Increased Phospholipase A2 Activity Research Articles

Benzothiadiazole treatment inhibits membrane lipid metabolism and straight-chain volatile compound release in Penicillium expansum-inoculated apple fruit

Benzo-(1, 2, 3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) is the first synthetic chemical elicitor that induces resistance against postharvest diseases in fruit and vegetables. However, little information is available on how BTH application affects membrane lipid metabolism and volatile compounds (VOCs) biosynthesis in infected fruit. The results of this study indicated that BTH treatment maintained cell membrane integrity, increased phospholipase A2 (PLA2) activity, and decreased phospholipase C (PLC) and D (PLD) activities in Penicillium expansum-inoculated apple fruit. BTH enhanced phosphatidic acid (PA) content, maintained phosphatidylcholine (PC) and phosphatidylinositol (PI) levels, and increased unsaturated fatty acids (USFA) content. Additionally, BTH decreased the activity of lipoxygenase (LOX), hydroperoxidelyase (HPL), alcohol dehydrogenase (ADH) and alcohol acyltransferase (AAT), and reduced the content of straight-chain VOCs in inoculated fruit. Therefore, BTH could maintain cell membrane integrity in the P. expansum-inoculated apple fruit by inhibiting PLD and PLC activities and PA content. A higher accumulation of USFAs is contributed by increasing PLA2 activity with BTH. In addition, BTH could inhibit the enzymes activities of HPL, LOX, ADH and AAT in LOX pathway, resulting in a less release of straight-chain VOCs in the inoculated fruit during incubation.

High Plasma Concentration of Non-Esterified Polyunsaturated Fatty Acids Is a Specific Feature of Severe COVID-19 Pneumonia

Background: The pathogenesis of severe COVID-19 is frequently associated with an uncontrolled inflammatory response. Severe forms of COVID-19 appear to be more frequent in obese patients, but an association with metabolic disorders is not established. Here, we focused on lipoprotein metabolism in patients hospitalized for severe pneumonia, depending on COVID-19 status.Methods: Thirty-four non-COVID-19 and 27 COVID-19 patients with severe pneumonia were enrolled. Most of them required intensive care. Plasma lipid levels, lipoprotein metabolism, and clinical and biological features were assessed.Findings: Despite similar initial metabolic comorbidities and respiratory severity, COVID-19 patients displayed a lower acute phase response with higher plasmatic concentrations of non-esterified fatty acids (NEFAs). NEFA profiling was characterised by higher level of polyunsaturated NEFAs (mainly linoleic and arachidonic acids) in COVID-19 patients, suggesting an increase in phospholipase A2 activity. Multivariable analysis showed that among severe pneumonia, COVID-19-associated pneumonia was associated with higher NEFAs, lower apolipoprotein E and lower high-density lipoprotein cholesterol concentrations, independently of body mass index, sequential organ failure (SOFA) score, and C-reactive protein levels.Trial Registration: NCT04435223Funding Statement: This study was supported by grant (MN) from the COVIDOLIP – AOIc2020 (Institutional grant), by the INSERM (Centre de Recherche UMR 1231) and the ANR Investissements d’Avenir Grant (ANR-11 LABX-0021-01, Labex Lipstic).Declaration of Interest: The authors declare no existing conflict of interest.Ethics Approval Statement: The study fulfilled legal and ethics requirements: Approval was obtained from the CPP (Comité de Protection des Personnes SUD MEDITERRANEE V; 2017-A03404-49) for the original study and an amendment was obtained to include supplementary patients with severe COVID-19. All subjects (or their legal representatives) received written information and provided their consent to participate.

A Peptide Inhibitor of NADPH Oxidase (NOX2) Activation Markedly Decreases Mouse Lung Injury and Mortality Following Administration of Lipopolysaccharide (LPS).

We have previously derived three related peptides, based on a nine-amino acid sequence in human or rat/mouse surfactant protein A, that inhibit the phospholipase A2 activity of peroxiredoxin 6 (Prdx6) and prevent the activation of lung NADPH oxidase (type 2). The present study evaluated the effect of these Prdx6-inhibitory peptides (PIP) in a mouse (C57Bl/6) model of acute lung injury following lipopolysaccharide (LPS) administration. All three peptides (PIP-1, 2 and 3) similarly inhibited the production of reactive O2 species (ROS) in isolated mouse lungs as detected by the oxidation of Amplex red. PIP-2 inhibited both the increased phospholipase A2 activity of Prdx6 and lung reactive oxygen species (ROS) production following treatment of mice with intratracheal LPS (5 µg/g body wt.). Pre-treatment of mice with PIP-2 prevented LPS-mediated lung injury while treatment with PIP-2 at 12 or 16 h after LPS administration led to reversal of lung injury when evaluated 12 or 8 h later, respectively. With a higher dose of LPS (15 µg/g body wt.), mortality was 100% at 48 h in untreated mice but only 28% in mice that were treated at 12–24 h intervals, with PIP-2 beginning at 12 h after LPS administration. Treatment with PIP-2 also markedly decreased mortality after intraperitoneal LPS (15 µg/g body wt.), used as a model of sepsis. This study shows the dramatic effectiveness of a peptide inhibitor of Prdx6 against lung injury and mouse mortality in LPS models. We propose that the PIP nonapeptides may be a useful modality to prevent or to treat human ALI.

The role of modification of innate immunity in development of premature labore

To clarify the role of the infectious factor in the development of premature birth (PB) in women in serum, the content of TLR-4, the p65 subunit of the nuclear factor NF-kB, the cytokine TNF-a and the activity of PLA2 (phospholipase A2) were determinated by the enzyme immunoassay was studied. The profile of bioregulators in women with premature births was characterized by a high content of TLR-4, TNF-a and an increase in PLA2 activity and a decrease in the activity of the p65 subunit of NF-kB. 89 women aged 20-39 years were examined at 34-40 weeks gestation. They were divided into two groups: 42 women with preterm birth at 34-36.6 weeks, the control group is represented by 47 patients. The risk factors for PB are the presence of PB in history, endocervicitis, colpitis, dysbiosis, diseases of the urinary system (chronic pyelonephritis, chronic cystitis), aggravated obstetric and gynecological history (the threat of abortion during gestation, moderate preeclampsia, anemia of the pregnant woman). The obtained data of the studied bioregulators testify to the role of the infectious inflammatory process in the development of PB, which is evidenced by the high level of TLR-4, a component of innate immunity leading to the activation of the TLR-4 signaling pathway, which increases the activity of PLA2-factor of premature contractile activity of the uterus.

Specific inhibition of Xenorhabdus hominickii, an entomopathogenic bacterium, against different types of host insect phospholipase A2.

Phospholipase A2 (PLA2) hydrolyzes ester bond of phospholipids at the sn-2 position to release free fatty acid and lysophospholipids. Some PLA2s preferentially release arachidonic acid which is subsequently oxygenated into eicosanoids to mediate immune responses in insects. Xenorhabdus hominickii is an entomopathogenic bacterium that can suppress insect immunity by inhibiting PLA2 activity. However, little is known about target PLA2 types inhibited by X. hominickii. Therefore, the objective of this study was to determine PLA2 types in the host insect, Spodoptera exigua using specific inhibitors. All developmental stages of S. exigua possessed significant PLA2 activities, with late larval stages showing relatively higher PLA2 activities. In different larval tissues, hemocytes had higher PLA2 activities than fat body, gut, or epidermis. Various developmental and tissue extracts exhibited differential susceptibilities to three different PLA2 inhibitors. Late larva-to-adult stages were highly susceptible to all three different types of PLA2 inhibitors. In contrast, extracts from egg and young larval stages were not susceptible to secretory PLA2 (sPLA2) or calcium-independent cellular PLA2 (iPLA2) inhibitors, although they were susceptible to a calcium-dependent cellular PLA2 (cPLA2) inhibitor in a dose-dependent manner. Different tissues of fifth instars exhibited variation in susceptibility to inhibitors, with epidermal tissue being sensitive to cPLA2 inhibitor only while other tissues were sensitive to all three types of inhibitors. Bacterial challenge with heat-killed X. hominickii significantly increased PLA2 activity. However, live bacteria suppressed the induction of PLA2 activity. An organic extract of X. hominickii-culture broth inhibited the susceptibility of S. exigua to sPLA2- and iPLA2- specific inhibitors, but not to cPLA2-specific inhibitor. Oxindole, a component of the organic extract, exhibited an inhibitory pattern similar to the organic extract. Taken together, our results indicate that S. exigua possesses different PLA2 types and that X. hominickii can inhibit PLA2s susceptible to sPLA2- and iPLA2- specific inhibitors.

Diapocynin, a dimer of the NADPH oxidase inhibitor apocynin, reduces ROS production and prevents force loss in eccentrically contracting dystrophic muscle.

Elevation of intracellular Ca2+, excessive ROS production and increased phospholipase A2 activity contribute to the pathology in dystrophin-deficient muscle. Moreover, Ca2+, ROS and phospholipase A2, in particular iPLA2, are thought to potentiate each other in positive feedback loops. NADPH oxidases (NOX) have been considered as a major source of ROS in muscle and have been reported to be overexpressed in muscles of mdx mice. We report here on our investigations regarding the effect of diapocynin, a dimer of the commonly used NOX inhibitor apocynin, on the activity of iPLA2, Ca2+ handling and ROS generation in dystrophic myotubes. We also examined the effects of diapocynin on force production and recovery ability of isolated EDL muscles exposed to eccentric contractions in vitro, a damaging procedure to which dystrophic muscle is extremely sensitive. In dystrophic myotubes, diapocynin inhibited ROS production, abolished iPLA2 activity and reduced Ca2+ influx through stretch-activated and store-operated channels, two major pathways responsible for excessive Ca2+ entry in dystrophic muscle. Diapocynin also prevented force loss induced by eccentric contractions of mdx muscle close to the value of wild-type muscle and reduced membrane damage as seen by Procion orange dye uptake. These findings support the central role played by NOX-ROS in the pathogenic cascade leading to muscular dystrophy and suggest diapocynin as an effective NOX inhibitor that might be helpful for future therapeutic approaches.

Gossypol Increases Expression of the Pro-apoptotic BH3-only Protein NOXA through a Novel Mechanism Involving Phospholipase A2, Cytoplasmic Calcium, and Endoplasmic Reticulum Stress

Gossypol is a putative BH3 mimetic proposed to inhibit BCL2 and BCLXL based on cell-free assays. We demonstrated previously that gossypol failed to directly inhibit BCL2 in cells or induce apoptosis in chronic lymphocytic leukemia (CLL) cells or platelets, which require BCL2 or BCLXL, respectively, for survival. Here, we demonstrate that gossypol rapidly increased activity of phospholipase A2 (PLA2), which led to an increase in cytoplasmic calcium, endoplasmic reticulum (ER) stress, and up-regulation of the BH3-only protein NOXA. Pretreatment with the PLA2 inhibitor, aristolochic acid, abrogated the increase in calcium, ER stress, and NOXA. Calcium chelation also abrogated the gossypol-induced increase in calcium, ER stress, and NOXA, but not the increase in PLA2 activity, indicating that PLA2 is upstream of these events. In addition, incubating cells with the two products of PLA2 (lysophosphatidic acid and arachidonic acid) mimicked treatment with gossypol. NOXA is a pro-apoptotic protein that functions by binding the BCL2 family proteins MCL1 and BFL1. The BCL2 inhibitor ABT-199 is currently in clinical trials for CLL. Resistance to ABT-199 can occur from up-regulation of other BCL2 family proteins, and this resistance can be mimicked by culturing CLL cells on CD154(+) stroma cells. We report here that AT-101, a derivative of gossypol in clinical trials, overcomes stroma-mediated resistance to ABT-199 in primary CLL cells, suggesting that a combination of these drugs may be efficacious in the clinic.

Increased Lysophosphatidyleth-anolamine and Diacylglycerol levels in Alzheimer’s Disease Plasma

Background: Previous studies have demonstrated deficits in biosynthesis of plasmalogens and sphingolipids in Alzheimer ’s Disease (AD). Objective: We undertook an analysis of alternate biomarkers of lipid synthesis, metabolism, and remodeling “Lands” cycle in the plasma of control and cognitively impaired patients based upon their Mini-Mental State Examination (MMSE) scores. Methods: Plasma levels of 600 lipids were measured utilizing a high-resolution mass spectrometric shotgun analysis platform. Results: The lyso metabolites of phosphatidylethanolamines and phosphatidylglycerols, along with diacyglycerols were all elevated in the plasma of patients with cognitive impairment.There were no significant differences in the plasma levels of fatty acids metabolized by peroxisomes. Conclusion: The increased levels of lysolipids and diacylglycerols in theplasma of all patient groups suggest that lipid remodeling is dysfunctional early in the AD disease process. It remains to be determined if this involves increased phospholipase A2 activity, decreased acyltransferase activity, or decreased cellular uptake of lysophospholipids for subsequent acylation.

Poster #S140 THE INFLUENCE OF AHI1 VARIANTS ON THE DIAGNOSIS AND TREATMENT OUTCOME IN SCHIZOPHRENIA

Changes in endothelium functions during ischemia are thought to be of importance in numerous pathological conditions, with, for instance, an increase in the release of inflammatory mediators like prostaglandins. Here, we showed that hypoxia increases phospholipase A2 (PLA2) activity in human umbilical vein endothelial cells. Both basal PLA2 activity and PG synthesis are sensitive to BEL and AACOCF3, respectively, inhibitors of calcium-independent PLA2 (iPLA2) and cytosolic PLA2 (cPLA2), while OPC, an inhibitor of soluble PLA2 (sPLA2) only inhibited the hypoxia-induced AA release and PGF2α synthesis. Hypoxia does not alter expression of iPLA2, sPLA2 and cPLA2 and cycloheximide did not inhibit PLA2 activation, indicating that hypoxia-induced increase in PLA2 activity is due to activation rather than induction. However, mRNA levels for sPLA2 displayed a 2-fold increase after 2 hr incubation under hypoxia. BAPTA, an intracellular calcium chelator, partially inhibited the AA release in normoxia and in hypoxia. Direct assays of specific PLA2 activity showed an increase in sPLA2 activity but not in cPLA2 activity after 2 hr hypoxia. Taken together, these results indicate that the hypoxia-induced increase in PLA2 activity is mostly due to the activation of sPLA2.

Short-Term Cigarette Smoke Exposure Leads to Metabolic Alterations in Lung Alveolar Cells

Cigarette smoke (CS)-induced alveolar destruction and energy metabolism changes are known contributors to the pathophysiology of chronic obstructive pulmonary disease (COPD). This study examines the effect of CS exposure on metabolism in alveolar type II cells. Male A/J mice (8 wk old) were exposed to CS generated from a smoking machine for 4 or 8 weeks, and a recovery group was exposed to CS for 8 weeks and allowed to recover for 2 weeks. Alveolar type II cells were isolated from air- or CS- exposed mice. Acute CS exposure led to a reversible airspace enlargement in A/J mice as measured by the increase in mean linear intercept, indicative of alveolar destruction. The effect of CS exposure on cellular respiration was studied using the XF Extracellular Flux Analyzer. A decrease in respiration while metabolizing glucose was observed in the CS-exposed group, indicating altered glycolysis that was compensated by an increase in palmitate utilization; palmitate utilization was accompanied by an increase in the expression of CD36 and carnitine-palmitoyl transferase 1 in type II alveolar cells for the transport of palmitate into the cells and into mitochondria, respectively. The increase in palmitate use for energy production likely affects the surfactant biosynthesis pathway, as evidenced by the decrease in phosphatidylcholine levels and the increase in phospholipase A2 activity after CS exposure. These findings help our understanding of the mechanism underlying the surfactant deficiency observed in smokers and provide a target to delay the onset of COPD.

Bioactive lysophosphatidylcholine 16:0 and 18:0 are elevated in lungs of asthmatic subjects.

PurposeAsthma is a chronic inflammatory disease of the airways, and is associated with upregulation of phospholipase A2 (PLA2), the enzyme that hydrolyzes phosphatidylcholine, producing lysophosphatidylcholine (LPC) and free fatty acids. LPC is a lipid mediator with known pro-inflammatory and pro-atherogenic properties, and is believed to be a critical factor in cardiovascular diseases. We postulate that asthmatic subjects have an elevated content of LPC in the lung lining fluids.MethodsEight non-asthmatic controls and seven asthmatic subjects were recruited for broncho-alveolar lavage fluids (BALF) collection for analysis of LPC by high performance liquid chromatography-tandem mass spectrometry.ResultsLPC16:0 and LPC18:0 were significantly elevated in the BALF of asthmatics with impaired lung function characteristic of moderate asthma, but not mild asthma. The increased LPC content in BALF was accompanied by increased PLA2 activity. Furthermore, qRT-PCR analysis of the BALF cell fraction indicated increased secretory PLA2-X (sPLA2-X).ConclusionsThe increased LPC content in the lung lining fluids is a potential critical lipid mediator in the initiation and/or progression of airway epithelial injury in asthma.

Окислювальний стрес у лейкоцитах крові,про/антиоксидантний статус та жирнокислотний склад ліпідів підшлункової залози за експериментального гострого панкреатиту в щурів

In an experimental model of acute pancreatitis (AP) in rats no alteration in leukocyte's viability was found by flow cytometry as compared to control. After 1 day of AP production of reactive oxygen forms in granulocytes was increased more than 5 times, but after 3 days their level was decreased. Alterations of pro/antioxidant status and specific changes in the fatty acid composition in the pancreas were established. With the development of AP, the processes of lipids peroxidation were intensified while antioxidant system was altered, that was evidenced by inflammation in the pancreas. In these conditions, the increase of phospholipase A2 activity was accompanied by significant changes of fatty acid composition of the total lipids in the pancreas. This increased relative total content of saturated fatty acids, in particular myristic, palmitic and stearic acid increased, while the total content of polyunsaturated essential fatty acids omega-3 (linolenic, eicosapentaenoic, dokozapentayenoic, docosahexaenoic) decreased. The preparation containing omega-3 polyunsaturated fatty acids partially normalized the lipid and fatty acids composition as well as prooxidant-antioxidant system.

Metabolic shift in lung alveolar cell mitochondria following acrolein exposure

Acrolein, an α,β unsaturated electrophile, is an environmental pollutant released in ambient air from diesel exhausts and cooking oils. This study examines the role of acrolein in altering mitochondrial function and metabolism in lung-specific cells. RLE-6TN, H441, and primary alveolar type II (pAT2) cells were exposed to acrolein for 4 h, and its effect on mitochondrial oxygen consumption rates was studied by XF Extracellular Flux analysis. Low-dose acrolein exposure decreased mitochondrial respiration in a dose-dependent manner because of alteration in the metabolism of glucose in all the three cell types. Acrolein inhibited glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity, leading to decreased substrate availability for mitochondrial respiration in RLE-6TN, H441, and pAT2 cells; the reduced GAPDH activity was compensated in pAT2 cells by an increase in the activity of glucose-6-phosphate dehydrogenase, the regulatory control of the pentose phosphate pathway. The decrease in pyruvate from glucose metabolism resulted in utilization of alternative sources to support mitochondrial energy production: palmitate-BSA complex increased mitochondrial respiration in RLE-6TN and pAT2 cells. The presence of palmitate in alveolar cells for surfactant biosynthesis may prove to be the alternative fuel source for mitochondrial respiration. Accordingly, a decrease in phosphatidylcholine levels and an increase in phospholipase A2 activity were found in the alveolar cells after acrolein exposure. These findings have implications for understanding the decrease in surfactant levels frequently observed in pathophysiological situations with altered lung function following exposure to environmental toxicants.

Rac1 mediates cytokine-stimulated hemocyte spreading via prostaglandin biosynthesis in the beet armyworm, Spodoptera exigua

Cell spreading is an integral component of insect hemocytic immune reactions to infections and invasions. Cell spreading is accomplished by cytoskeleton rearrangement, which is activated by three major immune mediators, biogenic monoamines, plasmatocyte-spreading peptide (PSP), and eicosanoids, particularly prostaglandin E2 (PGE2). However, little is known about how these immune mediators activate hemocyte spreading at the intra-cellular level. A small G protein, Rac1, acts in cytoskeleton arrangements in mammalian cells. Based on this information, we identified a Rac1 transcript (SeRac1) in hemocytes prepared from Spodoptera exigua. SeRac1 was expressed in most developmental stages and in the two main immunity-conferring tissues, hemocytes and fat body, in larvae. In response to bacterial challenge, its expression was up-regulated by >37-fold at 2h post-injection and returned to a basal level about 2h later. Silencing SeRac1 expression inhibited hemocyte spreading in response to three immune mediators, octopamine, 5-hydroxytryptamine, and PSP. Addition of PGE2 to SeRac1-silenced larvae rescued the influence of these three mediators on hemocyte spreading. These compounds also increased phospholipase A2 activity via SeRac1, which leads to prostaglandin biosynthesis. We infer that SeRac1 transduces OA, 5-HT, and PSP signaling via activating biosynthesis of prostaglandins and possibly other eicosanoids.

HDAC Inhibition Induces Increased Choline Uptake and Elevated Phosphocholine Levels in MCF7 Breast Cancer Cells

Histone deacetylase (HDAC) inhibitors have emerged as effective antineoplastic agents in the clinic. Studies from our lab and others have reported that magnetic resonance spectroscopy (MRS)-detectable phosphocholine (PC) is elevated following SAHA treatment, providing a potential noninvasive biomarker of response. Typically, elevated PC is associated with cancer while a decrease in PC accompanies response to antineoplastic treatment. The goal of this study was therefore to elucidate the underlying biochemical mechanism by which HDAC inhibition leads to elevated PC. We investigated the effect of SAHA on MCF-7 breast cancer cells using 13C MRS to monitor [1,2-13C] choline uptake and phosphorylation to PC. We found that PC synthesis was significantly higher in treated cells, representing 154±19% of control. This was within standard deviation of the increase in total PC levels detected by 31P MRS (129±7% of control). Furthermore, cellular choline kinase activity was elevated (177±31%), while cytidylyltransferase activity was unchanged. Expression of the intermediate-affinity choline transporter SLC44A1 and choline kinase α increased (144% and 161%, respectively) relative to control, as determined by mRNA microarray analysis with protein-level confirmation by Western blotting. Taken together, our findings indicate that the increase in PC levels following SAHA treatment results from its elevated synthesis. Additionally, the concentration of glycerophosphocholine (GPC) increased significantly with treatment to 210±45%. This is likely due to the upregulated expression of several phospholipase A2 (PLA2) isoforms, resulting in increased PLA2 activity (162±18%) in SAHA-treated cells. Importantly, the levels of total choline (tCho)-containing metabolites, comprised of choline, PC and GPC, are readily detectable clinically using 1H MRS. Our findings thus provide an important step in validating clinically translatable non-invasive imaging methods for follow-up diagnostics of HDAC inhibitor treatment.

O48 Partition entre comportement homéostatique et non homéostatique de l’action centrale de la ghréline dans le contrôle de la balance énergétique

Cell spreading is an integral component of insect hemocytic immune reactions to infections and invasions. Cell spreading is accomplished by cytoskeleton rearrangement, which is activated by three major immune mediators, biogenic monoamines, plasmatocyte-spreading peptide (PSP), and eicosanoids, particularly prostaglandin E2 (PGE2). However, little is known about how these immune mediators activate hemocyte spreading at the intra-cellular level. A small G protein, Rac1, acts in cytoskeleton arrangements in mammalian cells. Based on this information, we identified a Rac1 transcript (SeRac1) in hemocytes prepared from Spodoptera exigua. SeRac1 was expressed in most developmental stages and in the two main immunity-conferring tissues, hemocytes and fat body, in larvae. In response to bacterial challenge, its expression was up-regulated by >37-fold at 2 h post-injection and returned to a basal level about 2 h later. Silencing SeRac1 expression inhibited hemocyte spreading in response to three immune mediators, octopamine, 5-hydroxytryptamine, and PSP. Addition of PGE2 to SeRac1-silenced larvae rescued the influence of these three mediators on hemocyte spreading. These compounds also increased phospholipase A2 activity via SeRac1, which leads to prostaglandin biosynthesis. We infer that SeRac1 transduces OA, 5-HT, and PSP signaling via activating biosynthesis of prostaglandins and possibly other eicosanoids.

Serum phospholipase A2 activity in patients with aspirin-induced asthma

Urinary excretion of leukotrienes is greater in patients with aspirin-induced asthma (AIA) than in other patients with asthma in remission, and is greater still during an aspirin-induced attack. We therefore hypothesized that increased phospholipase A2 (PLA2) activity leads to increased leukotriene synthesis when non-steroidal antiinflammatory drugs inhibit cyclooxygenase in patients with AIA, and that PLA2 activity increases further during an aspirin induced attack. To test this hypothesis, we measured the serum PLA2 activity in adult asthmatic patients, and compared the activity in those with AIA to the activity in those without AIA. The subjects were 43 patients with asthma in remission, 17 with AIA and 26 without AIA. Serum PLA2 activity was also measured before and after intravenous administration of lysine-aspirin in three patients with AIA and in one without AIA. Serum PLA2 activity was measured by radioimmunoassay. Serum PLA2 activity in patients with AIA, in those without AIA, and in healthy controls was 300.9 +/- 52.9, 294.4 +/- 65.3 and 171.7 +/- 41.8 pmol/ml/min, respectively. Serum PLA2 activity in asthmatic patients was significantly higher than in healthy controls (p < 0.01), but there was no difference between patients with and without AIA. Intravenous lysine-aspirin provoked asthmatic attacks in three patients with AIA. However, intravenous lysine-aspirin did not significantly change serum PLA2 activity in the three patients with AIA or in the patient without AIA. These results indicate that although PLA2 may be involved in the pathogenesis of bronchial asthma, it is not specific to AIA. Thus, the pathophysiology of AIA remains unclear and further investigation is needed.

Lipidomic analyses of the mouse brain after antidepressant treatment: evidence for endogenous release of long-chain fatty acids?

Recently, there has been considerable interest in a possible link between changes in brain polyunsaturated fatty acids, neural membrane phospholipid degradation, serotonergic neurotransmission, and depression. The present study aims to examine effects of antidepressants on lipids in different regions of the brain at individual molecular species level, using the novel technique of lipidomics. Balb/C mice received daily intraperitoneal (i.p.) injections of 10 mg/kg of the antidepressants maprotiline, fluoxetine and paroxetine for 4 wk. The prefrontal cortex, hippocampus, striatum and cerebellum were harvested, and lipid profiles compared to those of saline-injected mice. Treatment with maprotiline and paroxetine, but not fluoxetine, resulted in significant decreases in phosphatidylcholine (PC) species, PC36:1, PC38:3, PC40:2p, PC40:6, PC40:5, PC42:7p, PC42:6p and PC42:5p in the prefrontal neocortex. The decreases in phospholipids were accompanied by increases in lysophospholipid species, lysoPC16:0, lysoPC18:2 and lysoPC18:0 in the prefrontal cortex, indicating increase in phospholipase A2 activity and possible release of long-chain fatty acids. Maprotiline and paroxetine treatment also resulted in decreases in sphingomyelin and increases in several ceramide species in the prefrontal cortex. It is postulated that endogenous release of long-chain fatty acids may be related to the mechanism of action of maprotiline and paroxetine.

Increased Phospholipase A2 Activity and Inflammatory Response But Decreased Nerve Growth Factor Expression in the Olfactory Bulbectomized Rat Model of Depression: Effects of Chronic Ethyl-Eicosapentaenoate Treatment

An increased inflammatory response and deficient synthesis of neurotrophic factors (NTFs) may contribute to the etiology of depression. However, the interrelationship between inflammation and NTFs is unknown. Recently, ethyl-eicosapentaenoate (EPA) has been used to treat depression. The mechanism by which EPA benefits depression is also unclear. Using the olfactory bulbectomized (OB) rat model of depression, this study evaluated two pathways from bulbectomy to the induction of depression-like changes (the inflammation-hypothalamic-pituitary-adrenal axis-stress response pathway and inflammation-nerve growth factor-memory pathway) and the effect of EPA on these pathways. When compared with sham-operated rats fed a control diet, significantly increased locomotor and rearing activities in an "open field," impaired memory in the Morris water maze, increased expression of corticotrophin-releasing factor (CRF), and increased secretion of corticosterone were found in OB rats. mRNA expression of nerve growth factor (NGF) was significantly lower in the hippocampus, and phospholipase A2 (PLA2) was higher in the hypothalamus; this change was associated with increased interleukin-1beta (IL-1beta) and prostaglandin E2 (PGE2) in the serum and brain. EPA treatments normalized these behavioral impairments and reduced CRF expression and corticosterone secretion. EPA also reduced serum concentrations of IL-1beta and PGE2, but reversed NGF reduction. Similar to the effects of EPA, the anti-inflammatory drug celecoxib significantly reduced blood PGE2, IL-1beta, and corticosterone concentrations and increased NGF expression in OB rats. Furthermore, anti-NGF treatment blocked EPA effects on behavior. These results suggest that an interaction exists between inflammation and NGF in the depression model. EPA may improve depression via its anti-inflammation properties and the upregulation of NGF.

Conditioning training and retrieval increase phospholipase A2 activity in the cerebral cortex of rats

In rats, phospholipase A(2) (PLA(2)) activity was found to be increased in the hippocampus immediately after training and retrieval of a contextual fear conditioning paradigm (step-down inhibitory avoidance [IA] task). In the present study we investigated whether PLA(2) is also activated in the cerebral cortex of rats in association with contextual fear learning and retrieval. We observed that IA training induces a rapid (immediately after training) and long-lasting (3 h after training) activation of PLA(2) in both frontal and parietal cortices. However, immediately after retrieval (measured 24 h after training), PLA(2) activity was increased just in the parietal cortex. These findings suggest that PLA(2) activity is differentially required in the frontal and parietal cortices for the mechanisms of contextual learning and retrieval. Because reduced brain PLA(2) activity has been reported in Alzheimer disease, our results suggest that stimulation of PLA(2) activity may offer new treatment strategies for this disease.