasis. We examined the effects of this short-chain fatty acid and Toll-like receptor 2 (TLR) and TLR4 engagement on inflammatory/immunity-associated genes, cyclo-oxygenases (COXs), prostaglandins (PGs) and leukotrienes (LTs) in human monocytes. Before RNA isolation, freshly isolated human monocytes were co-incubated for different time-points with 1 mm n-butyrate alone or in combination with bacterial stimuli. Based on a knowledge-driven approach, a signature of 180 immunity/inflammation-associated genes was picked and real-time PCR analysis was performed. Pathway analysis was carried out using a web-based database analysing program. Based on these gene expression studies the findings were evaluated at the protein/mediator level by Western blot analysis, FACS and ELISA. Following co-incubation with n-butyrate and lipopolysaccharide, key enzymes of the eicosanoid pathway, like PTGS2 (COX-2), TXS, ALOX5, LTA4H and LTC4S, were significantly up-regulated compared with stimulation with lipopolysaccharide alone. Furthermore, release of the lipid mediators PGE(2), 15d-PGJ(2), LTB(4) and thromboxane B(2) was increased by n-butyrate. Regarding signalling, n-butyrate had no additional effect on mitogen-activated protein kinase and interfered differently with early and late phases of nuclear factor-κB signalling. Our results suggest that among many other mediators of eicosanoid signalling n-butyrate massively induces PGE(2) production by increasing the expression of PTGS2 (COX-2) in monocytes following TLR4 and TLR2 activation and induces secretion of LTB(4) and thromboxane B(2). This underscores the role of n-butyrate as a crucial mediator of gut-specific immunity.

Increased saturated fatty acids in obesity alter resolution of inflammation in part by stimulating prostaglandin production

Extensive evidence indicates that nutrient excess associated with obesity and type 2 diabetes activates innate immune responses that lead to chronic, sterile low-grade inflammation, and obese and diabetic humans also have deficits in wound healing and increased susceptibility to infections. Nevertheless, the mechanisms that sustain unresolved inflammation during obesity remain unclear. In this study, we report that saturated free fatty acids that are elevated in obesity alter resolution of acute sterile inflammation by promoting neutrophil survival and decreasing macrophage phagocytosis. Using a targeted mass spectrometry-based lipidomics approach, we found that in db/db mice, PGE2/D2 levels were elevated in inflammatory exudates during the development of acute peritonitis. Moreover, in isolated macrophages, palmitic acid stimulated cyclooxygenase-2 induction and prostanoid production. Defects in macrophage phagocytosis induced by palmitic acid were mimicked by PGE2 and PGD2 and were reversed by cyclooxygenase inhibition or prostanoid receptor antagonism. Macrophages isolated from obese-diabetic mice expressed prostanoid receptors, EP2 and DP1, and contained significantly higher levels of downstream effector, cAMP, compared with wild-type mice. Therapeutic administration of EP2/DP1 dual receptor antagonist, AH6809, decreased neutrophil accumulation in the peritoneum of db/db mice, as well as the accumulation of apoptotic cells in the thymus. Taken together, these studies provide new insights into the mechanisms underlying altered innate immune responses in obesity and suggest that targeting specific prostanoid receptors may represent a novel strategy for resolving inflammation and restoring phagocyte defects in obese and diabetic individuals.

Specific lipid mediator signatures of human phagocytes: microparticles stimulate macrophage efferocytosis and pro-resolving mediators

Phagocytes orchestrate acute inflammation and host defense. Here we carried out lipid mediator (LM) metabololipidomics profiling distinct phagocytes: neutrophils (PMN), apoptotic PMN, and macrophages. Efferocytosis increased specialized pro-resolving mediator (SPM) biosynthesis, including Resolvin D1 (RvD1), RvD2, and RvE2, which were further elevated by PMN microparticles. Apoptotic PMN gave elevated prostaglandin E(2), lipoxin B(4) and RvE2, whereas zymosan-stimulated PMN showed predominantly leukotriene B(4) and 20-OH-leukotriene B(4), as well as lipoxin marker 5,15-diHETE. Using deuterium-labeled precursors (d(8)-arachidonic acid, d(5)-eicosapentaenoic acid, and d(5)-docosahexaenoic acid), we found that apoptotic PMN and microparticles contributed to SPM biosynthesis during efferocytosis. M2 macrophages produced SPM including maresin-1 (299 ± 8 vs 45 ± 6 pg/2.5 × 10(5) cells; P < .01) and lower amounts of leukotriene B(4) and prostaglandin than M1. Apoptotic PMN uptake by both macrophage subtypes led to modulation of their LM profiles. Leukotriene B(4) was down-regulated in M2 (668 ± 81 vs 351 ± 39 pg/2.5 × 10(5) cells; P < .01), whereas SPM including lipoxin A(4) (977 ± 173 vs 675 ± 167 pg/2.5 × 10(5) cells; P < .05) were increased. Conversely, uptake of apoptotic PMN by M2 macrophages reduced (∼ 25%) overall LM. Together, these results establish LM signature profiles of human phagocytes and related subpopulations. Moreover, they provide evidence for microparticle regulation of specific endogenous LM during defined stages of the acute inflammatory process and their dynamic changes in human primary phagocytes.

Metabolomics-lipidomics of eicosanoids and docosanoids generated by phagocytes

Lipid mediators derived from essential fatty acids, such as arachidonic acid, play important roles in physiologic and pathophysiologic processes. Prostaglandins, thromboxane, and leukotrienes are well-known eicosanoids that play critical roles in hemodynamics and inflammation. New families of mediators were recently uncovered that constitute a new genus stimulating resolution of acute inflammation, and are organ-protective. These include the resolvins (E-series and D-series), protectins (neuroprotectin D1/protectin D1), and maresins biosynthesized from omega-3 essential fatty acids. Phagocytes play major roles in tissue homeostasis and have a high capacity to produce these mediators, which depend on their tissue and state of activation. It is important to select appropriate methods for identifying target mediators and pathway biomarkers. In this unit, we review state-of-the-art approaches to identify and profile eicosanoid and docosanoid pathways, including specialized pro-resolving mediators resolvins, protectins, and maresins, in relation to their biosynthesis and inactivation by neutrophils and macrophages.

Novel proresolving aspirin-triggered DHA pathway

Endogenous mechanisms in the resolution of acute inflammation are of interest because excessive inflammation underlies many pathologic abnormalities. We report an aspirin-triggered DHA metabolome that biosynthesizes a potent product in inflammatory exudates and human leukocytes, namely aspirin-triggered Neuroprotectin D1/Protectin D1 [AT-(NPD1/PD1)]. The complete stereochemistry of AT-(NPD1/PD1) proved to be 10R,17R-dihydroxydocosa-4Z,7Z,11E,13E,15Z,19Z-hexaenoic acid. The chirality of hydroxyl groups and geometry of the conjugated triene system essential for bioactivity were established by matching biological materials with stereochemically pure isomers prepared by organic synthesis. AT-(NPD1/PD1) reduced neutrophil (PMN) recruitment in murine peritonitis in a dose-dependent fashion whereby neither a Δ(15)-trans-isomer nor DHA was effective. With human cells, AT-(NPD1/PD1) decreased transendothelial PMN migration as well as enhanced efferocytosis of apoptotic human PMN by macrophages. These results indicate that AT-(NPD1/PD1) is a potent anti-inflammatory proresolving molecule.

Oxidases and oxygenases in regulation of neutrophil redox pathways in Behçet's disease patients

This study aimed to determine plasma and neutrophil oxidase activities that may contribute to vascular inflammation in Behçet's disease (BD) patients. Cyclooxygenase (COX), NADPH oxidase and myeloperoxidase (MPO) activity was determined in neutrophils isolated from BD patients and healthy controls. Functional assay of NADPH oxidase was significantly increased in BD patients, both at basal conditions and in response to fMLP stimulation. There was a significant increase in plasma MPO activity in the disease group as compared to controls. Total COX activity was significantly increased in BD neutrophils. The increase in total COX activity was accompanied with enhanced activity of COX-2, differentiated by using the COX-1 isoform-specific inhibitor SC-560. Neutrophil nitrate/nitrite levels showed no significant difference in BD; however, plasma nitrate/nitrite contents in BD patients were significantly greater compared to controls. In conclusion, increased plasma MPO, neutrophil NADPH and COX activities may contribute to intravascular inflammation documented in BD patients.

A phospholipase A₂ from Bothrops asper snake venom activates neutrophils in culture: expression of cyclooxygenase-2 and PGE₂ biosynthesis

In this study, the production of prostaglandin E₂ (PGE₂) and up-regulation in cyclooxygenase (COX) pathway induced by a phospholipase A₂ (PLA₂), myotoxin-III (MT-III), purified from Bothrops asper snake venom, in isolated neutrophils were investigated. The arachidonic acid (AA) production and the participation of intracellular PLA₂s (cytosolic PLA₂ and Ca(2+)-independent PLA₂) in these events were also evaluated. MT-III induced COX-2, but not COX-1 gene and protein expression in neutrophils and increased PGE₂ levels. Pretreatment of neutrophils with COX-2 and COX-1 inhibitors reduced PGE₂ production induced by MT-III. Arachidonyl trifluoromethyl ketone (AACOCF₃), an intracellular PLA₂ inhibitor, but not bromoenol lactone (BEL), an iPLA₂ inhibitor, suppressed the MT-III-induced AA and PGE₂ release. In conclusion, MT-III directly stimulates neutrophils inducing COX-2 mRNA and protein expression followed by production of PGE₂. COX-2 isoform is preeminent over COX-1 for production of PGE₂ stimulated by MT-III. PGE₂ and AA release by MT-III probably is related to cPLA₂ activation.

[Neutrophil: foe or friend?]

Neutrophils are well-recognized phagocytes in the first line of host defense, and are also a major source of pro-inflammatory cytokines, chemokines and lipid mediators, thereby contributing to the onset and early orchestration of the inflammatory response. In contrast, recent studies indicate that neutrophils have tools to limit the magnitude and length of an inflammatory response, and may take part in engaging the resolution process. This article describes endogenous signals that may transform the phenotype of a neutrophil: from a pro-inflammatory cell to one that promotes resolution. Adenosine, an autacoid which can be found at high concentrations in inflammatory sites, inhibits several inflammatory functions of the neutrophil via engagement of the A2A receptor and reshapes the profile of lipid mediators and cytokines released, causing cells to terminate the release of pro-inflammatory signals while progressing toward resolution. These endogenous resolution pathways may represent a key target for better treatments of inflammatory diseases.

Impact of anti-inflammatory agents on the gene expression profile of stimulated human neutrophils: unraveling endogenous resolution pathways

Adenosine, prostaglandin E(2), or increased intracellular cyclic AMP concentration each elicit potent anti-inflammatory events in human neutrophils by inhibiting functions such as phagocytosis, superoxide production, adhesion and cytokine release. However, the endogenous molecular pathways mediating these actions are poorly understood. In the present study, we examined their impact on the gene expression profile of stimulated neutrophils. Purified blood neutrophils from healthy donors were stimulated with a cocktail of inflammatory agonists in the presence of at least one of the following anti-inflammatory agents: adenosine A(2A) receptor agonist CGS 21680, prostaglandin E(2), cyclic-AMP-elevating compounds forskolin and RO 20-1724. Total RNA was analyzed using gene chips and real-time PCR. Genes encoding transcription factors, enzymes and regulatory proteins, as well as secreted cytokines/chemokines showed differential expression. We identified 15 genes for which the anti-inflammatory agents altered mRNA levels. The agents affected the expression profile in remarkably similar fashion, suggesting a central mechanism limiting cell activation. We have identified a set of genes that may be part of important resolution pathways that interfere with cell activation. Identification of these pathways will improve understanding of the capacity of tissues to terminate inflammatory responses and contribute to the development of therapeutic strategies based on endogenous resolution.

Effects of cyclooxygenase-2 gene inactivation on cardiac autonomic and left ventricular function in experimental diabetes

Glucose-mediated oxidative stress and the upregulation of cyclooxygenase (COX)-2 pathway activity have been implicated in the pathogenesis of several vascular complications of diabetes including diabetic neuropathy. However, in nondiabetic subjects, the cardiovascular safety of selective COX-2 inhibition is controversial. The aim of this study was to explore the links between hyperglycemia, oxidative stress, activation of the COX-2 pathway, cardiac sympathetic integrity, and the development of left ventricular (LV) dysfunction in experimental diabetes. R wave-to-R wave interval (R-R interval) and parameters of LV function measured by echocardiography using 1% isoflurane, LV sympathetic nerve fiber density, LV collagen content, and markers of myocardial oxidative stress, inflammation, and PG content were assessed after 6 mo in control and diabetic COX-2-deficient (COX-2(-/-)) and littermate, wild-type (COX-2(+/+)) mice. There were no differences in blood glucose, LV echocardiographic measures, collagen content, sympathetic nerve fiber density, and markers of oxidative stress and inflammation between nondiabetic (ND) COX-2(+/+) and COX-2(-/-) mice at baseline and thereafter. After 6 mo, diabetic COX-2(+/+) mice developed significant deteriorations in the R-R interval and signs of LV dysfunction. These were associated with a loss of LV sympathetic nerve fiber density, increased LV collagen content, and a significant increase in myocardial oxidative stress and inflammation compared with those of ND mice. Diabetic COX-2(-/-) mice were protected against all these biochemical, structural, and functional deficits. These data suggest that in experimental diabetes, selective COX-2 inactivation confers protection against sympathetic denervation and LV dysfunction by reducing intramyocardial oxidative stress, inflammation, and myocardial fibrosis.

Blood COX-2 and PGES gene transcription during the peripartum period of dairy cows with normal puerperium or with uterine infection

In the dairy cow, puerperal uterine intra-luminal concentrations of PGE(2) are related to the establishment and severity of uterine infections. Here we evaluated whether the blood concentrations of PGE(2) and the gene transcription profiles of enzymes involved in its synthesis (cyclooxygenase-2 and prostaglandin E synthase) could be used as markers of predisposition and/or presence of puerperal uterine infections. We also studied the relationship between the endocrine status and the leukocyte profiles around parturition and the transcription patterns of the genes. Finally, we have characterized the in vitro gene transcription and expression response to a challenge of LPS. Gene transcription profiles, quantified by real-time PCR, were similar in normal puerperium and metritis/endometritis cows, indicating that they are not suitable markers of predisposition to/presence of puerperal uterine infections. Transcription decreased from 2 weeks before parturition until parturition, when a minimum was attained, and then increased during the first week postpartum. The lowest gene transcription, at parturition, was coincidental with the highest total leukocytes, polymorphonuclear neutrophils and CD14 positive cell numbers. It is suggested that by this mechanism, a large number of PMN can be recruited into the uterus after parturition, avoiding an excessive acute inflammatory response. The lowest gene transcription was also coincidental with the surge in cortisol concentrations, indicating that this hormone plays a main immunomodulatory role around parturition. Gene transcription was significantly greater after stimulation with LPS than in non-stimulated blood. We suggest that this PGE(2) producing cells might arrive to the uterine lumen, contributing to the local PGE(2) concentrations and mediating the inflammatory response.

Neutrophil-induced skeletal muscle damage: a calculated and controlled response following hindlimb unloading and reloading

Neutrophils phagocyte necrotic debris and release cytokines, enzymes, and oxidative factors. In the present study, we investigated the contribution of neutrophils to muscle injury, dysfunction, and recovery using an unloading and reloading model. Mice were submitted to 10 days of hindlimb unloading and were transiently depleted in neutrophils with anti-Ly6G/Ly6C antibody prior to reloading. Leukocyte accumulation and muscle function were assessed immunohistologically and functionally in vitro. In addition, soleus muscles submitted to unloading and reloading were incubated in vitro with LPS (100 microg/ml) to determine whether exogenous stimulus would activate neutrophil response and produce extensive muscle damage. Contractile properties were recorded every hour for 6 h, and muscles were subsequently incubated in procion orange to assess muscle damage. Neutrophil depletion affected neither the loss in muscle force nor the time of recovery in atrophied and reloaded soleus muscles. However, atrophied and reloaded soleus muscles that contained high concentration of neutrophils experienced a 20% greater loss in force than atrophied and reloaded soleus muscles depleted in neutrophils following in vitro incubation with LPS. Procion orange dye also confirmed that neutrophils induced a 2.5-fold increase in muscle membrane damage in the presence of LPS. These results show that neutrophil infiltration during modified mechanical loading is highly regulated and efficiently eliminated, with no significant muscle fiber injury unless the activation state of neutrophils is modified by the presence of LPS.

Nucleobindin co-localizes and associates with cyclooxygenase (COX)-2 in human neutrophils

The inducible cyclooxygenase isoform (COX-2) is associated with inflammation, tumorigenesis, as well as with physiological events. Despite efforts deployed in order to understand the biology of this multi-faceted enzyme, much remains to be understood. Nucleobindin (Nuc), a ubiquitous Ca²⁺-binding protein, possesses a putative COX-binding domain. In this study, we investigated its expression and subcellular localization in human neutrophils, its affinity for COX-2 as well as its possible impact on PGE₂ biosynthesis. Complementary subcellular localization approaches including nitrogen cavitation coupled to Percoll fractionation, immunofluorescence, confocal and electron microscopy collectively placed Nuc, COX-2, and all of the main enzymes involved in prostanoid synthesis, in the Golgi apparatus and endoplasmic reticulum of human neutrophils. Immunoprecipitation experiments indicated a high affinity between Nuc and COX-2. Addition of human recombinant (hr) Nuc to purified hrCOX-2 dose-dependently caused an increase in PGE₂ biosynthesis in response to arachidonic acid. Co-incubation of Nuc with COX-2-expressing neutrophil lysates also increased their capacity to produce PGE₂. Moreover, neutrophil transfection with hrNuc specifically enhanced PGE₂ biosynthesis. Together, these results identify a COX-2-associated protein which may have an impact in prostanoid biosynthesis.

Induction and function of lipocalin prostaglandin D synthase in host immunity

Although mainly expressed in neuronal cells, lipocalin-type PGD synthase (L-PGDS) is detected in the macrophages infiltrated to atherosclerotic plaques. However, the regulation and significance of L-PGDS expression in macrophages are unknown. Here, we found that treatment of macrophages with bacterial endotoxin (LPS) or Pseudomonas induced L-PGDS expression. Epigenetic suppression of L-PGDS expression in macrophages blunted a majority of PGD(2) produced after LPS treatment. Chromatin immunoprecipitation assays show that L-PGDS induction was regulated positively by AP-1, but negatively by p53. L-PGDS expression was detected in whole lung and alveolar macrophages treated with LPS or Pseudomonas. L-PGDS overexpressing transgenic mice improved clearance of Pseudomonas from the lung compared with nontransgenic mice. Similarly, intratracheal instillation of PGD(2) enhanced removal of Pseudomonas from the lung in mice. In contrast, L-PGDS knockout mice were impaired in their ability to remove Pseudomonas from the lung. Together, our results identify induction of L-PGDS expression by inflammatory stimuli or bacterial infection, the regulatory mechanism of L-PGDS induction, and the protective role of L-PGDS expression in host immune response. Our study suggests a potential therapeutic usage of L-PGDS or PGD(2) against Pseudomonas pneumonia.

The non-steroidal anti-inflammatory drug piroxicam blocks ligand binding to the formyl peptide receptor but not the formyl peptide receptor like 1

The anti-inflammatory drug piroxicam has been reported to affect the production of reactive oxygen species in phagocytes. This anti-inflammatory effect is thought to be mediated through inhibition of cyclooxygenase (COX), an enzyme important for prostaglandin synthesis. We have compared the effects of piroxicam on superoxide production mediated by two closely related G-protein coupled receptors expressed on neutrophils, the formyl peptide receptor (FPR) and the formyl peptide receptor like 1 (FPRL1). Neutrophils were stimulated with agonists that bind specifically to FPR (the peptide ligand N-formyl-Met-Leu-Phe, fMLF) or FPRL1 (the peptide ligand Trp-Lys-Tyr-Met-Val-L-Met-NH(2), WKYMVM) or both of these receptors (the peptide ligand Trp-Lys-Tyr-Met-Val-D-Met-NH(2), WKYMVm). Piroxicam reduced the neutrophil superoxide production induced by the FPR agonist but had no significant effect on the FPRL1 induced response. Neutrophil intracellular calcium changes induced by the agonist WKYMVm (that triggers both FPR and FPRL1) were only inhibited by piroxicam when the drug was combined with the FPRL1 specific antagonist, Trp-Arg-Trp-Trp-Trp-Trp (WRW(4)), and this was true also for the inhibition of superoxide anion release. Receptor-binding analysis showed that the fluorescently labelled FPR specific ligand N-formyl-Nle-Leu-Phe-Nle-Tyr-Lys (fNLFNYK), was competed for in a dose-dependent manner, by the FPR ligand fMLF and as well as by piroxicam. We show that piroxicam inhibits the neutrophil responses triggered through FPR, but not through FPRL1 and this inhibition is due to a reduced binding of the activating ligand to its cell surface receptor.

Characterization of prostaglandin E2 generation through the cyclooxygenase (COX)-2 pathway in human neutrophils

In the present study, we characterized the generation of prostaglandin (PG)E2 in human neutrophils. We found that the Ca2+-dependent type IV cytosolic phospholipase A2 (cPLA2) was pivotally involved in the COX-2-mediated generation of PGE2 in response to a calcium ionophore, as determined by the use of selected PLA2 inhibitors. PGE2 biosynthesis elicited by bacterial-derived peptides or by phagocytic stimuli acting on cell surface receptors also showed to be dependent on cPLA2 activity. We then assessed metabolism of unesterified arachidonic acid (AA), and observed that PGE2 production becomes favored over that of LTB4 with higher AA concentrations. Withdrawal of calcium prevented the generation of PGE2 in response to a calcium ionophore but did not affect the up-regulation of COX-2 or its capacity to convert AA, thus limiting its implication at the level of cPLA2 activation. Of the main eicosanoids produced by neutrophils, only LTB4 was able to up-regulate COX-2 expression. Finally, the only PGE synthase isoform found in neutrophils is microsomal PGE synthase-1; it co-localized with COX-2 and its expression appeared mainly constitutive. These results highlight key differences in regulatory processes of the 5-LO and COX pathways, and enhance our knowledge at several levels in the PGE2 biosynthesis in neutrophils.

Dynamic simulations on the arachidonic acid metabolic network

Drug molecules not only interact with specific targets, but also alter the state and function of the associated biological network. How to design drugs and evaluate their functions at the systems level becomes a key issue in highly efficient and low-side-effect drug design. The arachidonic acid metabolic network is the network that produces inflammatory mediators, in which several enzymes, including cyclooxygenase-2 (COX-2), have been used as targets for anti-inflammatory drugs. However, neither the century-old nonsteriodal anti-inflammatory drugs nor the recently revocatory Vioxx have provided completely successful anti-inflammatory treatment. To gain more insights into the anti-inflammatory drug design, the authors have studied the dynamic properties of arachidonic acid (AA) metabolic network in human polymorphous leukocytes. Metabolic flux, exogenous AA effects, and drug efficacy have been analyzed using ordinary differential equations. The flux balance in the AA network was found to be important for efficient and safe drug design. When only the 5-lipoxygenase (5-LOX) inhibitor was used, the flux of the COX-2 pathway was increased significantly, showing that a single functional inhibitor cannot effectively control the production of inflammatory mediators. When both COX-2 and 5-LOX were blocked, the production of inflammatory mediators could be completely shut off. The authors have also investigated the differences between a dual-functional COX-2 and 5-LOX inhibitor and a mixture of these two types of inhibitors. Their work provides an example for the integration of systems biology and drug discovery.

The Toll‐like receptor 7/8‐ligand resiquimod (R‐848) primes human neutrophils for leukotriene B4, prostaglandin E2and platelet‐activating factor biosynthesis

Toll-like receptors (TLR) recognize pathogen-associated molecular patterns and play important roles in the innate immune system. While single-stranded viral RNA is the natural ligand of TLR7/TLR8, the imidazoquinoline resiquimod (R-848) is recognized as a potent synthetic agonist of TLR7/TLR8. We investigated the effects of TLR7/8 activation on lipid mediator production in polymorphonuclear leukocytes exposed to R-848. Although R-848 had minimal effects by itself, it strongly enhanced leukotriene B4 formation on subsequent stimulation by fMLP, platelet-activating factor, and the ionophore A23187. R-848 acted via TLR8 but not TLR7 as shown by the lack of effect of the TLR7-specific ligand imiquimod. Priming with R-848 also resulted in enhanced arachidonic acid release and platelet-activating factor formation following fMLP stimulation, as well as enhanced prostaglandin E2 synthesis following the addition of arachidonic acid. Western blot analysis demonstrated that R-848 induced the phosphorylation of the cytosolic phospholipase A2alpha, promoted 5-lipoxygenase translocation and potently stimulated the expression of the type 2 cyclooxygenase. Bafilomycin A1, an inhibitor of endosomal acidification, efficiently inhibited all R-848-induced effects. These studies demonstrate that TLR8 signaling strongly promotes inflammatory lipid mediator biosynthesis and provide novel insights on innate immune response to viral infections.

Regulation of cyclooxygenase activity in cultured endometrial stromal cells by granulocyte-macrophage colony-stimulating factor

OBJECTIVE

To assess the ability of granulocyte-macrophage colony-stimulating factor (GM-CSF) to regulate cyclooxygenase (COX) enzyme activity and prostaglandins (PGs) synthesis, specifically PGE2 production in stromal cells, neither of which have been addressed in the literature.

DESIGN

Prospective study.

SETTING

Department of obstetrics and gynecology at a university hospital.

PATIENT(S)

Human luteal phase endometrium was obtained from surgical specimens (n = 6) for clinical indications.

INTERVENTION(S)

Confluent stromal cells were stimulated with GM-CSF.

MAIN OUTCOME MEASURE(S)

Expression of COX mRNA, COX enzyme activity, and PGE2 level in cultured stromal cells.

RESULT(S)

Confluent stromal cell cultures treated with P and E2 for 9 days were stimulated with GM-CSF. After treatment of 12 hours, low-dose GM-CSF (0.001-0.1 ng/mL) increased COX-2 mRNA levels in stromal cell, whereas high dose GM-CSF (1-100 ng/mL) decreased COX-1 and COX-2 mRNA levels. After treatment of 48 hours, low concentrations of GM-CSF (0.001-0.1 ng/mL) increased total COX and COX-2 enzyme activity, whereas high concentrations of GM-CSF (1-100 ng/mL) inhibited COX and COX-2 activity; The PGE2 levels decreased by 31% to 393.3 pg/mL (P < .05) with concentrations of GM-CSF increasing from 1 ng/mL to 100 ng/mL.

CONCLUSION(S)

There appeared to be a biphasic pattern of COX-2 enzyme response to GM-CSF with low concentrations increasing activity and high concentrations inhibiting activity. It is possible that GM-CSF may provide critical regulation of PG production in the preimplantation period.

Orally administered FPRL1 receptor agonist peptide MMK-1 inhibits etoposide-induced alopecia by a mechanism different from intraperitoneally administered MMK-1

Oral administration for 6 days of 100 mg/kg MMK-1, an agonist peptide selective for the FPRL1 receptor, suppressed alopecia induced by the anticancer drug etoposide in neonatal rats. The anti-alopecia effect of orally administered MMK-1 was not inhibited by pyrilamine or cimetidine, antagonists for histamine H1 and H2 receptors, respectively, which blocked the anti-alopecia effect of intraperitoneally administered MMK-1 at a dose of 10 mg/kg for 4 days. However, the anti-alopecia effect of orally administered MMK-1 was inhibited by indomethacin, an inhibitor of cyclooxygenase (COX), or AH-23848B, an antagonist of the EP4 receptor for prostaglandin (PG) E2, suggesting involvement of PGE2 release and the EP4 receptor in the oral MMK-1 anti-alopecia mechanism. The anti-alopecia effect of orally administered MMK-1 was also blocked by an inhibitor of nuclear factor-kappaB (NF-kappaB), pyrrolidine dithiocarbamate, suggesting that the oral anti-alopecia effect of MMK-1 may be mediated by activation of NF-kappaB. These results suggest that MMK-1 bound to FPRL1 receptor might suppress etoposide-induced apoptosis of hair follicle cells and alopecia by way of PGE2 release and NF-kappaB activation.

Effects of acute ethanol administration on LPS-induced expression of cyclooxygenase-2 and inducible nitric oxide synthase in rat alveolar macrophages

BACKGROUND

Activation of alveolar macrophages acts as a primary defense mechanism of lung with immunologic and inflammatory processes. Incidence of respiratory distress syndrome (ARDS) has been reported to be higher in alcoholics than that in nonalcoholics. Both cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are induced by inflammatory stimuli such as LPS and cytokines and are involved in host defense. COX-2 and iNOS have been reported to play important roles in pathophysiology of ARDS. The aim of the present study was to elucidate whether acute ethanol administration to rats affects on COX-2 and iNOS expression in isolated alveolar macrophages.

METHODS

Ethanol (4.5 g per kg body weight as a 20% solution) was intraperitoneally injected to male Wistar rats. At 2.5 hrs after the injection, alveolar macrophages were collected from rats by bronchoalveolar lavage and were stimulated with lipopolysaccharide (LPS, 1 mug/ml). Expression of COX-2 and iNOS and activation of MAPKs was evaluated by Western blotting.

RESULTS

In alveolar macrophages isolated from ethanol-treated rats, LPS-stimulated production of both prostaglandin E2 and nitrite was significantly lower than that in macrophages isolated from vehicle-treated control rats. LPS-induced expression of both COX-2 and iNOS was significantly lower in macrophages from ethanol-treated rats than that in macrophages from the control rats, while expression of beta-actin was not different in these groups. LPS increased phosphorylation of both extracellular signal-regulated protein kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). The levels of phosphorylated ERK and p38 were significantly lower in macrophages from ethanol-treated rats compared with those from the control rats. Treatment of macrophages with ethanol (100 - 400 mM) in vitro significantly inhibited expression of COX-2 in a concentration-dependent manner, while only a high concentration (400 mM) of ethanol significantly inhibited expression of iNOS. Ethanol also inhibited COX-2 expression in the presence of Tiron. Expression of COX-2 and iNOS was significantly inhibited by U0126 but not by SB203580.

CONCLUSION

In rat alveolar macrophages, LPS-induced expression of COX-2 and iNOS is mediated by ERK MAPK but not by p38 MAPK. Acute ethanol administration to rats attenuates induction of both COX-2 and iNOS in alveolar macrophages by inhibiting phosphorylation of ERK.

Role of insulin on PGE2 generation during LPS-induced lung inflammation in rats

Alterations in arachidonic acid (AA) metabolism have been reported to occur in diabetes mellitus. The present study was carried out to verify if these alterations are due to the relative lack of insulin or to high levels of blood glucose. Male Wistar rats were rendered diabetic by alloxan injection (42 mg/kg, i.v.), 10 or 30 days before the experiments. Some diabetic rats received a single dose (4 IU, s.c.) of NPH insulin 2 h before an intratracheal instillation of lipopolysaccharide (LPS, 750 microg) or saline. Six hours after LPS challenge, the following parameters were analysed: blood glucose levels, total and differential leukocyte counts in bronchoalveolar lavage (BAL) fluid; linoleic acid and AA content in blood neutrophils (HPLC), and levels of prostaglandin (PG)E(2) in BAL (ELISA). Relative to controls, a reduced number of neutrophils (18%) and decreased amounts of PGE(2) (40%) were observed in the BAL fluid of diabetic rats in response to LPS. A single dose of insulin was not able to reduce blood sugar levels to normal values, but instead resulted in the normalization of both leukocyte migration to the lungs and levels of PGE(2). Accordingly, these abnormalities might be primarily linked to a continuing insulin deficiency rather than to secondary hyperglycaemia occurring in the diabetic rat. In conclusion, data presented suggest that insulin might regulate neutrophil migration and generation of PGE(2) during the course of acute lung injury induced by LPS.

Molecular cloning and tissue distribution of microsomal-1 and cytosolic prostaglandin E synthases in macaque

Prostaglandins derived from arachidonic acid are involved in a wide variety of physiological and pathological processes. The primary enzymes involved in the production of PGE2 from arachidonic acid are cyclooxygenases and prostaglandin E synthases. These enzymes have been identified in human, but only partially in the monkey where microsomal PGES-1 and cytosolic PGES have not been characterized. The present study was undertaken to clone these enzymes and to study their tissue distribution, along with mPGES-2. The coding sequence of Macaque mPGES-1 is 98% homologous to human mPGES-1 at the nucleic acid level and the deduced amino acid sequence has 98% homology with the human protein. The Macaque cPGES cDNA is more than 99% homologous to the human and the deduced amino acids sequence is identical to that of the human cPGES. By Northern blot analysis, we found that mPGES-2 and cPGES mRNA were expressed in the endometrium, myometrium, ovary and oviduct, albeit at different levels, while mPGES-1 mRNA was detected at a weak level, mainly in the oviduct. Western Blot analysis revealed that mPGES-2, mPGES-1 and cPGES proteins were present in all tissues tested. These results suggest that production of PGE2 in Macaque may involve more than one PGES and that further studies will be needed to fully understand the conditions under which each PGES contributes to PGE2 production.

Immunomodulatory impact of the A2A adenosine receptor on the profile of chemokines produced by neutrophils

In LPS-stimulated human neutrophils, engagement of the adenosine A2A receptor selectively prevented the expression and release of TNF-alpha, MIP-1alpha/CCL3, MIP-1beta/CCL4, MIP-2alpha/CXCL2, and MIP-3alpha/CCL20. In mice lacking the A2A receptor, granulocytes that migrated into the air pouch 4 h after LPS injection expressed higher mRNA levels of TNF-alpha, MIP-1alpha, and MIP-1beta than PMNs from wild-type mice. In mononuclear cells present in the air pouch 72 h after LPS injection, expression of IL-1beta, TNF-alpha, IL-6, and MCP-2/CCL6 was higher in A2AR knockout mice. In addition to highlighting neutrophils as an early and pivotal target for mediating adenosine anti-inflammatory activities, these results identify TNF-alpha and the MIP chemokine family as gene products whose expression is pivotally affected by activation of A2AR in LPS-activated PMNs. Modulation by A2AR in the production of inflammatory signals by PMNs may thus influence the evolution of an inflammatory response by reducing the activation status of inflammatory cells.

Andrographolide interferes with binding of nuclear factor-kappaB to DNA in HL-60-derived neutrophilic cells

1. Andrographolide, the major active component from Andrographis paniculata, has shown to possess anti-inflammatory activity. Andrographolide inhibits the expression of several proinflammatory proteins that exhibit a nuclear factor kappa B (NF-kappaB) binding site in their gene. 2. In the present study, we analyzed the effect of andrographolide on the activation of NF-kappaB induced by platelet-activating factor (PAF) and N-formyl-methionyl-leucyl-phenylalanine (fMLP) in HL-60 cells differentiated to neutrophils. 3. PAF (100 nM) and fMLP (100 nM) induced activation of NF-kappaB as determined by degradation of inhibitory factor B alpha (IkappaB alpha) using Western blotting in cytosolic extracts and by binding to DNA using electrophoretic mobility shift assay (EMSA) in nuclear extracts. 4. Andrographolide (5 and 50 microM) inhibited the NF-kappaB-luciferase activity induced by PAF. However, andrographolide did not reduce phosphorylation of p38 MAPK or ERK1/2 and did not change IkappaB alpha degradation induced by PAF and fMLP. 5. Andrographolide reduced the DNA binding of NF-kappaB in whole cells and in nuclear extracts induced by PAF and fMLP. 6. Andrographolide reduced cyclooxygenase-2 (COX-2) expression induced by PAF and fMLP in HL-60/neutrophils. 7. It is concluded that andrographolide exerts its anti-inflammatory effects by inhibiting NF-kappaB binding to DNA, and thus reducing the expression of proinflammatory proteins, such as COX-2.

Accelerative effect of a selective cyclooxygenase-2 inhibitor on Fas-mediated apoptosis in human neutrophils

Inflammatory stimuli, such as cytokines, can induce cyclooxygenase-2 (COX-2) expression in neutrophils. Selective, anti-inflammatory COX-2 inhibitors have been developed for patients with acute inflammatory diseases. Recent work has shown that selective COX-2 inhibitors interfere with tumor cell growth. The purpose of this study was to examine the capability of selective COX-2 inhibitors on Fas-mediated apoptosis in cytokine-stimulated neutrophils. Tumor necrosis factor-alpha (TNF-alpha) and granulocyte-macrophage colony-stimulating factor (GM-CSF) enhanced prostaglandin E2 (PGE2) release through the induction of COX-2 in neutrophils. This effect was not seen with either interleukin (IL)-1beta or IL-8. TNF-alpha-and GM-CSF-induced PGE2 release was blocked by the addition of the selective COX-2 inhibitor, N-(2-cyclohexyloxy-4-nitrophenyl)-methanesulfonamide (NS-398; 1 microM). GM-CSF, IL-1beta and IL-8 suppressed Fas-mediated apoptosis in neutrophils; however, this effect was not seen with TNF-alpha. The anti-apoptotic effect of cytokines on Fas-mediated neutrophil apoptosis was attenuated by the addition of NS-398 (100 microM). These results suggest that NS-398 operates via two distinct mechanisms for regulating apoptosis and COX-2 activation in neutrophils. This distinction is indicated by the difference in concentration of NS-398 required for acceleration of Fas-mediated neutrophil apoptosis, and the inhibition of PGE2 synthesis. Moreover, NS-398 suppressed the anti-apoptotic activity of IL-8 and IL-1beta, but did not induce COX-2; therefore, the pro-apoptotic mechanism of the selective COX-2 inhibitor may be unrelated to COX-2 activity. Thus, a selective COX-2 inhibitor may contribute to the reduction of acute inflammation through the enhancement of neutrophil apoptosis.

Neutrophils from pregnant women produce thromboxane and tumor necrosis factor-alpha in response to linoleic acid and oxidative stress

OBJECTIVE

Preeclampsia is associated with oxidative stress, neutrophil activation, neutrophil infiltration into systemic vasculature, and elevated plasma levels of linoleic acid, the fatty acid precursor to arachidonic acid and its metabolite, thromboxane. In this study we evaluated whether linoleic acid under conditions of oxidative stress would stimulate neutrophil production of thromboxane and tumor necrosis factor-alpha.

STUDY DESIGN

Neutrophils were isolated from 14 normal pregnant women. Western blot demonstrated cyclooxygenase-2 expression at 18 hours of incubation, so this incubation time was used for experiments. Neutrophils (2 x 10(6) cells/mL) were incubated in Dulbecco's modified Eagle's medium/F-12 with: (1) linoleic acid control; (2) an oxidizing solution enriched with linoleic acid; (3) oxidizing solution enriched with linoleic acid plus indomethacin; (4) oxidizing solution enriched with linoleic acid plus aspirin; (5) oxidizing solution enriched with linoleic acid plus NS-398, a specific inhibitor of cyclooxygenase-2; or (6) oxidizing solution enriched with linoleic acid plus pinane thromboxane, a thromboxane synthase inhibitor and receptor blocker.

RESULTS

Oxidizing solution enriched with linoleic acid significantly increased oxidative stress in neutrophils. Compared with linoleic acid, oxidizing solution enriched with linoleic acid significantly increased neutrophil production of thromboxane and tumor necrosis factor-alpha. Indomethacin and aspirin inhibited oxidizing solution enriched with linoleic acid stimulation of thromboxane, but NS-398 was equally effective implicating cyclooxygenase-2 in the thromboxane response. Indomethacin inhibited oxidizing solution enriched with linoleic acid stimulation of tumor necrosis factor-alpha, but so did pinane thromboxane implicating thromboxane in the tumor necrosis factor-alpha response.

CONCLUSIONS

These data demonstrate that exposure of neutrophils from normal pregnant women to conditions present in preeclamptic women results in neutrophil activation with release of thromboxane and tumor necrosis factor-alpha. Newly synthesized thromboxane is cyclooxygenase-2 dependent and plays a role in the tumor necrosis factor-alpha response. Our data suggest a mechanism for maternal vasoconstriction and vascular inflammation in preeclampsia because activated, thromboxane-secreting neutrophils migrate across endothelium into the microenvironment of the vasculature in which they could promote vasoconstriction, whereas release of tumor necrosis factor-alpha could cause vascular inflammation.

Aspirin resistance

Treatment failures occur with any drug and aspirin is no exception. Evidence is growing to indicate that there are subpopulations that do not respond to antithrombotic action of aspirin. The term 'aspirin resistance' has been used to describe a number of different phenomena, including inability of aspirin to: (i) protect against cardiovascular events despite its regular intake; (ii) to affect various laboratory tests, reflecting platelet activity. Research on aspirin resistance yielded interesting results in clinical pharmacology and pharmacogenetics. Future studies will show whether genotyping for polymorphisms might be of value in everyday clinical use of aspirin. Present data indicate that in survivors of recent myocardial infarction or unstable angina, patients receiving coronary artery bypass grafts, as well as in subjects with hypercholesterolemia, aspirin resistance has to be considered when implementing antithrombotic therapy. However, in individual patients the available laboratory tests are of no particular use to predict reliably the clinical outcome or to guide in making therapeutic decision. Prospective clinical trials seem necessary to reach such conclusions.

Glycerylprostaglandin synthesis by resident peritoneal macrophages in response to a zymosan stimulus

Cyclooxygenase (COX)-2 oxygenates arachidonic acid (AA) and 2-arachidonylglycerol (2-AG) to endoperoxides, which are subsequently transformed to prostaglandins (PGs) and glycerylprostaglandins (PG-Gs). PG-G formation has not been demonstrated in intact cells treated with a physiological agonist. Resident peritoneal macrophages, which express COX-1, were pretreated with lipopolysaccharide to induce COX-2. Addition of zymosan caused release of 2-AG and production of the glyceryl esters of PGE2 and PGI2 over 60 min. The total quantity of PG-Gs (16 +/- 6 pmol/10(7) cells) was much lower than that of the corresponding PGs produced from AA (21,000 +/- 7,000 pmol/10(7) cells). The differences in PG-G and PG production were partially explained by differences in the amounts of 2-AG and AA released in response to zymosan. The selective COX-2 inhibitor, SC236, reduced PG-G and PG production by 49 and 17%, respectively, indicating a significant role for COX-1 in PG-G and especially PG synthesis. Time course studies indicated that COX-2-dependent oxygenation rapidly declined 20 min after zymosan addition. When exogenous 2-AG was added to macrophages, a substantial portion was hydrolyzed to AA and converted to PGs; 1 microm 2-AG yielded 820 +/- 200 pmol of PGs/10(7) cells and 78 +/- 41 pmol of PG-Gs/10(7) cells. SC236 reduced PG-G and PG production from exogenous 2-AG by 88 and 76%, respectively, indicating a more significant role for COX-2 in the utilization of exogenous substrate. In conclusion, lipopolysaccharide-pretreated macrophages produce PG-Gs from endogenous 2-AG during zymosan phagocytosis, but PG-G formation is limited by substrate hydrolysis and inactivation of COX-2.

Anti-alopecia mechanisms of soymetide-4, an immunostimulating peptide derived from soy beta-conglycinin

Previously, we found that orally administered soymetide-4 (MITL), an immunostimulating peptide derived from soybean beta-conglycinin alpha' subunit, suppressed alopecia induced by the anti-cancer drug etoposide in neonatal rats. Soymetide-4 has weak affinity for N-formyl-methionyl-leucyl-phenylalanine (fMLP) receptor. fMLP showed an anti-alopecia effect after intraperitoneal administration, though it was inactive after oral administration. Anti-alopecia effect of fMLP was blocked by pyrilamine or cimetidine, antagonists for histamine H1 or H2 receptor, respectively. However, the anti-alopecia effect of soymetide-4 was not inhibited by the histamine antagonists but by indomethacin, an inhibitor of cyclooxygenase (COX), or AH-23848B, an antagonist of the EP4 receptor for PGE2. Anti-alopecia effect of soymetide-4 was also blocked by pyrrolidine dithiocarbamate, an inhibitor of nuclear factor-kappaB (NF-kappaB). These results suggest that PGE2, which is produced after activation of COX by soymetide-4, might suppress apoptosis of hair matrix cells and etoposide-induced alopecia by activating NF-kappaB.

Cyclooxygenase 2 Plays a Pivotal Role in the Resolution of Acute Lung Injury

Acute lung injury (ALI) is a severe illness with excess mortality and no specific therapy. In its early exudative phase, neutrophil activation and accumulation in the lung lead to hypoxemia, widespread tissue damage, and respiratory failure. In clinical trials, inhibition of proinflammatory mediators has not proven effective. In this study, we pursued a new investigative strategy that emphasizes mediators promoting resolution from lung injury. A new spontaneously resolving experimental murine model of ALI from acid aspiration was developed to identify endogenous proresolving mechanisms. ALI increased cyclooxygenase 2 (COX-2) expression in murine lung. Selective pharmacologic inhibition or gene disruption of COX-2 blocked resolution of ALI. COX-2-derived products increased levels of the proresolving lipid mediators lipoxin A4 (LXA4) and, in the presence of aspirin, 15-epi-LXA4. Both LXA4 and 15-epi-LXA4 interact with the LXA4 receptor (ALX) to mediate anti-inflammatory actions. ALX expression was markedly induced by acid injury and transgenic mice with increased ALX expression displayed dramatic protection from ALI. Together, these findings indicate a protective role in ALI for COX-2-derived mediators, in part via enhanced lipoxin signaling, and carry potential therapeutic implications for this devastating clinical disorder.

Potentiation of neutrophil cyclooxygenase-2 by adenosine: an early anti-inflammatory signal

Neutrophils, which are often the first to migrate at inflamed sites, can generate leukotriene B(4) from the 5-lipoxygenase pathway and prostaglandin E(2) through the inducible cyclooxygenase-2 pathway. Adenosine, an endogenous autacoid with several anti-inflammatory properties, blocks the synthesis of leukotriene B(4) while it potentiates the cyclooxygenase-2 pathway in fMLP-treated neutrophils, following activation of the A(2A) receptor. Using the murine air pouch model of inflammation, we observed that inflammatory leukocytes from mice lacking the A(2A) receptor have less cyclooxygenase-2 induction than wild-type animals. In human leukocytes, A(2A) receptor activation specifically elicited potentiation of cyclooxygenase-2 in neutrophils, but not in monocytes. Signal transduction studies indicated that the cAMP, ERK1/2, PI-3K and p38K intracellular pathways are implicated both in the direct upregulation of cyclooxygenase-2 and in its potentiation. Together, these results indicate that neutrophils are particularly important mediators of adenosine's effects. Given the uncontrolled inflammatory phenotype observed in knockout mice and in view of the potent inhibitory actions of prostaglandin E(2) on inflammatory cells, an increased cyclooxygenase-2 expression resulting from A(2A) receptor activation, observed particularly in neutrophils, may take part in an early modulatory mechanism promoting anti-inflammatory activities of adenosine.

Inhibitory action of ethanol on cyclooxygenase-2 expression through suppression of the extracellular signal-related kinase-mediated pathway in rat alveolar macrophages

The purpose of the present study was to elucidate the effects of ethanol on expression of cyclooxygenase in alveolar macrophages. Rat alveolar macrophages were collected by bronchoalveolar lavage and stimulated by lipopolysaccharide. Lipopolysaccharide-induced cyclooxygenase-2 expression and prostaglandin E2 production were inhibited by ethanol (100-200 mM) in a concentration-dependent manner. Ethanol at 100-200 mM concentration-dependently inhibited cyclooxygenase-2 mRNA expression. Lipopolysaccharide-stimulated phosphorylation of both extracellular signal-related kinase and p38 mitogen-activated protein kinase was also significantly inhibited by ethanol (50-200 mM). Cyclooxygenase-2 expression was significantly inhibited by U0126 but was not affected by SB203580. In the presence of SB203580, lipopolysaccharide-induced cyclooxygenase-2 expression was also inhibited by ethanol (50-200 mM). On the other hand, cyclooxygenase-1 was expressed constitutively in alveolar macrophages and cyclooxygenase-1 expression was affected neither by lipopolysaccharide nor ethanol. Lipopolysaccharide-induced expression of inducible nitric oxide synthase in alveolar macrophages was not affected by ethanol at 50-200 mM. These results suggest that lipopolysaccharide-induced expression of cyclooxygenase-2 is mediated by extracellular signal-related kinase but not by p38 kinase and that ethanol selectively attenuates cyclooxygenase-2 expression mainly by inhibiting activation of extracellular signal-related kinase.

Cyclooxygenase-1, but not -2, is upregulated in NB4 leukemic cells and human primary promyelocytic blasts during differentiation

Cyclooxygenase (COX)-1 or -2 and specific prostaglandin (PG) synthases catalyze the formation of various PGs. We investigated the expression and activity of COX-1 and -2 during granulocyte-oriented maturation induced by all-trans-retinoic acid (ATRA) of NB4 cells, originated from a human acute promyelocytic leukemia (APL), and in blasts from APL patients. The expression of COX isoenzymes or prostaglandin synthases was also investigated in circulating granulocytes and human bone marrow. COX-1 was expressed and enzymatically active in NB4 cells and primary blasts. COX-1 mRNA and protein were induced by ATRA. COX-1 protein increased approximately 2-3.5-fold by culture day 3 in NB4 cells and primary blasts, while basal COX-2 expression was very low and unaffected by ATRA. COX-1-dependent PGE(2) biosynthesis increased during differentiation approx. 5-fold. Indomethacin and the selective COX-1 inhibitor SC-560, but not selective COX-2 inhibition, impaired NB4 differentiation, reducing NADPH-oxidase activity, CD11b and CD11c expression. The immunohistochemistry of granulocytes and myeloid precursors in the bone marrow showed a large prevalence of COX-1 as compared to COX-2. In conclusion, COX-1 is induced during ATRA-dependent maturation and appears to contribute to myeloid differentiation both in vitro and ex vivo, and COX-1 activity may potentiate the differentiation of human APL.Leukemia (2004) 18, 1373-1379. doi:10.1038/sj.leu.2403407 Published online 10 June 2004