Nonsteroidal antiinflammatory drugs exert differential effects on neutrophil function and plasma membrane viscosity. Studies in human neutrophils and liposomes

Induction of mitochondrial toxicity by non-steroidal anti-inflammatory drugs (NSAIDs): The ultimate trade-off governing the therapeutic merits and demerits of these wonder drugs

Non-steroidal anti-inflammatory drugs (NSAIDs) are most extensively used over-the-counter FDA-approved analgesic medicines for treating inflammation, musculoskeletal pain, arthritis, pyrexia and menstrual cramps. Moreover, aspirin is widely used against cardiovascular complications. Owing to their non-addictive nature, NSAIDs are also commissioned as safer opioid-sparing alternatives in acute trauma and post-surgical treatments. In fact, therapeutic spectrum of NSAIDs is expanding. These "wonder-drugs" are now repurposed against lung diseases, diabetes, neurodegenerative disorders, fungal infections and most notably cancer, due to their efficacy against chemoresistance, radio-resistance and cancer stem cells. However, prolonged NSAID treatment accompany several adverse effects. Mechanistically, apart from cyclooxygenase inhibition, NSAIDs directly target mitochondria to induce cell death. Interestingly, there are also incidences of dose-dependent effects where NSAIDs are found to improve mitochondrial health thereby suggesting plausible mitohormesis. While mitochondria-targeted effects of NSAIDs are discretely studied, a comprehensive account emphasizing the multiple dimensions in which NSAIDs affect mitochondrial structure-function integrity, leading to cell death, is lacking. This review discusses the current understanding of NSAID-mitochondria interactions in the pathophysiological background. This is essential for assessing the risk-benefit trade-offs of NSAIDs for judiciously strategizing NSAID-based approaches to manage pain and inflammation as well as formulating effective anti-cancer strategies. We also discuss recent developments constituting selective mitochondria-targeted NSAIDs including theranostics, mitocans, chimeric small molecules, prodrugs and nanomedicines that rationally optimize safer application of NSAIDs. Thus, we present a comprehensive understanding of therapeutic merits and demerits of NSAIDs with mitochondria at its cross roads. This would help in NSAID-based disease management research and drug development.

Acetaminophen Has Lipid Composition-Dependent Membrane Interactivity That Could Be Related to Nephrotoxicity but Not to Analgesic Activity and Hepatotoxicity

OBJECTIVE

Although acetaminophen is one of the most widely used over-the-counter drugs, the mechanisms by which this classical drug exerts analgesic, hepatotoxic, and nephrotoxic effects remain unclear. We hypothesized that acetaminophen might act on cellular membranes of nerves, liver, and kidneys. In order to verify this hypothesis, we studied the interactivity of acetaminophen with biomimetic lipid bilayer membranes by comparing with structurally related phenacetin.

METHODS

Liposomal membranes (unilamellar vesicles suspended in the buffer of pH 7.4) were prepared with phospholipids and cholesterol to mimic the membrane lipid composition of neuronal cells, hepatocytes, and nephrocytes. They were subjected to reactions with acetaminophen and phenacetin at clinically relevant concentrations, followed by measuring fluorescence polarization to determine their membrane interactivity to modify membrane fluidity.

RESULTS

Acetaminophen and phenacetin interacted with neuro-mimetic and hepato-mimetic membranes to increase membrane fluidity at 10-100 μM. Both drugs were more effective in fluidizing hepato-mimetic membranes than neuro-mimetic membranes. Although the relative membrane-interacting potency was phenacetin >> acetaminophen in neuro-mimetic and hepato-mimetic membranes, such membrane effects conflicted with their relative analgesic and hepatotoxic effects. Acetaminophen and phenacetin strongly interacted with nephro-mimetic membranes to increase membrane fluidity at 2-100 μM and 0.1-100 μM, respectively. Phenacetin interacted significantly with nephro-mimetic membranes at lower concentrations (<2 μM) than acetaminophen, which was consistent with their relative nephrotoxic effects.

CONCLUSION

In comparison with phenacetin, lipid composition-dependent membrane interactivity of acetaminophen could be related to nephrotoxicity but not to analgesic activity and hepatotoxicity.

Biological and chemical insight into Gaultheria procumbens fruits: a rich source of anti-inflammatory and antioxidant salicylate glycosides and procyanidins for food and functional application

The fruits of Gaultheria procumbens are traditionally used for culinary and healing purposes as anti-inflammatory agents. In the present work, the active components of the fruits were identified (UHPLC-PDA-ESI-MS3, preparative HPLC isolation, and NMR structural studies), and their biological capacity was evaluated in vitro in cell-based and non-cellular models. The fruits were revealed to be the richest known dietary source of salicylates (38.5 mg per g fruit dw). They are also rich in procyanidins (28.5 mg per g fruit dw). Among five tested solvents, acetone was the most efficient in concentrating the phenolic matrix (39 identified compounds; 191.3 mg g-1, 121.7 mg g-1, and 50.9 mg g-1 dry extract for total phenolics, salicylates, and procyanidins, respectively). In comparison to positive controls (dexamethasone, indomethacin, and quercetin), the extract (AE) and pure salicylates exhibited strong inhibitory activity towards pro-inflammatory enzymes (cyclooxygenase-2 and hyaluronidase). The analytes were found to be non-cytotoxic (flow cytometry) towards human neutrophils ex vivo. Moreover, they significantly, in a dose-dependent manner, downregulated the release of ROS, TNF-α, IL-1β, and elastase-2 and slightly inhibited the secretion of IL-8 and metalloproteinase-9 in the cells. The observed effects might support the usage of G. procumbens fruits as functional components of an anti-inflammatory diet and indicate the potential of AE for use in adjuvant treatment of inflammatory disorders cross-linked with oxidative stress and associated with the excessive production of TNF-α, IL-1β, and elastase-2.

Membrane Interactions of Phytochemicals as Their Molecular Mechanism Applicable to the Discovery of Drug Leads from Plants

In addition to interacting with functional proteins such as receptors, ion channels, and enzymes, a variety of drugs mechanistically act on membrane lipids to change the physicochemical properties of biomembranes as reported for anesthetic, adrenergic, cholinergic, non-steroidal anti-inflammatory, analgesic, antitumor, antiplatelet, antimicrobial, and antioxidant drugs. As well as these membrane-acting drugs, bioactive plant components, phytochemicals, with amphiphilic or hydrophobic structures, are presumed to interact with biological membranes and biomimetic membranes prepared with phospholipids and cholesterol, resulting in the modification of membrane fluidity, microviscosity, order, elasticity, and permeability with the potencies being consistent with their pharmacological effects. A novel mechanistic point of view of phytochemicals would lead to a better understanding of their bioactivities, an insight into their medicinal benefits, and a strategic implication for discovering drug leads from plants. This article reviews the membrane interactions of different classes of phytochemicals by highlighting their induced changes in membrane property. The phytochemicals to be reviewed include membrane-interactive flavonoids, terpenoids, stilbenoids, capsaicinoids, phloroglucinols, naphthodianthrones, organosulfur compounds, alkaloids, anthraquinonoids, ginsenosides, pentacyclic triterpene acids, and curcuminoids. The membrane interaction’s applicability to the discovery of phytochemical drug leads is also discussed while referring to previous screening and isolating studies.

High doses of salicylate and aspirin are inhibitory on acid-sensing ion channels and protective against acidosis-induced neuronal injury in the rat cortical neuron

Aspirin and its main metabolite salicylate are widely used to relieve pain, treat inflammatory diseases, and prevent ischemic stroke. Multiple pathways are responsible for the therapeutic actions exerted by these drugs. One of the pathways is targeting neuronal receptors/ion channels in the central nervous system. Correspondingly, increasing evidence has implicated acid-sensing ion channels (ASICs) in the processes of the diseases that are medicated by aspirin and salicylate. We therefore employed whole-cell patch-clamp recordings to examine the effects of salicylate as well as aspirin on ASICs in cultured cortical neurons of the rat. We recorded rapid and reversible inhibition of ASIC current by millimolar concentrations of aspirin and salicylate and found that salicylate reduced acidosis-induced membrane depolarization. These data suggest that ASICs in the cortex are molecular targets of high doses of aspirin and salicylate. In addition, the results from lactate dehydrogenase release measurement showed that high doses of aspirin and salicylate protected the cortical neuron from acidosis-induced neuronal injury. These findings may contribute to a better understanding of the therapeutic mechanisms of aspirin and salicylate actions in the brain and provide new evidence on aspirin and salicylate used as neuroprotective agents in the treatment of ischemic stroke.

Interaction of salicylate and a terpenoid plant extract with model membranes: reconciling experiments and simulations

We investigate the effects of two structurally similar small cyclic molecules: salicylic acid and perillic acid on a zwitterionic model lipid bilayer, and show that both molecules might have biological activity related to membrane thinning. Salicylic acid is a nonsteroidal antiinflammatory drug, some of the pharmacological properties of which arise from its interaction with the lipid bilayer component of the plasma membrane. Prior simulations show that salicylate orders zwitterionic lipid membranes. However, this is in conflict with Raman scattering and vesicle fluctuation analysis data, which suggest the opposite. We show using extensive molecular dynamics simulations, cumulatively >2.5 μs, that salicylic acid indeed disorders membranes with concomitant membrane thinning and that the conflict arose because prior simulations suffered from artifacts related to the sodium-ion induced condensation of zwitterionic lipids modeled by the Berger force field. Perillic acid is a terpenoid plant extract that has antiinfective and anticancer properties, and is extensively used in eastern medicine. We found that perillic acid causes large-scale membrane thinning and could therefore exert its antimicrobial properties via a membrane-lytic mechanism reminiscent of antimicrobial peptides. Being more amphipathic, perillic acid is more potent in disrupting lipid headgroup packing, and significantly modifies headgroup dipole orientation. Like salicylate, the membrane thinning effect of perillic acid is masked by the presence of sodium ions. As an alternative to sodium cations, we advocate the straightforward solution of using larger countercations like potassium or tetra-methyl-ammonium that will maintain electroneutrality but not interact strongly with, and thus not condense, the lipid bilayer.

Acetaminophen (paracetamol) inhibits myeloperoxidase-catalyzed oxidant production and biological damage at therapeutically achievable concentrations

The heme peroxidase enzyme myeloperoxidase (MPO) is released by activated neutrophils and monocytes, where it uses hydrogen peroxide (H(2)O(2)) to catalyze the production of the potent oxidants hypochlorous acid (HOCl), hypobromous acid (HOBr) and hypothiocyanous acid (HOSCN) from halide and pseudohalide (SCN(-)) ions. These oxidants have been implicated as key mediators of tissue damage in many human inflammatory diseases including atherosclerosis, asthma, rheumatoid arthritis, cystic fibrosis and some cancers. It is shown here that acetaminophen (paracetamol), a phenol-based drug with analgesic and antipyretic actions, is an efficient inhibitor of HOCl and HOBr generation by isolated MPO-H(2)O(2)-halide systems. With physiological halide concentrations, acetaminophen concentrations required for 50% inhibition of oxidant formation (IC(50)) were 77+/-6microM (100mMCl(-)) and 92+/-2microM (100mMCl(-) plus 100microMBr(-)), as measured by trapping of oxidants with taurine. The IC(50) for inhibition of HOCl generation by human neutrophils was ca. 100microM. These values are lower than the maximal therapeutic plasma concentrations of acetaminophen (< or =150microM) resulting from typical dosing regimes. Acetaminophen did not diminish superoxide generation by neutrophils, as measured by lucigenin-dependent chemiluminescence. Inhibition of HOCl production was associated with the generation of fluorescent acetaminophen oxidation products, consistent with acetaminophen acting as a competitive substrate of MPO. Inhibition by acetaminophen was maintained in the presence of heparan sulfate and extracellular matrix, materials implicated in the sequestration of MPO at sites of inflammation in vivo. Overall, these data indicate that acetaminophen may be an important modulator of MPO activity in vivo.

Membrane Activity-Guided Isolation of Antiproliferative and Antiplatelet Constituent from Evodiopanax Innovans

Bark of Evodiopanax innovans (Araliaceae) was subjected to membrane activity-guided extraction and chromatographic fractionation. The potency to interact with lipid membranes and change their fluidity was determined by measuring fluorescence polarization of liposomal and cell membranes. Plant preparations, including the MeOH extract and the specified fraction, reduced the fluidity of model biomembranes prepared with different phospholipids and cholesterol. Further purification led to the isolation of maltol 3- O-β-glucopyranoside, which inhibited tumor cell growth and platelet aggregation, together with rigidifying the cell membranes as well as the membrane-active antitumor compound (-)-epigallocatechin gallate and doxorubicin. The isolate at 100 μM and 1.0 mM showed growth inhibition of 13–49% against tumor cells cultured for 24 and 48 h. At 1.8–3.6 mM, it also produced 50% inhibition of platelet aggregation induced by collagen, adenosine 5′-diphosphate and thrombin. E. innovans is considered as a medicinal plant containing a potent bioactive constituent that exerts antiproliferative and antiplatelet effects through interaction with cell membranes to modify their fluidity.

Neutrophil effector functions triggered by Fc-gamma and/or complement receptors are dependent on B-ring hydroxylation pattern and physicochemical properties of flavonols

Tissue damage in autoimmune diseases involves excessive production of reactive oxygen species (ROS) triggered by immune complexes (IC) and neutrophil (PMN) interactions via receptors for the Fc portion of IgG (FcgammaR) and complement receptors (CR). Modulation of both the effector potential of these receptors and ROS generation may be relevant to the maintenance of body homeostasis. In the present study, the modulatory effect of four flavonols (myricetin, quercetin, kaempferol, galangin) on rabbit PMN oxidative metabolism, specifically stimulated via FcgammaR, CR or both classes of receptors, was evaluated by luminol- and lucigenin-dependent chemiluminescence assays. Results showed that flavonol inhibitory effect was not dependent on the cell membrane receptor class stimulated but related to the lipophilicity of the compounds (their apparent partition coefficient values were obtained by high-performance liquid chromatography), and was also inversely related to the number of hydroxyl groups in the flavonol B ring and the ROS-scavenger activity (assessed by the luminol--H2O2--horseradish peroxidase reaction). Under the experimental conditions the flavonols tested were not toxic to PMNs (evaluated by lactate dehydrogenase release and trypan blue exclusion) and did not interfere with IC-induced phagocytosis (evaluated by transmission electron microscopy). Our results suggested that inhibition of IC-stimulated PMNs effector functions by the flavonols tested herein was the result of cooperation of different cellular mechanisms.

Inhibitory and enhancing effects of piroxicam on whole blood chemiluminescence

The effects of piroxicam on the production of reactive oxygen species by stimulated phagocytes was studied in whole blood by a chemiluminescence (CL) technique in relation to maximum activity, localization and kinetics of radical generation. We found that piroxicam dose-dependently inhibited total (intra- and extracellular) zymosan-stimulated luminol CL (LCL) at a high stimulant concentration (p = 0.0001). Piroxicam additionally decreased cytochalasin B-reduced LCL, which shows that the effect of the drug should be sought in the extracellular component of the response. Piroxicam inhibited the first phase of extracellular LCL in a dose-dependent manner (p = 0.0001) and revealed itself as an enhancing agent of CL in later time intervals after the start of respiratory burst, in a model system containing horseradish peroxidase (HRP) and sodium azide. It enhanced LCL of a cell-free system, i.e. influenced the CL due to HRP-catalysed decomposition of hydrogen peroxide. It also dose-dependently inhibited the early extracellular superoxide production, evaluated by lucigenin CL (p = 0.022). Piroxicam inhibited the total fMLP-stimulated LCL by 70% approximately and, only by about 30%, the first phase of fMLP-stimulated extracellular LCL, which presupposes an effect on myeloperoxidase-catalysed formation of hypochloric acid. Piroxicam slightly increased the intracellular LCL by phagocytes (p = 0.02), an effect that is probably connected with its ability to induce the release of secondary messengers in signal transduction. In conclusion, the anti-inflammatory effect of piroxicam is probably related to the inhibition of the extracellular generation of superoxide and hypochloric acid in the early stages of phagocyte activation.

Detection of Drug−Membrane Interactions in Individual Phospholipid Vesicles by Confocal Raman Microscopy

Optical-trapping confocal Raman microscopy is developed as a method to study the interactions of drugs or other compounds with the membranes of individual phospholipid vesicles. This technique allows membrane disorder, permeability, and drug localization to be assessed without the need for labeling of the membrane or the compounds of interest. We have applied this technique to study the interactions of two nonsteroidal antiinflammatory drugs, salicylate and ibuprofen, with vesicles prepared from 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The results show that both salicylate and ibuprofen increase membrane disorder, as determined from increases in the Raman scattering from gauche conformers in the phospholipid acyl chains. By monitoring the Raman scattering of the drug molecules in optically trapped DMPC vesicles, the membrane permeability and partitioning of the drugs could be determined; the spatial distributions of the drugs were also measured by scanning the laser focus through surface-adhered 1,2-dipalmitoyl-sn-glycero-3-phosphocholine vesicles, producing a profile of the vesicle and its contents. Though the membrane is permeable to both drugs, ibuprofen preferentially accumulates in the membrane, whereas salicylate does not. The measured ibuprofen accumulation agrees quantitatively with the water/octanol partition coefficient of the drug and the estimated volume of the lipid membrane. The results suggest that ibuprofen localizes in the hydrophobic acyl chain region of the membrane, whereas salicylate weakly associates with the phospholipid headgroups.

Increased Interleukin-18 in Patients With Juvenile Idiopathic Arthritis and Early Attachment Loss

BACKGROUND

Patients with juvenile idiopathic arthritis (JIA) have been shown to have incipient attachment loss (AL) more frequently than systemically healthy individuals. This study investigated neutrophil activity and proinflammatory cytokines in these patients and aged-matched controls.

METHODS

Elastase activity, measured with a low molecular weight substrate (S-2484), and interleukin-1beta (IL-1beta), measured with the enzyme-linked immunosorbent assay (ELISA), were analyzed in the gingival fluid of 38 patients with JIA and 29 controls. IL-1beta and interleukin-18 (IL-18) were measured with ELISA in the serum of the same groups. Subgingival plaque was analyzed by DNA probes to detect 12 bacteria.

RESULTS

Significantly elevated serum levels of IL-1beta and IL-18 were found in the JIA group. No differences were found in the gingival fluid levels of elastase and IL-1beta between groups, or in the frequency of subjects positive to most of the bacteria analyzed, except F. nucleatum, C. rectus, P. micros, and S. intermedius, which were significantly more frequent in the control group. When the JIA group was subdivided according to the presence/absence of AL, IL-18 was significantly increased in the JIA subgroup with AL compared to those without it. There were no differences in the subgingival microbiota between the subgroups.

CONCLUSION

The findings of increased serum IL-18 and IL-1beta in patients with JIA accompanied by a similar subgingival microbiota suggest that the increased frequency of incipient attachment loss observed in these patients might be due to their altered systemic inflammatory response, making them more susceptible to periodontal disease.

High-dose aspirin is neuroprotective in a rat focal ischemia model

Acetylsalicylic acid (ASA) is neuroprotective through various pharmacological action sites. We used a temporary middle cerebral artery occlusion (tMCAO) model in 56 Wistar rats to assess whether repeated ASA injections at 30 min, 6 h, 1, 2, 3, and 4 days after stroke onset are neuroprotective. Animals were sacrificed 5 days after MCAO; infarct size was analyzed with 2,3,5-triphenyltetrazolium chloride staining. As compared to saline (164+/-13 mm(3), n=14), only repeated injections of 40 mg/kg ASA (79+/-18 mm(3), n=14, P=0.0029), but not of 20 mg/kg ASA (129+/-19 mm(3), n=15), reduced infarct volume significantly. No significant change was noted with 40 mg/kg ASA injected only once at 30 min after MCAO (117+/-16 mm(3), n=13).

Zeta-potential measurements as a tool to quantify the effect of charged drugs on the surface potential of egg phosphatidylcholine liposomes

The binding of charged drugs to neutral phosphatidylcholine membranes was assessed by measuring their zeta-potential values in the presence of different drug concentrations. This methodology was applied to the study of the concentration effects of two nonsteroidal antiinflammatory drugs (NSAIDs). Results revealed an intense membrane charging that was proportional to the amount of negatively charged drug in the media. A mathematical formalism was adapted and an analytical expression derived to calculate directly surface potentials from zeta-potential data. The membrane loading state, expressed as the number of molecules per unit area, was calculated for the negative and for the neutral forms of the drugs. An approach was also developed that allows the determination of the maximum number of molecules per unit area by fitting a binding isotherm to the dependence of the number molecules per unit area with the drug concentration. The calculation of the maximum mol lipid/drug ratio can also be estimated and related to the binding stoichiometry, as well as to the maximum lipid loading capacity. Furthermore, the concentration profiles for both drugs can be established in terms of the distance to the liposome surface. The developed methodology allowed for the simultaneous determination of partition coefficients (Kp) for the NSAIDs in lipid/aqueous media because zeta-potential values can be related to the drug concentration at the lipid/ aqueous media interface. Alternative independent methodologies were used to determine Kp: spectrophotometric and centrifugation assays. A mathematical relation was developed to compare the Kp values determined from the zeta-potential data with those obtained from the other techniques used because in the former case they are calculated on the basis of the number of molecules per unit area and in the latter on the basis of the total drug concentrations in solution, and the values of the partition coefficients obtained from all the techniques were found to be equal, within the experimental error. This methodology constitutes a more straightforward method than the other techniques used because partition coefficients for all drug forms (charged and noncharged) can be assessed with a minimum number of experimental determinations and it allows for a characterization of the electrostatic properties of neutral membranes upon binding of charged drugs.

Non-prostaglandin effects of aspirin III and salicylate: inhibition of integrin-dependent human neutrophil aggregation and inflammation in COX 2- and NF kappa B (P105)-knockout mice

Two, non-prostaglandin effects of antiinflammatory levels of salicylates (i.e. aspirin III) are shown here: 1) Exposure of neutrophils to aspirin or sodium salicylate inhibited Erk activity and integrin-dependent aggregation of neutrophils, consistent with antiinflammation but not COX inhibition. Inhibition of Mek (proximal activator of Erk) also blocked stimulation of Erk and neutrophil aggregation by FMLP and arachidonic acid. Thus, the antiinflammatory effects of salicylates may be mediated by inhibition of Erk signaling required for integrin-mediated responses. 2) Acute inflammation was induced in murine air-pouches of wild-type mice and mice rendered deficient in either COX-2 or p105, the precursor of p50 of NF kappa B. The antiinflammatory effects of aspirin and sodium salicylate were independent of the presence of COX-2 or p105 component of NF kappa B or the levels of prostaglandins at the inflammatory site. In contrast, glucocorticoid action depended on the p105.

Aspirin inhibits p44/42 mitogen-activated protein kinase and is protective against hypoxia/reoxygenation neuronal damage

BACKGROUND AND PURPOSE

Acetylsalicylic acid (ASA) is preventive against stroke and protects against focal brain ischemia in rats. We studied the mechanisms of the manner in which ASA provides neuroprotection against hypoxia/reoxygenation (H/R) injury.

METHODS

Spinal cord cultures exposed to 20 hours of hypoxia followed by reoxygenation were treated with a vehicle, ASA or inhibitors of inducible nitric oxide synthase (iNOS), mitogen-activated protein kinases p38 MAPK and ERK1/2, or an N-methyl-d-aspartic acid (NMDA) receptor antagonist. Cell viability was assessed by LDH release measurement and cell counts. Prostaglandin production was measured by enzyme immunoassay, MAPK signaling by immunoblotting, and DNA binding of nuclear factor-kappaB (NF-kappaB) and activating protein-1 (AP-1) by electrophoretic mobility shift assay.

RESULTS

One to 3 mmol/L ASA inhibited H/R-induced neuronal death when present during H/R but not when administered only for the reoxygenation period. Prostaglandin E2 production was very low and was not altered by ASA. The AP-1 and NF-kappaB DNA binding activities increased after H/R. ASA increased the H/R-induced AP-1 binding but had no effect on NF-kappaB binding. H/R induced a sustained ERK1/2 activation followed by neuronal death, whereas no changes in p38 or c-Jun N-terminal kinase were detected. ASA strongly inhibited this ERK1/2 activation. PD98059, an ERK1/2 inhibitor, was also neuroprotective, prevented H/R-induced ERK1/2 activation, and had no effect on NF-kappaB binding activity. Inhibition of NMDA receptors, iNOS, or p38 MAPK did not provide neuroprotection.

CONCLUSIONS

Inhibition of the sustained activation of ERK1/2 may partially contribute to neuroprotection achieved by ASA against H/R injury.

Risks and benefits of nonsteroidal anti-inflammatory drugs in children: a comparison with paracetamol

Nonsteroidal anti-inflammatory drugs (NSAIDs) possess antipyretic, analgesic and anti-inflammatory effects. They are frequently used in children and have numerous therapeutic indications, the most common ones being fever, postoperative pain and inflammatory disorders, such as juvenile idiopathic arthritis (JIA) and Kawasaki disease. Their major mechanism of action is through inhibition of prostaglandin biosynthesis by blockade of cyclo-oxygenase (COX). The disposition of most NSAIDs has been mainly studied in infants > or = 2 years of age. Compared with adults, the volume of distribution and clearance of NSAIDs such as diclofenac, ibuprofen (infants aged between 3 months and 2.5 years), ketorolac and nimesulide were increased in children. The elimination half-life was similar in children to that in adults. These pharmacokinetic differences might be clinically significant with the need for higher loading and/or maintenance doses in children. Ibuprofen, acetylsalicylic acid (ASA) and acetaminophen are the most frequently used agents for fever reduction in children. Over the past 20 years, because of the association between ASA use and Reye's syndrome, most of the interest has been directed toward ibuprofen and acetaminophen. In view of its comparable antipyretic efficacy, but superior tolerability profile, acetaminophen, when used appropriately with age-adapted formulations, should remain the first-line therapy in the treatment of childhood fever. At the moment, there is no scientific evidence to recommend simultaneous use of these two antipyretic drugs. Most NSAIDs provide mild to moderate analgesia, with the exception of ketorolac which has a strong analgesic activity. The analgesic efficacy of ketorolac, ketoprofen, diclofenac and ibuprofen in the treatment of postoperative pain has been mainly studied following a single dose, in children of > or = 1 year of age undergoing minor surgeries. In this setting, when used either alone or in adjunct to caudal or epidural anaesthesia, they were associated with an opioid-sparing effect and were well tolerated. With the exception of ketorolac use in children undergoing tonsillectomy, where controversy exists regarding the risk of postoperative haemorrhage, NSAIDs have not been associated with an increased risk of perioperative bleeding. NSAIDs are the first-line therapy in JIA. They appear to be equally effective and tolerated, with the exception of ASA which is associated with more adverse effects. ASA has been used for many years in the treatment of Kawasaki disease and is part of the standard modality of treatment in combination with intravenous gammaglobulins. More recently, lung inflammation associated with cystic fibrosis (CF) has become a new target for NSAIDs. Despite promising preliminary results with ibuprofen, numerous questions need to be answered before this new strategy becomes part of the conventional treatment of patients with CF. In summary, NSAIDs are effective in reducing fever, alleviating pain and reducing inflammation in children, with a good tolerance profile. Pharmacokinetic studies are needed to characterise the disposition of NSAIDs in very young infants in order to use them rationally. To date, no studies have been published on the disposition, tolerability and efficacy of specific COX-2 inhibitors in children. Further clinical experience with these agents in adults is warranted before undergoing trials with specific COX-2 inhibitors in children.

Cyclooxygenase-2 regulates granulocyte-macrophage colony-stimulating factor, but not interleukin-8, production by human vascular cells: role of cAMP

Vascular smooth muscle is now recognized as an important site of mediator generation under inflammatory conditions. Indeed, the release of leukocyte activators, such as granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-8, by human arterial smooth muscle cells has recently been demonstrated. However, the potential for venous cells to release GM-CSF has not been addressed. We have shown that human vascular smooth muscle cells express the "inflammatory" form of cyclooxygenase (COX), cyclooxygenase-2 (COX-2), when stimulated with cytokines. In some nonvascular cell types, the COX activity has been shown to regulate the release of GM-CSF and IL-8, although the nature of the isoform responsible was not addressed. We show that human venous smooth muscle cells, like their arterial counterparts, release GM-CSF after stimulation with IL-1beta. Similarly, both cell types released IL-8. Under the same conditions, we found that COX-2 activity suppressed GM-CSF, but not IL-8, release by both types of human vascular cells. Moreover, the prostacyclin mimetic, cicaprost, and the cAMP analogue, dibutyryl cAMP, inhibited GM-CSF release from these cells. These observations suggest that COX-2 activity suppresses GM-CSF release via a cAMP-dependent pathway in human vascular cells and illustrates a novel mechanism by which this enzyme can modulate immune and inflammatory events.

Effect of arachidonic acid metabolic inhibitors on hypoxia/reoxygenation-induced renal cell injury

The present study was undertaken to examine the role of arachidonic acid (AA) metabolites in hypoxia/reoxygenation (H/R)-induced renal cell injury in rabbit renal cortical slices using AA metabolic inhibitors. Inhibitors of cyclooxygenase (indomethacin and diclofenac sodium) and lipoxygenase pathways (nordihydroguaiaretic acid, caffeic acid, and eicosapentaenoic acid) reduced H/R-induced LDH release in a dose-dependent manner, whereas an inhibitor of cytochrome P-450 monooxygenase pathway ethoxyresorufin was not effective. AA increased LDH release in control slices, and the effect was not altered by indomethacin and nordihydroguaiaretic acid. The protective effect of indomethacin was not affected by addition of PGE2, a main product of cyclooxygenase pathway in the kidney. H2O2-induced LDH release was prevented by inhibitors of lipoxygenase but not by inhibitors of cyclooxygenase and cytochrome P-450 monooxygenase H/R-induced LDH release was not altered by iron chelators, phenanthroline and deferoxamine, and a potent antioxidant, N,N'-diphenyl-p-phenylenediamine, suggesting that the H/R-induced cell injury is not attributed to a generation of reactive oxygen species. Morphological studies showed that H/R-induced structural changes including cell necrosis were significantly prevented by indomethacin. These results suggest that inhibitors of cyclooxygenase and lipoxygenase pathways exert a direct protective effect against the H/R-induced cell injury in renal tubules. Whether these effects are mediated by alterations of AA metabolic pathways is not certain.

Antagonism between the metabolic responses induced by epinephrine and piroxicam on isolated rat hepatocytes

Nonsteroidal anti-inflammatory drugs (NSAIDs) are one of the most employed therapeutic agents. They have a wide spectrum of biological effects, some of which are independent of cyclooxygenase inhibition, such as the alterations on the components of signal transduction systems. In particular, previous data from our laboratory suggested an antagonism between epinephrine and piroxicam, one of the most prescribed NSAIDs. Thus, this study deals with the epinephrine-piroxicam antagonism recorded for metabolic responses in isolated rat hepatocytes. The obtained results show that epinephrine stimulates lactate and ethanol consumption, stimulates glucose release from lactate only, and has no effect on cellular triacylglycerides content. Otherwise, in a dose-dependent basis, piroxicam stimulates lactate and ethanol consumption accompanied by an increase in triacylglycerides content, without changes in glucose release by hepatocytes. Piroxicam blocks the epinephrine-induced stimulation of glucose release from lactate, and epinephrine blocks the piroxicam-mediated increase in triacylglycerides content from lactate or ethanol. In contrast, the effects of epinephrine and piroxicam, promoting the consumption of lactate and ethanol, are not antagonized or added after the simultaneous administration of both compounds. This last result is probably related to the ability of both compounds to stimulate oxygen consumption. On isolated rat liver mitochondria, micromolar doses of piroxicam partially uncouple oxidative phosphorylation, and paradoxically stimulates an ATP-dependent mitochondrial function as citrullinogenesis. These results show for first time, on isolated rat hepatocytes, an antagonism between the metabolic responses of epinephrine and piroxicam, at the concentration found in plasma after its therapeutical administration.

Interaction of indomethacin and naproxen with gastric surface-active phospholipids: a possible mechanism for the gastric toxicity of nonsteroidal anti-inflammatory drugs (NSAIDs)

The possibility that the molecular mechanism underlying the topical gastric irritancy of nonsteroidal anti-inflammatory drugs (NSAIDs) may involve alterations in the surface-active properties of gastric phospholipids was investigated. Indomethacin and naproxen were intragastrically administered to rats and the hydrophobicity of the luminal surface of the stomach wall was assessed by contact angle analysis. Both NSAIDs have the ability to attenuate the phospholipid-related hydrophobic properties of the gastric mucosa by more than 80-85% in a dose-dependent fashion. Potential molecular interactions between both NSAIDs and surface-active phospholipids were analyzed using fluorescent probes. Indomethacin has the ability to displace, in a dose-dependent manner, ANS (1-anilino-8-naphthalene sulphonate), a fluorescent anionic probe previously bound to the head group of phosphatidylcholine molecules. Estimations of the resonance fluorescence transfer between naproxen and the surface probe ANS or the hydrophobic probe, pyrene, bound to dipalmitoylphosphatidylcholine (DPPC) vesicles revealed that naproxen diffuses within the phospholipid bilayers. The dynamic of the gastric lipid material extracted from the surface scraping material (SSM) of the mucosa was altered by the NSAID as shown by the increase in the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene (DPH) (at 25 degrees, rSSM = 0.106+/-0.006, rssM + indomethacin = 0.137+/-0.005, and rSSM + naproxen = 0.133+/-0.007, P < 0.001). The thermodynamic behavior of a model bilayer containing DPPC was also perturbed by the NSAIDs tested. These results provide evidence that NSAIDs may reduce the ability of gastric surface-active phospholipids to form a hydrophobic protective layer.

Modes of action of aspirin-like drugs: salicylates inhibit erk activation and integrin-dependent neutrophil adhesion

The anti-inflammatory effects of high-dose salicylates are well recognized, incompletely understood and unlikely due entirely to cyclooxygenase (COX) inhibition. We have previously reported a role for activation of the kinase Erk in CD11b/CD18 integrin-dependent adhesiveness of human neutrophils, a critical step in inflammation. We now report the effects of salicylates on neutrophil Erk and adhesion. Exposure of neutrophils to aspirin or sodium salicylate (poor COX inhibitor) inhibited Erk activity and adhesiveness of formylmethionyl-leucyl-phenylalanine- and arachidonic acid-stimulated neutrophils, consistent with anti-inflammation but not COX inhibition (IC50s = 1-8 mM). In contrast, indomethacin blocked neither Erk nor adhesion. Inhibition of Mek (proximal activator of Erk) also blocked stimulation of Erk and adhesion by formylmethionyl-leucyl-phenylalanineand arachidonic acid. Salicylate inhibition of Erk was independent of protein kinase A activation and generation of extracellular adenosine. These data are consistent with a role for Erk in stimulated neutrophil adhesion, and suggest that anti-inflammatory effects of salicylates may be mediated via inhibition of Erk signaling required for integrin-mediated responses.

Integrin-dependent homotypic adhesion of neutrophils. Arachidonic acid activates Raf-1/Mek/Erk via a 5-lipoxygenase- dependent pathway

AA stimulates integrin-dependent neutrophil adhesion, a critical early step in acute inflammation. However, neither the signaling pathway(s) of AA-stimulated adhesion, nor whether AA acts directly or through the generation of active metabolites, has been elucidated. Previously, we have observed a tight association between neutrophil Erk activation and homotypic adhesion in response to chemoattractants acting through G protein-linked receptors. We now report a similar association between homotypic adhesion and Erk activation in response to AA. Erk activation was cyclooxygenase independent and required AA metabolism to 5(S)- hydroperoxyeicosatetraenoic acid (5-HpETE) via 5-lipoxygenase, but not the further lipoxygenase-dependent metabolism of 5-HpETE to leukotrienes. AA stimulation of Erk was accompanied by Raf-1 activation and was sensitive to inhibitors of Raf-1 and Mek. Whereas activation of Erk by AA was pertussis toxin sensitive, [3H]-AA binding to neutrophils was not saturable, suggesting that an AA metabolite activates a G protein. Consistent with this hypothesis, Erk activation by 5(S)-hydroxyeicosatetraenoic acid (5-HETE; lipoxygenase-independent metabolite of 5-HpETE) was also pertussis toxin sensitive. These data suggest that a 5-lipoxygenase metabolite of AA, e.g., 5-HETE, is released from AA-treated cells to engage a plasma membrane-associated, pertussis toxin-sensitive, G protein-linked receptor, leading to activation of Erk and adhesion via the Raf-1/Mek signal transduction pathway.

Necrotizing soft tissue infections reported with nonsteroidal antiinflammatory drugs

BACKGROUND

Recent reports of necrotizing fasciitis in children with varicella who received a nonsteroidal antiinflammatory drug (NSAID) recall earlier concerns regarding the possibility of relationships between infections and NSAIDs. We searched the Food and Drug Administration's Spontaneous Reporting System (SRS) for necrotizing soft tissue infections reported in conjunction with the use of NSAIDs, to identify common features.

METHODS

A computer search of NSAID listings in the adverse event database recovered reports with codes for selected infection and necrosis-related diagnostic categories. From review of individual reports classified under these codes, cases were selected if the terms "necrotizing fasciitis," "necrotic," or "gangrenous" appeared in the adverse drug reaction description. Demographic, drug use, and disease course information were gathered.

FINDINGS

Thirty-three cases were identified, of which 10 were fatal. Over two-thirds of the patients were younger than 40 years. Thirty (91%) had a possible portal of entry for infection. Most received NSAIDs for acute conditions including varicella, trauma, and postoperative or postpartum pain; 7 received an NSAID by intramuscular injection. Specific NSAIDs accounting for most reports were also among those likely to be most heavily used in the relevant populations.

INTERPRETATION

Common features of these rare case reports of necrotizing soft tissue infections with NSAID use include characteristics such as age, portal of infection entry, indication for NSAID use, route of administration, and individual NSAIDs. The total number of SRS cases does not suggest that necrotizing infection is frequent with NSAIDs or likely without other risk factors. Controlled observational studies would help to define any causal contribution of these factors to the evolution of severe infection.

NSAIDs upregulate beta 2-integrin expression on human neutrophils through a calcium-dependent pathway

BACKGROUND

Margination of circulating neutrophils (PMN) into the gastric microcirculation is an early and critical event in the pathogenesis of non-steroidal antinflammatory drug (NSAID)-induced gastropathy. This effect is mediated through the upregulation of beta 2 integrins on the PMN surface.

AIMS

To investigate whether indomethacin modulates: (1) Mac-1 expression; (2) Ca2+ mobilization ([Ca2+]i), protein kinase C and nitric oxide accumulation; and (3) mitogen-associated protein kinase phosphorylation in human PMN.

METHODS

Human PMN were isolated by centrifugation through a double Ficoll gradient. [Ca2+]i was measured in PMN loaded with fura-2 and Mac-1 expression by flow cytometry.

RESULTS

Indomethacin caused a concentration- and time-dependent upregulation of CD11b and CD18 expression and PMN adhesion to endothelial cells. Maximal upregulation of Mac-1 expression (40-50%) occurred after a 30-min incubation with 0.1mM indomethacin. The effect was prevented by removing the Ca2+. Ionomycin and thapsigargin caused a 7-10-fold increase in [Ca2+]i and a 2-4-fold increase in Mac-1 expression. Indomethacin induced a concentration-dependent phosphorylation of a 41-kDa mitogen-associated protein kinase. Tyrosine kinase inhibitors prevented the effect of indomethacin on Mac-1 expression and Ca2+ mobilization. Indomethacin and ionomycin increased superoxide generation, myeloperoxidase secretion and PMN adherence to endothelial cells and stimulated nitric oxide production. Indomethacin-induced Mac-1 upregulation was prevented by a nitric oxide synthase inhibitor.

CONCLUSIONS

Indomethacin-induced upregulation of Mac-1 is mediated by changes in [Ca2+]i and nitric oxide. Phosphorylation of the 41-kDa mitogen-associated protein isoform is a previously unreported target of NSAID action. These effects might help to explain the ability of indomethacin to cause gastric neutrophil margination.

A flow-cytometric method to evaluate drug antiaggregating effect on rat neutrophils

Neutrophils are one of the first cellular populations to become involved in inflammatory processes and some features of the response to inflammatory stimuli can be partially reproduced in vitro by treatment with chemotactic peptides such as N-formyl-methionyl-leucyl-phenylalanine (FMLP). Nonsteroidal antiinflammatory drugs (NSAIDs), such as indomethacin, are known to interfere in vitro with human and rat neutrophil functions and to inhibit FMLP-induced aggregation. In this article we define the scatter parameters of rat neutrophils and demonstrate that flow-cytometric analysis of these cells can be used to analyze the inhibiting action of drugs in an in vitro model of aggregation. We show, in fact, that indomethacin at 100 microM (p < 0.05) and 200 microM (p < 0.01) is able to significantly reduce rat neutrophil aggregation. These results confirm the data obtained by light transmittance aggregometry and indicate that cytometric analysis of aggregation phenomena is a technique suitable for the screening of antiaggregating drugs.

Plasma and synovial fluid interleukin-1, interleukin-6 and substance P concentrations in rheumatoid arthritis patients: effect of the nonsteroidal anti inflammatory drugs indomethacin, diclofenac and naproxen

We performed an open, between patients, placebo controlled study in order to evaluate the effect of the treatment with the non steroidal anti inflammatory drugs indomethacin, diclofenac and naproxen on the concentrations of the cytokines IL-1 beta and IL-6 and of the neuropeptide substance P in plasma and synovial fluid of 24 rheumatoid arthritis patients. All patients had high synovial fluid cytokine and substance P levels, and high plasma cytokine levels at the beginning of the study. The treatment with the non steroidal anti inflammatory drugs significantly decreased both plasma and synovial fluid IL-6 and synovial fluid substance P in comparison to placebo, but did not affect IL-1 beta concentrations. This effect can participate in the therapeutic effect of non steroidal anti inflammatory drugs in rheumatoid arthritis.

Inhibition of human neutrophil function by tolfenamic acid involves inhibition of Ca2+ influx

The present work was designed to study the pharmacological control of the receptor-mediated activation of human neutrophils by tolfenamic acid (2(-)[(3-chloro-2-methylphenyl)-amino]benzoic acid). Tolfenamic acid inhibited in a concentration-dependent manner the degranulation response and Ca2+ influx in neutrophils activated either by the chemotactic peptide fMLP (N-formyl-methionyl-leucylphenylalanine) or Ca2+ ionophore A23187 (calcimycin). When fMLP was used to activate neutrophils, tolfenamic acid (30 microM) reduced Ca2+ influx by 50% and degranulation by 20%. A23187-triggered Ca2+ influx and degranulation were inhibited by 60% and 40%, respectively, by 30 microM tolfenamic acid. Tolfenamic acid did not inhibit the release of Ca2+ from intracellular stores induced either by fMLP or A23187. To confirm the inhibition of receptor-mediated cation influx by tolfenamic acid, the agonist induced Mn2+ influx was studied in Ca2+ free medium. Tolfenamic acid (10-30 microM) reduced fMLP-stimulated Mn2+ influx in neutrophils in a concentration-dependent manner. The simultaneous Ca2+ release from intracellular stores was not affected. Protein kinase C activity in sonicated human neutrophils and the purified enzyme from rat brain were inhibited by the protein kinase inhibitor H-7 (1-(5-isoquinolinylsulfonyl)-2-methylpiperazine) but not by tolfenamic acid. Both failed to inhibit neutrophil degranulation induced by phorbol myristate acetate, a protein kinase C activator. Tolfenamic acid (100 microM) increased the cellular cAMP levels up to 1.3-fold in the presence of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. No effects on cellular cGMP levels were found.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of folate on the methotrexate/indomethacin interaction in a murine cancer cell line

1. The effect of folate on the interaction between methotrexate (a folate analogue) and indomethacin has been examined in murine NC carcinoma cells. 2. Conditioning of NC cells to a physiological (20 nM) folate concentration after culture in a high folate concentration increased the response to methotrexate. The sensitivity of these conditioned cells to methotrexate related inversely to the folate concentration. 3. At 20 nM and 2 microM folate, indomethacin 1 micrograms ml-1 potentiated the cytotoxicity of methotrexate 4 and 8 ng ml-1 (both P < 0.03). 4. When NC cells were incubated with [3H]-methotrexate at 20 nM and 2 microM folate, there was a trend for increased tritium accumulation with indomethacin 0.36 micrograms ml-1 (1 microM; P < 0.01). 5. We conclude that the folate concentration can affect the sensitivity of NC cells to methotrexate, although the degree of potentiation of cytotoxicity by indomethacin remains similar.

Influence of nifedipine on plasma membrane fluidity and oxidative burst of polymorphonuclear leucocytes

It has been demonstrated that the calcium antagonist nifedipine inhibits the reactive oxygen species (ROS) production by polymorphonuclear leucocytes (PMNLs) activated with phorbol myristate acetate (PMA), but the mechanism underlying this effect is still unknown. In the present study we investigated the influence of nifedipine on the PMNL plasma membrane using 1-(4-trimethylaminophenyl)-6-phenyl-1,3,5,hexatriene (TMA-DPH) fluorescence polarization (P) and on PMA- and N-formyl-methionyl-leucyl-phenylalanine (FMLP)-induced ROS production, measured by luminol-dependent chemiluminescence (CL). The plasma membrane fluidity of untreated PMNLs, expressed as P, was 0.371 +/- 0.008. After preincubation of 15 min, nifedipine induced a significant change in P values only at a concentration of 10(-4) M (P = 0.00018). After preincubation of 60 min significant changes in P values were also observed at concentrations of 10(-6) M (P = 0.023) and 10(-7) M (P = 0.023). PMA-induced ROS production by PMNLs was markedly inhibited by nifedipine. Nifedipine also determined a striking change in the FMLP-induced CL response, characterized by both an overall inhibition of PMNL activity and a modification of the kinetics of the oxidative burst (rapid increase in ROS production followed by a pronounced drop in the PMNL response). Such a pattern was found at concentrations of 10(-4) M (preincubation time: 15 min), 10(-6) M and 10(-7) M (preincubation time: 60 min). These findings indicate that nifedipine directly interacts with the PMNLs by inducing a marked decrease in plasma membrane fluidity and an inhibition of the oxidative burst.

The non-steroidal anti-inflammatory drug, indomethacin, as an inhibitor of HIV replication

Indomethacin, a common non-steroidal anti-inflammatory drug (NSAID), has been used to treat rheumatoid arthritis. Although indomethacin has also been used as an immunopotentiator and symptomatic NSAID in AIDS, its effect on HIV replication is unknown. MT-4 lymphocytes were inoculated with HIV in the presence of indomethacin and tested for p24 expression by ELISA. The 50% inhibition (IC50) was 10 microM, corresponding to plasma levels after administration of 50 mg oral indomethacin. The antiviral effect appears to be specific since no toxicity has been observed at the IC50 dose, and unrelated NSAIDs have not shown the activity at clinical doses. Indomethacin may, thus, represent a new class of anti-HIV drug.

Ketoprofen and prednisolone do not modulate neutrophil CR1, CR3 and Fc gamma RIII expression in healthy volunteers

We assessed the effect of ketoprofen and prednisolone on the complement receptors (CR1 and CR3) and Fc gamma RIII expression on polymorphonuclears in an ex vivo study, using a randomized, single-blind, placebo-controlled, parallel design. Twenty-four healthy, male, Caucasian volunteers received either oral ketoprofen 100 mg twice daily, or prednisolone 5 mg twice daily, or placebo twice daily for 7.5 days. CR1, CR3 and Fc gamma RIII on unstimulated and FMLP-, C5a-, LTB4-, and GM-CSF-stimulated neutrophils were assessed using specific monoclonal antibodies and flow cytometry. No statistically significant drug effect was found for CR1, CR3, and Fc gamma RIII expression on polymorphonuclears. An in vitro study also yielded negative results. These findings do not support the hypothesis that the effect of non-steroidal antiinflammatory drugs on neutrophils is due to CR1, CR3, or Fc gamma RIII modulation.

Cytoprotection by diclofenac sodium after intestinal ischemia/reperfusion injury

Intestinal injury resulting from ischemia/reperfusion (I/R) is of fundamental importance in clinical pediatric surgery. I/R injury results from inadequate oxygen delivery as well as a secondary inflammatory response involving neutrophils and oxidants. This study was designed to evaluate a novel use for diclofenac sodium (DS), a nonsteroidal antiinflammatory agent, and to compare it with traditional antioxidants in this setting. Rats were subjected to intestinal ischemia followed by reperfusion. When killed, samples were obtained for measurement of intestinal myeloperoxidase (MPO), a measure of neutrophil sequestration, as well as for adenosine triphosphate (ATP) content, a marker of tissue injury. Animals exposed to I/R injury had significant neutrophil sequestration in the intestine by 120 minutes of ischemia, and this persisted after 60 minutes of reperfusion. DS pretreatment did not prevent neutrophil sequestration in the intestine. Analysis of intestinal ATP content demonstrated a decrease in intestinal ATP after 120 minutes of ischemia, and this did not change with 60 minutes of reperfusion. Pretreatment with DS significantly attenuated this intestinal ATP depletion. Furthermore, with 120 minutes of ischemia and 60 minutes of reperfusion, ATP preservation with DS pretreatment exceeded that obtained using the following conventional antioxidants: a xanthine-oxidase inhibitor (lodoxamide), deferoxamine, dimethysulfoxide, and superoxide dismutase plus catalase. DS has a significant cytoprotective effect for intestine subjected to I/R injury, exceeding that of conventional antioxidants. DS does not attenuate injury by preventing neutrophil influx into injured intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonsteroidal antiinflammatory agents inhibit stimulated neutrophil adhesion to endothelium: adenosine dependent and independent mechanisms

All nonsteroidal antiinflammatory drugs (NSAIDs) inhibit neutrophil aggregation (homotypic cell-cell adhesion) and do so without affecting expression of CD11b/CD18. Since the first step in acute inflammation is a critical interaction between neutrophils and the vascular endothelium (heterotypic cell-cell adhesion), we determined whether NSAIDs diminish the adherence of neutrophils to the endothelium. At antiinflammatory concentrations (0.5-5 mM) sodium salicylate, an NSAID that does not inhibit prostaglandin synthesis, inhibited stimulated but not unstimulated neutrophil adherence to endothelial cells (IC50 < 1 mM, P < 0.00001). Salicylates have previously been shown to inhibit oxidative phosphorylation and, predictably, sodium salicylate inhibited oxidative phosphorylation, as evidenced by depletion of ATP stores (875 +/- 75 pmol/10(6) PMN, [2.92 +/- 0.25 mM]) in stimulated (FMLP, 0.1 microM) but not resting neutrophils treated with antiinflammatory doses of sodium salicylate (EC50 = 1 mM, P < 0.00001). Indomethacin and piroxicam (10 and 30 microM) only minimally decreased ATP concentrations in stimulated and resting neutrophils. ATP is metabolized to adenosine, and we have previously demonstrated that both endogenously released (180-200 nM) and exogenous adenosine (IC50 = 250 nM) inhibit stimulated neutrophil adherence to endothelial cells. To determine whether the increased metabolism of ATP and the resultant increase in adenosine release were responsible for inhibition of neutrophil adhesion to endothelium, we determined whether addition of adenosine deaminase (ADA, 0.125 IU/ml), an enzyme that converts extracellular adenosine to its inactive metabolite, inosine, affected inhibition of neutrophil adhesion to endothelium by stimulated neutrophils. ADA significantly reversed inhibition of neutrophil adherence to endothelium by sodium salicylate (0.5-5 mM, P < 0.00001). This suggests that sodium salicylate inhibits neutrophil adherence by increasing adenosine release. Whereas indomethacin and piroxicam (10-50 microM) also inhibited stimulated neutrophil adherence to endothelial cells, ADA did not affect their inhibition of adherence. These studies demonstrate a heretofore unexpected antiinflammatory mechanism for salicylates: salicylates increase ATP hydrolysis and thereby enhance release of adenosine. Moreover, these data are consistent with the hypothesis that NSAIDs differ from one another with respect to their mechanisms of action.

Long-term effect of nonsteroidal anti-inflammatory drugs on the production of cytokines and other inflammatory mediators by blood cells of patients with osteoarthritis

Most of the previous studies dealing with the effect of nonsteroidal anti-inflammatory drugs (NSAIDs) on the synthesis of inflammatory mediators involved in joint damage have been done in cells cultured in vitro or in blood cells from patients treated for short periods of time. In this work we have evaluated the long-term effect of aceclofenac, a new NSAID, and diclofenac on the production of a series of inflammatory mediators by blood cells from 30 patients with severe knee osteoarthritis. Both aceclofenac and diclofenac significantly inhibited prostaglandin E2 (PGE2) synthesis by blood mononuclear and polymorphonuclear cells after 180 days of treatment. However, no clear effect was noted on leukotriene B4 (LTB4) and platelet activating factor (PAF) production. The generation of O-2 by polymorphonuclear cells, stimulated with FMLP, was decreased after 15 days of treatment with both drugs, but reached normal values after 180 days. Interleukin-1 beta (IL-1 beta) production decreased significantly at 180 days with both drugs in the group of high producer patients. In a few (n = 3) patients with high basal mononuclear cell tumor necrosis factor alpha (TNF alpha) production, this also decreased on treatment for 180 days with the NSAIDs. In the remaining low TNF alpha-producing patients, TNF alpha production tended to increase. Interleukin-6 (IL-6) synthesis was not affected by aceclofenac while it was diminished by diclofenac. The decrease in IL-6 in all treated patients was significantly correlated with a worsening of the clinical condition. On the whole, these data could afford a pathogenetic basis for the long-term employment of these drugs in patients with inflammatory conditions.

Fc alpha R expression on polymorphonuclear leukocyte and superoxide generation in IgA nephropathy

Superoxide (O2-) production and Fc alpha R antigen expression of circulating polymorphonuclear leukocytes (PMNL) isolated from patients with IgA nephropathy (IgAN) and non-IgA mesangial proliferative glomerulonephritis (PGN) and healthy volunteers were investigated to establish their biological importance in the immunopathogenesis of mesangial proliferative glomerulonephritis. PMNL from both patient groups showed increased O2- production when stimulated with N-formyl methionyl leucyl phenylalanine (FMLP) and phorbol myristate acetate (PMA). The increased O2- generation demonstrated a positive correlation with the degree of proteinuria. Aggregated IgA caused enhanced O2- production only in patients with IgAN who also showed a significant correlation with proteinuria. Increased expression of Fc alpha R on circulating PMNL was observed in IgAN patients as determined by flow cytometric analysis. The amount of Fc alpha R on PMNL was positively correlated with O2- generation triggered with IgA aggregates. These results suggest that: 1. Circulating PMNL may potentially be participating in the pathogenesis of glomerular injury in mesangial proliferative glomerulonephritis, and 2. IgA aggregates/immune complexes may contribute to the immunopathogenesis of IgAN through augmenting the Fc alpha receptor-mediated generation of superoxide anion.

Inhibition of neutrophil function by aspirin-like drugs (NSAIDS): requirement for assembly of heterotrimeric G proteins in bilayer phospholipid

Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit neutrophil functions via mechanisms that are independent of their effects on prostaglandin biosynthesis. We examined the effects of sodium salicylate and piroxicam on GTP/GDP exchange by a regulatory G protein (G alpha i). Plasma membrane and cytosol of human neutrophils were prepared by nitrogen cavitation and discontinuous sucrose density centrifugation. Salicylate (3 mM) and piroxicam (50 microM) reduced [35S]GTP gamma S binding to purified plasma membranes [65 +/- 3.7 and 75 +/- 5.3% (P < 0.003) of control, respectively]. Membrane-associated G alpha/beta gamma was solubilized by treatment of plasma membranes with sodium cholate. NSAIDs did not inhibit binding of GTP to solubilized G alpha/beta gamma derived from detergent-treated plasma membranes. Lipid reconstitution was achieved by detergent dialysis followed by the addition of bilayer liposomes (phosphatidylcholine). Salicylate and piroxicam inhibited GTP gamma S binding to G alpha/beta gamma derived from solubilized plasma membranes reconstituted in phosphatidylcholine vesicles (bilayer structures) but had no effect when phosphatidylethanolamine (hexagonal phase II structure) was used for reconstitution. Salicylate and piroxicam had no effect on GTP binding to cytosolic fractions in which soluble G alpha i exists as a free subunit, suggesting that the effect required either assembly of G alpha i/beta gamma heterotrimer or the presence of a lipid bilayer. Although the addition of purified bovine beta gamma subunits to dialyzed cytosol increased both the total GIP binding capacity and the pertussis toxin-dependent ADP-ribosylation of G alpha i, consistent with assembly of a G protein heterotrimer, NSAIDs had no effect on GTP binding. In contrast, NSAIDs inhibited GTP binding to heterotrimeric G alpha cytosol/beta gamma bovine when the complex was inserted into bilayer liposomes. The data indicate that salicylate and piroxicam disrupt neutrophil function via their capacity to interfere with GTP/GDP exchange at an alpha subunit of a regulatory G protein, an effect which requires assembly of the active heterotrimer G alpha i/beta gamma in a phospholipid bilayer.

Effect of ibuprofen and diclofenac on the chemotaxis induced by substance P and transforming growth factor-beta on human monocytes and polymorphonuclear cells

The neuropeptide substance P and the cytokine transforming growth factor-beta are potent chemotactic factors for monocytes or polymorphonuclear cells. They are present in synovial fluid of arthritic patients, and participate in the pathogenesis of arthritis. We investigated, in vitro, the effect of two non-steroidal anti-inflammatory drugs, ibuprofen and diclofenac, on the chemotactic effect of substance P and transforming growth factor-beta at concentrations that can be present in the synovial fluid of arthritic patients. Both drugs decrease the chemotaxis induced by substance P and transforming growth factor-beta, at concentrations that can be easily reached in the synovial fluid during therapy. This event could be involved in the effect of some non-steroidal anti-inflammatory drugs on the development and progress of arthritic disease.

Comparison of naproxen and acetaminophen in a two-year study of treatment of osteoarthritis of the knee

OBJECTIVE

To compare the relative safety and efficacy of naproxen and acetaminophen in the treatment of osteoarthritis (OA) of the knee. The major outcome measures were radiographic progression and withdrawal from the trial due to lack of efficacy.

METHODS

One hundred seventy-eight patients with OA of the knee were enrolled in a 2-year prospective, controlled, double-blind multicenter trial and were randomly assigned to receive acetaminophen (ACT) or naproxen (NPX) treatment.

RESULTS

After 6 weeks of treatment, modest improvement in pain on motion and in physician's global assessment was seen in both the ACT and the NPX groups, and the NPX group also had modest improvement in pain at rest and in 50-foot walk time. Sixty-two patients completed the 2-year study. Among these patients, radiographic progression was similar in the 2 treatment groups. Withdrawal from the trial due to lack of drug efficacy was slightly more frequent among patients in the ACT group (22% versus 16%), but withdrawal due to adverse drug effects was slightly more common in the NPX group (23% versus 18%).

CONCLUSION

The efficacy of ACT treatment and NPX treatment was similar, although it was slightly better for NPX. The toxicity rate was slightly lower with ACT. However, the high rate of withdrawal in both treatment groups suggests that neither is satisfactory for the treatment of OA.

Bovine acute mastitis: effects of intravenous sodium salicylate on endotoxin-induced intramammary inflammation

Effects of the nonsteroidal antiinflammatory agent sodium salicylate on endotoxin-induced mastitis were evaluated in lactating cows. Escherichia coli endotoxin was administered to a mammary quarter 1 h after initiation of a 12-h i.v. infusion of sodium salicylate. Milk SCC, BSA concentrations in milk, mammary inflammation, rectal temperature, appetite, milk production, and plasma and lymph PGF2 alpha were monitored. Gross mammary inflammation was not reduced by salicylate infusion, nor did sodium salicylate prevent increased milk SCC or BSA concentrations in milk, although treatment tended to decrease the magnitude of these responses. Sodium salicylate decreased subcutaneous abdominal vein PGF2 alpha metabolite, and PGF2 alpha metabolite tended to be reduced in lymph during the acute phase of inflammation. The increased rectal temperature after endotoxin infusion was reduced in cows treated with sodium salicylate. Appetite was reduced after endotoxin infusion in untreated cows and those treated with sodium salicylate. Milk production declined after endotoxin challenge in all cows. Although sodium salicylate did not substantially reduce mammary inflammation, it had an antipyretic effect and reduced PGF2 alpha metabolite in mammary blood.

Conformational analysis of arachidonic and related fatty acids using molecular dynamics simulations

Arachidonic acid has recently gained attention as a result of current evidence indicating that it may play the role of a 'second messenger' in signal transduction processes. In order to gain insight into the mechanism behind its action, quenched molecular dynamics simulations were performed on arachidonic (20:4) and related fatty acids: linoleic (18:2), oleic (18:1), arachidic (20:0), and stearic (18:0). The angle-iron structure, representative of arachidonic acid in the crystal or very-low-temperature state, readily gave way at higher temperature to a dominant hairpin structure whereby the COOH end of arachidonic acid comes into close proximity with the C14-15 pi-bond resulting in a packed pi-bond-rich loop. The lowest energy conformer for arachidonic acid was found to be 10.65 kcal/mol below that of the energy-minimized crystal structure. In the case of saturated fatty acids, the crystal all-trans conformation remained the lowest energy form. Analysis of conformational energy contours for carbon-carbon torsion angles representative of fatty acids suggest that the flexibility of arachidonic acid is, in part, a result of the relative torsional freedom of C-C (single) bonds located between or adjacent to C = C (double) bonds. It is hypothesized that the ability of arachidonic acid to form packed structures with curved regions containing pi-bonds may allow for hydrophobic interactions with proteins, and/or hydrogen bonding between the pi-bonds of arachidonic acid and polar groups of the protein structures.

Modification of neutrophil functions by naftifine

Naftifine (NF), a topical antimycotic agent, is highly active in vitro and in vivo against a wide range of pathogenic fungi. NF inhibits human polymorphonuclear leucocyte (PMN) chemotaxis. Following stimulation with zymosan-activated serum, 85-97% of the PMNs exhibited detectable membrane ruffling and polarity. In contrast, NF-treated PMNs did not exhibit such chemotactic factor-induced shape changes. We also analysed the effect of NF on PMN superoxide anion (O2-) and chemiluminescence (CL) production, as a measure of respiratory burst activity. Stimulation of PMNs pre-incubated with NF (37 degrees C for 30 min at 1-150 micrograms/ml) by FMLP, PMA and zymosan resulted in a dose-dependent inhibition in PMN CL. Doses of NF which depressed chemotaxis, inhibited CL and diminished O2- production in a statistically significant manner (P < 0.05-0.001). In conclusion, NF alters membrane-related responses in PMNs, and this alteration may be associated with a change in PMN morphology. Binding of NF to PMN membrane sterol, with a subsequent alteration in membrane configuration, is the most likely cause of the inhibition of PMN function. The data collectively document biochemical and morphological differences between control and NF-treated PMNs as determined by stimulus-specific CL and O2- generation and membrane shape change. Such differences may account, in part, for its efficacy in inflammatory fungal skin diseases.

Arachidonic acid increases the activity of the assembled NADPH oxidase in cytoplasmic membranes and endosomes

The effect of arachidonic acid (AA) on the assembled NADPH oxidase activity in cytoplasmic membranes and in endosomes separated from human neutrophils was studied. These two fractions were separated on a Percoll-sucrose density gradient from PMA-stimulated neutrophils preincubated with fluorescein isothiocyanate-conjugated dextran (FITC-dextran). In both fractions, NADPH oxidase activity could be detected with the addition of NADPH and cytochrome c, indicating the presence of an assembled activated form of the enzyme. Addition of AA at low concentrations (ED50 = 1 microM and 0.1 microM for cytoplasmic membranes and FITC-dextran endosomes, respectively) caused an increase in the activity of the assembled NADPH oxidase found in these fractions. Addition of 10 microM AA to the assembled oxidase in cytoplasmic membranes or endosomes significantly increased the Vmax (1.37 and 1.45 nmol O2/min compared with 2.05 and 2.20 nmol O2/min in the absence of presence of AA, respectively) and lowered the Km for NADPH (35 microM and 40 microM compared with 7.5 microM and 7.2 microM in the absence or presence of AA, respectively). These results suggest that AA increases the activity of the assembled NADPH oxidase by elevating the number of its active forms and increasing its affinity to the substrate.

Nitric oxide, an endothelial cell relaxation factor, inhibits neutrophil superoxide anion production via a direct action on the NADPH oxidase

Nitric oxide provokes vasodilation and inhibits platelet aggregation. We examined the effect of nitric oxide on superoxide anion production by three sources: activated intact neutrophils, xanthine oxidase/hypoxanthine, and the NADPH oxidase. Nitric oxide significantly inhibited the generation of superoxide anion by neutrophils exposed to either FMLP (10(-7)M) or PMA (150 ng/ml) (IC50 = 30 microM). To determine whether the effect of nitric oxide on the respiratory burst was due to simple scavenging of O2+, kinetic studies that compared effects on neutrophils and the cell-free xanthine oxidase system were performed. Nitric oxide inhibited O2+ produced by xanthine oxidase only when added simultaneously with substrate, consistent with the short half-life of NO in oxygenated solution. In contrast, the addition of nitric oxide to neutrophils 20 min before FMLP resulted in the inhibition of O2+ production, which suggests formation of a stable intermediate. The effect of nitric oxide on the cell-free NADPH oxidase superoxide-generating system was also examined: The addition of NO before arachidonate activation (t = -6 min) significantly inhibited superoxide anion production. Nitric oxide did not inhibit O2+ when added at NADPH initiation (t = 0). Treatment of the membrane but not cytosolic component of the oxidase was sufficient to inhibit O2+ generation. The data suggest that nitric oxide inhibits neutrophil O2+ production via direct effects on membrane components of the NADPH oxidase. This action must occur before the assembly of the activated complex.